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author | David Walter Seikel | 2013-01-13 18:54:10 +1000 |
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committer | David Walter Seikel | 2013-01-13 18:54:10 +1000 |
commit | 959831f4ef5a3e797f576c3de08cd65032c997ad (patch) | |
tree | e7351908be5995f0b325b2ebeaa02d5a34b82583 /libraries/irrlicht-1.8/source/Irrlicht/libpng/libpng.3 | |
parent | Add info about changes to Irrlicht. (diff) | |
download | SledjHamr-959831f4ef5a3e797f576c3de08cd65032c997ad.zip SledjHamr-959831f4ef5a3e797f576c3de08cd65032c997ad.tar.gz SledjHamr-959831f4ef5a3e797f576c3de08cd65032c997ad.tar.bz2 SledjHamr-959831f4ef5a3e797f576c3de08cd65032c997ad.tar.xz |
Remove damned ancient DOS line endings from Irrlicht. Hopefully I did not go overboard.
Diffstat (limited to 'libraries/irrlicht-1.8/source/Irrlicht/libpng/libpng.3')
-rw-r--r-- | libraries/irrlicht-1.8/source/Irrlicht/libpng/libpng.3 | 11904 |
1 files changed, 5952 insertions, 5952 deletions
diff --git a/libraries/irrlicht-1.8/source/Irrlicht/libpng/libpng.3 b/libraries/irrlicht-1.8/source/Irrlicht/libpng/libpng.3 index 1d72ab4..14b1567 100644 --- a/libraries/irrlicht-1.8/source/Irrlicht/libpng/libpng.3 +++ b/libraries/irrlicht-1.8/source/Irrlicht/libpng/libpng.3 | |||
@@ -1,5952 +1,5952 @@ | |||
1 | .TH LIBPNG 3 "February 18, 2012" | 1 | .TH LIBPNG 3 "February 18, 2012" |
2 | .SH NAME | 2 | .SH NAME |
3 | libpng \- Portable Network Graphics (PNG) Reference Library 1.5.9 | 3 | libpng \- Portable Network Graphics (PNG) Reference Library 1.5.9 |
4 | .SH SYNOPSIS | 4 | .SH SYNOPSIS |
5 | \fI\fB | 5 | \fI\fB |
6 | 6 | ||
7 | \fB#include <png.h>\fP | 7 | \fB#include <png.h>\fP |
8 | 8 | ||
9 | \fI\fB | 9 | \fI\fB |
10 | 10 | ||
11 | \fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP | 11 | \fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP |
12 | 12 | ||
13 | \fI\fB | 13 | \fI\fB |
14 | 14 | ||
15 | \fBvoid png_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP | 15 | \fBvoid png_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP |
16 | 16 | ||
17 | \fI\fB | 17 | \fI\fB |
18 | 18 | ||
19 | \fBvoid png_build_grayscale_palette (int \fP\fIbit_depth\fP\fB, png_colorp \fIpalette\fP\fB);\fP | 19 | \fBvoid png_build_grayscale_palette (int \fP\fIbit_depth\fP\fB, png_colorp \fIpalette\fP\fB);\fP |
20 | 20 | ||
21 | \fI\fB | 21 | \fI\fB |
22 | 22 | ||
23 | \fBpng_voidp png_calloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP | 23 | \fBpng_voidp png_calloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP |
24 | 24 | ||
25 | \fI\fB | 25 | \fI\fB |
26 | 26 | ||
27 | \fBvoid png_chunk_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP | 27 | \fBvoid png_chunk_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP |
28 | 28 | ||
29 | \fI\fB | 29 | \fI\fB |
30 | 30 | ||
31 | \fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP | 31 | \fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP |
32 | 32 | ||
33 | \fI\fB | 33 | \fI\fB |
34 | 34 | ||
35 | \fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP | 35 | \fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP |
36 | 36 | ||
37 | \fI\fB | 37 | \fI\fB |
38 | 38 | ||
39 | \fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP | 39 | \fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP |
40 | 40 | ||
41 | \fI\fB | 41 | \fI\fB |
42 | 42 | ||
43 | \fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP | 43 | \fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP |
44 | 44 | ||
45 | \fI\fB | 45 | \fI\fB |
46 | 46 | ||
47 | \fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP | 47 | \fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP |
48 | 48 | ||
49 | \fI\fB | 49 | \fI\fB |
50 | 50 | ||
51 | \fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP | 51 | \fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP |
52 | 52 | ||
53 | \fI\fB | 53 | \fI\fB |
54 | 54 | ||
55 | \fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP | 55 | \fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP |
56 | 56 | ||
57 | \fI\fB | 57 | \fI\fB |
58 | 58 | ||
59 | \fBpng_structp png_create_read_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP | 59 | \fBpng_structp png_create_read_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP |
60 | 60 | ||
61 | \fI\fB | 61 | \fI\fB |
62 | 62 | ||
63 | \fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP | 63 | \fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP |
64 | 64 | ||
65 | \fI\fB | 65 | \fI\fB |
66 | 66 | ||
67 | \fBpng_structp png_create_write_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP | 67 | \fBpng_structp png_create_write_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP |
68 | 68 | ||
69 | \fI\fB | 69 | \fI\fB |
70 | 70 | ||
71 | \fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask)\fP\fB);\fP | 71 | \fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask)\fP\fB);\fP |
72 | 72 | ||
73 | \fI\fB | 73 | \fI\fB |
74 | 74 | ||
75 | \fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP | 75 | \fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP |
76 | 76 | ||
77 | \fI\fB | 77 | \fI\fB |
78 | 78 | ||
79 | \fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP | 79 | \fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP |
80 | 80 | ||
81 | \fI\fB | 81 | \fI\fB |
82 | 82 | ||
83 | \fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP | 83 | \fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP |
84 | 84 | ||
85 | \fI\fB | 85 | \fI\fB |
86 | 86 | ||
87 | \fBvoid png_err (png_structp \fIpng_ptr\fP\fB);\fP | 87 | \fBvoid png_err (png_structp \fIpng_ptr\fP\fB);\fP |
88 | 88 | ||
89 | \fI\fB | 89 | \fI\fB |
90 | 90 | ||
91 | \fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP | 91 | \fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP |
92 | 92 | ||
93 | \fI\fB | 93 | \fI\fB |
94 | 94 | ||
95 | \fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP | 95 | \fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP |
96 | 96 | ||
97 | \fI\fB | 97 | \fI\fB |
98 | 98 | ||
99 | \fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP | 99 | \fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP |
100 | 100 | ||
101 | \fI\fB | 101 | \fI\fB |
102 | 102 | ||
103 | \fBvoid png_free_default (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP | 103 | \fBvoid png_free_default (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP |
104 | 104 | ||
105 | \fI\fB | 105 | \fI\fB |
106 | 106 | ||
107 | \fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP | 107 | \fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP |
108 | 108 | ||
109 | \fI\fB | 109 | \fI\fB |
110 | 110 | ||
111 | \fBpng_byte png_get_bit_depth (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 111 | \fBpng_byte png_get_bit_depth (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
112 | 112 | ||
113 | \fI\fB | 113 | \fI\fB |
114 | 114 | ||
115 | \fBpng_uint_32 png_get_bKGD (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP | 115 | \fBpng_uint_32 png_get_bKGD (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP |
116 | 116 | ||
117 | \fI\fB | 117 | \fI\fB |
118 | 118 | ||
119 | \fBpng_byte png_get_channels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 119 | \fBpng_byte png_get_channels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
120 | 120 | ||
121 | \fI\fB | 121 | \fI\fB |
122 | 122 | ||
123 | \fBpng_uint_32 png_get_cHRM (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, double \fP\fI*green_y\fP\fB, double \fP\fI*blue_x\fP\fB, double \fI*blue_y\fP\fB);\fP | 123 | \fBpng_uint_32 png_get_cHRM (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, double \fP\fI*green_y\fP\fB, double \fP\fI*blue_x\fP\fB, double \fI*blue_y\fP\fB);\fP |
124 | 124 | ||
125 | \fI\fB | 125 | \fI\fB |
126 | 126 | ||
127 | \fBpng_uint_32 png_get_cHRM_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_uint_32 \fP\fI*green_x\fP\fB, png_uint_32 \fP\fI*green_y\fP\fB, png_uint_32 \fP\fI*blue_x\fP\fB, png_uint_32 \fI*blue_y\fP\fB);\fP | 127 | \fBpng_uint_32 png_get_cHRM_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_uint_32 \fP\fI*green_x\fP\fB, png_uint_32 \fP\fI*green_y\fP\fB, png_uint_32 \fP\fI*blue_x\fP\fB, png_uint_32 \fI*blue_y\fP\fB);\fP |
128 | 128 | ||
129 | \fI\fB | 129 | \fI\fB |
130 | 130 | ||
131 | \fBpng_uint_32 png_get_cHRM_XYZ (png_structp \fIpng_ptr, | 131 | \fBpng_uint_32 png_get_cHRM_XYZ (png_structp \fIpng_ptr, |
132 | 132 | ||
133 | \fBpng_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*red_X\fP\fB, double \fP\fI*red_Y\fP\fB, double \fI*red_Z, | 133 | \fBpng_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*red_X\fP\fB, double \fP\fI*red_Y\fP\fB, double \fI*red_Z, |
134 | 134 | ||
135 | \fBdouble \fP\fI*green_X\fP\fB, double \fP\fI*green_Y\fP\fB, double \fP\fI*green_Z\fP\fB, double \fI*blue_X, | 135 | \fBdouble \fP\fI*green_X\fP\fB, double \fP\fI*green_Y\fP\fB, double \fP\fI*green_Z\fP\fB, double \fI*blue_X, |
136 | 136 | ||
137 | \fBdouble \fP\fI*blue_Y\fP\fB, double \fI*blue_Z\fP\fB);\fP | 137 | \fBdouble \fP\fI*blue_Y\fP\fB, double \fI*blue_Z\fP\fB);\fP |
138 | 138 | ||
139 | \fI\fB | 139 | \fI\fB |
140 | 140 | ||
141 | \fBpng_uint_32 png_get_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fI*int_red_X\fP\fB, png_fixed_point \fP\fI*int_red_Y\fP\fB, png_fixed_point \fP\fI*int_red_Z\fP\fB, png_fixed_point \fP\fI*int_green_X\fP\fB, png_fixed_point \fP\fI*int_green_Y\fP\fB, png_fixed_point \fP\fI*int_green_Z\fP\fB, png_fixed_point \fP\fI*int_blue_X\fP\fB, png_fixed_point \fP\fI*int_blue_Y\fP\fB, png_fixed_point \fI*int_blue_Z\fP\fB);\fP | 141 | \fBpng_uint_32 png_get_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fI*int_red_X\fP\fB, png_fixed_point \fP\fI*int_red_Y\fP\fB, png_fixed_point \fP\fI*int_red_Z\fP\fB, png_fixed_point \fP\fI*int_green_X\fP\fB, png_fixed_point \fP\fI*int_green_Y\fP\fB, png_fixed_point \fP\fI*int_green_Z\fP\fB, png_fixed_point \fP\fI*int_blue_X\fP\fB, png_fixed_point \fP\fI*int_blue_Y\fP\fB, png_fixed_point \fI*int_blue_Z\fP\fB);\fP |
142 | 142 | ||
143 | \fI\fB | 143 | \fI\fB |
144 | 144 | ||
145 | \fBpng_uint_32 png_get_chunk_cache_max (png_const_structp \fIpng_ptr\fP\fB);\fP | 145 | \fBpng_uint_32 png_get_chunk_cache_max (png_const_structp \fIpng_ptr\fP\fB);\fP |
146 | 146 | ||
147 | \fI\fB | 147 | \fI\fB |
148 | 148 | ||
149 | \fBpng_alloc_size_t png_get_chunk_malloc_max (png_const_structp \fIpng_ptr\fP\fB);\fP | 149 | \fBpng_alloc_size_t png_get_chunk_malloc_max (png_const_structp \fIpng_ptr\fP\fB);\fP |
150 | 150 | ||
151 | \fI\fB | 151 | \fI\fB |
152 | 152 | ||
153 | \fBpng_byte png_get_color_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 153 | \fBpng_byte png_get_color_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
154 | 154 | ||
155 | \fI\fB | 155 | \fI\fB |
156 | 156 | ||
157 | \fBpng_uint_32 png_get_compression_buffer_size (png_const_structp \fIpng_ptr\fP\fB);\fP | 157 | \fBpng_uint_32 png_get_compression_buffer_size (png_const_structp \fIpng_ptr\fP\fB);\fP |
158 | 158 | ||
159 | \fI\fB | 159 | \fI\fB |
160 | 160 | ||
161 | \fBpng_byte png_get_compression_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 161 | \fBpng_byte png_get_compression_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
162 | 162 | ||
163 | \fI\fB | 163 | \fI\fB |
164 | 164 | ||
165 | \fBpng_byte png_get_copyright (png_const_structp \fIpng_ptr\fP\fB);\fP | 165 | \fBpng_byte png_get_copyright (png_const_structp \fIpng_ptr\fP\fB);\fP |
166 | 166 | ||
167 | \fI\fB | 167 | \fI\fB |
168 | 168 | ||
169 | \fBpng_uint_32 png_get_current_row_number \fI(png_const_structp\fP\fB);\fP | 169 | \fBpng_uint_32 png_get_current_row_number \fI(png_const_structp\fP\fB);\fP |
170 | 170 | ||
171 | \fI\fB | 171 | \fI\fB |
172 | 172 | ||
173 | \fBpng_byte png_get_current_pass_number \fI(png_const_structp\fP\fB);\fP | 173 | \fBpng_byte png_get_current_pass_number \fI(png_const_structp\fP\fB);\fP |
174 | 174 | ||
175 | \fI\fB | 175 | \fI\fB |
176 | 176 | ||
177 | \fBpng_voidp png_get_error_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP | 177 | \fBpng_voidp png_get_error_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP |
178 | 178 | ||
179 | \fI\fB | 179 | \fI\fB |
180 | 180 | ||
181 | \fBpng_byte png_get_filter_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 181 | \fBpng_byte png_get_filter_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
182 | 182 | ||
183 | \fI\fB | 183 | \fI\fB |
184 | 184 | ||
185 | \fBpng_uint_32 png_get_gAMA (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP | 185 | \fBpng_uint_32 png_get_gAMA (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP |
186 | 186 | ||
187 | \fI\fB | 187 | \fI\fB |
188 | 188 | ||
189 | \fBpng_uint_32 png_get_gAMA_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP | 189 | \fBpng_uint_32 png_get_gAMA_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP |
190 | 190 | ||
191 | \fI\fB | 191 | \fI\fB |
192 | 192 | ||
193 | \fBpng_byte png_get_header_ver (png_const_structp \fIpng_ptr\fP\fB);\fP | 193 | \fBpng_byte png_get_header_ver (png_const_structp \fIpng_ptr\fP\fB);\fP |
194 | 194 | ||
195 | \fI\fB | 195 | \fI\fB |
196 | 196 | ||
197 | \fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP | 197 | \fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP |
198 | 198 | ||
199 | \fI\fB | 199 | \fI\fB |
200 | 200 | ||
201 | \fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP | 201 | \fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP |
202 | 202 | ||
203 | \fI\fB | 203 | \fI\fB |
204 | 204 | ||
205 | \fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP | 205 | \fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP |
206 | 206 | ||
207 | \fI\fB | 207 | \fI\fB |
208 | 208 | ||
209 | \fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, int \fP\fI*compression_type\fP\fB, int \fI*filter_type\fP\fB);\fP | 209 | \fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, int \fP\fI*compression_type\fP\fB, int \fI*filter_type\fP\fB);\fP |
210 | 210 | ||
211 | \fI\fB | 211 | \fI\fB |
212 | 212 | ||
213 | \fBpng_uint_32 png_get_image_height (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 213 | \fBpng_uint_32 png_get_image_height (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
214 | 214 | ||
215 | \fI\fB | 215 | \fI\fB |
216 | 216 | ||
217 | \fBpng_uint_32 png_get_image_width (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 217 | \fBpng_uint_32 png_get_image_width (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
218 | 218 | ||
219 | \fI\fB | 219 | \fI\fB |
220 | 220 | ||
221 | \fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP | 221 | \fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP |
222 | 222 | ||
223 | \fI\fB | 223 | \fI\fB |
224 | 224 | ||
225 | \fBpng_byte png_get_interlace_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 225 | \fBpng_byte png_get_interlace_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
226 | 226 | ||
227 | \fI\fB | 227 | \fI\fB |
228 | 228 | ||
229 | \fBpng_const_bytep png_get_io_chunk_name (png_structp \fIpng_ptr\fP\fB);\fP | 229 | \fBpng_const_bytep png_get_io_chunk_name (png_structp \fIpng_ptr\fP\fB);\fP |
230 | 230 | ||
231 | \fI\fB | 231 | \fI\fB |
232 | 232 | ||
233 | \fBpng_uint_32 png_get_io_chunk_type (png_const_structp \fIpng_ptr\fP\fB);\fP | 233 | \fBpng_uint_32 png_get_io_chunk_type (png_const_structp \fIpng_ptr\fP\fB);\fP |
234 | 234 | ||
235 | \fI\fB | 235 | \fI\fB |
236 | 236 | ||
237 | \fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP | 237 | \fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP |
238 | 238 | ||
239 | \fI\fB | 239 | \fI\fB |
240 | 240 | ||
241 | \fBpng_uint_32 png_get_io_state (png_structp \fIpng_ptr\fP\fB);\fP | 241 | \fBpng_uint_32 png_get_io_state (png_structp \fIpng_ptr\fP\fB);\fP |
242 | 242 | ||
243 | \fI\fB | 243 | \fI\fB |
244 | 244 | ||
245 | \fBpng_byte png_get_libpng_ver (png_const_structp \fIpng_ptr\fP\fB);\fP | 245 | \fBpng_byte png_get_libpng_ver (png_const_structp \fIpng_ptr\fP\fB);\fP |
246 | 246 | ||
247 | \fI\fB | 247 | \fI\fB |
248 | 248 | ||
249 | \fBpng_voidp png_get_mem_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP | 249 | \fBpng_voidp png_get_mem_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP |
250 | 250 | ||
251 | \fI\fB | 251 | \fI\fB |
252 | 252 | ||
253 | \fBpng_uint_32 png_get_oFFs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP | 253 | \fBpng_uint_32 png_get_oFFs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP |
254 | 254 | ||
255 | \fI\fB | 255 | \fI\fB |
256 | 256 | ||
257 | \fBpng_uint_32 png_get_pCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_charp \fP\fI*units\fP\fB, png_charpp \fI*params\fP\fB);\fP | 257 | \fBpng_uint_32 png_get_pCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_charp \fP\fI*units\fP\fB, png_charpp \fI*params\fP\fB);\fP |
258 | 258 | ||
259 | \fI\fB | 259 | \fI\fB |
260 | 260 | ||
261 | \fBpng_uint_32 png_get_pHYs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP | 261 | \fBpng_uint_32 png_get_pHYs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP |
262 | 262 | ||
263 | \fI\fB | 263 | \fI\fB |
264 | 264 | ||
265 | \fBfloat png_get_pixel_aspect_ratio (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 265 | \fBfloat png_get_pixel_aspect_ratio (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
266 | 266 | ||
267 | \fI\fB | 267 | \fI\fB |
268 | 268 | ||
269 | \fBpng_uint_32 png_get_pHYs_dpi (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP | 269 | \fBpng_uint_32 png_get_pHYs_dpi (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP |
270 | 270 | ||
271 | \fI\fB | 271 | \fI\fB |
272 | 272 | ||
273 | \fBpng_fixed_point png_get_pixel_aspect_ratio_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 273 | \fBpng_fixed_point png_get_pixel_aspect_ratio_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
274 | 274 | ||
275 | \fI\fB | 275 | \fI\fB |
276 | 276 | ||
277 | \fBpng_uint_32 png_get_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 277 | \fBpng_uint_32 png_get_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
278 | 278 | ||
279 | \fI\fB | 279 | \fI\fB |
280 | 280 | ||
281 | \fBpng_uint_32 png_get_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 281 | \fBpng_uint_32 png_get_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
282 | 282 | ||
283 | \fI\fB | 283 | \fI\fB |
284 | 284 | ||
285 | \fBpng_voidp png_get_progressive_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP | 285 | \fBpng_voidp png_get_progressive_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP |
286 | 286 | ||
287 | \fI\fB | 287 | \fI\fB |
288 | 288 | ||
289 | \fBpng_uint_32 png_get_PLTE (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP | 289 | \fBpng_uint_32 png_get_PLTE (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP |
290 | 290 | ||
291 | \fI\fB | 291 | \fI\fB |
292 | 292 | ||
293 | \fBpng_byte png_get_rgb_to_gray_status (png_const_structp \fIpng_ptr) | 293 | \fBpng_byte png_get_rgb_to_gray_status (png_const_structp \fIpng_ptr) |
294 | 294 | ||
295 | \fBpng_uint_32 png_get_rowbytes (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 295 | \fBpng_uint_32 png_get_rowbytes (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
296 | 296 | ||
297 | \fI\fB | 297 | \fI\fB |
298 | 298 | ||
299 | \fBpng_bytepp png_get_rows (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 299 | \fBpng_bytepp png_get_rows (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
300 | 300 | ||
301 | \fI\fB | 301 | \fI\fB |
302 | 302 | ||
303 | \fBpng_uint_32 png_get_sBIT (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP | 303 | \fBpng_uint_32 png_get_sBIT (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP |
304 | 304 | ||
305 | \fI\fB | 305 | \fI\fB |
306 | 306 | ||
307 | \fBvoid png_get_sCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, double* \fP\fIwidth\fP\fB, double* \fIheight\fP\fB);\fP | 307 | \fBvoid png_get_sCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, double* \fP\fIwidth\fP\fB, double* \fIheight\fP\fB);\fP |
308 | 308 | ||
309 | \fI\fB | 309 | \fI\fB |
310 | 310 | ||
311 | \fBvoid png_get_sCAL_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_fixed_pointp \fP\fIwidth\fP\fB, png_fixed_pointp \fIheight\fP\fB);\fP | 311 | \fBvoid png_get_sCAL_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_fixed_pointp \fP\fIwidth\fP\fB, png_fixed_pointp \fIheight\fP\fB);\fP |
312 | 312 | ||
313 | \fI\fB | 313 | \fI\fB |
314 | 314 | ||
315 | \fBvoid png_get_sCAL_s (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_charpp \fP\fIwidth\fP\fB, png_charpp \fIheight\fP\fB);\fP | 315 | \fBvoid png_get_sCAL_s (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_charpp \fP\fIwidth\fP\fB, png_charpp \fIheight\fP\fB);\fP |
316 | 316 | ||
317 | \fI\fB | 317 | \fI\fB |
318 | 318 | ||
319 | \fBpng_bytep png_get_signature (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP | 319 | \fBpng_bytep png_get_signature (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP |
320 | 320 | ||
321 | \fI\fB | 321 | \fI\fB |
322 | 322 | ||
323 | \fBpng_uint_32 png_get_sPLT (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP | 323 | \fBpng_uint_32 png_get_sPLT (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP |
324 | 324 | ||
325 | \fI\fB | 325 | \fI\fB |
326 | 326 | ||
327 | \fBpng_uint_32 png_get_sRGB (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int \fI*file_srgb_intent\fP\fB);\fP | 327 | \fBpng_uint_32 png_get_sRGB (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int \fI*file_srgb_intent\fP\fB);\fP |
328 | 328 | ||
329 | \fI\fB | 329 | \fI\fB |
330 | 330 | ||
331 | \fBpng_uint_32 png_get_text (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP | 331 | \fBpng_uint_32 png_get_text (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP |
332 | 332 | ||
333 | \fI\fB | 333 | \fI\fB |
334 | 334 | ||
335 | \fBpng_uint_32 png_get_tIME (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP | 335 | \fBpng_uint_32 png_get_tIME (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP |
336 | 336 | ||
337 | \fI\fB | 337 | \fI\fB |
338 | 338 | ||
339 | \fBpng_uint_32 png_get_tRNS (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans_alpha\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_color\fP\fB);\fP | 339 | \fBpng_uint_32 png_get_tRNS (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans_alpha\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_color\fP\fB);\fP |
340 | 340 | ||
341 | \fI\fB | 341 | \fI\fB |
342 | 342 | ||
343 | \fB/* This function is really an inline macro. \fI*/ | 343 | \fB/* This function is really an inline macro. \fI*/ |
344 | 344 | ||
345 | \fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP | 345 | \fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP |
346 | 346 | ||
347 | \fI\fB | 347 | \fI\fB |
348 | 348 | ||
349 | \fBpng_uint_32 png_get_uint_31 (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIbuf\fP\fB);\fP | 349 | \fBpng_uint_32 png_get_uint_31 (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIbuf\fP\fB);\fP |
350 | 350 | ||
351 | \fI\fB | 351 | \fI\fB |
352 | 352 | ||
353 | \fB/* This function is really an inline macro. \fI*/ | 353 | \fB/* This function is really an inline macro. \fI*/ |
354 | 354 | ||
355 | \fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP | 355 | \fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP |
356 | 356 | ||
357 | \fI\fB | 357 | \fI\fB |
358 | 358 | ||
359 | \fBpng_uint_32 png_get_unknown_chunks (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP | 359 | \fBpng_uint_32 png_get_unknown_chunks (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP |
360 | 360 | ||
361 | \fI\fB | 361 | \fI\fB |
362 | 362 | ||
363 | \fBpng_voidp png_get_user_chunk_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP | 363 | \fBpng_voidp png_get_user_chunk_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP |
364 | 364 | ||
365 | \fI\fB | 365 | \fI\fB |
366 | 366 | ||
367 | \fBpng_uint_32 png_get_user_height_max (png_const_structp \fIpng_ptr\fP\fB);\fP | 367 | \fBpng_uint_32 png_get_user_height_max (png_const_structp \fIpng_ptr\fP\fB);\fP |
368 | 368 | ||
369 | \fI\fB | 369 | \fI\fB |
370 | 370 | ||
371 | \fBpng_voidp png_get_user_transform_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP | 371 | \fBpng_voidp png_get_user_transform_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP |
372 | 372 | ||
373 | \fI\fB | 373 | \fI\fB |
374 | 374 | ||
375 | \fBpng_uint_32 png_get_user_width_max (png_const_structp \fIpng_ptr\fP\fB);\fP | 375 | \fBpng_uint_32 png_get_user_width_max (png_const_structp \fIpng_ptr\fP\fB);\fP |
376 | 376 | ||
377 | \fI\fB | 377 | \fI\fB |
378 | 378 | ||
379 | \fBpng_uint_32 png_get_valid (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP | 379 | \fBpng_uint_32 png_get_valid (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP |
380 | 380 | ||
381 | \fI\fB | 381 | \fI\fB |
382 | 382 | ||
383 | \fBfloat png_get_x_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 383 | \fBfloat png_get_x_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
384 | 384 | ||
385 | \fI\fB | 385 | \fI\fB |
386 | 386 | ||
387 | \fBpng_fixed_point png_get_x_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 387 | \fBpng_fixed_point png_get_x_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
388 | 388 | ||
389 | \fI\fB | 389 | \fI\fB |
390 | 390 | ||
391 | \fBpng_int_32 png_get_x_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 391 | \fBpng_int_32 png_get_x_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
392 | 392 | ||
393 | \fI\fB | 393 | \fI\fB |
394 | 394 | ||
395 | \fBpng_int_32 png_get_x_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 395 | \fBpng_int_32 png_get_x_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
396 | 396 | ||
397 | \fI\fB | 397 | \fI\fB |
398 | 398 | ||
399 | \fBpng_uint_32 png_get_x_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 399 | \fBpng_uint_32 png_get_x_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
400 | 400 | ||
401 | \fI\fB | 401 | \fI\fB |
402 | 402 | ||
403 | \fBpng_uint_32 png_get_x_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 403 | \fBpng_uint_32 png_get_x_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
404 | 404 | ||
405 | \fI\fB | 405 | \fI\fB |
406 | 406 | ||
407 | \fBfloat png_get_y_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 407 | \fBfloat png_get_y_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
408 | 408 | ||
409 | \fI\fB | 409 | \fI\fB |
410 | 410 | ||
411 | \fBpng_fixed_point png_get_y_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 411 | \fBpng_fixed_point png_get_y_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
412 | 412 | ||
413 | \fI\fB | 413 | \fI\fB |
414 | 414 | ||
415 | \fBpng_int_32 png_get_y_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 415 | \fBpng_int_32 png_get_y_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
416 | 416 | ||
417 | \fI\fB | 417 | \fI\fB |
418 | 418 | ||
419 | \fBpng_int_32 png_get_y_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 419 | \fBpng_int_32 png_get_y_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
420 | 420 | ||
421 | \fI\fB | 421 | \fI\fB |
422 | 422 | ||
423 | \fBpng_uint_32 png_get_y_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 423 | \fBpng_uint_32 png_get_y_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
424 | 424 | ||
425 | \fI\fB | 425 | \fI\fB |
426 | 426 | ||
427 | \fBpng_uint_32 png_get_y_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP | 427 | \fBpng_uint_32 png_get_y_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP |
428 | 428 | ||
429 | \fI\fB | 429 | \fI\fB |
430 | 430 | ||
431 | \fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP | 431 | \fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP |
432 | 432 | ||
433 | \fI\fB | 433 | \fI\fB |
434 | 434 | ||
435 | \fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP | 435 | \fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP |
436 | 436 | ||
437 | \fI\fB | 437 | \fI\fB |
438 | 438 | ||
439 | \fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP | 439 | \fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP |
440 | 440 | ||
441 | \fI\fB | 441 | \fI\fB |
442 | 442 | ||
443 | \fBvoid png_longjmp (png_structp \fP\fIpng_ptr\fP\fB, int \fIval\fP\fB);\fP | 443 | \fBvoid png_longjmp (png_structp \fP\fIpng_ptr\fP\fB, int \fIval\fP\fB);\fP |
444 | 444 | ||
445 | \fI\fB | 445 | \fI\fB |
446 | 446 | ||
447 | \fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP | 447 | \fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP |
448 | 448 | ||
449 | \fI\fB | 449 | \fI\fB |
450 | 450 | ||
451 | \fBpng_voidp png_malloc_default (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP | 451 | \fBpng_voidp png_malloc_default (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP |
452 | 452 | ||
453 | \fI\fB | 453 | \fI\fB |
454 | 454 | ||
455 | \fBpng_voidp png_malloc_warn (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP | 455 | \fBpng_voidp png_malloc_warn (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP |
456 | 456 | ||
457 | \fI\fB | 457 | \fI\fB |
458 | 458 | ||
459 | \fBpng_uint_32 png_permit_mng_features (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fImng_features_permitted\fP\fB);\fP | 459 | \fBpng_uint_32 png_permit_mng_features (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fImng_features_permitted\fP\fB);\fP |
460 | 460 | ||
461 | \fI\fB | 461 | \fI\fB |
462 | 462 | ||
463 | \fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP | 463 | \fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP |
464 | 464 | ||
465 | \fI\fB | 465 | \fI\fB |
466 | 466 | ||
467 | \fBpng_size_t png_process_data_pause \fP\fI(png_structp\fP\fB, int \fIsave\fP\fB);\fP | 467 | \fBpng_size_t png_process_data_pause \fP\fI(png_structp\fP\fB, int \fIsave\fP\fB);\fP |
468 | 468 | ||
469 | \fI\fB | 469 | \fI\fB |
470 | 470 | ||
471 | \fBpng_uint_32 png_process_data_skip \fI(png_structp\fP\fB);\fP | 471 | \fBpng_uint_32 png_process_data_skip \fI(png_structp\fP\fB);\fP |
472 | 472 | ||
473 | \fI\fB | 473 | \fI\fB |
474 | 474 | ||
475 | \fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP | 475 | \fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP |
476 | 476 | ||
477 | \fI\fB | 477 | \fI\fB |
478 | 478 | ||
479 | \fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP | 479 | \fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP |
480 | 480 | ||
481 | \fI\fB | 481 | \fI\fB |
482 | 482 | ||
483 | \fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP | 483 | \fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP |
484 | 484 | ||
485 | \fI\fB | 485 | \fI\fB |
486 | 486 | ||
487 | \fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP | 487 | \fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP |
488 | 488 | ||
489 | \fI\fB | 489 | \fI\fB |
490 | 490 | ||
491 | \fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP | 491 | \fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP |
492 | 492 | ||
493 | \fI\fB | 493 | \fI\fB |
494 | 494 | ||
495 | \fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP | 495 | \fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP |
496 | 496 | ||
497 | \fI\fB | 497 | \fI\fB |
498 | 498 | ||
499 | \fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP | 499 | \fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP |
500 | 500 | ||
501 | \fI\fB | 501 | \fI\fB |
502 | 502 | ||
503 | \fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP | 503 | \fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP |
504 | 504 | ||
505 | \fI\fB | 505 | \fI\fB |
506 | 506 | ||
507 | \fBint png_reset_zstream (png_structp \fIpng_ptr\fP\fB);\fP | 507 | \fBint png_reset_zstream (png_structp \fIpng_ptr\fP\fB);\fP |
508 | 508 | ||
509 | \fI\fB | 509 | \fI\fB |
510 | 510 | ||
511 | \fBvoid png_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP | 511 | \fBvoid png_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP |
512 | 512 | ||
513 | \fI\fB | 513 | \fI\fB |
514 | 514 | ||
515 | \fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP | 515 | \fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP |
516 | 516 | ||
517 | \fI\fB | 517 | \fI\fB |
518 | 518 | ||
519 | \fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP | 519 | \fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP |
520 | 520 | ||
521 | \fI\fB | 521 | \fI\fB |
522 | 522 | ||
523 | \fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP | 523 | \fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP |
524 | 524 | ||
525 | \fI\fB | 525 | \fI\fB |
526 | 526 | ||
527 | \fBvoid png_set_alpha_mode (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, double \fIoutput_gamma\fP\fB);\fP | 527 | \fBvoid png_set_alpha_mode (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, double \fIoutput_gamma\fP\fB);\fP |
528 | 528 | ||
529 | \fI\fB | 529 | \fI\fB |
530 | 530 | ||
531 | \fBvoid png_set_alpha_mode_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, png_fixed_point \fIoutput_gamma\fP\fB);\fP | 531 | \fBvoid png_set_alpha_mode_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, png_fixed_point \fIoutput_gamma\fP\fB);\fP |
532 | 532 | ||
533 | \fI\fB | 533 | \fI\fB |
534 | 534 | ||
535 | \fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP | 535 | \fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP |
536 | 536 | ||
537 | \fI\fB | 537 | \fI\fB |
538 | 538 | ||
539 | \fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP | 539 | \fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP |
540 | 540 | ||
541 | \fI\fB | 541 | \fI\fB |
542 | 542 | ||
543 | \fBvoid png_set_benign_errors (png_structp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP | 543 | \fBvoid png_set_benign_errors (png_structp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP |
544 | 544 | ||
545 | \fI\fB | 545 | \fI\fB |
546 | 546 | ||
547 | \fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP | 547 | \fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP |
548 | 548 | ||
549 | \fI\fB | 549 | \fI\fB |
550 | 550 | ||
551 | \fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP | 551 | \fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP |
552 | 552 | ||
553 | \fI\fB | 553 | \fI\fB |
554 | 554 | ||
555 | \fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP | 555 | \fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP |
556 | 556 | ||
557 | \fI\fB | 557 | \fI\fB |
558 | 558 | ||
559 | \fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP | 559 | \fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP |
560 | 560 | ||
561 | \fI\fB | 561 | \fI\fB |
562 | 562 | ||
563 | \fBvoid png_set_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIred_X\fP\fB, double \fP\fIred_Y\fP\fB, double \fP\fIred_Z\fP\fB, double \fP\fIgreen_X\fP\fB, double \fIgreen_Y, | 563 | \fBvoid png_set_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIred_X\fP\fB, double \fP\fIred_Y\fP\fB, double \fP\fIred_Z\fP\fB, double \fP\fIgreen_X\fP\fB, double \fIgreen_Y, |
564 | 564 | ||
565 | \fBdouble \fP\fIgreen_Z\fP\fB, double \fP\fIblue_X\fP\fB, double \fP\fIblue_Y\fP\fB, double \fIblue_Z\fP\fB);\fP | 565 | \fBdouble \fP\fIgreen_Z\fP\fB, double \fP\fIblue_X\fP\fB, double \fP\fIblue_Y\fP\fB, double \fIblue_Z\fP\fB);\fP |
566 | 566 | ||
567 | \fI\fB | 567 | \fI\fB |
568 | 568 | ||
569 | \fBvoid png_set_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fIint_red_X\fP\fB, png_fixed_point \fP\fIint_red_Y\fP\fB, png_fixed_point \fP\fIint_red_Z\fP\fB, png_fixed_point \fP\fIint_green_X\fP\fB, png_fixed_point \fP\fIint_green_Y\fP\fB, png_fixed_point \fP\fIint_green_Z\fP\fB, png_fixed_point \fP\fIint_blue_X\fP\fB, png_fixed_point \fP\fIint_blue_Y\fP\fB, png_fixed_point \fIint_blue_Z\fP\fB);\fP | 569 | \fBvoid png_set_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fIint_red_X\fP\fB, png_fixed_point \fP\fIint_red_Y\fP\fB, png_fixed_point \fP\fIint_red_Z\fP\fB, png_fixed_point \fP\fIint_green_X\fP\fB, png_fixed_point \fP\fIint_green_Y\fP\fB, png_fixed_point \fP\fIint_green_Z\fP\fB, png_fixed_point \fP\fIint_blue_X\fP\fB, png_fixed_point \fP\fIint_blue_Y\fP\fB, png_fixed_point \fIint_blue_Z\fP\fB);\fP |
570 | 570 | ||
571 | \fI\fB | 571 | \fI\fB |
572 | 572 | ||
573 | \fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP | 573 | \fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP |
574 | 574 | ||
575 | \fI\fB | 575 | \fI\fB |
576 | 576 | ||
577 | \fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP | 577 | \fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP |
578 | 578 | ||
579 | \fI\fB | 579 | \fI\fB |
580 | 580 | ||
581 | \fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP | 581 | \fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP |
582 | 582 | ||
583 | \fI\fB | 583 | \fI\fB |
584 | 584 | ||
585 | \fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP | 585 | \fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP |
586 | 586 | ||
587 | \fI\fB | 587 | \fI\fB |
588 | 588 | ||
589 | \fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP | 589 | \fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP |
590 | 590 | ||
591 | \fI\fB | 591 | \fI\fB |
592 | 592 | ||
593 | \fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP | 593 | \fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP |
594 | 594 | ||
595 | \fI\fB | 595 | \fI\fB |
596 | 596 | ||
597 | \fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP | 597 | \fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP |
598 | 598 | ||
599 | \fI\fB | 599 | \fI\fB |
600 | 600 | ||
601 | \fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP | 601 | \fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP |
602 | 602 | ||
603 | \fI\fB | 603 | \fI\fB |
604 | 604 | ||
605 | \fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP | 605 | \fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP |
606 | 606 | ||
607 | \fI\fB | 607 | \fI\fB |
608 | 608 | ||
609 | \fBvoid png_set_expand_16 (png_structp \fIpng_ptr\fP\fB);\fP | 609 | \fBvoid png_set_expand_16 (png_structp \fIpng_ptr\fP\fB);\fP |
610 | 610 | ||
611 | \fI\fB | 611 | \fI\fB |
612 | 612 | ||
613 | \fBvoid png_set_expand_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP | 613 | \fBvoid png_set_expand_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP |
614 | 614 | ||
615 | \fI\fB | 615 | \fI\fB |
616 | 616 | ||
617 | \fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP | 617 | \fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP |
618 | 618 | ||
619 | \fI\fB | 619 | \fI\fB |
620 | 620 | ||
621 | \fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP | 621 | \fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP |
622 | 622 | ||
623 | \fI\fB | 623 | \fI\fB |
624 | 624 | ||
625 | \fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP | 625 | \fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP |
626 | 626 | ||
627 | \fI\fB | 627 | \fI\fB |
628 | 628 | ||
629 | \fBvoid png_set_filter_heuristics_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_fixed_point_p \fP\fIfilter_weights\fP\fB, png_fixed_point_p \fIfilter_costs\fP\fB);\fP | 629 | \fBvoid png_set_filter_heuristics_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_fixed_point_p \fP\fIfilter_weights\fP\fB, png_fixed_point_p \fIfilter_costs\fP\fB);\fP |
630 | 630 | ||
631 | \fI\fB | 631 | \fI\fB |
632 | 632 | ||
633 | \fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP | 633 | \fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP |
634 | 634 | ||
635 | \fI\fB | 635 | \fI\fB |
636 | 636 | ||
637 | \fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP | 637 | \fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP |
638 | 638 | ||
639 | \fI\fB | 639 | \fI\fB |
640 | 640 | ||
641 | \fBvoid png_set_gamma_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIscreen_gamma\fP\fB, png_uint_32 \fIdefault_file_gamma\fP\fB);\fP | 641 | \fBvoid png_set_gamma_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIscreen_gamma\fP\fB, png_uint_32 \fIdefault_file_gamma\fP\fB);\fP |
642 | 642 | ||
643 | \fI\fB | 643 | \fI\fB |
644 | 644 | ||
645 | \fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP | 645 | \fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP |
646 | 646 | ||
647 | \fI\fB | 647 | \fI\fB |
648 | 648 | ||
649 | \fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP | 649 | \fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP |
650 | 650 | ||
651 | \fI\fB | 651 | \fI\fB |
652 | 652 | ||
653 | \fBvoid png_set_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP | 653 | \fBvoid png_set_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP |
654 | 654 | ||
655 | \fI\fB | 655 | \fI\fB |
656 | 656 | ||
657 | \fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP | 657 | \fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP |
658 | 658 | ||
659 | \fI\fB | 659 | \fI\fB |
660 | 660 | ||
661 | \fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP | 661 | \fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP |
662 | 662 | ||
663 | \fI\fB | 663 | \fI\fB |
664 | 664 | ||
665 | \fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP | 665 | \fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP |
666 | 666 | ||
667 | \fI\fB | 667 | \fI\fB |
668 | 668 | ||
669 | \fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP | 669 | \fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP |
670 | 670 | ||
671 | \fI\fB | 671 | \fI\fB |
672 | 672 | ||
673 | \fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP | 673 | \fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP |
674 | 674 | ||
675 | \fI\fB | 675 | \fI\fB |
676 | 676 | ||
677 | \fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP | 677 | \fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP |
678 | 678 | ||
679 | \fI\fB | 679 | \fI\fB |
680 | 680 | ||
681 | \fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP | 681 | \fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP |
682 | 682 | ||
683 | \fI\fB | 683 | \fI\fB |
684 | 684 | ||
685 | \fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fIfilter_type\fP\fB);\fP | 685 | \fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fIfilter_type\fP\fB);\fP |
686 | 686 | ||
687 | \fI\fB | 687 | \fI\fB |
688 | 688 | ||
689 | \fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP | 689 | \fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP |
690 | 690 | ||
691 | \fI\fB | 691 | \fI\fB |
692 | 692 | ||
693 | \fBjmp_buf* png_set_longjmp_fn (png_structp \fP\fIpng_ptr\fP\fB, png_longjmp_ptr \fP\fIlongjmp_fn\fP\fB, size_t \fIjmp_buf_size\fP\fB);\fP | 693 | \fBjmp_buf* png_set_longjmp_fn (png_structp \fP\fIpng_ptr\fP\fB, png_longjmp_ptr \fP\fIlongjmp_fn\fP\fB, size_t \fIjmp_buf_size\fP\fB);\fP |
694 | 694 | ||
695 | \fI\fB | 695 | \fI\fB |
696 | 696 | ||
697 | \fBvoid png_set_chunk_malloc_max (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIuser_chunk_cache_max\fP\fB);\fP | 697 | \fBvoid png_set_chunk_malloc_max (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIuser_chunk_cache_max\fP\fB);\fP |
698 | 698 | ||
699 | \fI\fB | 699 | \fI\fB |
700 | 700 | ||
701 | \fBvoid png_set_compression_buffer_size (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP | 701 | \fBvoid png_set_compression_buffer_size (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP |
702 | 702 | ||
703 | \fI\fB | 703 | \fI\fB |
704 | 704 | ||
705 | \fBvoid png_set_mem_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP | 705 | \fBvoid png_set_mem_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP |
706 | 706 | ||
707 | \fI\fB | 707 | \fI\fB |
708 | 708 | ||
709 | \fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP | 709 | \fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP |
710 | 710 | ||
711 | \fI\fB | 711 | \fI\fB |
712 | 712 | ||
713 | \fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP | 713 | \fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP |
714 | 714 | ||
715 | \fI\fB | 715 | \fI\fB |
716 | 716 | ||
717 | \fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP | 717 | \fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP |
718 | 718 | ||
719 | \fI\fB | 719 | \fI\fB |
720 | 720 | ||
721 | \fBvoid png_set_palette_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP | 721 | \fBvoid png_set_palette_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP |
722 | 722 | ||
723 | \fI\fB | 723 | \fI\fB |
724 | 724 | ||
725 | \fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP | 725 | \fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP |
726 | 726 | ||
727 | \fI\fB | 727 | \fI\fB |
728 | 728 | ||
729 | \fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP | 729 | \fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP |
730 | 730 | ||
731 | \fI\fB | 731 | \fI\fB |
732 | 732 | ||
733 | \fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP | 733 | \fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP |
734 | 734 | ||
735 | \fI\fB | 735 | \fI\fB |
736 | 736 | ||
737 | \fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP | 737 | \fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP |
738 | 738 | ||
739 | \fI\fB | 739 | \fI\fB |
740 | 740 | ||
741 | \fBvoid png_set_quantize (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_quantize\fP\fB);\fP | 741 | \fBvoid png_set_quantize (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_quantize\fP\fB);\fP |
742 | 742 | ||
743 | \fI\fB | 743 | \fI\fB |
744 | 744 | ||
745 | \fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP | 745 | \fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP |
746 | 746 | ||
747 | \fI\fB | 747 | \fI\fB |
748 | 748 | ||
749 | \fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP | 749 | \fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP |
750 | 750 | ||
751 | \fI\fB | 751 | \fI\fB |
752 | 752 | ||
753 | \fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP | 753 | \fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP |
754 | 754 | ||
755 | \fI\fB | 755 | \fI\fB |
756 | 756 | ||
757 | \fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP | 757 | \fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP |
758 | 758 | ||
759 | \fI\fB | 759 | \fI\fB |
760 | 760 | ||
761 | \fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP | 761 | \fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP |
762 | 762 | ||
763 | \fI\fB | 763 | \fI\fB |
764 | 764 | ||
765 | \fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_uint_32 \fP\fIred\fP\fB, png_uint_32 \fIgreen\fP\fB);\fP | 765 | \fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_uint_32 \fP\fIred\fP\fB, png_uint_32 \fIgreen\fP\fB);\fP |
766 | 766 | ||
767 | \fI\fB | 767 | \fI\fB |
768 | 768 | ||
769 | \fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP | 769 | \fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP |
770 | 770 | ||
771 | \fI\fB | 771 | \fI\fB |
772 | 772 | ||
773 | \fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP | 773 | \fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP |
774 | 774 | ||
775 | \fI\fB | 775 | \fI\fB |
776 | 776 | ||
777 | \fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP | 777 | \fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP |
778 | 778 | ||
779 | \fI\fB | 779 | \fI\fB |
780 | 780 | ||
781 | \fBvoid png_set_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_fixed_point \fP\fIwidth\fP\fB, png_fixed_point \fIheight\fP\fB);\fP | 781 | \fBvoid png_set_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_fixed_point \fP\fIwidth\fP\fB, png_fixed_point \fIheight\fP\fB);\fP |
782 | 782 | ||
783 | \fI\fB | 783 | \fI\fB |
784 | 784 | ||
785 | \fBvoid png_set_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP | 785 | \fBvoid png_set_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP |
786 | 786 | ||
787 | \fI\fB | 787 | \fI\fB |
788 | 788 | ||
789 | \fBvoid png_set_scale_16 (png_structp \fIpng_ptr\fP\fB);\fP | 789 | \fBvoid png_set_scale_16 (png_structp \fIpng_ptr\fP\fB);\fP |
790 | 790 | ||
791 | \fI\fB | 791 | \fI\fB |
792 | 792 | ||
793 | \fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP | 793 | \fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP |
794 | 794 | ||
795 | \fI\fB | 795 | \fI\fB |
796 | 796 | ||
797 | \fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP | 797 | \fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP |
798 | 798 | ||
799 | \fI\fB | 799 | \fI\fB |
800 | 800 | ||
801 | \fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP | 801 | \fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP |
802 | 802 | ||
803 | \fI\fB | 803 | \fI\fB |
804 | 804 | ||
805 | \fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP | 805 | \fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP |
806 | 806 | ||
807 | \fI\fB | 807 | \fI\fB |
808 | 808 | ||
809 | \fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP | 809 | \fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP |
810 | 810 | ||
811 | \fI\fB | 811 | \fI\fB |
812 | 812 | ||
813 | \fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP | 813 | \fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP |
814 | 814 | ||
815 | \fI\fB | 815 | \fI\fB |
816 | 816 | ||
817 | \fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP | 817 | \fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP |
818 | 818 | ||
819 | \fI\fB | 819 | \fI\fB |
820 | 820 | ||
821 | \fBvoid png_set_strip_error_numbers (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIstrip_mode\fP\fB);\fP | 821 | \fBvoid png_set_strip_error_numbers (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIstrip_mode\fP\fB);\fP |
822 | 822 | ||
823 | \fI\fB | 823 | \fI\fB |
824 | 824 | ||
825 | \fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP | 825 | \fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP |
826 | 826 | ||
827 | \fI\fB | 827 | \fI\fB |
828 | 828 | ||
829 | \fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP | 829 | \fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP |
830 | 830 | ||
831 | \fI\fB | 831 | \fI\fB |
832 | 832 | ||
833 | \fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP | 833 | \fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP |
834 | 834 | ||
835 | \fI\fB | 835 | \fI\fB |
836 | 836 | ||
837 | \fBvoid png_set_text_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP | 837 | \fBvoid png_set_text_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP |
838 | 838 | ||
839 | \fI\fB | 839 | \fI\fB |
840 | 840 | ||
841 | \fBvoid png_set_text_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP | 841 | \fBvoid png_set_text_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP |
842 | 842 | ||
843 | \fI\fB | 843 | \fI\fB |
844 | 844 | ||
845 | \fBvoid png_set_text_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP | 845 | \fBvoid png_set_text_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP |
846 | 846 | ||
847 | \fI\fB | 847 | \fI\fB |
848 | 848 | ||
849 | \fBvoid png_set_text_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP | 849 | \fBvoid png_set_text_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP |
850 | 850 | ||
851 | \fI\fB | 851 | \fI\fB |
852 | 852 | ||
853 | \fBvoid \fP\fIpng_set_text_compression_method\fP\fB, (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod)\fP\fB);\fP | 853 | \fBvoid \fP\fIpng_set_text_compression_method\fP\fB, (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod)\fP\fB);\fP |
854 | 854 | ||
855 | \fI\fB | 855 | \fI\fB |
856 | 856 | ||
857 | \fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP | 857 | \fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP |
858 | 858 | ||
859 | \fI\fB | 859 | \fI\fB |
860 | 860 | ||
861 | \fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans_alpha\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_color\fP\fB);\fP | 861 | \fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans_alpha\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_color\fP\fB);\fP |
862 | 862 | ||
863 | \fI\fB | 863 | \fI\fB |
864 | 864 | ||
865 | \fBvoid png_set_tRNS_to_alpha (png_structp \fIpng_ptr\fP\fB);\fP | 865 | \fBvoid png_set_tRNS_to_alpha (png_structp \fIpng_ptr\fP\fB);\fP |
866 | 866 | ||
867 | \fI\fB | 867 | \fI\fB |
868 | 868 | ||
869 | \fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP | 869 | \fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP |
870 | 870 | ||
871 | \fI\fB | 871 | \fI\fB |
872 | 872 | ||
873 | \fBvoid png_set_unknown_chunk_location (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP | 873 | \fBvoid png_set_unknown_chunk_location (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP |
874 | 874 | ||
875 | \fI\fB | 875 | \fI\fB |
876 | 876 | ||
877 | \fBvoid png_set_user_limits (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIuser_width_max\fP\fB, png_uint_32 \fIuser_height_max\fP\fB);\fP | 877 | \fBvoid png_set_user_limits (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIuser_width_max\fP\fB, png_uint_32 \fIuser_height_max\fP\fB);\fP |
878 | 878 | ||
879 | \fI\fB | 879 | \fI\fB |
880 | 880 | ||
881 | \fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP | 881 | \fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP |
882 | 882 | ||
883 | \fI\fB | 883 | \fI\fB |
884 | 884 | ||
885 | \fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP | 885 | \fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP |
886 | 886 | ||
887 | \fI\fB | 887 | \fI\fB |
888 | 888 | ||
889 | \fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP | 889 | \fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP |
890 | 890 | ||
891 | \fI\fB | 891 | \fI\fB |
892 | 892 | ||
893 | \fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP | 893 | \fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP |
894 | 894 | ||
895 | \fI\fB | 895 | \fI\fB |
896 | 896 | ||
897 | \fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP | 897 | \fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP |
898 | 898 | ||
899 | \fI\fB | 899 | \fI\fB |
900 | 900 | ||
901 | \fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP | 901 | \fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP |
902 | 902 | ||
903 | \fI\fB | 903 | \fI\fB |
904 | 904 | ||
905 | \fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP | 905 | \fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP |
906 | 906 | ||
907 | \fI\fB | 907 | \fI\fB |
908 | 908 | ||
909 | \fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP | 909 | \fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP |
910 | 910 | ||
911 | \fI\fB | 911 | \fI\fB |
912 | 912 | ||
913 | \fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP | 913 | \fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP |
914 | 914 | ||
915 | \fI\fB | 915 | \fI\fB |
916 | 916 | ||
917 | \fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP | 917 | \fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP |
918 | 918 | ||
919 | \fI\fB | 919 | \fI\fB |
920 | 920 | ||
921 | \fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP | 921 | \fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP |
922 | 922 | ||
923 | \fI\fB | 923 | \fI\fB |
924 | 924 | ||
925 | \fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP | 925 | \fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP |
926 | 926 | ||
927 | \fI\fB | 927 | \fI\fB |
928 | 928 | ||
929 | \fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP | 929 | \fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP |
930 | 930 | ||
931 | \fI\fB | 931 | \fI\fB |
932 | 932 | ||
933 | \fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP | 933 | \fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP |
934 | 934 | ||
935 | \fI\fB | 935 | \fI\fB |
936 | 936 | ||
937 | \fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP | 937 | \fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP |
938 | 938 | ||
939 | \fI\fB | 939 | \fI\fB |
940 | 940 | ||
941 | \fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP | 941 | \fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP |
942 | 942 | ||
943 | \fI\fB | 943 | \fI\fB |
944 | 944 | ||
945 | \fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP | 945 | \fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP |
946 | 946 | ||
947 | \fI\fB | 947 | \fI\fB |
948 | 948 | ||
949 | \fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP | 949 | \fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP |
950 | 950 | ||
951 | \fI\fB | 951 | \fI\fB |
952 | 952 | ||
953 | \fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP | 953 | \fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP |
954 | 954 | ||
955 | \fI\fB | 955 | \fI\fB |
956 | 956 | ||
957 | \fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP | 957 | \fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP |
958 | 958 | ||
959 | \fI\fB | 959 | \fI\fB |
960 | 960 | ||
961 | \fBvoidpf png_zalloc (voidpf \fP\fIpng_ptr\fP\fB, uInt \fP\fIitems\fP\fB, uInt \fIsize\fP\fB);\fP | 961 | \fBvoidpf png_zalloc (voidpf \fP\fIpng_ptr\fP\fB, uInt \fP\fIitems\fP\fB, uInt \fIsize\fP\fB);\fP |
962 | 962 | ||
963 | \fI\fB | 963 | \fI\fB |
964 | 964 | ||
965 | \fBvoid png_zfree (voidpf \fP\fIpng_ptr\fP\fB, voidpf \fIptr\fP\fB);\fP | 965 | \fBvoid png_zfree (voidpf \fP\fIpng_ptr\fP\fB, voidpf \fIptr\fP\fB);\fP |
966 | 966 | ||
967 | \fI\fB | 967 | \fI\fB |
968 | 968 | ||
969 | .SH DESCRIPTION | 969 | .SH DESCRIPTION |
970 | The | 970 | The |
971 | .I libpng | 971 | .I libpng |
972 | library supports encoding, decoding, and various manipulations of | 972 | library supports encoding, decoding, and various manipulations of |
973 | the Portable Network Graphics (PNG) format image files. It uses the | 973 | the Portable Network Graphics (PNG) format image files. It uses the |
974 | .IR zlib(3) | 974 | .IR zlib(3) |
975 | compression library. | 975 | compression library. |
976 | Following is a copy of the libpng-manual.txt file that accompanies libpng. | 976 | Following is a copy of the libpng-manual.txt file that accompanies libpng. |
977 | .SH LIBPNG.TXT | 977 | .SH LIBPNG.TXT |
978 | libpng-manual.txt - A description on how to use and modify libpng | 978 | libpng-manual.txt - A description on how to use and modify libpng |
979 | 979 | ||
980 | libpng version 1.5.9 - February 18, 2012 | 980 | libpng version 1.5.9 - February 18, 2012 |
981 | Updated and distributed by Glenn Randers-Pehrson | 981 | Updated and distributed by Glenn Randers-Pehrson |
982 | <glennrp at users.sourceforge.net> | 982 | <glennrp at users.sourceforge.net> |
983 | Copyright (c) 1998-2011 Glenn Randers-Pehrson | 983 | Copyright (c) 1998-2011 Glenn Randers-Pehrson |
984 | 984 | ||
985 | This document is released under the libpng license. | 985 | This document is released under the libpng license. |
986 | For conditions of distribution and use, see the disclaimer | 986 | For conditions of distribution and use, see the disclaimer |
987 | and license in png.h | 987 | and license in png.h |
988 | 988 | ||
989 | Based on: | 989 | Based on: |
990 | 990 | ||
991 | libpng versions 0.97, January 1998, through 1.5.9 - February 18, 2012 | 991 | libpng versions 0.97, January 1998, through 1.5.9 - February 18, 2012 |
992 | Updated and distributed by Glenn Randers-Pehrson | 992 | Updated and distributed by Glenn Randers-Pehrson |
993 | Copyright (c) 1998-2011 Glenn Randers-Pehrson | 993 | Copyright (c) 1998-2011 Glenn Randers-Pehrson |
994 | 994 | ||
995 | libpng 1.0 beta 6 version 0.96 May 28, 1997 | 995 | libpng 1.0 beta 6 version 0.96 May 28, 1997 |
996 | Updated and distributed by Andreas Dilger | 996 | Updated and distributed by Andreas Dilger |
997 | Copyright (c) 1996, 1997 Andreas Dilger | 997 | Copyright (c) 1996, 1997 Andreas Dilger |
998 | 998 | ||
999 | libpng 1.0 beta 2 - version 0.88 January 26, 1996 | 999 | libpng 1.0 beta 2 - version 0.88 January 26, 1996 |
1000 | For conditions of distribution and use, see copyright | 1000 | For conditions of distribution and use, see copyright |
1001 | notice in png.h. Copyright (c) 1995, 1996 Guy Eric | 1001 | notice in png.h. Copyright (c) 1995, 1996 Guy Eric |
1002 | Schalnat, Group 42, Inc. | 1002 | Schalnat, Group 42, Inc. |
1003 | 1003 | ||
1004 | Updated/rewritten per request in the libpng FAQ | 1004 | Updated/rewritten per request in the libpng FAQ |
1005 | Copyright (c) 1995, 1996 Frank J. T. Wojcik | 1005 | Copyright (c) 1995, 1996 Frank J. T. Wojcik |
1006 | December 18, 1995 & January 20, 1996 | 1006 | December 18, 1995 & January 20, 1996 |
1007 | 1007 | ||
1008 | .SH I. Introduction | 1008 | .SH I. Introduction |
1009 | 1009 | ||
1010 | This file describes how to use and modify the PNG reference library | 1010 | This file describes how to use and modify the PNG reference library |
1011 | (known as libpng) for your own use. There are five sections to this | 1011 | (known as libpng) for your own use. There are five sections to this |
1012 | file: introduction, structures, reading, writing, and modification and | 1012 | file: introduction, structures, reading, writing, and modification and |
1013 | configuration notes for various special platforms. In addition to this | 1013 | configuration notes for various special platforms. In addition to this |
1014 | file, example.c is a good starting point for using the library, as | 1014 | file, example.c is a good starting point for using the library, as |
1015 | it is heavily commented and should include everything most people | 1015 | it is heavily commented and should include everything most people |
1016 | will need. We assume that libpng is already installed; see the | 1016 | will need. We assume that libpng is already installed; see the |
1017 | INSTALL file for instructions on how to install libpng. | 1017 | INSTALL file for instructions on how to install libpng. |
1018 | 1018 | ||
1019 | For examples of libpng usage, see the files "example.c", "pngtest.c", | 1019 | For examples of libpng usage, see the files "example.c", "pngtest.c", |
1020 | and the files in the "contrib" directory, all of which are included in | 1020 | and the files in the "contrib" directory, all of which are included in |
1021 | the libpng distribution. | 1021 | the libpng distribution. |
1022 | 1022 | ||
1023 | Libpng was written as a companion to the PNG specification, as a way | 1023 | Libpng was written as a companion to the PNG specification, as a way |
1024 | of reducing the amount of time and effort it takes to support the PNG | 1024 | of reducing the amount of time and effort it takes to support the PNG |
1025 | file format in application programs. | 1025 | file format in application programs. |
1026 | 1026 | ||
1027 | The PNG specification (second edition), November 2003, is available as | 1027 | The PNG specification (second edition), November 2003, is available as |
1028 | a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at | 1028 | a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at |
1029 | <http://www.w3.org/TR/2003/REC-PNG-20031110/ | 1029 | <http://www.w3.org/TR/2003/REC-PNG-20031110/ |
1030 | The W3C and ISO documents have identical technical content. | 1030 | The W3C and ISO documents have identical technical content. |
1031 | 1031 | ||
1032 | The PNG-1.2 specification is available at | 1032 | The PNG-1.2 specification is available at |
1033 | <http://www.libpng.org/pub/png/documents/>. It is technically equivalent | 1033 | <http://www.libpng.org/pub/png/documents/>. It is technically equivalent |
1034 | to the PNG specification (second edition) but has some additional material. | 1034 | to the PNG specification (second edition) but has some additional material. |
1035 | 1035 | ||
1036 | The PNG-1.0 specification is available | 1036 | The PNG-1.0 specification is available |
1037 | as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a | 1037 | as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a |
1038 | W3C Recommendation <http://www.w3.org/TR/REC.png.html>. | 1038 | W3C Recommendation <http://www.w3.org/TR/REC.png.html>. |
1039 | 1039 | ||
1040 | Some additional chunks are described in the special-purpose public chunks | 1040 | Some additional chunks are described in the special-purpose public chunks |
1041 | documents at <http://www.libpng.org/pub/png/documents/>. | 1041 | documents at <http://www.libpng.org/pub/png/documents/>. |
1042 | 1042 | ||
1043 | Other information | 1043 | Other information |
1044 | about PNG, and the latest version of libpng, can be found at the PNG home | 1044 | about PNG, and the latest version of libpng, can be found at the PNG home |
1045 | page, <http://www.libpng.org/pub/png/>. | 1045 | page, <http://www.libpng.org/pub/png/>. |
1046 | 1046 | ||
1047 | Most users will not have to modify the library significantly; advanced | 1047 | Most users will not have to modify the library significantly; advanced |
1048 | users may want to modify it more. All attempts were made to make it as | 1048 | users may want to modify it more. All attempts were made to make it as |
1049 | complete as possible, while keeping the code easy to understand. | 1049 | complete as possible, while keeping the code easy to understand. |
1050 | Currently, this library only supports C. Support for other languages | 1050 | Currently, this library only supports C. Support for other languages |
1051 | is being considered. | 1051 | is being considered. |
1052 | 1052 | ||
1053 | Libpng has been designed to handle multiple sessions at one time, | 1053 | Libpng has been designed to handle multiple sessions at one time, |
1054 | to be easily modifiable, to be portable to the vast majority of | 1054 | to be easily modifiable, to be portable to the vast majority of |
1055 | machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy | 1055 | machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy |
1056 | to use. The ultimate goal of libpng is to promote the acceptance of | 1056 | to use. The ultimate goal of libpng is to promote the acceptance of |
1057 | the PNG file format in whatever way possible. While there is still | 1057 | the PNG file format in whatever way possible. While there is still |
1058 | work to be done (see the TODO file), libpng should cover the | 1058 | work to be done (see the TODO file), libpng should cover the |
1059 | majority of the needs of its users. | 1059 | majority of the needs of its users. |
1060 | 1060 | ||
1061 | Libpng uses zlib for its compression and decompression of PNG files. | 1061 | Libpng uses zlib for its compression and decompression of PNG files. |
1062 | Further information about zlib, and the latest version of zlib, can | 1062 | Further information about zlib, and the latest version of zlib, can |
1063 | be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>. | 1063 | be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>. |
1064 | The zlib compression utility is a general purpose utility that is | 1064 | The zlib compression utility is a general purpose utility that is |
1065 | useful for more than PNG files, and can be used without libpng. | 1065 | useful for more than PNG files, and can be used without libpng. |
1066 | See the documentation delivered with zlib for more details. | 1066 | See the documentation delivered with zlib for more details. |
1067 | You can usually find the source files for the zlib utility wherever you | 1067 | You can usually find the source files for the zlib utility wherever you |
1068 | find the libpng source files. | 1068 | find the libpng source files. |
1069 | 1069 | ||
1070 | Libpng is thread safe, provided the threads are using different | 1070 | Libpng is thread safe, provided the threads are using different |
1071 | instances of the structures. Each thread should have its own | 1071 | instances of the structures. Each thread should have its own |
1072 | png_struct and png_info instances, and thus its own image. | 1072 | png_struct and png_info instances, and thus its own image. |
1073 | Libpng does not protect itself against two threads using the | 1073 | Libpng does not protect itself against two threads using the |
1074 | same instance of a structure. | 1074 | same instance of a structure. |
1075 | 1075 | ||
1076 | .SH II. Structures | 1076 | .SH II. Structures |
1077 | 1077 | ||
1078 | There are two main structures that are important to libpng, png_struct | 1078 | There are two main structures that are important to libpng, png_struct |
1079 | and png_info. Both are internal structures that are no longer exposed | 1079 | and png_info. Both are internal structures that are no longer exposed |
1080 | in the libpng interface (as of libpng 1.5.0). | 1080 | in the libpng interface (as of libpng 1.5.0). |
1081 | 1081 | ||
1082 | The png_info structure is designed to provide information about the | 1082 | The png_info structure is designed to provide information about the |
1083 | PNG file. At one time, the fields of png_info were intended to be | 1083 | PNG file. At one time, the fields of png_info were intended to be |
1084 | directly accessible to the user. However, this tended to cause problems | 1084 | directly accessible to the user. However, this tended to cause problems |
1085 | with applications using dynamically loaded libraries, and as a result | 1085 | with applications using dynamically loaded libraries, and as a result |
1086 | a set of interface functions for png_info (the png_get_*() and png_set_*() | 1086 | a set of interface functions for png_info (the png_get_*() and png_set_*() |
1087 | functions) was developed, and direct access to the png_info fields was | 1087 | functions) was developed, and direct access to the png_info fields was |
1088 | deprecated.. | 1088 | deprecated.. |
1089 | 1089 | ||
1090 | The png_struct structure is the object used by the library to decode a | 1090 | The png_struct structure is the object used by the library to decode a |
1091 | single image. As of 1.5.0 this structure is also not exposed. | 1091 | single image. As of 1.5.0 this structure is also not exposed. |
1092 | 1092 | ||
1093 | Almost all libpng APIs require a pointer to a png_struct as the first argument. | 1093 | Almost all libpng APIs require a pointer to a png_struct as the first argument. |
1094 | Many (in particular the png_set and png_get APIs) also require a pointer | 1094 | Many (in particular the png_set and png_get APIs) also require a pointer |
1095 | to png_info as the second argument. Some application visible macros | 1095 | to png_info as the second argument. Some application visible macros |
1096 | defined in png.h designed for basic data access (reading and writing | 1096 | defined in png.h designed for basic data access (reading and writing |
1097 | integers in the PNG format) don't take a png_info pointer, but it's almost | 1097 | integers in the PNG format) don't take a png_info pointer, but it's almost |
1098 | always safe to assume that a (png_struct*) has to be passed to call an API | 1098 | always safe to assume that a (png_struct*) has to be passed to call an API |
1099 | function. | 1099 | function. |
1100 | 1100 | ||
1101 | You can have more than one png_info structure associated with an image, | 1101 | You can have more than one png_info structure associated with an image, |
1102 | as illustrated in pngtest.c, one for information valid prior to the | 1102 | as illustrated in pngtest.c, one for information valid prior to the |
1103 | IDAT chunks and another (called "end_info" below) for things after them. | 1103 | IDAT chunks and another (called "end_info" below) for things after them. |
1104 | 1104 | ||
1105 | The png.h header file is an invaluable reference for programming with libpng. | 1105 | The png.h header file is an invaluable reference for programming with libpng. |
1106 | And while I'm on the topic, make sure you include the libpng header file: | 1106 | And while I'm on the topic, make sure you include the libpng header file: |
1107 | 1107 | ||
1108 | #include <png.h> | 1108 | #include <png.h> |
1109 | 1109 | ||
1110 | and also (as of libpng-1.5.0) the zlib header file, if you need it: | 1110 | and also (as of libpng-1.5.0) the zlib header file, if you need it: |
1111 | 1111 | ||
1112 | #include <zlib.h> | 1112 | #include <zlib.h> |
1113 | 1113 | ||
1114 | .SS Types | 1114 | .SS Types |
1115 | 1115 | ||
1116 | The png.h header file defines a number of integral types used by the | 1116 | The png.h header file defines a number of integral types used by the |
1117 | APIs. Most of these are fairly obvious; for example types corresponding | 1117 | APIs. Most of these are fairly obvious; for example types corresponding |
1118 | to integers of particular sizes and types for passing color values. | 1118 | to integers of particular sizes and types for passing color values. |
1119 | 1119 | ||
1120 | One exception is how non-integral numbers are handled. For application | 1120 | One exception is how non-integral numbers are handled. For application |
1121 | convenience most APIs that take such numbers have C (double) arguments, | 1121 | convenience most APIs that take such numbers have C (double) arguments, |
1122 | however internally PNG, and libpng, use 32 bit signed integers and encode | 1122 | however internally PNG, and libpng, use 32 bit signed integers and encode |
1123 | the value by multiplying by 100,000. As of libpng 1.5.0 a convenience | 1123 | the value by multiplying by 100,000. As of libpng 1.5.0 a convenience |
1124 | macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point) | 1124 | macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point) |
1125 | which is simply (png_int_32). | 1125 | which is simply (png_int_32). |
1126 | 1126 | ||
1127 | All APIs that take (double) arguments also have a matching API that | 1127 | All APIs that take (double) arguments also have a matching API that |
1128 | takes the corresponding fixed point integer arguments. The fixed point | 1128 | takes the corresponding fixed point integer arguments. The fixed point |
1129 | API has the same name as the floating point one with "_fixed" appended. | 1129 | API has the same name as the floating point one with "_fixed" appended. |
1130 | The actual range of values permitted in the APIs is frequently less than | 1130 | The actual range of values permitted in the APIs is frequently less than |
1131 | the full range of (png_fixed_point) (-21474 to +21474). When APIs require | 1131 | the full range of (png_fixed_point) (-21474 to +21474). When APIs require |
1132 | a non-negative argument the type is recorded as png_uint_32 above. Consult | 1132 | a non-negative argument the type is recorded as png_uint_32 above. Consult |
1133 | the header file and the text below for more information. | 1133 | the header file and the text below for more information. |
1134 | 1134 | ||
1135 | Special care must be take with sCAL chunk handling because the chunk itself | 1135 | Special care must be take with sCAL chunk handling because the chunk itself |
1136 | uses non-integral values encoded as strings containing decimal floating point | 1136 | uses non-integral values encoded as strings containing decimal floating point |
1137 | numbers. See the comments in the header file. | 1137 | numbers. See the comments in the header file. |
1138 | 1138 | ||
1139 | .SS Configuration | 1139 | .SS Configuration |
1140 | 1140 | ||
1141 | The main header file function declarations are frequently protected by C | 1141 | The main header file function declarations are frequently protected by C |
1142 | preprocessing directives of the form: | 1142 | preprocessing directives of the form: |
1143 | 1143 | ||
1144 | #ifdef PNG_feature_SUPPORTED | 1144 | #ifdef PNG_feature_SUPPORTED |
1145 | declare-function | 1145 | declare-function |
1146 | #endif | 1146 | #endif |
1147 | ... | 1147 | ... |
1148 | #ifdef PNG_feature_SUPPORTED | 1148 | #ifdef PNG_feature_SUPPORTED |
1149 | use-function | 1149 | use-function |
1150 | #endif | 1150 | #endif |
1151 | 1151 | ||
1152 | The library can be built without support for these APIs, although a | 1152 | The library can be built without support for these APIs, although a |
1153 | standard build will have all implemented APIs. Application programs | 1153 | standard build will have all implemented APIs. Application programs |
1154 | should check the feature macros before using an API for maximum | 1154 | should check the feature macros before using an API for maximum |
1155 | portability. From libpng 1.5.0 the feature macros set during the build | 1155 | portability. From libpng 1.5.0 the feature macros set during the build |
1156 | of libpng are recorded in the header file "pnglibconf.h" and this file | 1156 | of libpng are recorded in the header file "pnglibconf.h" and this file |
1157 | is always included by png.h. | 1157 | is always included by png.h. |
1158 | 1158 | ||
1159 | If you don't need to change the library configuration from the default, skip to | 1159 | If you don't need to change the library configuration from the default, skip to |
1160 | the next section ("Reading"). | 1160 | the next section ("Reading"). |
1161 | 1161 | ||
1162 | Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all | 1162 | Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all |
1163 | of the build project files in the 'projects' directory simply copy | 1163 | of the build project files in the 'projects' directory simply copy |
1164 | scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build | 1164 | scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build |
1165 | systems do not permit easy auto-configuration of the library - they only | 1165 | systems do not permit easy auto-configuration of the library - they only |
1166 | support the default configuration. | 1166 | support the default configuration. |
1167 | 1167 | ||
1168 | The easiest way to make minor changes to the libpng configuration when | 1168 | The easiest way to make minor changes to the libpng configuration when |
1169 | auto-configuration is supported is to add definitions to the command line | 1169 | auto-configuration is supported is to add definitions to the command line |
1170 | using (typically) CPPFLAGS. For example: | 1170 | using (typically) CPPFLAGS. For example: |
1171 | 1171 | ||
1172 | CPPFLAGS=-DPNG_NO_FLOATING_ARITHMETIC | 1172 | CPPFLAGS=-DPNG_NO_FLOATING_ARITHMETIC |
1173 | 1173 | ||
1174 | will change the internal libpng math implementation for gamma correction and | 1174 | will change the internal libpng math implementation for gamma correction and |
1175 | other arithmetic calculations to fixed point, avoiding the need for fast | 1175 | other arithmetic calculations to fixed point, avoiding the need for fast |
1176 | floating point support. The result can be seen in the generated pnglibconf.h - | 1176 | floating point support. The result can be seen in the generated pnglibconf.h - |
1177 | make sure it contains the changed feature macro setting. | 1177 | make sure it contains the changed feature macro setting. |
1178 | 1178 | ||
1179 | If you need to make more extensive configuration changes - more than one or two | 1179 | If you need to make more extensive configuration changes - more than one or two |
1180 | feature macro settings - you can either add -DPNG_USER_CONFIG to the build | 1180 | feature macro settings - you can either add -DPNG_USER_CONFIG to the build |
1181 | command line and put a list of feature macro settings in pngusr.h or you can set | 1181 | command line and put a list of feature macro settings in pngusr.h or you can set |
1182 | DFA_XTRA (a makefile variable) to a file containing the same information in the | 1182 | DFA_XTRA (a makefile variable) to a file containing the same information in the |
1183 | form of 'option' settings. | 1183 | form of 'option' settings. |
1184 | 1184 | ||
1185 | A. Changing pnglibconf.h | 1185 | A. Changing pnglibconf.h |
1186 | 1186 | ||
1187 | A variety of methods exist to build libpng. Not all of these support | 1187 | A variety of methods exist to build libpng. Not all of these support |
1188 | reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be | 1188 | reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be |
1189 | rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand. | 1189 | rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand. |
1190 | 1190 | ||
1191 | Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt to | 1191 | Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt to |
1192 | pnglibconf.h and changing the lines defining the supported features, paying | 1192 | pnglibconf.h and changing the lines defining the supported features, paying |
1193 | very close attention to the 'option' information in scripts/pnglibconf.dfa | 1193 | very close attention to the 'option' information in scripts/pnglibconf.dfa |
1194 | that describes those features and their requirements. This is easy to get | 1194 | that describes those features and their requirements. This is easy to get |
1195 | wrong. | 1195 | wrong. |
1196 | 1196 | ||
1197 | B. Configuration using DFA_XTRA | 1197 | B. Configuration using DFA_XTRA |
1198 | 1198 | ||
1199 | Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later | 1199 | Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later |
1200 | variant such as 'nawk' or 'gawk', is available. The configure build will | 1200 | variant such as 'nawk' or 'gawk', is available. The configure build will |
1201 | automatically find an appropriate awk and build pnglibconf.h. | 1201 | automatically find an appropriate awk and build pnglibconf.h. |
1202 | The scripts/pnglibconf.mak file contains a set of make rules for doing the | 1202 | The scripts/pnglibconf.mak file contains a set of make rules for doing the |
1203 | same thing if configure is not used, and many of the makefiles in the scripts | 1203 | same thing if configure is not used, and many of the makefiles in the scripts |
1204 | directory use this approach. | 1204 | directory use this approach. |
1205 | 1205 | ||
1206 | When rebuilding simply write a new file containing changed options and set | 1206 | When rebuilding simply write a new file containing changed options and set |
1207 | DFA_XTRA to the name of this file. This causes the build to append the new file | 1207 | DFA_XTRA to the name of this file. This causes the build to append the new file |
1208 | to the end of scripts/pnglibconf.dfa. The pngusr.dfa file should contain lines | 1208 | to the end of scripts/pnglibconf.dfa. The pngusr.dfa file should contain lines |
1209 | of the following forms: | 1209 | of the following forms: |
1210 | 1210 | ||
1211 | everything = off | 1211 | everything = off |
1212 | 1212 | ||
1213 | This turns all optional features off. Include it at the start of pngusr.dfa to | 1213 | This turns all optional features off. Include it at the start of pngusr.dfa to |
1214 | make it easier to build a minimal configuration. You will need to turn at least | 1214 | make it easier to build a minimal configuration. You will need to turn at least |
1215 | some features on afterward to enable either reading or writing code, or both. | 1215 | some features on afterward to enable either reading or writing code, or both. |
1216 | 1216 | ||
1217 | option feature on | 1217 | option feature on |
1218 | option feature off | 1218 | option feature off |
1219 | 1219 | ||
1220 | Enable or disable a single feature. This will automatically enable other | 1220 | Enable or disable a single feature. This will automatically enable other |
1221 | features required by a feature that is turned on or disable other features that | 1221 | features required by a feature that is turned on or disable other features that |
1222 | require a feature which is turned off. Conflicting settings will cause an error | 1222 | require a feature which is turned off. Conflicting settings will cause an error |
1223 | message to be emitted by awk. | 1223 | message to be emitted by awk. |
1224 | 1224 | ||
1225 | setting feature default value | 1225 | setting feature default value |
1226 | 1226 | ||
1227 | Changes the default value of setting 'feature' to 'value'. There are a small | 1227 | Changes the default value of setting 'feature' to 'value'. There are a small |
1228 | number of settings listed at the top of pnglibconf.h, they are documented in the | 1228 | number of settings listed at the top of pnglibconf.h, they are documented in the |
1229 | source code. Most of these values have performance implications for the library | 1229 | source code. Most of these values have performance implications for the library |
1230 | but most of them have no visible effect on the API. Some can also be overridden | 1230 | but most of them have no visible effect on the API. Some can also be overridden |
1231 | from the API. | 1231 | from the API. |
1232 | 1232 | ||
1233 | This method of building a customized pnglibconf.h is illustrated in | 1233 | This method of building a customized pnglibconf.h is illustrated in |
1234 | contrib/pngminim/*. See the "$(PNGCONF):" target in the makefile and | 1234 | contrib/pngminim/*. See the "$(PNGCONF):" target in the makefile and |
1235 | pngusr.dfa in these directories. | 1235 | pngusr.dfa in these directories. |
1236 | 1236 | ||
1237 | C. Configuration using PNG_USR_CONFIG | 1237 | C. Configuration using PNG_USR_CONFIG |
1238 | 1238 | ||
1239 | If -DPNG_USR_CONFIG is added to the CFLAGS when pnglibconf.h is built the file | 1239 | If -DPNG_USR_CONFIG is added to the CFLAGS when pnglibconf.h is built the file |
1240 | pngusr.h will automatically be included before the options in | 1240 | pngusr.h will automatically be included before the options in |
1241 | scripts/pnglibconf.dfa are processed. Your pngusr.h file should contain only | 1241 | scripts/pnglibconf.dfa are processed. Your pngusr.h file should contain only |
1242 | macro definitions turning features on or off or setting settings. | 1242 | macro definitions turning features on or off or setting settings. |
1243 | 1243 | ||
1244 | Apart from the global setting "everything = off" all the options listed above | 1244 | Apart from the global setting "everything = off" all the options listed above |
1245 | can be set using macros in pngusr.h: | 1245 | can be set using macros in pngusr.h: |
1246 | 1246 | ||
1247 | #define PNG_feature_SUPPORTED | 1247 | #define PNG_feature_SUPPORTED |
1248 | 1248 | ||
1249 | is equivalent to: | 1249 | is equivalent to: |
1250 | 1250 | ||
1251 | option feature on | 1251 | option feature on |
1252 | 1252 | ||
1253 | #define PNG_NO_feature | 1253 | #define PNG_NO_feature |
1254 | 1254 | ||
1255 | is equivalent to: | 1255 | is equivalent to: |
1256 | 1256 | ||
1257 | option feature off | 1257 | option feature off |
1258 | 1258 | ||
1259 | #define PNG_feature value | 1259 | #define PNG_feature value |
1260 | 1260 | ||
1261 | is equivalent to: | 1261 | is equivalent to: |
1262 | 1262 | ||
1263 | setting feature default value | 1263 | setting feature default value |
1264 | 1264 | ||
1265 | Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the | 1265 | Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the |
1266 | pngusr file you supply override the contents of scripts/pnglibconf.dfa | 1266 | pngusr file you supply override the contents of scripts/pnglibconf.dfa |
1267 | 1267 | ||
1268 | If confusing or incomprehensible behavior results it is possible to | 1268 | If confusing or incomprehensible behavior results it is possible to |
1269 | examine the intermediate file pnglibconf.dfn to find the full set of | 1269 | examine the intermediate file pnglibconf.dfn to find the full set of |
1270 | dependency information for each setting and option. Simply locate the | 1270 | dependency information for each setting and option. Simply locate the |
1271 | feature in the file and read the C comments that precede it. | 1271 | feature in the file and read the C comments that precede it. |
1272 | 1272 | ||
1273 | This method is also illustrated in the contrib/pngminim/* makefiles and | 1273 | This method is also illustrated in the contrib/pngminim/* makefiles and |
1274 | pngusr.h. | 1274 | pngusr.h. |
1275 | 1275 | ||
1276 | .SH III. Reading | 1276 | .SH III. Reading |
1277 | 1277 | ||
1278 | We'll now walk you through the possible functions to call when reading | 1278 | We'll now walk you through the possible functions to call when reading |
1279 | in a PNG file sequentially, briefly explaining the syntax and purpose | 1279 | in a PNG file sequentially, briefly explaining the syntax and purpose |
1280 | of each one. See example.c and png.h for more detail. While | 1280 | of each one. See example.c and png.h for more detail. While |
1281 | progressive reading is covered in the next section, you will still | 1281 | progressive reading is covered in the next section, you will still |
1282 | need some of the functions discussed in this section to read a PNG | 1282 | need some of the functions discussed in this section to read a PNG |
1283 | file. | 1283 | file. |
1284 | 1284 | ||
1285 | .SS Setup | 1285 | .SS Setup |
1286 | 1286 | ||
1287 | You will want to do the I/O initialization(*) before you get into libpng, | 1287 | You will want to do the I/O initialization(*) before you get into libpng, |
1288 | so if it doesn't work, you don't have much to undo. Of course, you | 1288 | so if it doesn't work, you don't have much to undo. Of course, you |
1289 | will also want to insure that you are, in fact, dealing with a PNG | 1289 | will also want to insure that you are, in fact, dealing with a PNG |
1290 | file. Libpng provides a simple check to see if a file is a PNG file. | 1290 | file. Libpng provides a simple check to see if a file is a PNG file. |
1291 | To use it, pass in the first 1 to 8 bytes of the file to the function | 1291 | To use it, pass in the first 1 to 8 bytes of the file to the function |
1292 | png_sig_cmp(), and it will return 0 (false) if the bytes match the | 1292 | png_sig_cmp(), and it will return 0 (false) if the bytes match the |
1293 | corresponding bytes of the PNG signature, or nonzero (true) otherwise. | 1293 | corresponding bytes of the PNG signature, or nonzero (true) otherwise. |
1294 | Of course, the more bytes you pass in, the greater the accuracy of the | 1294 | Of course, the more bytes you pass in, the greater the accuracy of the |
1295 | prediction. | 1295 | prediction. |
1296 | 1296 | ||
1297 | If you are intending to keep the file pointer open for use in libpng, | 1297 | If you are intending to keep the file pointer open for use in libpng, |
1298 | you must ensure you don't read more than 8 bytes from the beginning | 1298 | you must ensure you don't read more than 8 bytes from the beginning |
1299 | of the file, and you also have to make a call to png_set_sig_bytes_read() | 1299 | of the file, and you also have to make a call to png_set_sig_bytes_read() |
1300 | with the number of bytes you read from the beginning. Libpng will | 1300 | with the number of bytes you read from the beginning. Libpng will |
1301 | then only check the bytes (if any) that your program didn't read. | 1301 | then only check the bytes (if any) that your program didn't read. |
1302 | 1302 | ||
1303 | (*): If you are not using the standard I/O functions, you will need | 1303 | (*): If you are not using the standard I/O functions, you will need |
1304 | to replace them with custom functions. See the discussion under | 1304 | to replace them with custom functions. See the discussion under |
1305 | Customizing libpng. | 1305 | Customizing libpng. |
1306 | 1306 | ||
1307 | 1307 | ||
1308 | FILE *fp = fopen(file_name, "rb"); | 1308 | FILE *fp = fopen(file_name, "rb"); |
1309 | if (!fp) | 1309 | if (!fp) |
1310 | { | 1310 | { |
1311 | return (ERROR); | 1311 | return (ERROR); |
1312 | } | 1312 | } |
1313 | 1313 | ||
1314 | fread(header, 1, number, fp); | 1314 | fread(header, 1, number, fp); |
1315 | is_png = !png_sig_cmp(header, 0, number); | 1315 | is_png = !png_sig_cmp(header, 0, number); |
1316 | 1316 | ||
1317 | if (!is_png) | 1317 | if (!is_png) |
1318 | { | 1318 | { |
1319 | return (NOT_PNG); | 1319 | return (NOT_PNG); |
1320 | } | 1320 | } |
1321 | 1321 | ||
1322 | 1322 | ||
1323 | Next, png_struct and png_info need to be allocated and initialized. In | 1323 | Next, png_struct and png_info need to be allocated and initialized. In |
1324 | order to ensure that the size of these structures is correct even with a | 1324 | order to ensure that the size of these structures is correct even with a |
1325 | dynamically linked libpng, there are functions to initialize and | 1325 | dynamically linked libpng, there are functions to initialize and |
1326 | allocate the structures. We also pass the library version, optional | 1326 | allocate the structures. We also pass the library version, optional |
1327 | pointers to error handling functions, and a pointer to a data struct for | 1327 | pointers to error handling functions, and a pointer to a data struct for |
1328 | use by the error functions, if necessary (the pointer and functions can | 1328 | use by the error functions, if necessary (the pointer and functions can |
1329 | be NULL if the default error handlers are to be used). See the section | 1329 | be NULL if the default error handlers are to be used). See the section |
1330 | on Changes to Libpng below regarding the old initialization functions. | 1330 | on Changes to Libpng below regarding the old initialization functions. |
1331 | The structure allocation functions quietly return NULL if they fail to | 1331 | The structure allocation functions quietly return NULL if they fail to |
1332 | create the structure, so your application should check for that. | 1332 | create the structure, so your application should check for that. |
1333 | 1333 | ||
1334 | png_structp png_ptr = png_create_read_struct | 1334 | png_structp png_ptr = png_create_read_struct |
1335 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, | 1335 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, |
1336 | user_error_fn, user_warning_fn); | 1336 | user_error_fn, user_warning_fn); |
1337 | 1337 | ||
1338 | if (!png_ptr) | 1338 | if (!png_ptr) |
1339 | return (ERROR); | 1339 | return (ERROR); |
1340 | 1340 | ||
1341 | png_infop info_ptr = png_create_info_struct(png_ptr); | 1341 | png_infop info_ptr = png_create_info_struct(png_ptr); |
1342 | 1342 | ||
1343 | if (!info_ptr) | 1343 | if (!info_ptr) |
1344 | { | 1344 | { |
1345 | png_destroy_read_struct(&png_ptr, | 1345 | png_destroy_read_struct(&png_ptr, |
1346 | (png_infopp)NULL, (png_infopp)NULL); | 1346 | (png_infopp)NULL, (png_infopp)NULL); |
1347 | return (ERROR); | 1347 | return (ERROR); |
1348 | } | 1348 | } |
1349 | 1349 | ||
1350 | If you want to use your own memory allocation routines, | 1350 | If you want to use your own memory allocation routines, |
1351 | use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use | 1351 | use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use |
1352 | png_create_read_struct_2() instead of png_create_read_struct(): | 1352 | png_create_read_struct_2() instead of png_create_read_struct(): |
1353 | 1353 | ||
1354 | png_structp png_ptr = png_create_read_struct_2 | 1354 | png_structp png_ptr = png_create_read_struct_2 |
1355 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, | 1355 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, |
1356 | user_error_fn, user_warning_fn, (png_voidp) | 1356 | user_error_fn, user_warning_fn, (png_voidp) |
1357 | user_mem_ptr, user_malloc_fn, user_free_fn); | 1357 | user_mem_ptr, user_malloc_fn, user_free_fn); |
1358 | 1358 | ||
1359 | The error handling routines passed to png_create_read_struct() | 1359 | The error handling routines passed to png_create_read_struct() |
1360 | and the memory alloc/free routines passed to png_create_struct_2() | 1360 | and the memory alloc/free routines passed to png_create_struct_2() |
1361 | are only necessary if you are not using the libpng supplied error | 1361 | are only necessary if you are not using the libpng supplied error |
1362 | handling and memory alloc/free functions. | 1362 | handling and memory alloc/free functions. |
1363 | 1363 | ||
1364 | When libpng encounters an error, it expects to longjmp back | 1364 | When libpng encounters an error, it expects to longjmp back |
1365 | to your routine. Therefore, you will need to call setjmp and pass | 1365 | to your routine. Therefore, you will need to call setjmp and pass |
1366 | your png_jmpbuf(png_ptr). If you read the file from different | 1366 | your png_jmpbuf(png_ptr). If you read the file from different |
1367 | routines, you will need to update the longjmp buffer every time you enter | 1367 | routines, you will need to update the longjmp buffer every time you enter |
1368 | a new routine that will call a png_*() function. | 1368 | a new routine that will call a png_*() function. |
1369 | 1369 | ||
1370 | See your documentation of setjmp/longjmp for your compiler for more | 1370 | See your documentation of setjmp/longjmp for your compiler for more |
1371 | information on setjmp/longjmp. See the discussion on libpng error | 1371 | information on setjmp/longjmp. See the discussion on libpng error |
1372 | handling in the Customizing Libpng section below for more information | 1372 | handling in the Customizing Libpng section below for more information |
1373 | on the libpng error handling. If an error occurs, and libpng longjmp's | 1373 | on the libpng error handling. If an error occurs, and libpng longjmp's |
1374 | back to your setjmp, you will want to call png_destroy_read_struct() to | 1374 | back to your setjmp, you will want to call png_destroy_read_struct() to |
1375 | free any memory. | 1375 | free any memory. |
1376 | 1376 | ||
1377 | if (setjmp(png_jmpbuf(png_ptr))) | 1377 | if (setjmp(png_jmpbuf(png_ptr))) |
1378 | { | 1378 | { |
1379 | png_destroy_read_struct(&png_ptr, &info_ptr, | 1379 | png_destroy_read_struct(&png_ptr, &info_ptr, |
1380 | &end_info); | 1380 | &end_info); |
1381 | fclose(fp); | 1381 | fclose(fp); |
1382 | return (ERROR); | 1382 | return (ERROR); |
1383 | } | 1383 | } |
1384 | 1384 | ||
1385 | Pass (png_infopp)NULL instead of &end_info if you didn't create | 1385 | Pass (png_infopp)NULL instead of &end_info if you didn't create |
1386 | an end_info structure. | 1386 | an end_info structure. |
1387 | 1387 | ||
1388 | If you would rather avoid the complexity of setjmp/longjmp issues, | 1388 | If you would rather avoid the complexity of setjmp/longjmp issues, |
1389 | you can compile libpng with PNG_NO_SETJMP, in which case | 1389 | you can compile libpng with PNG_NO_SETJMP, in which case |
1390 | errors will result in a call to PNG_ABORT() which defaults to abort(). | 1390 | errors will result in a call to PNG_ABORT() which defaults to abort(). |
1391 | 1391 | ||
1392 | You can #define PNG_ABORT() to a function that does something | 1392 | You can #define PNG_ABORT() to a function that does something |
1393 | more useful than abort(), as long as your function does not | 1393 | more useful than abort(), as long as your function does not |
1394 | return. | 1394 | return. |
1395 | 1395 | ||
1396 | Now you need to set up the input code. The default for libpng is to | 1396 | Now you need to set up the input code. The default for libpng is to |
1397 | use the C function fread(). If you use this, you will need to pass a | 1397 | use the C function fread(). If you use this, you will need to pass a |
1398 | valid FILE * in the function png_init_io(). Be sure that the file is | 1398 | valid FILE * in the function png_init_io(). Be sure that the file is |
1399 | opened in binary mode. If you wish to handle reading data in another | 1399 | opened in binary mode. If you wish to handle reading data in another |
1400 | way, you need not call the png_init_io() function, but you must then | 1400 | way, you need not call the png_init_io() function, but you must then |
1401 | implement the libpng I/O methods discussed in the Customizing Libpng | 1401 | implement the libpng I/O methods discussed in the Customizing Libpng |
1402 | section below. | 1402 | section below. |
1403 | 1403 | ||
1404 | png_init_io(png_ptr, fp); | 1404 | png_init_io(png_ptr, fp); |
1405 | 1405 | ||
1406 | If you had previously opened the file and read any of the signature from | 1406 | If you had previously opened the file and read any of the signature from |
1407 | the beginning in order to see if this was a PNG file, you need to let | 1407 | the beginning in order to see if this was a PNG file, you need to let |
1408 | libpng know that there are some bytes missing from the start of the file. | 1408 | libpng know that there are some bytes missing from the start of the file. |
1409 | 1409 | ||
1410 | png_set_sig_bytes(png_ptr, number); | 1410 | png_set_sig_bytes(png_ptr, number); |
1411 | 1411 | ||
1412 | You can change the zlib compression buffer size to be used while | 1412 | You can change the zlib compression buffer size to be used while |
1413 | reading compressed data with | 1413 | reading compressed data with |
1414 | 1414 | ||
1415 | png_set_compression_buffer_size(png_ptr, buffer_size); | 1415 | png_set_compression_buffer_size(png_ptr, buffer_size); |
1416 | 1416 | ||
1417 | where the default size is 8192 bytes. Note that the buffer size | 1417 | where the default size is 8192 bytes. Note that the buffer size |
1418 | is changed immediately and the buffer is reallocated immediately, | 1418 | is changed immediately and the buffer is reallocated immediately, |
1419 | instead of setting a flag to be acted upon later. | 1419 | instead of setting a flag to be acted upon later. |
1420 | 1420 | ||
1421 | If you want CRC errors to be handled in a different manner than | 1421 | If you want CRC errors to be handled in a different manner than |
1422 | the default, use | 1422 | the default, use |
1423 | 1423 | ||
1424 | png_set_crc_action(png_ptr, crit_action, ancil_action); | 1424 | png_set_crc_action(png_ptr, crit_action, ancil_action); |
1425 | 1425 | ||
1426 | The values for png_set_crc_action() say how libpng is to handle CRC errors in | 1426 | The values for png_set_crc_action() say how libpng is to handle CRC errors in |
1427 | ancillary and critical chunks, and whether to use the data contained | 1427 | ancillary and critical chunks, and whether to use the data contained |
1428 | therein. Note that it is impossible to "discard" data in a critical | 1428 | therein. Note that it is impossible to "discard" data in a critical |
1429 | chunk. | 1429 | chunk. |
1430 | 1430 | ||
1431 | Choices for (int) crit_action are | 1431 | Choices for (int) crit_action are |
1432 | PNG_CRC_DEFAULT 0 error/quit | 1432 | PNG_CRC_DEFAULT 0 error/quit |
1433 | PNG_CRC_ERROR_QUIT 1 error/quit | 1433 | PNG_CRC_ERROR_QUIT 1 error/quit |
1434 | PNG_CRC_WARN_USE 3 warn/use data | 1434 | PNG_CRC_WARN_USE 3 warn/use data |
1435 | PNG_CRC_QUIET_USE 4 quiet/use data | 1435 | PNG_CRC_QUIET_USE 4 quiet/use data |
1436 | PNG_CRC_NO_CHANGE 5 use the current value | 1436 | PNG_CRC_NO_CHANGE 5 use the current value |
1437 | 1437 | ||
1438 | Choices for (int) ancil_action are | 1438 | Choices for (int) ancil_action are |
1439 | PNG_CRC_DEFAULT 0 error/quit | 1439 | PNG_CRC_DEFAULT 0 error/quit |
1440 | PNG_CRC_ERROR_QUIT 1 error/quit | 1440 | PNG_CRC_ERROR_QUIT 1 error/quit |
1441 | PNG_CRC_WARN_DISCARD 2 warn/discard data | 1441 | PNG_CRC_WARN_DISCARD 2 warn/discard data |
1442 | PNG_CRC_WARN_USE 3 warn/use data | 1442 | PNG_CRC_WARN_USE 3 warn/use data |
1443 | PNG_CRC_QUIET_USE 4 quiet/use data | 1443 | PNG_CRC_QUIET_USE 4 quiet/use data |
1444 | PNG_CRC_NO_CHANGE 5 use the current value | 1444 | PNG_CRC_NO_CHANGE 5 use the current value |
1445 | 1445 | ||
1446 | .SS Setting up callback code | 1446 | .SS Setting up callback code |
1447 | 1447 | ||
1448 | You can set up a callback function to handle any unknown chunks in the | 1448 | You can set up a callback function to handle any unknown chunks in the |
1449 | input stream. You must supply the function | 1449 | input stream. You must supply the function |
1450 | 1450 | ||
1451 | read_chunk_callback(png_structp png_ptr, | 1451 | read_chunk_callback(png_structp png_ptr, |
1452 | png_unknown_chunkp chunk); | 1452 | png_unknown_chunkp chunk); |
1453 | { | 1453 | { |
1454 | /* The unknown chunk structure contains your | 1454 | /* The unknown chunk structure contains your |
1455 | chunk data, along with similar data for any other | 1455 | chunk data, along with similar data for any other |
1456 | unknown chunks: */ | 1456 | unknown chunks: */ |
1457 | 1457 | ||
1458 | png_byte name[5]; | 1458 | png_byte name[5]; |
1459 | png_byte *data; | 1459 | png_byte *data; |
1460 | png_size_t size; | 1460 | png_size_t size; |
1461 | 1461 | ||
1462 | /* Note that libpng has already taken care of | 1462 | /* Note that libpng has already taken care of |
1463 | the CRC handling */ | 1463 | the CRC handling */ |
1464 | 1464 | ||
1465 | /* put your code here. Search for your chunk in the | 1465 | /* put your code here. Search for your chunk in the |
1466 | unknown chunk structure, process it, and return one | 1466 | unknown chunk structure, process it, and return one |
1467 | of the following: */ | 1467 | of the following: */ |
1468 | 1468 | ||
1469 | return (-n); /* chunk had an error */ | 1469 | return (-n); /* chunk had an error */ |
1470 | return (0); /* did not recognize */ | 1470 | return (0); /* did not recognize */ |
1471 | return (n); /* success */ | 1471 | return (n); /* success */ |
1472 | } | 1472 | } |
1473 | 1473 | ||
1474 | (You can give your function another name that you like instead of | 1474 | (You can give your function another name that you like instead of |
1475 | "read_chunk_callback") | 1475 | "read_chunk_callback") |
1476 | 1476 | ||
1477 | To inform libpng about your function, use | 1477 | To inform libpng about your function, use |
1478 | 1478 | ||
1479 | png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr, | 1479 | png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr, |
1480 | read_chunk_callback); | 1480 | read_chunk_callback); |
1481 | 1481 | ||
1482 | This names not only the callback function, but also a user pointer that | 1482 | This names not only the callback function, but also a user pointer that |
1483 | you can retrieve with | 1483 | you can retrieve with |
1484 | 1484 | ||
1485 | png_get_user_chunk_ptr(png_ptr); | 1485 | png_get_user_chunk_ptr(png_ptr); |
1486 | 1486 | ||
1487 | If you call the png_set_read_user_chunk_fn() function, then all unknown | 1487 | If you call the png_set_read_user_chunk_fn() function, then all unknown |
1488 | chunks will be saved when read, in case your callback function will need | 1488 | chunks will be saved when read, in case your callback function will need |
1489 | one or more of them. This behavior can be changed with the | 1489 | one or more of them. This behavior can be changed with the |
1490 | png_set_keep_unknown_chunks() function, described below. | 1490 | png_set_keep_unknown_chunks() function, described below. |
1491 | 1491 | ||
1492 | At this point, you can set up a callback function that will be | 1492 | At this point, you can set up a callback function that will be |
1493 | called after each row has been read, which you can use to control | 1493 | called after each row has been read, which you can use to control |
1494 | a progress meter or the like. It's demonstrated in pngtest.c. | 1494 | a progress meter or the like. It's demonstrated in pngtest.c. |
1495 | You must supply a function | 1495 | You must supply a function |
1496 | 1496 | ||
1497 | void read_row_callback(png_structp png_ptr, | 1497 | void read_row_callback(png_structp png_ptr, |
1498 | png_uint_32 row, int pass); | 1498 | png_uint_32 row, int pass); |
1499 | { | 1499 | { |
1500 | /* put your code here */ | 1500 | /* put your code here */ |
1501 | } | 1501 | } |
1502 | 1502 | ||
1503 | (You can give it another name that you like instead of "read_row_callback") | 1503 | (You can give it another name that you like instead of "read_row_callback") |
1504 | 1504 | ||
1505 | To inform libpng about your function, use | 1505 | To inform libpng about your function, use |
1506 | 1506 | ||
1507 | png_set_read_status_fn(png_ptr, read_row_callback); | 1507 | png_set_read_status_fn(png_ptr, read_row_callback); |
1508 | 1508 | ||
1509 | When this function is called the row has already been completely processed and | 1509 | When this function is called the row has already been completely processed and |
1510 | the 'row' and 'pass' refer to the next row to be handled. For the | 1510 | the 'row' and 'pass' refer to the next row to be handled. For the |
1511 | non-interlaced case the row that was just handled is simply one less than the | 1511 | non-interlaced case the row that was just handled is simply one less than the |
1512 | passed in row number, and pass will always be 0. For the interlaced case the | 1512 | passed in row number, and pass will always be 0. For the interlaced case the |
1513 | same applies unless the row value is 0, in which case the row just handled was | 1513 | same applies unless the row value is 0, in which case the row just handled was |
1514 | the last one from one of the preceding passes. Because interlacing may skip a | 1514 | the last one from one of the preceding passes. Because interlacing may skip a |
1515 | pass you cannot be sure that the preceding pass is just 'pass-1', if you really | 1515 | pass you cannot be sure that the preceding pass is just 'pass-1', if you really |
1516 | need to know what the last pass is record (row,pass) from the callback and use | 1516 | need to know what the last pass is record (row,pass) from the callback and use |
1517 | the last recorded value each time. | 1517 | the last recorded value each time. |
1518 | 1518 | ||
1519 | As with the user transform you can find the output row using the | 1519 | As with the user transform you can find the output row using the |
1520 | PNG_ROW_FROM_PASS_ROW macro. | 1520 | PNG_ROW_FROM_PASS_ROW macro. |
1521 | 1521 | ||
1522 | .SS Unknown-chunk handling | 1522 | .SS Unknown-chunk handling |
1523 | 1523 | ||
1524 | Now you get to set the way the library processes unknown chunks in the | 1524 | Now you get to set the way the library processes unknown chunks in the |
1525 | input PNG stream. Both known and unknown chunks will be read. Normal | 1525 | input PNG stream. Both known and unknown chunks will be read. Normal |
1526 | behavior is that known chunks will be parsed into information in | 1526 | behavior is that known chunks will be parsed into information in |
1527 | various info_ptr members while unknown chunks will be discarded. This | 1527 | various info_ptr members while unknown chunks will be discarded. This |
1528 | behavior can be wasteful if your application will never use some known | 1528 | behavior can be wasteful if your application will never use some known |
1529 | chunk types. To change this, you can call: | 1529 | chunk types. To change this, you can call: |
1530 | 1530 | ||
1531 | png_set_keep_unknown_chunks(png_ptr, keep, | 1531 | png_set_keep_unknown_chunks(png_ptr, keep, |
1532 | chunk_list, num_chunks); | 1532 | chunk_list, num_chunks); |
1533 | keep - 0: default unknown chunk handling | 1533 | keep - 0: default unknown chunk handling |
1534 | 1: ignore; do not keep | 1534 | 1: ignore; do not keep |
1535 | 2: keep only if safe-to-copy | 1535 | 2: keep only if safe-to-copy |
1536 | 3: keep even if unsafe-to-copy | 1536 | 3: keep even if unsafe-to-copy |
1537 | 1537 | ||
1538 | You can use these definitions: | 1538 | You can use these definitions: |
1539 | PNG_HANDLE_CHUNK_AS_DEFAULT 0 | 1539 | PNG_HANDLE_CHUNK_AS_DEFAULT 0 |
1540 | PNG_HANDLE_CHUNK_NEVER 1 | 1540 | PNG_HANDLE_CHUNK_NEVER 1 |
1541 | PNG_HANDLE_CHUNK_IF_SAFE 2 | 1541 | PNG_HANDLE_CHUNK_IF_SAFE 2 |
1542 | PNG_HANDLE_CHUNK_ALWAYS 3 | 1542 | PNG_HANDLE_CHUNK_ALWAYS 3 |
1543 | 1543 | ||
1544 | chunk_list - list of chunks affected (a byte string, | 1544 | chunk_list - list of chunks affected (a byte string, |
1545 | five bytes per chunk, NULL or '\0' if | 1545 | five bytes per chunk, NULL or '\0' if |
1546 | num_chunks is 0) | 1546 | num_chunks is 0) |
1547 | 1547 | ||
1548 | num_chunks - number of chunks affected; if 0, all | 1548 | num_chunks - number of chunks affected; if 0, all |
1549 | unknown chunks are affected. If nonzero, | 1549 | unknown chunks are affected. If nonzero, |
1550 | only the chunks in the list are affected | 1550 | only the chunks in the list are affected |
1551 | 1551 | ||
1552 | Unknown chunks declared in this way will be saved as raw data onto a | 1552 | Unknown chunks declared in this way will be saved as raw data onto a |
1553 | list of png_unknown_chunk structures. If a chunk that is normally | 1553 | list of png_unknown_chunk structures. If a chunk that is normally |
1554 | known to libpng is named in the list, it will be handled as unknown, | 1554 | known to libpng is named in the list, it will be handled as unknown, |
1555 | according to the "keep" directive. If a chunk is named in successive | 1555 | according to the "keep" directive. If a chunk is named in successive |
1556 | instances of png_set_keep_unknown_chunks(), the final instance will | 1556 | instances of png_set_keep_unknown_chunks(), the final instance will |
1557 | take precedence. The IHDR and IEND chunks should not be named in | 1557 | take precedence. The IHDR and IEND chunks should not be named in |
1558 | chunk_list; if they are, libpng will process them normally anyway. | 1558 | chunk_list; if they are, libpng will process them normally anyway. |
1559 | If you know that your application will never make use of some particular | 1559 | If you know that your application will never make use of some particular |
1560 | chunks, use PNG_HANDLE_CHUNK_NEVER (or 1) as demonstrated below. | 1560 | chunks, use PNG_HANDLE_CHUNK_NEVER (or 1) as demonstrated below. |
1561 | 1561 | ||
1562 | Here is an example of the usage of png_set_keep_unknown_chunks(), | 1562 | Here is an example of the usage of png_set_keep_unknown_chunks(), |
1563 | where the private "vpAg" chunk will later be processed by a user chunk | 1563 | where the private "vpAg" chunk will later be processed by a user chunk |
1564 | callback function: | 1564 | callback function: |
1565 | 1565 | ||
1566 | png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'}; | 1566 | png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'}; |
1567 | 1567 | ||
1568 | #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) | 1568 | #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) |
1569 | png_byte unused_chunks[]= | 1569 | png_byte unused_chunks[]= |
1570 | { | 1570 | { |
1571 | 104, 73, 83, 84, (png_byte) '\0', /* hIST */ | 1571 | 104, 73, 83, 84, (png_byte) '\0', /* hIST */ |
1572 | 105, 84, 88, 116, (png_byte) '\0', /* iTXt */ | 1572 | 105, 84, 88, 116, (png_byte) '\0', /* iTXt */ |
1573 | 112, 67, 65, 76, (png_byte) '\0', /* pCAL */ | 1573 | 112, 67, 65, 76, (png_byte) '\0', /* pCAL */ |
1574 | 115, 67, 65, 76, (png_byte) '\0', /* sCAL */ | 1574 | 115, 67, 65, 76, (png_byte) '\0', /* sCAL */ |
1575 | 115, 80, 76, 84, (png_byte) '\0', /* sPLT */ | 1575 | 115, 80, 76, 84, (png_byte) '\0', /* sPLT */ |
1576 | 116, 73, 77, 69, (png_byte) '\0', /* tIME */ | 1576 | 116, 73, 77, 69, (png_byte) '\0', /* tIME */ |
1577 | }; | 1577 | }; |
1578 | #endif | 1578 | #endif |
1579 | 1579 | ||
1580 | ... | 1580 | ... |
1581 | 1581 | ||
1582 | #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) | 1582 | #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) |
1583 | /* ignore all unknown chunks: */ | 1583 | /* ignore all unknown chunks: */ |
1584 | png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0); | 1584 | png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0); |
1585 | 1585 | ||
1586 | /* except for vpAg: */ | 1586 | /* except for vpAg: */ |
1587 | png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1); | 1587 | png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1); |
1588 | 1588 | ||
1589 | /* also ignore unused known chunks: */ | 1589 | /* also ignore unused known chunks: */ |
1590 | png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks, | 1590 | png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks, |
1591 | (int)sizeof(unused_chunks)/5); | 1591 | (int)sizeof(unused_chunks)/5); |
1592 | #endif | 1592 | #endif |
1593 | 1593 | ||
1594 | .SS User limits | 1594 | .SS User limits |
1595 | 1595 | ||
1596 | The PNG specification allows the width and height of an image to be as | 1596 | The PNG specification allows the width and height of an image to be as |
1597 | large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns. | 1597 | large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns. |
1598 | Since very few applications really need to process such large images, | 1598 | Since very few applications really need to process such large images, |
1599 | we have imposed an arbitrary 1-million limit on rows and columns. | 1599 | we have imposed an arbitrary 1-million limit on rows and columns. |
1600 | Larger images will be rejected immediately with a png_error() call. If | 1600 | Larger images will be rejected immediately with a png_error() call. If |
1601 | you wish to change this limit, you can use | 1601 | you wish to change this limit, you can use |
1602 | 1602 | ||
1603 | png_set_user_limits(png_ptr, width_max, height_max); | 1603 | png_set_user_limits(png_ptr, width_max, height_max); |
1604 | 1604 | ||
1605 | to set your own limits, or use width_max = height_max = 0x7fffffffL | 1605 | to set your own limits, or use width_max = height_max = 0x7fffffffL |
1606 | to allow all valid dimensions (libpng may reject some very large images | 1606 | to allow all valid dimensions (libpng may reject some very large images |
1607 | anyway because of potential buffer overflow conditions). | 1607 | anyway because of potential buffer overflow conditions). |
1608 | 1608 | ||
1609 | You should put this statement after you create the PNG structure and | 1609 | You should put this statement after you create the PNG structure and |
1610 | before calling png_read_info(), png_read_png(), or png_process_data(). | 1610 | before calling png_read_info(), png_read_png(), or png_process_data(). |
1611 | 1611 | ||
1612 | When writing a PNG datastream, put this statement before calling | 1612 | When writing a PNG datastream, put this statement before calling |
1613 | png_write_info() or png_write_png(). | 1613 | png_write_info() or png_write_png(). |
1614 | 1614 | ||
1615 | If you need to retrieve the limits that are being applied, use | 1615 | If you need to retrieve the limits that are being applied, use |
1616 | 1616 | ||
1617 | width_max = png_get_user_width_max(png_ptr); | 1617 | width_max = png_get_user_width_max(png_ptr); |
1618 | height_max = png_get_user_height_max(png_ptr); | 1618 | height_max = png_get_user_height_max(png_ptr); |
1619 | 1619 | ||
1620 | The PNG specification sets no limit on the number of ancillary chunks | 1620 | The PNG specification sets no limit on the number of ancillary chunks |
1621 | allowed in a PNG datastream. You can impose a limit on the total number | 1621 | allowed in a PNG datastream. You can impose a limit on the total number |
1622 | of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with | 1622 | of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with |
1623 | 1623 | ||
1624 | png_set_chunk_cache_max(png_ptr, user_chunk_cache_max); | 1624 | png_set_chunk_cache_max(png_ptr, user_chunk_cache_max); |
1625 | 1625 | ||
1626 | where 0x7fffffffL means unlimited. You can retrieve this limit with | 1626 | where 0x7fffffffL means unlimited. You can retrieve this limit with |
1627 | 1627 | ||
1628 | chunk_cache_max = png_get_chunk_cache_max(png_ptr); | 1628 | chunk_cache_max = png_get_chunk_cache_max(png_ptr); |
1629 | 1629 | ||
1630 | This limit also applies to the number of buffers that can be allocated | 1630 | This limit also applies to the number of buffers that can be allocated |
1631 | by png_decompress_chunk() while decompressing iTXt, zTXt, and iCCP chunks. | 1631 | by png_decompress_chunk() while decompressing iTXt, zTXt, and iCCP chunks. |
1632 | 1632 | ||
1633 | You can also set a limit on the amount of memory that a compressed chunk | 1633 | You can also set a limit on the amount of memory that a compressed chunk |
1634 | other than IDAT can occupy, with | 1634 | other than IDAT can occupy, with |
1635 | 1635 | ||
1636 | png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max); | 1636 | png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max); |
1637 | 1637 | ||
1638 | and you can retrieve the limit with | 1638 | and you can retrieve the limit with |
1639 | 1639 | ||
1640 | chunk_malloc_max = png_get_chunk_malloc_max(png_ptr); | 1640 | chunk_malloc_max = png_get_chunk_malloc_max(png_ptr); |
1641 | 1641 | ||
1642 | Any chunks that would cause either of these limits to be exceeded will | 1642 | Any chunks that would cause either of these limits to be exceeded will |
1643 | be ignored. | 1643 | be ignored. |
1644 | 1644 | ||
1645 | .SS Information about your system | 1645 | .SS Information about your system |
1646 | 1646 | ||
1647 | If you intend to display the PNG or to incorporate it in other image data you | 1647 | If you intend to display the PNG or to incorporate it in other image data you |
1648 | need to tell libpng information about your display or drawing surface so that | 1648 | need to tell libpng information about your display or drawing surface so that |
1649 | libpng can convert the values in the image to match the display. | 1649 | libpng can convert the values in the image to match the display. |
1650 | 1650 | ||
1651 | From libpng-1.5.4 this information can be set before reading the PNG file | 1651 | From libpng-1.5.4 this information can be set before reading the PNG file |
1652 | header. In earlier versions png_set_gamma() existed but behaved incorrectly if | 1652 | header. In earlier versions png_set_gamma() existed but behaved incorrectly if |
1653 | called before the PNG file header had been read and png_set_alpha_mode() did not | 1653 | called before the PNG file header had been read and png_set_alpha_mode() did not |
1654 | exist. | 1654 | exist. |
1655 | 1655 | ||
1656 | If you need to support versions prior to libpng-1.5.4 test the version number | 1656 | If you need to support versions prior to libpng-1.5.4 test the version number |
1657 | as illustrated below using "PNG_LIBPNG_VER >= 10504" and follow the procedures | 1657 | as illustrated below using "PNG_LIBPNG_VER >= 10504" and follow the procedures |
1658 | described in the appropriate manual page. | 1658 | described in the appropriate manual page. |
1659 | 1659 | ||
1660 | You give libpng the encoding expected by your system expressed as a 'gamma' | 1660 | You give libpng the encoding expected by your system expressed as a 'gamma' |
1661 | value. You can also specify a default encoding for the PNG file in | 1661 | value. You can also specify a default encoding for the PNG file in |
1662 | case the required information is missing from the file. By default libpng | 1662 | case the required information is missing from the file. By default libpng |
1663 | assumes that the PNG data matches your system, to keep this default call: | 1663 | assumes that the PNG data matches your system, to keep this default call: |
1664 | 1664 | ||
1665 | png_set_gamma(png_ptr, screen_gamma, 1/screen_gamma/*file gamma*/); | 1665 | png_set_gamma(png_ptr, screen_gamma, 1/screen_gamma/*file gamma*/); |
1666 | 1666 | ||
1667 | or you can use the fixed point equivalent: | 1667 | or you can use the fixed point equivalent: |
1668 | 1668 | ||
1669 | png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma, PNG_FP_1/screen_gamma); | 1669 | png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma, PNG_FP_1/screen_gamma); |
1670 | 1670 | ||
1671 | If you don't know the gamma for your system it is probably 2.2 - a good | 1671 | If you don't know the gamma for your system it is probably 2.2 - a good |
1672 | approximation to the IEC standard for display systems (sRGB). If images are | 1672 | approximation to the IEC standard for display systems (sRGB). If images are |
1673 | too contrasty or washed out you got the value wrong - check your system | 1673 | too contrasty or washed out you got the value wrong - check your system |
1674 | documentation! | 1674 | documentation! |
1675 | 1675 | ||
1676 | Many systems permit the system gamma to be changed via a lookup table in the | 1676 | Many systems permit the system gamma to be changed via a lookup table in the |
1677 | display driver, a few systems, including older Macs, change the response by | 1677 | display driver, a few systems, including older Macs, change the response by |
1678 | default. As of 1.5.4 three special values are available to handle common | 1678 | default. As of 1.5.4 three special values are available to handle common |
1679 | situations: | 1679 | situations: |
1680 | 1680 | ||
1681 | PNG_DEFAULT_sRGB: Indicates that the system conforms to the IEC 61966-2-1 | 1681 | PNG_DEFAULT_sRGB: Indicates that the system conforms to the IEC 61966-2-1 |
1682 | standard. This matches almost all systems. | 1682 | standard. This matches almost all systems. |
1683 | PNG_GAMMA_MAC_18: Indicates that the system is an older (pre Mac OS 10.6) | 1683 | PNG_GAMMA_MAC_18: Indicates that the system is an older (pre Mac OS 10.6) |
1684 | Apple Macintosh system with the default settings. | 1684 | Apple Macintosh system with the default settings. |
1685 | PNG_GAMMA_LINEAR: Just the fixed point value for 1.0 - indicates that the | 1685 | PNG_GAMMA_LINEAR: Just the fixed point value for 1.0 - indicates that the |
1686 | system expects data with no gamma encoding. | 1686 | system expects data with no gamma encoding. |
1687 | 1687 | ||
1688 | You would use the linear (unencoded) value if you need to process the pixel | 1688 | You would use the linear (unencoded) value if you need to process the pixel |
1689 | values further because this avoids the need to decode and reencode each | 1689 | values further because this avoids the need to decode and reencode each |
1690 | component value whenever arithmetic is performed. A lot of graphics software | 1690 | component value whenever arithmetic is performed. A lot of graphics software |
1691 | uses linear values for this reason, often with higher precision component values | 1691 | uses linear values for this reason, often with higher precision component values |
1692 | to preserve overall accuracy. | 1692 | to preserve overall accuracy. |
1693 | 1693 | ||
1694 | The second thing you may need to tell libpng about is how your system handles | 1694 | The second thing you may need to tell libpng about is how your system handles |
1695 | alpha channel information. Some, but not all, PNG files contain an alpha | 1695 | alpha channel information. Some, but not all, PNG files contain an alpha |
1696 | channel. To display these files correctly you need to compose the data onto a | 1696 | channel. To display these files correctly you need to compose the data onto a |
1697 | suitable background, as described in the PNG specification. | 1697 | suitable background, as described in the PNG specification. |
1698 | 1698 | ||
1699 | Libpng only supports composing onto a single color (using png_set_background; | 1699 | Libpng only supports composing onto a single color (using png_set_background; |
1700 | see below). Otherwise you must do the composition yourself and, in this case, | 1700 | see below). Otherwise you must do the composition yourself and, in this case, |
1701 | you may need to call png_set_alpha_mode: | 1701 | you may need to call png_set_alpha_mode: |
1702 | 1702 | ||
1703 | #if PNG_LIBPNG_VER >= 10504 | 1703 | #if PNG_LIBPNG_VER >= 10504 |
1704 | png_set_alpha_mode(png_ptr, mode, screen_gamma); | 1704 | png_set_alpha_mode(png_ptr, mode, screen_gamma); |
1705 | #else | 1705 | #else |
1706 | png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma); | 1706 | png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma); |
1707 | #endif | 1707 | #endif |
1708 | 1708 | ||
1709 | The screen_gamma value is the same as the argument to png_set_gamma; however, | 1709 | The screen_gamma value is the same as the argument to png_set_gamma; however, |
1710 | how it affects the output depends on the mode. png_set_alpha_mode() sets the | 1710 | how it affects the output depends on the mode. png_set_alpha_mode() sets the |
1711 | file gamma default to 1/screen_gamma, so normally you don't need to call | 1711 | file gamma default to 1/screen_gamma, so normally you don't need to call |
1712 | png_set_gamma. If you need different defaults call png_set_gamma() before | 1712 | png_set_gamma. If you need different defaults call png_set_gamma() before |
1713 | png_set_alpha_mode() - if you call it after it will override the settings made | 1713 | png_set_alpha_mode() - if you call it after it will override the settings made |
1714 | by png_set_alpha_mode(). | 1714 | by png_set_alpha_mode(). |
1715 | 1715 | ||
1716 | The mode is as follows: | 1716 | The mode is as follows: |
1717 | 1717 | ||
1718 | PNG_ALPHA_PNG: The data is encoded according to the PNG specification. Red, | 1718 | PNG_ALPHA_PNG: The data is encoded according to the PNG specification. Red, |
1719 | green and blue, or gray, components are gamma encoded color | 1719 | green and blue, or gray, components are gamma encoded color |
1720 | values and are not premultiplied by the alpha value. The | 1720 | values and are not premultiplied by the alpha value. The |
1721 | alpha value is a linear measure of the contribution of the | 1721 | alpha value is a linear measure of the contribution of the |
1722 | pixel to the corresponding final output pixel. | 1722 | pixel to the corresponding final output pixel. |
1723 | 1723 | ||
1724 | You should normally use this format if you intend to perform | 1724 | You should normally use this format if you intend to perform |
1725 | color correction on the color values; most, maybe all, color | 1725 | color correction on the color values; most, maybe all, color |
1726 | correction software has no handling for the alpha channel and, | 1726 | correction software has no handling for the alpha channel and, |
1727 | anyway, the math to handle pre-multiplied component values is | 1727 | anyway, the math to handle pre-multiplied component values is |
1728 | unnecessarily complex. | 1728 | unnecessarily complex. |
1729 | 1729 | ||
1730 | Before you do any arithmetic on the component values you need | 1730 | Before you do any arithmetic on the component values you need |
1731 | to remove the gamma encoding and multiply out the alpha | 1731 | to remove the gamma encoding and multiply out the alpha |
1732 | channel. See the PNG specification for more detail. It is | 1732 | channel. See the PNG specification for more detail. It is |
1733 | important to note that when an image with an alpha channel is | 1733 | important to note that when an image with an alpha channel is |
1734 | scaled, linear encoded, pre-multiplied component values must | 1734 | scaled, linear encoded, pre-multiplied component values must |
1735 | be used! | 1735 | be used! |
1736 | 1736 | ||
1737 | The remaining modes assume you don't need to do any further color correction or | 1737 | The remaining modes assume you don't need to do any further color correction or |
1738 | that if you do, your color correction software knows all about alpha (it | 1738 | that if you do, your color correction software knows all about alpha (it |
1739 | probably doesn't!) | 1739 | probably doesn't!) |
1740 | 1740 | ||
1741 | PNG_ALPHA_STANDARD: The data libpng produces | 1741 | PNG_ALPHA_STANDARD: The data libpng produces |
1742 | is encoded in the standard way | 1742 | is encoded in the standard way |
1743 | assumed by most correctly written graphics software. | 1743 | assumed by most correctly written graphics software. |
1744 | The gamma encoding will be removed by libpng and the | 1744 | The gamma encoding will be removed by libpng and the |
1745 | linear component values will be pre-multiplied by the | 1745 | linear component values will be pre-multiplied by the |
1746 | alpha channel. | 1746 | alpha channel. |
1747 | 1747 | ||
1748 | With this format the final image must be re-encoded to | 1748 | With this format the final image must be re-encoded to |
1749 | match the display gamma before the image is displayed. | 1749 | match the display gamma before the image is displayed. |
1750 | If your system doesn't do that, yet still seems to | 1750 | If your system doesn't do that, yet still seems to |
1751 | perform arithmetic on the pixels without decoding them, | 1751 | perform arithmetic on the pixels without decoding them, |
1752 | it is broken - check out the modes below. | 1752 | it is broken - check out the modes below. |
1753 | 1753 | ||
1754 | With PNG_ALPHA_STANDARD libpng always produces linear | 1754 | With PNG_ALPHA_STANDARD libpng always produces linear |
1755 | component values, whatever screen_gamma you supply. The | 1755 | component values, whatever screen_gamma you supply. The |
1756 | screen_gamma value is, however, used as a default for | 1756 | screen_gamma value is, however, used as a default for |
1757 | the file gamma if the PNG file has no gamma information. | 1757 | the file gamma if the PNG file has no gamma information. |
1758 | 1758 | ||
1759 | If you call png_set_gamma() after png_set_alpha_mode() you | 1759 | If you call png_set_gamma() after png_set_alpha_mode() you |
1760 | will override the linear encoding. Instead the | 1760 | will override the linear encoding. Instead the |
1761 | pre-multiplied pixel values will be gamma encoded but | 1761 | pre-multiplied pixel values will be gamma encoded but |
1762 | the alpha channel will still be linear. This may | 1762 | the alpha channel will still be linear. This may |
1763 | actually match the requirements of some broken software, | 1763 | actually match the requirements of some broken software, |
1764 | but it is unlikely. | 1764 | but it is unlikely. |
1765 | 1765 | ||
1766 | While linear 8-bit data is often used it has | 1766 | While linear 8-bit data is often used it has |
1767 | insufficient precision for any image with a reasonable | 1767 | insufficient precision for any image with a reasonable |
1768 | dynamic range. To avoid problems, and if your software | 1768 | dynamic range. To avoid problems, and if your software |
1769 | supports it, use png_set_expand_16() to force all | 1769 | supports it, use png_set_expand_16() to force all |
1770 | components to 16 bits. | 1770 | components to 16 bits. |
1771 | 1771 | ||
1772 | PNG_ALPHA_OPTIMIZED: This mode is the same | 1772 | PNG_ALPHA_OPTIMIZED: This mode is the same |
1773 | as PNG_ALPHA_STANDARD except that | 1773 | as PNG_ALPHA_STANDARD except that |
1774 | completely opaque pixels are gamma encoded according to | 1774 | completely opaque pixels are gamma encoded according to |
1775 | the screen_gamma value. Pixels with alpha less than 1.0 | 1775 | the screen_gamma value. Pixels with alpha less than 1.0 |
1776 | will still have linear components. | 1776 | will still have linear components. |
1777 | 1777 | ||
1778 | Use this format if you have control over your | 1778 | Use this format if you have control over your |
1779 | compositing software and do don't do other arithmetic | 1779 | compositing software and do don't do other arithmetic |
1780 | (such as scaling) on the data you get from libpng. Your | 1780 | (such as scaling) on the data you get from libpng. Your |
1781 | compositing software can simply copy opaque pixels to | 1781 | compositing software can simply copy opaque pixels to |
1782 | the output but still has linear values for the | 1782 | the output but still has linear values for the |
1783 | non-opaque pixels. | 1783 | non-opaque pixels. |
1784 | 1784 | ||
1785 | In normal compositing, where the alpha channel encodes | 1785 | In normal compositing, where the alpha channel encodes |
1786 | partial pixel coverage (as opposed to broad area | 1786 | partial pixel coverage (as opposed to broad area |
1787 | translucency), the inaccuracies of the 8-bit | 1787 | translucency), the inaccuracies of the 8-bit |
1788 | representation of non-opaque pixels are irrelevant. | 1788 | representation of non-opaque pixels are irrelevant. |
1789 | 1789 | ||
1790 | You can also try this format if your software is broken; | 1790 | You can also try this format if your software is broken; |
1791 | it might look better. | 1791 | it might look better. |
1792 | 1792 | ||
1793 | PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; | 1793 | PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; |
1794 | however, all component values, | 1794 | however, all component values, |
1795 | including the alpha channel are gamma encoded. This is | 1795 | including the alpha channel are gamma encoded. This is |
1796 | an appropriate format to try if your software, or more | 1796 | an appropriate format to try if your software, or more |
1797 | likely hardware, is totally broken, i.e., if it performs | 1797 | likely hardware, is totally broken, i.e., if it performs |
1798 | linear arithmetic directly on gamma encoded values. | 1798 | linear arithmetic directly on gamma encoded values. |
1799 | 1799 | ||
1800 | In most cases of broken software or hardware the bug in the final display | 1800 | In most cases of broken software or hardware the bug in the final display |
1801 | manifests as a subtle halo around composited parts of the image. You may not | 1801 | manifests as a subtle halo around composited parts of the image. You may not |
1802 | even perceive this as a halo; the composited part of the image may simply appear | 1802 | even perceive this as a halo; the composited part of the image may simply appear |
1803 | separate from the background, as though it had been cut out of paper and pasted | 1803 | separate from the background, as though it had been cut out of paper and pasted |
1804 | on afterward. | 1804 | on afterward. |
1805 | 1805 | ||
1806 | If you don't have to deal with bugs in software or hardware, or if you can fix | 1806 | If you don't have to deal with bugs in software or hardware, or if you can fix |
1807 | them, there are three recommended ways of using png_set_alpha_mode(): | 1807 | them, there are three recommended ways of using png_set_alpha_mode(): |
1808 | 1808 | ||
1809 | png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG, | 1809 | png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG, |
1810 | screen_gamma); | 1810 | screen_gamma); |
1811 | 1811 | ||
1812 | You can do color correction on the result (libpng does not currently | 1812 | You can do color correction on the result (libpng does not currently |
1813 | support color correction internally). When you handle the alpha channel | 1813 | support color correction internally). When you handle the alpha channel |
1814 | you need to undo the gamma encoding and multiply out the alpha. | 1814 | you need to undo the gamma encoding and multiply out the alpha. |
1815 | 1815 | ||
1816 | png_set_alpha_mode(png_ptr, PNG_ALPHA_STANDARD, | 1816 | png_set_alpha_mode(png_ptr, PNG_ALPHA_STANDARD, |
1817 | screen_gamma); | 1817 | screen_gamma); |
1818 | png_set_expand_16(png_ptr); | 1818 | png_set_expand_16(png_ptr); |
1819 | 1819 | ||
1820 | If you are using the high level interface, don't call png_set_expand_16(); | 1820 | If you are using the high level interface, don't call png_set_expand_16(); |
1821 | instead pass PNG_TRANSFORM_EXPAND_16 to the interface. | 1821 | instead pass PNG_TRANSFORM_EXPAND_16 to the interface. |
1822 | 1822 | ||
1823 | With this mode you can't do color correction, but you can do arithmetic, | 1823 | With this mode you can't do color correction, but you can do arithmetic, |
1824 | including composition and scaling, on the data without further processing. | 1824 | including composition and scaling, on the data without further processing. |
1825 | 1825 | ||
1826 | png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED, | 1826 | png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED, |
1827 | screen_gamma); | 1827 | screen_gamma); |
1828 | 1828 | ||
1829 | You can avoid the expansion to 16-bit components with this mode, but you | 1829 | You can avoid the expansion to 16-bit components with this mode, but you |
1830 | lose the ability to scale the image or perform other linear arithmetic. | 1830 | lose the ability to scale the image or perform other linear arithmetic. |
1831 | All you can do is compose the result onto a matching output. Since this | 1831 | All you can do is compose the result onto a matching output. Since this |
1832 | mode is libpng-specific you also need to write your own composition | 1832 | mode is libpng-specific you also need to write your own composition |
1833 | software. | 1833 | software. |
1834 | 1834 | ||
1835 | If you don't need, or can't handle, the alpha channel you can call | 1835 | If you don't need, or can't handle, the alpha channel you can call |
1836 | png_set_background() to remove it by compositing against a fixed color. Don't | 1836 | png_set_background() to remove it by compositing against a fixed color. Don't |
1837 | call png_set_strip_alpha() to do this - it will leave spurious pixel values in | 1837 | call png_set_strip_alpha() to do this - it will leave spurious pixel values in |
1838 | transparent parts of this image. | 1838 | transparent parts of this image. |
1839 | 1839 | ||
1840 | png_set_background(png_ptr, &background_color, | 1840 | png_set_background(png_ptr, &background_color, |
1841 | PNG_BACKGROUND_GAMMA_SCREEN, 0, 1); | 1841 | PNG_BACKGROUND_GAMMA_SCREEN, 0, 1); |
1842 | 1842 | ||
1843 | The background_color is an RGB or grayscale value according to the data format | 1843 | The background_color is an RGB or grayscale value according to the data format |
1844 | libpng will produce for you. Because you don't yet know the format of the PNG | 1844 | libpng will produce for you. Because you don't yet know the format of the PNG |
1845 | file, if you call png_set_background at this point you must arrange for the | 1845 | file, if you call png_set_background at this point you must arrange for the |
1846 | format produced by libpng to always have 8-bit or 16-bit components and then | 1846 | format produced by libpng to always have 8-bit or 16-bit components and then |
1847 | store the color as an 8-bit or 16-bit color as appropriate. The color contains | 1847 | store the color as an 8-bit or 16-bit color as appropriate. The color contains |
1848 | separate gray and RGB component values, so you can let libpng produce gray or | 1848 | separate gray and RGB component values, so you can let libpng produce gray or |
1849 | RGB output according to the input format, but low bit depth grayscale images | 1849 | RGB output according to the input format, but low bit depth grayscale images |
1850 | must always be converted to at least 8-bit format. (Even though low bit depth | 1850 | must always be converted to at least 8-bit format. (Even though low bit depth |
1851 | grayscale images can't have an alpha channel they can have a transparent | 1851 | grayscale images can't have an alpha channel they can have a transparent |
1852 | color!) | 1852 | color!) |
1853 | 1853 | ||
1854 | You set the transforms you need later, either as flags to the high level | 1854 | You set the transforms you need later, either as flags to the high level |
1855 | interface or libpng API calls for the low level interface. For reference the | 1855 | interface or libpng API calls for the low level interface. For reference the |
1856 | settings and API calls required are: | 1856 | settings and API calls required are: |
1857 | 1857 | ||
1858 | 8-bit values: | 1858 | 8-bit values: |
1859 | PNG_TRANSFORM_SCALE_16 | PNG_EXPAND | 1859 | PNG_TRANSFORM_SCALE_16 | PNG_EXPAND |
1860 | png_set_expand(png_ptr); png_set_scale_16(png_ptr); | 1860 | png_set_expand(png_ptr); png_set_scale_16(png_ptr); |
1861 | 1861 | ||
1862 | If you must get exactly the same inaccurate results | 1862 | If you must get exactly the same inaccurate results |
1863 | produced by default in versions prior to libpng-1.5.4, | 1863 | produced by default in versions prior to libpng-1.5.4, |
1864 | use PNG_TRANSFORM_STRIP_16 and png_set_strip_16(png_ptr) | 1864 | use PNG_TRANSFORM_STRIP_16 and png_set_strip_16(png_ptr) |
1865 | instead. | 1865 | instead. |
1866 | 1866 | ||
1867 | 16-bit values: | 1867 | 16-bit values: |
1868 | PNG_TRANSFORM_EXPAND_16 | 1868 | PNG_TRANSFORM_EXPAND_16 |
1869 | png_set_expand_16(png_ptr); | 1869 | png_set_expand_16(png_ptr); |
1870 | 1870 | ||
1871 | In either case palette image data will be expanded to RGB. If you just want | 1871 | In either case palette image data will be expanded to RGB. If you just want |
1872 | color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr) | 1872 | color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr) |
1873 | to the list. | 1873 | to the list. |
1874 | 1874 | ||
1875 | Calling png_set_background before the PNG file header is read will not work | 1875 | Calling png_set_background before the PNG file header is read will not work |
1876 | prior to libpng-1.5.4. Because the failure may result in unexpected warnings or | 1876 | prior to libpng-1.5.4. Because the failure may result in unexpected warnings or |
1877 | errors it is therefore much safer to call png_set_background after the head has | 1877 | errors it is therefore much safer to call png_set_background after the head has |
1878 | been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be | 1878 | been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be |
1879 | used with the high level interface. | 1879 | used with the high level interface. |
1880 | 1880 | ||
1881 | .SS The high-level read interface | 1881 | .SS The high-level read interface |
1882 | 1882 | ||
1883 | At this point there are two ways to proceed; through the high-level | 1883 | At this point there are two ways to proceed; through the high-level |
1884 | read interface, or through a sequence of low-level read operations. | 1884 | read interface, or through a sequence of low-level read operations. |
1885 | You can use the high-level interface if (a) you are willing to read | 1885 | You can use the high-level interface if (a) you are willing to read |
1886 | the entire image into memory, and (b) the input transformations | 1886 | the entire image into memory, and (b) the input transformations |
1887 | you want to do are limited to the following set: | 1887 | you want to do are limited to the following set: |
1888 | 1888 | ||
1889 | PNG_TRANSFORM_IDENTITY No transformation | 1889 | PNG_TRANSFORM_IDENTITY No transformation |
1890 | PNG_TRANSFORM_SCALE_16 Strip 16-bit samples to | 1890 | PNG_TRANSFORM_SCALE_16 Strip 16-bit samples to |
1891 | 8-bit accurately | 1891 | 8-bit accurately |
1892 | PNG_TRANSFORM_STRIP_16 Chop 16-bit samples to | 1892 | PNG_TRANSFORM_STRIP_16 Chop 16-bit samples to |
1893 | 8-bit less accurately | 1893 | 8-bit less accurately |
1894 | PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel | 1894 | PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel |
1895 | PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit | 1895 | PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit |
1896 | samples to bytes | 1896 | samples to bytes |
1897 | PNG_TRANSFORM_PACKSWAP Change order of packed | 1897 | PNG_TRANSFORM_PACKSWAP Change order of packed |
1898 | pixels to LSB first | 1898 | pixels to LSB first |
1899 | PNG_TRANSFORM_EXPAND Perform set_expand() | 1899 | PNG_TRANSFORM_EXPAND Perform set_expand() |
1900 | PNG_TRANSFORM_INVERT_MONO Invert monochrome images | 1900 | PNG_TRANSFORM_INVERT_MONO Invert monochrome images |
1901 | PNG_TRANSFORM_SHIFT Normalize pixels to the | 1901 | PNG_TRANSFORM_SHIFT Normalize pixels to the |
1902 | sBIT depth | 1902 | sBIT depth |
1903 | PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA | 1903 | PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA |
1904 | to BGRA | 1904 | to BGRA |
1905 | PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA | 1905 | PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA |
1906 | to AG | 1906 | to AG |
1907 | PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity | 1907 | PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity |
1908 | to transparency | 1908 | to transparency |
1909 | PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples | 1909 | PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples |
1910 | PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples | 1910 | PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples |
1911 | to RGB (or GA to RGBA) | 1911 | to RGB (or GA to RGBA) |
1912 | PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits | 1912 | PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits |
1913 | 1913 | ||
1914 | (This excludes setting a background color, doing gamma transformation, | 1914 | (This excludes setting a background color, doing gamma transformation, |
1915 | quantizing, and setting filler.) If this is the case, simply do this: | 1915 | quantizing, and setting filler.) If this is the case, simply do this: |
1916 | 1916 | ||
1917 | png_read_png(png_ptr, info_ptr, png_transforms, NULL) | 1917 | png_read_png(png_ptr, info_ptr, png_transforms, NULL) |
1918 | 1918 | ||
1919 | where png_transforms is an integer containing the bitwise OR of some | 1919 | where png_transforms is an integer containing the bitwise OR of some |
1920 | set of transformation flags. This call is equivalent to png_read_info(), | 1920 | set of transformation flags. This call is equivalent to png_read_info(), |
1921 | followed the set of transformations indicated by the transform mask, | 1921 | followed the set of transformations indicated by the transform mask, |
1922 | then png_read_image(), and finally png_read_end(). | 1922 | then png_read_image(), and finally png_read_end(). |
1923 | 1923 | ||
1924 | (The final parameter of this call is not yet used. Someday it might point | 1924 | (The final parameter of this call is not yet used. Someday it might point |
1925 | to transformation parameters required by some future input transform.) | 1925 | to transformation parameters required by some future input transform.) |
1926 | 1926 | ||
1927 | You must use png_transforms and not call any png_set_transform() functions | 1927 | You must use png_transforms and not call any png_set_transform() functions |
1928 | when you use png_read_png(). | 1928 | when you use png_read_png(). |
1929 | 1929 | ||
1930 | After you have called png_read_png(), you can retrieve the image data | 1930 | After you have called png_read_png(), you can retrieve the image data |
1931 | with | 1931 | with |
1932 | 1932 | ||
1933 | row_pointers = png_get_rows(png_ptr, info_ptr); | 1933 | row_pointers = png_get_rows(png_ptr, info_ptr); |
1934 | 1934 | ||
1935 | where row_pointers is an array of pointers to the pixel data for each row: | 1935 | where row_pointers is an array of pointers to the pixel data for each row: |
1936 | 1936 | ||
1937 | png_bytep row_pointers[height]; | 1937 | png_bytep row_pointers[height]; |
1938 | 1938 | ||
1939 | If you know your image size and pixel size ahead of time, you can allocate | 1939 | If you know your image size and pixel size ahead of time, you can allocate |
1940 | row_pointers prior to calling png_read_png() with | 1940 | row_pointers prior to calling png_read_png() with |
1941 | 1941 | ||
1942 | if (height > PNG_UINT_32_MAX/png_sizeof(png_byte)) | 1942 | if (height > PNG_UINT_32_MAX/png_sizeof(png_byte)) |
1943 | png_error (png_ptr, | 1943 | png_error (png_ptr, |
1944 | "Image is too tall to process in memory"); | 1944 | "Image is too tall to process in memory"); |
1945 | 1945 | ||
1946 | if (width > PNG_UINT_32_MAX/pixel_size) | 1946 | if (width > PNG_UINT_32_MAX/pixel_size) |
1947 | png_error (png_ptr, | 1947 | png_error (png_ptr, |
1948 | "Image is too wide to process in memory"); | 1948 | "Image is too wide to process in memory"); |
1949 | 1949 | ||
1950 | row_pointers = png_malloc(png_ptr, | 1950 | row_pointers = png_malloc(png_ptr, |
1951 | height*png_sizeof(png_bytep)); | 1951 | height*png_sizeof(png_bytep)); |
1952 | 1952 | ||
1953 | for (int i=0; i<height, i++) | 1953 | for (int i=0; i<height, i++) |
1954 | row_pointers[i]=NULL; /* security precaution */ | 1954 | row_pointers[i]=NULL; /* security precaution */ |
1955 | 1955 | ||
1956 | for (int i=0; i<height, i++) | 1956 | for (int i=0; i<height, i++) |
1957 | row_pointers[i]=png_malloc(png_ptr, | 1957 | row_pointers[i]=png_malloc(png_ptr, |
1958 | width*pixel_size); | 1958 | width*pixel_size); |
1959 | 1959 | ||
1960 | png_set_rows(png_ptr, info_ptr, &row_pointers); | 1960 | png_set_rows(png_ptr, info_ptr, &row_pointers); |
1961 | 1961 | ||
1962 | Alternatively you could allocate your image in one big block and define | 1962 | Alternatively you could allocate your image in one big block and define |
1963 | row_pointers[i] to point into the proper places in your block. | 1963 | row_pointers[i] to point into the proper places in your block. |
1964 | 1964 | ||
1965 | If you use png_set_rows(), the application is responsible for freeing | 1965 | If you use png_set_rows(), the application is responsible for freeing |
1966 | row_pointers (and row_pointers[i], if they were separately allocated). | 1966 | row_pointers (and row_pointers[i], if they were separately allocated). |
1967 | 1967 | ||
1968 | If you don't allocate row_pointers ahead of time, png_read_png() will | 1968 | If you don't allocate row_pointers ahead of time, png_read_png() will |
1969 | do it, and it'll be free'ed by libpng when you call png_destroy_*(). | 1969 | do it, and it'll be free'ed by libpng when you call png_destroy_*(). |
1970 | 1970 | ||
1971 | .SS The low-level read interface | 1971 | .SS The low-level read interface |
1972 | 1972 | ||
1973 | If you are going the low-level route, you are now ready to read all | 1973 | If you are going the low-level route, you are now ready to read all |
1974 | the file information up to the actual image data. You do this with a | 1974 | the file information up to the actual image data. You do this with a |
1975 | call to png_read_info(). | 1975 | call to png_read_info(). |
1976 | 1976 | ||
1977 | png_read_info(png_ptr, info_ptr); | 1977 | png_read_info(png_ptr, info_ptr); |
1978 | 1978 | ||
1979 | This will process all chunks up to but not including the image data. | 1979 | This will process all chunks up to but not including the image data. |
1980 | 1980 | ||
1981 | This also copies some of the data from the PNG file into the decode structure | 1981 | This also copies some of the data from the PNG file into the decode structure |
1982 | for use in later transformations. Important information copied in is: | 1982 | for use in later transformations. Important information copied in is: |
1983 | 1983 | ||
1984 | 1) The PNG file gamma from the gAMA chunk. This overwrites the default value | 1984 | 1) The PNG file gamma from the gAMA chunk. This overwrites the default value |
1985 | provided by an earlier call to png_set_gamma or png_set_alpha_mode. | 1985 | provided by an earlier call to png_set_gamma or png_set_alpha_mode. |
1986 | 1986 | ||
1987 | 2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This | 1987 | 2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This |
1988 | damages the information provided by an earlier call to png_set_background | 1988 | damages the information provided by an earlier call to png_set_background |
1989 | resulting in unexpected behavior. Libpng-1.5.4 no longer does this. | 1989 | resulting in unexpected behavior. Libpng-1.5.4 no longer does this. |
1990 | 1990 | ||
1991 | 3) The number of significant bits in each component value. Libpng uses this to | 1991 | 3) The number of significant bits in each component value. Libpng uses this to |
1992 | optimize gamma handling by reducing the internal lookup table sizes. | 1992 | optimize gamma handling by reducing the internal lookup table sizes. |
1993 | 1993 | ||
1994 | 4) The transparent color information from a tRNS chunk. This can be modified by | 1994 | 4) The transparent color information from a tRNS chunk. This can be modified by |
1995 | a later call to png_set_tRNS. | 1995 | a later call to png_set_tRNS. |
1996 | 1996 | ||
1997 | .SS Querying the info structure | 1997 | .SS Querying the info structure |
1998 | 1998 | ||
1999 | Functions are used to get the information from the info_ptr once it | 1999 | Functions are used to get the information from the info_ptr once it |
2000 | has been read. Note that these fields may not be completely filled | 2000 | has been read. Note that these fields may not be completely filled |
2001 | in until png_read_end() has read the chunk data following the image. | 2001 | in until png_read_end() has read the chunk data following the image. |
2002 | 2002 | ||
2003 | png_get_IHDR(png_ptr, info_ptr, &width, &height, | 2003 | png_get_IHDR(png_ptr, info_ptr, &width, &height, |
2004 | &bit_depth, &color_type, &interlace_type, | 2004 | &bit_depth, &color_type, &interlace_type, |
2005 | &compression_type, &filter_method); | 2005 | &compression_type, &filter_method); |
2006 | 2006 | ||
2007 | width - holds the width of the image | 2007 | width - holds the width of the image |
2008 | in pixels (up to 2^31). | 2008 | in pixels (up to 2^31). |
2009 | 2009 | ||
2010 | height - holds the height of the image | 2010 | height - holds the height of the image |
2011 | in pixels (up to 2^31). | 2011 | in pixels (up to 2^31). |
2012 | 2012 | ||
2013 | bit_depth - holds the bit depth of one of the | 2013 | bit_depth - holds the bit depth of one of the |
2014 | image channels. (valid values are | 2014 | image channels. (valid values are |
2015 | 1, 2, 4, 8, 16 and depend also on | 2015 | 1, 2, 4, 8, 16 and depend also on |
2016 | the color_type. See also | 2016 | the color_type. See also |
2017 | significant bits (sBIT) below). | 2017 | significant bits (sBIT) below). |
2018 | 2018 | ||
2019 | color_type - describes which color/alpha channels | 2019 | color_type - describes which color/alpha channels |
2020 | are present. | 2020 | are present. |
2021 | PNG_COLOR_TYPE_GRAY | 2021 | PNG_COLOR_TYPE_GRAY |
2022 | (bit depths 1, 2, 4, 8, 16) | 2022 | (bit depths 1, 2, 4, 8, 16) |
2023 | PNG_COLOR_TYPE_GRAY_ALPHA | 2023 | PNG_COLOR_TYPE_GRAY_ALPHA |
2024 | (bit depths 8, 16) | 2024 | (bit depths 8, 16) |
2025 | PNG_COLOR_TYPE_PALETTE | 2025 | PNG_COLOR_TYPE_PALETTE |
2026 | (bit depths 1, 2, 4, 8) | 2026 | (bit depths 1, 2, 4, 8) |
2027 | PNG_COLOR_TYPE_RGB | 2027 | PNG_COLOR_TYPE_RGB |
2028 | (bit_depths 8, 16) | 2028 | (bit_depths 8, 16) |
2029 | PNG_COLOR_TYPE_RGB_ALPHA | 2029 | PNG_COLOR_TYPE_RGB_ALPHA |
2030 | (bit_depths 8, 16) | 2030 | (bit_depths 8, 16) |
2031 | 2031 | ||
2032 | PNG_COLOR_MASK_PALETTE | 2032 | PNG_COLOR_MASK_PALETTE |
2033 | PNG_COLOR_MASK_COLOR | 2033 | PNG_COLOR_MASK_COLOR |
2034 | PNG_COLOR_MASK_ALPHA | 2034 | PNG_COLOR_MASK_ALPHA |
2035 | 2035 | ||
2036 | interlace_type - (PNG_INTERLACE_NONE or | 2036 | interlace_type - (PNG_INTERLACE_NONE or |
2037 | PNG_INTERLACE_ADAM7) | 2037 | PNG_INTERLACE_ADAM7) |
2038 | 2038 | ||
2039 | compression_type - (must be PNG_COMPRESSION_TYPE_BASE | 2039 | compression_type - (must be PNG_COMPRESSION_TYPE_BASE |
2040 | for PNG 1.0) | 2040 | for PNG 1.0) |
2041 | 2041 | ||
2042 | filter_method - (must be PNG_FILTER_TYPE_BASE | 2042 | filter_method - (must be PNG_FILTER_TYPE_BASE |
2043 | for PNG 1.0, and can also be | 2043 | for PNG 1.0, and can also be |
2044 | PNG_INTRAPIXEL_DIFFERENCING if | 2044 | PNG_INTRAPIXEL_DIFFERENCING if |
2045 | the PNG datastream is embedded in | 2045 | the PNG datastream is embedded in |
2046 | a MNG-1.0 datastream) | 2046 | a MNG-1.0 datastream) |
2047 | 2047 | ||
2048 | Any or all of interlace_type, compression_type, or | 2048 | Any or all of interlace_type, compression_type, or |
2049 | filter_method can be NULL if you are | 2049 | filter_method can be NULL if you are |
2050 | not interested in their values. | 2050 | not interested in their values. |
2051 | 2051 | ||
2052 | Note that png_get_IHDR() returns 32-bit data into | 2052 | Note that png_get_IHDR() returns 32-bit data into |
2053 | the application's width and height variables. | 2053 | the application's width and height variables. |
2054 | This is an unsafe situation if these are 16-bit | 2054 | This is an unsafe situation if these are 16-bit |
2055 | variables. In such situations, the | 2055 | variables. In such situations, the |
2056 | png_get_image_width() and png_get_image_height() | 2056 | png_get_image_width() and png_get_image_height() |
2057 | functions described below are safer. | 2057 | functions described below are safer. |
2058 | 2058 | ||
2059 | width = png_get_image_width(png_ptr, | 2059 | width = png_get_image_width(png_ptr, |
2060 | info_ptr); | 2060 | info_ptr); |
2061 | 2061 | ||
2062 | height = png_get_image_height(png_ptr, | 2062 | height = png_get_image_height(png_ptr, |
2063 | info_ptr); | 2063 | info_ptr); |
2064 | 2064 | ||
2065 | bit_depth = png_get_bit_depth(png_ptr, | 2065 | bit_depth = png_get_bit_depth(png_ptr, |
2066 | info_ptr); | 2066 | info_ptr); |
2067 | 2067 | ||
2068 | color_type = png_get_color_type(png_ptr, | 2068 | color_type = png_get_color_type(png_ptr, |
2069 | info_ptr); | 2069 | info_ptr); |
2070 | 2070 | ||
2071 | interlace_type = png_get_interlace_type(png_ptr, | 2071 | interlace_type = png_get_interlace_type(png_ptr, |
2072 | info_ptr); | 2072 | info_ptr); |
2073 | 2073 | ||
2074 | compression_type = png_get_compression_type(png_ptr, | 2074 | compression_type = png_get_compression_type(png_ptr, |
2075 | info_ptr); | 2075 | info_ptr); |
2076 | 2076 | ||
2077 | filter_method = png_get_filter_type(png_ptr, | 2077 | filter_method = png_get_filter_type(png_ptr, |
2078 | info_ptr); | 2078 | info_ptr); |
2079 | 2079 | ||
2080 | channels = png_get_channels(png_ptr, info_ptr); | 2080 | channels = png_get_channels(png_ptr, info_ptr); |
2081 | 2081 | ||
2082 | channels - number of channels of info for the | 2082 | channels - number of channels of info for the |
2083 | color type (valid values are 1 (GRAY, | 2083 | color type (valid values are 1 (GRAY, |
2084 | PALETTE), 2 (GRAY_ALPHA), 3 (RGB), | 2084 | PALETTE), 2 (GRAY_ALPHA), 3 (RGB), |
2085 | 4 (RGB_ALPHA or RGB + filler byte)) | 2085 | 4 (RGB_ALPHA or RGB + filler byte)) |
2086 | 2086 | ||
2087 | rowbytes = png_get_rowbytes(png_ptr, info_ptr); | 2087 | rowbytes = png_get_rowbytes(png_ptr, info_ptr); |
2088 | 2088 | ||
2089 | rowbytes - number of bytes needed to hold a row | 2089 | rowbytes - number of bytes needed to hold a row |
2090 | 2090 | ||
2091 | signature = png_get_signature(png_ptr, info_ptr); | 2091 | signature = png_get_signature(png_ptr, info_ptr); |
2092 | 2092 | ||
2093 | signature - holds the signature read from the | 2093 | signature - holds the signature read from the |
2094 | file (if any). The data is kept in | 2094 | file (if any). The data is kept in |
2095 | the same offset it would be if the | 2095 | the same offset it would be if the |
2096 | whole signature were read (i.e. if an | 2096 | whole signature were read (i.e. if an |
2097 | application had already read in 4 | 2097 | application had already read in 4 |
2098 | bytes of signature before starting | 2098 | bytes of signature before starting |
2099 | libpng, the remaining 4 bytes would | 2099 | libpng, the remaining 4 bytes would |
2100 | be in signature[4] through signature[7] | 2100 | be in signature[4] through signature[7] |
2101 | (see png_set_sig_bytes())). | 2101 | (see png_set_sig_bytes())). |
2102 | 2102 | ||
2103 | These are also important, but their validity depends on whether the chunk | 2103 | These are also important, but their validity depends on whether the chunk |
2104 | has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and | 2104 | has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and |
2105 | png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the | 2105 | png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the |
2106 | data has been read, or zero if it is missing. The parameters to the | 2106 | data has been read, or zero if it is missing. The parameters to the |
2107 | png_get_<chunk> are set directly if they are simple data types, or a | 2107 | png_get_<chunk> are set directly if they are simple data types, or a |
2108 | pointer into the info_ptr is returned for any complex types. | 2108 | pointer into the info_ptr is returned for any complex types. |
2109 | 2109 | ||
2110 | png_get_PLTE(png_ptr, info_ptr, &palette, | 2110 | png_get_PLTE(png_ptr, info_ptr, &palette, |
2111 | &num_palette); | 2111 | &num_palette); |
2112 | 2112 | ||
2113 | palette - the palette for the file | 2113 | palette - the palette for the file |
2114 | (array of png_color) | 2114 | (array of png_color) |
2115 | 2115 | ||
2116 | num_palette - number of entries in the palette | 2116 | num_palette - number of entries in the palette |
2117 | 2117 | ||
2118 | png_get_gAMA(png_ptr, info_ptr, &file_gamma); | 2118 | png_get_gAMA(png_ptr, info_ptr, &file_gamma); |
2119 | png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma); | 2119 | png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma); |
2120 | 2120 | ||
2121 | file_gamma - the gamma at which the file is | 2121 | file_gamma - the gamma at which the file is |
2122 | written (PNG_INFO_gAMA) | 2122 | written (PNG_INFO_gAMA) |
2123 | 2123 | ||
2124 | int_file_gamma - 100,000 times the gamma at which the | 2124 | int_file_gamma - 100,000 times the gamma at which the |
2125 | file is written | 2125 | file is written |
2126 | 2126 | ||
2127 | png_get_cHRM(png_ptr, info_ptr, &white_x, &white_y, &red_x, &red_y, | 2127 | png_get_cHRM(png_ptr, info_ptr, &white_x, &white_y, &red_x, &red_y, |
2128 | &green_x, &green_y, &blue_x, &blue_y) | 2128 | &green_x, &green_y, &blue_x, &blue_y) |
2129 | png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z, &green_X, | 2129 | png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z, &green_X, |
2130 | &green_Y, &green_Z, &blue_X, &blue_Y, &blue_Z) | 2130 | &green_Y, &green_Z, &blue_X, &blue_Y, &blue_Z) |
2131 | png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x, &int_white_y, | 2131 | png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x, &int_white_y, |
2132 | &int_red_x, &int_red_y, &int_green_x, &int_green_y, | 2132 | &int_red_x, &int_red_y, &int_green_x, &int_green_y, |
2133 | &int_blue_x, &int_blue_y) | 2133 | &int_blue_x, &int_blue_y) |
2134 | png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y, | 2134 | png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y, |
2135 | &int_red_Z, &int_green_X, &int_green_Y, &int_green_Z, | 2135 | &int_red_Z, &int_green_X, &int_green_Y, &int_green_Z, |
2136 | &int_blue_X, &int_blue_Y, &int_blue_Z) | 2136 | &int_blue_X, &int_blue_Y, &int_blue_Z) |
2137 | 2137 | ||
2138 | {white,red,green,blue}_{x,y} | 2138 | {white,red,green,blue}_{x,y} |
2139 | A color space encoding specified using the chromaticities | 2139 | A color space encoding specified using the chromaticities |
2140 | of the end points and the white point. (PNG_INFO_cHRM) | 2140 | of the end points and the white point. (PNG_INFO_cHRM) |
2141 | 2141 | ||
2142 | {red,green,blue}_{X,Y,Z} | 2142 | {red,green,blue}_{X,Y,Z} |
2143 | A color space encoding specified using the encoding end | 2143 | A color space encoding specified using the encoding end |
2144 | points - the CIE tristimulus specification of the intended | 2144 | points - the CIE tristimulus specification of the intended |
2145 | color of the red, green and blue channels in the PNG RGB | 2145 | color of the red, green and blue channels in the PNG RGB |
2146 | data. The white point is simply the sum of the three end | 2146 | data. The white point is simply the sum of the three end |
2147 | points. (PNG_INFO_cHRM) | 2147 | points. (PNG_INFO_cHRM) |
2148 | 2148 | ||
2149 | png_get_sRGB(png_ptr, info_ptr, &srgb_intent); | 2149 | png_get_sRGB(png_ptr, info_ptr, &srgb_intent); |
2150 | 2150 | ||
2151 | file_srgb_intent - the rendering intent (PNG_INFO_sRGB) | 2151 | file_srgb_intent - the rendering intent (PNG_INFO_sRGB) |
2152 | The presence of the sRGB chunk | 2152 | The presence of the sRGB chunk |
2153 | means that the pixel data is in the | 2153 | means that the pixel data is in the |
2154 | sRGB color space. This chunk also | 2154 | sRGB color space. This chunk also |
2155 | implies specific values of gAMA and | 2155 | implies specific values of gAMA and |
2156 | cHRM. | 2156 | cHRM. |
2157 | 2157 | ||
2158 | png_get_iCCP(png_ptr, info_ptr, &name, | 2158 | png_get_iCCP(png_ptr, info_ptr, &name, |
2159 | &compression_type, &profile, &proflen); | 2159 | &compression_type, &profile, &proflen); |
2160 | 2160 | ||
2161 | name - The profile name. | 2161 | name - The profile name. |
2162 | 2162 | ||
2163 | compression_type - The compression type; always | 2163 | compression_type - The compression type; always |
2164 | PNG_COMPRESSION_TYPE_BASE for PNG 1.0. | 2164 | PNG_COMPRESSION_TYPE_BASE for PNG 1.0. |
2165 | You may give NULL to this argument to | 2165 | You may give NULL to this argument to |
2166 | ignore it. | 2166 | ignore it. |
2167 | 2167 | ||
2168 | profile - International Color Consortium color | 2168 | profile - International Color Consortium color |
2169 | profile data. May contain NULs. | 2169 | profile data. May contain NULs. |
2170 | 2170 | ||
2171 | proflen - length of profile data in bytes. | 2171 | proflen - length of profile data in bytes. |
2172 | 2172 | ||
2173 | png_get_sBIT(png_ptr, info_ptr, &sig_bit); | 2173 | png_get_sBIT(png_ptr, info_ptr, &sig_bit); |
2174 | 2174 | ||
2175 | sig_bit - the number of significant bits for | 2175 | sig_bit - the number of significant bits for |
2176 | (PNG_INFO_sBIT) each of the gray, | 2176 | (PNG_INFO_sBIT) each of the gray, |
2177 | red, green, and blue channels, | 2177 | red, green, and blue channels, |
2178 | whichever are appropriate for the | 2178 | whichever are appropriate for the |
2179 | given color type (png_color_16) | 2179 | given color type (png_color_16) |
2180 | 2180 | ||
2181 | png_get_tRNS(png_ptr, info_ptr, &trans_alpha, | 2181 | png_get_tRNS(png_ptr, info_ptr, &trans_alpha, |
2182 | &num_trans, &trans_color); | 2182 | &num_trans, &trans_color); |
2183 | 2183 | ||
2184 | trans_alpha - array of alpha (transparency) | 2184 | trans_alpha - array of alpha (transparency) |
2185 | entries for palette (PNG_INFO_tRNS) | 2185 | entries for palette (PNG_INFO_tRNS) |
2186 | 2186 | ||
2187 | num_trans - number of transparent entries | 2187 | num_trans - number of transparent entries |
2188 | (PNG_INFO_tRNS) | 2188 | (PNG_INFO_tRNS) |
2189 | 2189 | ||
2190 | trans_color - graylevel or color sample values of | 2190 | trans_color - graylevel or color sample values of |
2191 | the single transparent color for | 2191 | the single transparent color for |
2192 | non-paletted images (PNG_INFO_tRNS) | 2192 | non-paletted images (PNG_INFO_tRNS) |
2193 | 2193 | ||
2194 | png_get_hIST(png_ptr, info_ptr, &hist); | 2194 | png_get_hIST(png_ptr, info_ptr, &hist); |
2195 | (PNG_INFO_hIST) | 2195 | (PNG_INFO_hIST) |
2196 | 2196 | ||
2197 | hist - histogram of palette (array of | 2197 | hist - histogram of palette (array of |
2198 | png_uint_16) | 2198 | png_uint_16) |
2199 | 2199 | ||
2200 | png_get_tIME(png_ptr, info_ptr, &mod_time); | 2200 | png_get_tIME(png_ptr, info_ptr, &mod_time); |
2201 | 2201 | ||
2202 | mod_time - time image was last modified | 2202 | mod_time - time image was last modified |
2203 | (PNG_VALID_tIME) | 2203 | (PNG_VALID_tIME) |
2204 | 2204 | ||
2205 | png_get_bKGD(png_ptr, info_ptr, &background); | 2205 | png_get_bKGD(png_ptr, info_ptr, &background); |
2206 | 2206 | ||
2207 | background - background color (of type | 2207 | background - background color (of type |
2208 | png_color_16p) (PNG_VALID_bKGD) | 2208 | png_color_16p) (PNG_VALID_bKGD) |
2209 | valid 16-bit red, green and blue | 2209 | valid 16-bit red, green and blue |
2210 | values, regardless of color_type | 2210 | values, regardless of color_type |
2211 | 2211 | ||
2212 | num_comments = png_get_text(png_ptr, info_ptr, | 2212 | num_comments = png_get_text(png_ptr, info_ptr, |
2213 | &text_ptr, &num_text); | 2213 | &text_ptr, &num_text); |
2214 | 2214 | ||
2215 | num_comments - number of comments | 2215 | num_comments - number of comments |
2216 | 2216 | ||
2217 | text_ptr - array of png_text holding image | 2217 | text_ptr - array of png_text holding image |
2218 | comments | 2218 | comments |
2219 | 2219 | ||
2220 | text_ptr[i].compression - type of compression used | 2220 | text_ptr[i].compression - type of compression used |
2221 | on "text" PNG_TEXT_COMPRESSION_NONE | 2221 | on "text" PNG_TEXT_COMPRESSION_NONE |
2222 | PNG_TEXT_COMPRESSION_zTXt | 2222 | PNG_TEXT_COMPRESSION_zTXt |
2223 | PNG_ITXT_COMPRESSION_NONE | 2223 | PNG_ITXT_COMPRESSION_NONE |
2224 | PNG_ITXT_COMPRESSION_zTXt | 2224 | PNG_ITXT_COMPRESSION_zTXt |
2225 | 2225 | ||
2226 | text_ptr[i].key - keyword for comment. Must contain | 2226 | text_ptr[i].key - keyword for comment. Must contain |
2227 | 1-79 characters. | 2227 | 1-79 characters. |
2228 | 2228 | ||
2229 | text_ptr[i].text - text comments for current | 2229 | text_ptr[i].text - text comments for current |
2230 | keyword. Can be empty. | 2230 | keyword. Can be empty. |
2231 | 2231 | ||
2232 | text_ptr[i].text_length - length of text string, | 2232 | text_ptr[i].text_length - length of text string, |
2233 | after decompression, 0 for iTXt | 2233 | after decompression, 0 for iTXt |
2234 | 2234 | ||
2235 | text_ptr[i].itxt_length - length of itxt string, | 2235 | text_ptr[i].itxt_length - length of itxt string, |
2236 | after decompression, 0 for tEXt/zTXt | 2236 | after decompression, 0 for tEXt/zTXt |
2237 | 2237 | ||
2238 | text_ptr[i].lang - language of comment (empty | 2238 | text_ptr[i].lang - language of comment (empty |
2239 | string for unknown). | 2239 | string for unknown). |
2240 | 2240 | ||
2241 | text_ptr[i].lang_key - keyword in UTF-8 | 2241 | text_ptr[i].lang_key - keyword in UTF-8 |
2242 | (empty string for unknown). | 2242 | (empty string for unknown). |
2243 | 2243 | ||
2244 | Note that the itxt_length, lang, and lang_key | 2244 | Note that the itxt_length, lang, and lang_key |
2245 | members of the text_ptr structure only exist when the | 2245 | members of the text_ptr structure only exist when the |
2246 | library is built with iTXt chunk support. Prior to | 2246 | library is built with iTXt chunk support. Prior to |
2247 | libpng-1.4.0 the library was built by default without | 2247 | libpng-1.4.0 the library was built by default without |
2248 | iTXt support. Also note that when iTXt is supported, | 2248 | iTXt support. Also note that when iTXt is supported, |
2249 | they contain NULL pointers when the "compression" | 2249 | they contain NULL pointers when the "compression" |
2250 | field contains PNG_TEXT_COMPRESSION_NONE or | 2250 | field contains PNG_TEXT_COMPRESSION_NONE or |
2251 | PNG_TEXT_COMPRESSION_zTXt. | 2251 | PNG_TEXT_COMPRESSION_zTXt. |
2252 | 2252 | ||
2253 | num_text - number of comments (same as | 2253 | num_text - number of comments (same as |
2254 | num_comments; you can put NULL here | 2254 | num_comments; you can put NULL here |
2255 | to avoid the duplication) | 2255 | to avoid the duplication) |
2256 | 2256 | ||
2257 | Note while png_set_text() will accept text, language, | 2257 | Note while png_set_text() will accept text, language, |
2258 | and translated keywords that can be NULL pointers, the | 2258 | and translated keywords that can be NULL pointers, the |
2259 | structure returned by png_get_text will always contain | 2259 | structure returned by png_get_text will always contain |
2260 | regular zero-terminated C strings. They might be | 2260 | regular zero-terminated C strings. They might be |
2261 | empty strings but they will never be NULL pointers. | 2261 | empty strings but they will never be NULL pointers. |
2262 | 2262 | ||
2263 | num_spalettes = png_get_sPLT(png_ptr, info_ptr, | 2263 | num_spalettes = png_get_sPLT(png_ptr, info_ptr, |
2264 | &palette_ptr); | 2264 | &palette_ptr); |
2265 | 2265 | ||
2266 | num_spalettes - number of sPLT chunks read. | 2266 | num_spalettes - number of sPLT chunks read. |
2267 | 2267 | ||
2268 | palette_ptr - array of palette structures holding | 2268 | palette_ptr - array of palette structures holding |
2269 | contents of one or more sPLT chunks | 2269 | contents of one or more sPLT chunks |
2270 | read. | 2270 | read. |
2271 | 2271 | ||
2272 | png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y, | 2272 | png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y, |
2273 | &unit_type); | 2273 | &unit_type); |
2274 | 2274 | ||
2275 | offset_x - positive offset from the left edge | 2275 | offset_x - positive offset from the left edge |
2276 | of the screen (can be negative) | 2276 | of the screen (can be negative) |
2277 | 2277 | ||
2278 | offset_y - positive offset from the top edge | 2278 | offset_y - positive offset from the top edge |
2279 | of the screen (can be negative) | 2279 | of the screen (can be negative) |
2280 | 2280 | ||
2281 | unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER | 2281 | unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER |
2282 | 2282 | ||
2283 | png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y, | 2283 | png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y, |
2284 | &unit_type); | 2284 | &unit_type); |
2285 | 2285 | ||
2286 | res_x - pixels/unit physical resolution in | 2286 | res_x - pixels/unit physical resolution in |
2287 | x direction | 2287 | x direction |
2288 | 2288 | ||
2289 | res_y - pixels/unit physical resolution in | 2289 | res_y - pixels/unit physical resolution in |
2290 | x direction | 2290 | x direction |
2291 | 2291 | ||
2292 | unit_type - PNG_RESOLUTION_UNKNOWN, | 2292 | unit_type - PNG_RESOLUTION_UNKNOWN, |
2293 | PNG_RESOLUTION_METER | 2293 | PNG_RESOLUTION_METER |
2294 | 2294 | ||
2295 | png_get_sCAL(png_ptr, info_ptr, &unit, &width, | 2295 | png_get_sCAL(png_ptr, info_ptr, &unit, &width, |
2296 | &height) | 2296 | &height) |
2297 | 2297 | ||
2298 | unit - physical scale units (an integer) | 2298 | unit - physical scale units (an integer) |
2299 | 2299 | ||
2300 | width - width of a pixel in physical scale units | 2300 | width - width of a pixel in physical scale units |
2301 | 2301 | ||
2302 | height - height of a pixel in physical scale units | 2302 | height - height of a pixel in physical scale units |
2303 | (width and height are doubles) | 2303 | (width and height are doubles) |
2304 | 2304 | ||
2305 | png_get_sCAL_s(png_ptr, info_ptr, &unit, &width, | 2305 | png_get_sCAL_s(png_ptr, info_ptr, &unit, &width, |
2306 | &height) | 2306 | &height) |
2307 | 2307 | ||
2308 | unit - physical scale units (an integer) | 2308 | unit - physical scale units (an integer) |
2309 | 2309 | ||
2310 | width - width of a pixel in physical scale units | 2310 | width - width of a pixel in physical scale units |
2311 | (expressed as a string) | 2311 | (expressed as a string) |
2312 | 2312 | ||
2313 | height - height of a pixel in physical scale units | 2313 | height - height of a pixel in physical scale units |
2314 | (width and height are strings like "2.54") | 2314 | (width and height are strings like "2.54") |
2315 | 2315 | ||
2316 | num_unknown_chunks = png_get_unknown_chunks(png_ptr, | 2316 | num_unknown_chunks = png_get_unknown_chunks(png_ptr, |
2317 | info_ptr, &unknowns) | 2317 | info_ptr, &unknowns) |
2318 | 2318 | ||
2319 | unknowns - array of png_unknown_chunk | 2319 | unknowns - array of png_unknown_chunk |
2320 | structures holding unknown chunks | 2320 | structures holding unknown chunks |
2321 | 2321 | ||
2322 | unknowns[i].name - name of unknown chunk | 2322 | unknowns[i].name - name of unknown chunk |
2323 | 2323 | ||
2324 | unknowns[i].data - data of unknown chunk | 2324 | unknowns[i].data - data of unknown chunk |
2325 | 2325 | ||
2326 | unknowns[i].size - size of unknown chunk's data | 2326 | unknowns[i].size - size of unknown chunk's data |
2327 | 2327 | ||
2328 | unknowns[i].location - position of chunk in file | 2328 | unknowns[i].location - position of chunk in file |
2329 | 2329 | ||
2330 | The value of "i" corresponds to the order in which the | 2330 | The value of "i" corresponds to the order in which the |
2331 | chunks were read from the PNG file or inserted with the | 2331 | chunks were read from the PNG file or inserted with the |
2332 | png_set_unknown_chunks() function. | 2332 | png_set_unknown_chunks() function. |
2333 | 2333 | ||
2334 | The value of "location" is a bitwise "or" of | 2334 | The value of "location" is a bitwise "or" of |
2335 | 2335 | ||
2336 | PNG_HAVE_IHDR (0x01) | 2336 | PNG_HAVE_IHDR (0x01) |
2337 | PNG_HAVE_PLTE (0x02) | 2337 | PNG_HAVE_PLTE (0x02) |
2338 | PNG_AFTER_IDAT (0x08) | 2338 | PNG_AFTER_IDAT (0x08) |
2339 | 2339 | ||
2340 | The data from the pHYs chunk can be retrieved in several convenient | 2340 | The data from the pHYs chunk can be retrieved in several convenient |
2341 | forms: | 2341 | forms: |
2342 | 2342 | ||
2343 | res_x = png_get_x_pixels_per_meter(png_ptr, | 2343 | res_x = png_get_x_pixels_per_meter(png_ptr, |
2344 | info_ptr) | 2344 | info_ptr) |
2345 | 2345 | ||
2346 | res_y = png_get_y_pixels_per_meter(png_ptr, | 2346 | res_y = png_get_y_pixels_per_meter(png_ptr, |
2347 | info_ptr) | 2347 | info_ptr) |
2348 | 2348 | ||
2349 | res_x_and_y = png_get_pixels_per_meter(png_ptr, | 2349 | res_x_and_y = png_get_pixels_per_meter(png_ptr, |
2350 | info_ptr) | 2350 | info_ptr) |
2351 | 2351 | ||
2352 | res_x = png_get_x_pixels_per_inch(png_ptr, | 2352 | res_x = png_get_x_pixels_per_inch(png_ptr, |
2353 | info_ptr) | 2353 | info_ptr) |
2354 | 2354 | ||
2355 | res_y = png_get_y_pixels_per_inch(png_ptr, | 2355 | res_y = png_get_y_pixels_per_inch(png_ptr, |
2356 | info_ptr) | 2356 | info_ptr) |
2357 | 2357 | ||
2358 | res_x_and_y = png_get_pixels_per_inch(png_ptr, | 2358 | res_x_and_y = png_get_pixels_per_inch(png_ptr, |
2359 | info_ptr) | 2359 | info_ptr) |
2360 | 2360 | ||
2361 | aspect_ratio = png_get_pixel_aspect_ratio(png_ptr, | 2361 | aspect_ratio = png_get_pixel_aspect_ratio(png_ptr, |
2362 | info_ptr) | 2362 | info_ptr) |
2363 | 2363 | ||
2364 | Each of these returns 0 [signifying "unknown"] if | 2364 | Each of these returns 0 [signifying "unknown"] if |
2365 | the data is not present or if res_x is 0; | 2365 | the data is not present or if res_x is 0; |
2366 | res_x_and_y is 0 if res_x != res_y | 2366 | res_x_and_y is 0 if res_x != res_y |
2367 | 2367 | ||
2368 | Note that because of the way the resolutions are | 2368 | Note that because of the way the resolutions are |
2369 | stored internally, the inch conversions won't | 2369 | stored internally, the inch conversions won't |
2370 | come out to exactly even number. For example, | 2370 | come out to exactly even number. For example, |
2371 | 72 dpi is stored as 0.28346 pixels/meter, and | 2371 | 72 dpi is stored as 0.28346 pixels/meter, and |
2372 | when this is retrieved it is 71.9988 dpi, so | 2372 | when this is retrieved it is 71.9988 dpi, so |
2373 | be sure to round the returned value appropriately | 2373 | be sure to round the returned value appropriately |
2374 | if you want to display a reasonable-looking result. | 2374 | if you want to display a reasonable-looking result. |
2375 | 2375 | ||
2376 | The data from the oFFs chunk can be retrieved in several convenient | 2376 | The data from the oFFs chunk can be retrieved in several convenient |
2377 | forms: | 2377 | forms: |
2378 | 2378 | ||
2379 | x_offset = png_get_x_offset_microns(png_ptr, info_ptr); | 2379 | x_offset = png_get_x_offset_microns(png_ptr, info_ptr); |
2380 | 2380 | ||
2381 | y_offset = png_get_y_offset_microns(png_ptr, info_ptr); | 2381 | y_offset = png_get_y_offset_microns(png_ptr, info_ptr); |
2382 | 2382 | ||
2383 | x_offset = png_get_x_offset_inches(png_ptr, info_ptr); | 2383 | x_offset = png_get_x_offset_inches(png_ptr, info_ptr); |
2384 | 2384 | ||
2385 | y_offset = png_get_y_offset_inches(png_ptr, info_ptr); | 2385 | y_offset = png_get_y_offset_inches(png_ptr, info_ptr); |
2386 | 2386 | ||
2387 | Each of these returns 0 [signifying "unknown" if both | 2387 | Each of these returns 0 [signifying "unknown" if both |
2388 | x and y are 0] if the data is not present or if the | 2388 | x and y are 0] if the data is not present or if the |
2389 | chunk is present but the unit is the pixel. The | 2389 | chunk is present but the unit is the pixel. The |
2390 | remark about inexact inch conversions applies here | 2390 | remark about inexact inch conversions applies here |
2391 | as well, because a value in inches can't always be | 2391 | as well, because a value in inches can't always be |
2392 | converted to microns and back without some loss | 2392 | converted to microns and back without some loss |
2393 | of precision. | 2393 | of precision. |
2394 | 2394 | ||
2395 | For more information, see the | 2395 | For more information, see the |
2396 | PNG specification for chunk contents. Be careful with trusting | 2396 | PNG specification for chunk contents. Be careful with trusting |
2397 | rowbytes, as some of the transformations could increase the space | 2397 | rowbytes, as some of the transformations could increase the space |
2398 | needed to hold a row (expand, filler, gray_to_rgb, etc.). | 2398 | needed to hold a row (expand, filler, gray_to_rgb, etc.). |
2399 | See png_read_update_info(), below. | 2399 | See png_read_update_info(), below. |
2400 | 2400 | ||
2401 | A quick word about text_ptr and num_text. PNG stores comments in | 2401 | A quick word about text_ptr and num_text. PNG stores comments in |
2402 | keyword/text pairs, one pair per chunk, with no limit on the number | 2402 | keyword/text pairs, one pair per chunk, with no limit on the number |
2403 | of text chunks, and a 2^31 byte limit on their size. While there are | 2403 | of text chunks, and a 2^31 byte limit on their size. While there are |
2404 | suggested keywords, there is no requirement to restrict the use to these | 2404 | suggested keywords, there is no requirement to restrict the use to these |
2405 | strings. It is strongly suggested that keywords and text be sensible | 2405 | strings. It is strongly suggested that keywords and text be sensible |
2406 | to humans (that's the point), so don't use abbreviations. Non-printing | 2406 | to humans (that's the point), so don't use abbreviations. Non-printing |
2407 | symbols are not allowed. See the PNG specification for more details. | 2407 | symbols are not allowed. See the PNG specification for more details. |
2408 | There is also no requirement to have text after the keyword. | 2408 | There is also no requirement to have text after the keyword. |
2409 | 2409 | ||
2410 | Keywords should be limited to 79 Latin-1 characters without leading or | 2410 | Keywords should be limited to 79 Latin-1 characters without leading or |
2411 | trailing spaces, but non-consecutive spaces are allowed within the | 2411 | trailing spaces, but non-consecutive spaces are allowed within the |
2412 | keyword. It is possible to have the same keyword any number of times. | 2412 | keyword. It is possible to have the same keyword any number of times. |
2413 | The text_ptr is an array of png_text structures, each holding a | 2413 | The text_ptr is an array of png_text structures, each holding a |
2414 | pointer to a language string, a pointer to a keyword and a pointer to | 2414 | pointer to a language string, a pointer to a keyword and a pointer to |
2415 | a text string. The text string, language code, and translated | 2415 | a text string. The text string, language code, and translated |
2416 | keyword may be empty or NULL pointers. The keyword/text | 2416 | keyword may be empty or NULL pointers. The keyword/text |
2417 | pairs are put into the array in the order that they are received. | 2417 | pairs are put into the array in the order that they are received. |
2418 | However, some or all of the text chunks may be after the image, so, to | 2418 | However, some or all of the text chunks may be after the image, so, to |
2419 | make sure you have read all the text chunks, don't mess with these | 2419 | make sure you have read all the text chunks, don't mess with these |
2420 | until after you read the stuff after the image. This will be | 2420 | until after you read the stuff after the image. This will be |
2421 | mentioned again below in the discussion that goes with png_read_end(). | 2421 | mentioned again below in the discussion that goes with png_read_end(). |
2422 | 2422 | ||
2423 | .SS Input transformations | 2423 | .SS Input transformations |
2424 | 2424 | ||
2425 | After you've read the header information, you can set up the library | 2425 | After you've read the header information, you can set up the library |
2426 | to handle any special transformations of the image data. The various | 2426 | to handle any special transformations of the image data. The various |
2427 | ways to transform the data will be described in the order that they | 2427 | ways to transform the data will be described in the order that they |
2428 | should occur. This is important, as some of these change the color | 2428 | should occur. This is important, as some of these change the color |
2429 | type and/or bit depth of the data, and some others only work on | 2429 | type and/or bit depth of the data, and some others only work on |
2430 | certain color types and bit depths. | 2430 | certain color types and bit depths. |
2431 | 2431 | ||
2432 | Transformations you request are ignored if they don't have any meaning for a | 2432 | Transformations you request are ignored if they don't have any meaning for a |
2433 | particular input data format. However some transformations can have an effect | 2433 | particular input data format. However some transformations can have an effect |
2434 | as a result of a previous transformation. If you specify a contradictory set of | 2434 | as a result of a previous transformation. If you specify a contradictory set of |
2435 | transformations, for example both adding and removing the alpha channel, you | 2435 | transformations, for example both adding and removing the alpha channel, you |
2436 | cannot predict the final result. | 2436 | cannot predict the final result. |
2437 | 2437 | ||
2438 | The color used for the transparency values should be supplied in the same | 2438 | The color used for the transparency values should be supplied in the same |
2439 | format/depth as the current image data. It is stored in the same format/depth | 2439 | format/depth as the current image data. It is stored in the same format/depth |
2440 | as the image data in a tRNS chunk, so this is what libpng expects for this data. | 2440 | as the image data in a tRNS chunk, so this is what libpng expects for this data. |
2441 | 2441 | ||
2442 | The color used for the background value depends on the need_expand argument as | 2442 | The color used for the background value depends on the need_expand argument as |
2443 | described below. | 2443 | described below. |
2444 | 2444 | ||
2445 | Data will be decoded into the supplied row buffers packed into bytes | 2445 | Data will be decoded into the supplied row buffers packed into bytes |
2446 | unless the library has been told to transform it into another format. | 2446 | unless the library has been told to transform it into another format. |
2447 | For example, 4 bit/pixel paletted or grayscale data will be returned | 2447 | For example, 4 bit/pixel paletted or grayscale data will be returned |
2448 | 2 pixels/byte with the leftmost pixel in the high-order bits of the | 2448 | 2 pixels/byte with the leftmost pixel in the high-order bits of the |
2449 | byte, unless png_set_packing() is called. 8-bit RGB data will be stored | 2449 | byte, unless png_set_packing() is called. 8-bit RGB data will be stored |
2450 | in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha() | 2450 | in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha() |
2451 | is called to insert filler bytes, either before or after each RGB triplet. | 2451 | is called to insert filler bytes, either before or after each RGB triplet. |
2452 | 16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant | 2452 | 16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant |
2453 | byte of the color value first, unless png_set_scale_16() is called to | 2453 | byte of the color value first, unless png_set_scale_16() is called to |
2454 | transform it to regular RGB RGB triplets, or png_set_filler() or | 2454 | transform it to regular RGB RGB triplets, or png_set_filler() or |
2455 | png_set_add alpha() is called to insert filler bytes, either before or | 2455 | png_set_add alpha() is called to insert filler bytes, either before or |
2456 | after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can | 2456 | after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can |
2457 | be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(), | 2457 | be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(), |
2458 | or png_set_scale_16(). | 2458 | or png_set_scale_16(). |
2459 | 2459 | ||
2460 | The following code transforms grayscale images of less than 8 to 8 bits, | 2460 | The following code transforms grayscale images of less than 8 to 8 bits, |
2461 | changes paletted images to RGB, and adds a full alpha channel if there is | 2461 | changes paletted images to RGB, and adds a full alpha channel if there is |
2462 | transparency information in a tRNS chunk. This is most useful on | 2462 | transparency information in a tRNS chunk. This is most useful on |
2463 | grayscale images with bit depths of 2 or 4 or if there is a multiple-image | 2463 | grayscale images with bit depths of 2 or 4 or if there is a multiple-image |
2464 | viewing application that wishes to treat all images in the same way. | 2464 | viewing application that wishes to treat all images in the same way. |
2465 | 2465 | ||
2466 | if (color_type == PNG_COLOR_TYPE_PALETTE) | 2466 | if (color_type == PNG_COLOR_TYPE_PALETTE) |
2467 | png_set_palette_to_rgb(png_ptr); | 2467 | png_set_palette_to_rgb(png_ptr); |
2468 | 2468 | ||
2469 | if (png_get_valid(png_ptr, info_ptr, | 2469 | if (png_get_valid(png_ptr, info_ptr, |
2470 | PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr); | 2470 | PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr); |
2471 | 2471 | ||
2472 | if (color_type == PNG_COLOR_TYPE_GRAY && | 2472 | if (color_type == PNG_COLOR_TYPE_GRAY && |
2473 | bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr); | 2473 | bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr); |
2474 | 2474 | ||
2475 | The first two functions are actually aliases for png_set_expand(), added | 2475 | The first two functions are actually aliases for png_set_expand(), added |
2476 | in libpng version 1.0.4, with the function names expanded to improve code | 2476 | in libpng version 1.0.4, with the function names expanded to improve code |
2477 | readability. In some future version they may actually do different | 2477 | readability. In some future version they may actually do different |
2478 | things. | 2478 | things. |
2479 | 2479 | ||
2480 | As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was | 2480 | As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was |
2481 | added. It expands the sample depth without changing tRNS to alpha. | 2481 | added. It expands the sample depth without changing tRNS to alpha. |
2482 | 2482 | ||
2483 | As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as | 2483 | As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as |
2484 | png_set_expand(); however, the resultant channels have 16 bits rather than 8. | 2484 | png_set_expand(); however, the resultant channels have 16 bits rather than 8. |
2485 | Use this when the output color or gray channels are made linear to avoid fairly | 2485 | Use this when the output color or gray channels are made linear to avoid fairly |
2486 | severe accuracy loss. | 2486 | severe accuracy loss. |
2487 | 2487 | ||
2488 | if (bit_depth < 16) | 2488 | if (bit_depth < 16) |
2489 | png_set_expand_16(png_ptr); | 2489 | png_set_expand_16(png_ptr); |
2490 | 2490 | ||
2491 | PNG can have files with 16 bits per channel. If you only can handle | 2491 | PNG can have files with 16 bits per channel. If you only can handle |
2492 | 8 bits per channel, this will strip the pixels down to 8-bit. | 2492 | 8 bits per channel, this will strip the pixels down to 8-bit. |
2493 | 2493 | ||
2494 | if (bit_depth == 16) | 2494 | if (bit_depth == 16) |
2495 | #if PNG_LIBPNG_VER >= 10504 | 2495 | #if PNG_LIBPNG_VER >= 10504 |
2496 | png_set_scale_16(png_ptr); | 2496 | png_set_scale_16(png_ptr); |
2497 | #else | 2497 | #else |
2498 | png_set_strip_16(png_ptr); | 2498 | png_set_strip_16(png_ptr); |
2499 | #endif | 2499 | #endif |
2500 | 2500 | ||
2501 | (The more accurate "png_set_scale_16()" API became available in libpng version | 2501 | (The more accurate "png_set_scale_16()" API became available in libpng version |
2502 | 1.5.4). | 2502 | 1.5.4). |
2503 | 2503 | ||
2504 | If you need to process the alpha channel on the image separately from the image | 2504 | If you need to process the alpha channel on the image separately from the image |
2505 | data (for example if you convert it to a bitmap mask) it is possible to have | 2505 | data (for example if you convert it to a bitmap mask) it is possible to have |
2506 | libpng strip the channel leaving just RGB or gray data: | 2506 | libpng strip the channel leaving just RGB or gray data: |
2507 | 2507 | ||
2508 | if (color_type & PNG_COLOR_MASK_ALPHA) | 2508 | if (color_type & PNG_COLOR_MASK_ALPHA) |
2509 | png_set_strip_alpha(png_ptr); | 2509 | png_set_strip_alpha(png_ptr); |
2510 | 2510 | ||
2511 | If you strip the alpha channel you need to find some other way of dealing with | 2511 | If you strip the alpha channel you need to find some other way of dealing with |
2512 | the information. If, instead, you want to convert the image to an opaque | 2512 | the information. If, instead, you want to convert the image to an opaque |
2513 | version with no alpha channel use png_set_background; see below. | 2513 | version with no alpha channel use png_set_background; see below. |
2514 | 2514 | ||
2515 | As of libpng version 1.5.2, almost all useful expansions are supported, the | 2515 | As of libpng version 1.5.2, almost all useful expansions are supported, the |
2516 | major ommissions are conversion of grayscale to indexed images (which can be | 2516 | major ommissions are conversion of grayscale to indexed images (which can be |
2517 | done trivially in the application) and conversion of indexed to grayscale (which | 2517 | done trivially in the application) and conversion of indexed to grayscale (which |
2518 | can be done by a trivial manipulation of the palette.) | 2518 | can be done by a trivial manipulation of the palette.) |
2519 | 2519 | ||
2520 | In the following table, the 01 means grayscale with depth<8, 31 means | 2520 | In the following table, the 01 means grayscale with depth<8, 31 means |
2521 | indexed with depth<8, other numerals represent the color type, "T" means | 2521 | indexed with depth<8, other numerals represent the color type, "T" means |
2522 | the tRNS chunk is present, A means an alpha channel is present, and O | 2522 | the tRNS chunk is present, A means an alpha channel is present, and O |
2523 | means tRNS or alpha is present but all pixels in the image are opaque. | 2523 | means tRNS or alpha is present but all pixels in the image are opaque. |
2524 | 2524 | ||
2525 | FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O | 2525 | FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O |
2526 | TO | 2526 | TO |
2527 | 01 - [G] - - - - - - - - - - - - - | 2527 | 01 - [G] - - - - - - - - - - - - - |
2528 | 31 [Q] Q [Q] [Q] [Q] Q Q Q Q Q Q [Q] [Q] Q Q | 2528 | 31 [Q] Q [Q] [Q] [Q] Q Q Q Q Q Q [Q] [Q] Q Q |
2529 | 0 1 G + . . G G G G G G B B GB GB | 2529 | 0 1 G + . . G G G G G G B B GB GB |
2530 | 0T lt Gt t + . Gt G G Gt G G Bt Bt GBt GBt | 2530 | 0T lt Gt t + . Gt G G Gt G G Bt Bt GBt GBt |
2531 | 0O lt Gt t . + Gt Gt G Gt Gt G Bt Bt GBt GBt | 2531 | 0O lt Gt t . + Gt Gt G Gt Gt G Bt Bt GBt GBt |
2532 | 2 C P C C C + . . C - - CB CB B B | 2532 | 2 C P C C C + . . C - - CB CB B B |
2533 | 2T Ct - Ct C C t + t - - - CBt CBt Bt Bt | 2533 | 2T Ct - Ct C C t + t - - - CBt CBt Bt Bt |
2534 | 2O Ct - Ct C C t t + - - - CBt CBt Bt Bt | 2534 | 2O Ct - Ct C C t t + - - - CBt CBt Bt Bt |
2535 | 3 [Q] p [Q] [Q] [Q] Q Q Q + . . [Q] [Q] Q Q | 2535 | 3 [Q] p [Q] [Q] [Q] Q Q Q + . . [Q] [Q] Q Q |
2536 | 3T [Qt] p [Qt][Q] [Q] Qt Qt Qt t + t [Qt][Qt] Qt Qt | 2536 | 3T [Qt] p [Qt][Q] [Q] Qt Qt Qt t + t [Qt][Qt] Qt Qt |
2537 | 3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt | 2537 | 3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt |
2538 | 4A lA G A T T GA GT GT GA GT GT + BA G GBA | 2538 | 4A lA G A T T GA GT GT GA GT GT + BA G GBA |
2539 | 4O lA GBA A T T GA GT GT GA GT GT BA + GBA G | 2539 | 4O lA GBA A T T GA GT GT GA GT GT BA + GBA G |
2540 | 6A CA PA CA C C A T tT PA P P C CBA + BA | 2540 | 6A CA PA CA C C A T tT PA P P C CBA + BA |
2541 | 6O CA PBA CA C C A tT T PA P P CBA C BA + | 2541 | 6O CA PBA CA C C A tT T PA P P CBA C BA + |
2542 | 2542 | ||
2543 | Within the matrix, | 2543 | Within the matrix, |
2544 | "+" identifies entries where 'from' and 'to' are the same. | 2544 | "+" identifies entries where 'from' and 'to' are the same. |
2545 | "-" means the transformation is not supported. | 2545 | "-" means the transformation is not supported. |
2546 | "." means nothing is necessary (a tRNS chunk can just be ignored). | 2546 | "." means nothing is necessary (a tRNS chunk can just be ignored). |
2547 | "t" means the transformation is obtained by png_set_tRNS. | 2547 | "t" means the transformation is obtained by png_set_tRNS. |
2548 | "A" means the transformation is obtained by png_set_add_alpha(). | 2548 | "A" means the transformation is obtained by png_set_add_alpha(). |
2549 | "X" means the transformation is obtained by png_set_expand(). | 2549 | "X" means the transformation is obtained by png_set_expand(). |
2550 | "1" means the transformation is obtained by | 2550 | "1" means the transformation is obtained by |
2551 | png_set_expand_gray_1_2_4_to_8() (and by png_set_expand() if there | 2551 | png_set_expand_gray_1_2_4_to_8() (and by png_set_expand() if there |
2552 | is no transparency in the original or the final format). | 2552 | is no transparency in the original or the final format). |
2553 | "C" means the transformation is obtained by png_set_gray_to_rgb(). | 2553 | "C" means the transformation is obtained by png_set_gray_to_rgb(). |
2554 | "G" means the transformation is obtained by png_set_rgb_to_gray(). | 2554 | "G" means the transformation is obtained by png_set_rgb_to_gray(). |
2555 | "P" means the transformation is obtained by | 2555 | "P" means the transformation is obtained by |
2556 | png_set_expand_palette_to_rgb(). | 2556 | png_set_expand_palette_to_rgb(). |
2557 | "p" means the transformation is obtained by png_set_packing(). | 2557 | "p" means the transformation is obtained by png_set_packing(). |
2558 | "Q" means the transformation is obtained by png_set_quantize(). | 2558 | "Q" means the transformation is obtained by png_set_quantize(). |
2559 | "T" means the transformation is obtained by png_set_tRNS_to_alpha(). | 2559 | "T" means the transformation is obtained by png_set_tRNS_to_alpha(). |
2560 | "B" means the transformation is obtained by png_set_background(), or | 2560 | "B" means the transformation is obtained by png_set_background(), or |
2561 | png_strip_alpha(). | 2561 | png_strip_alpha(). |
2562 | 2562 | ||
2563 | When an entry has multiple transforms listed all are required to cause the | 2563 | When an entry has multiple transforms listed all are required to cause the |
2564 | right overall transformation. When two transforms are separated by a comma | 2564 | right overall transformation. When two transforms are separated by a comma |
2565 | either will do the job. When transforms are enclosed in [] the transform should | 2565 | either will do the job. When transforms are enclosed in [] the transform should |
2566 | do the job but this is currently unimplemented - a different format will result | 2566 | do the job but this is currently unimplemented - a different format will result |
2567 | if the suggested transformations are used. | 2567 | if the suggested transformations are used. |
2568 | 2568 | ||
2569 | In PNG files, the alpha channel in an image | 2569 | In PNG files, the alpha channel in an image |
2570 | is the level of opacity. If you need the alpha channel in an image to | 2570 | is the level of opacity. If you need the alpha channel in an image to |
2571 | be the level of transparency instead of opacity, you can invert the | 2571 | be the level of transparency instead of opacity, you can invert the |
2572 | alpha channel (or the tRNS chunk data) after it's read, so that 0 is | 2572 | alpha channel (or the tRNS chunk data) after it's read, so that 0 is |
2573 | fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit | 2573 | fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit |
2574 | images) is fully transparent, with | 2574 | images) is fully transparent, with |
2575 | 2575 | ||
2576 | png_set_invert_alpha(png_ptr); | 2576 | png_set_invert_alpha(png_ptr); |
2577 | 2577 | ||
2578 | PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as | 2578 | PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as |
2579 | they can, resulting in, for example, 8 pixels per byte for 1 bit | 2579 | they can, resulting in, for example, 8 pixels per byte for 1 bit |
2580 | files. This code expands to 1 pixel per byte without changing the | 2580 | files. This code expands to 1 pixel per byte without changing the |
2581 | values of the pixels: | 2581 | values of the pixels: |
2582 | 2582 | ||
2583 | if (bit_depth < 8) | 2583 | if (bit_depth < 8) |
2584 | png_set_packing(png_ptr); | 2584 | png_set_packing(png_ptr); |
2585 | 2585 | ||
2586 | PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels | 2586 | PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels |
2587 | stored in a PNG image have been "scaled" or "shifted" up to the next | 2587 | stored in a PNG image have been "scaled" or "shifted" up to the next |
2588 | higher possible bit depth (e.g. from 5 bits/sample in the range [0,31] | 2588 | higher possible bit depth (e.g. from 5 bits/sample in the range [0,31] |
2589 | to 8 bits/sample in the range [0, 255]). However, it is also possible | 2589 | to 8 bits/sample in the range [0, 255]). However, it is also possible |
2590 | to convert the PNG pixel data back to the original bit depth of the | 2590 | to convert the PNG pixel data back to the original bit depth of the |
2591 | image. This call reduces the pixels back down to the original bit depth: | 2591 | image. This call reduces the pixels back down to the original bit depth: |
2592 | 2592 | ||
2593 | png_color_8p sig_bit; | 2593 | png_color_8p sig_bit; |
2594 | 2594 | ||
2595 | if (png_get_sBIT(png_ptr, info_ptr, &sig_bit)) | 2595 | if (png_get_sBIT(png_ptr, info_ptr, &sig_bit)) |
2596 | png_set_shift(png_ptr, sig_bit); | 2596 | png_set_shift(png_ptr, sig_bit); |
2597 | 2597 | ||
2598 | PNG files store 3-color pixels in red, green, blue order. This code | 2598 | PNG files store 3-color pixels in red, green, blue order. This code |
2599 | changes the storage of the pixels to blue, green, red: | 2599 | changes the storage of the pixels to blue, green, red: |
2600 | 2600 | ||
2601 | if (color_type == PNG_COLOR_TYPE_RGB || | 2601 | if (color_type == PNG_COLOR_TYPE_RGB || |
2602 | color_type == PNG_COLOR_TYPE_RGB_ALPHA) | 2602 | color_type == PNG_COLOR_TYPE_RGB_ALPHA) |
2603 | png_set_bgr(png_ptr); | 2603 | png_set_bgr(png_ptr); |
2604 | 2604 | ||
2605 | PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them | 2605 | PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them |
2606 | into 4 or 8 bytes for windowing systems that need them in this format: | 2606 | into 4 or 8 bytes for windowing systems that need them in this format: |
2607 | 2607 | ||
2608 | if (color_type == PNG_COLOR_TYPE_RGB) | 2608 | if (color_type == PNG_COLOR_TYPE_RGB) |
2609 | png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE); | 2609 | png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE); |
2610 | 2610 | ||
2611 | where "filler" is the 8 or 16-bit number to fill with, and the location is | 2611 | where "filler" is the 8 or 16-bit number to fill with, and the location is |
2612 | either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether | 2612 | either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether |
2613 | you want the filler before the RGB or after. This transformation | 2613 | you want the filler before the RGB or after. This transformation |
2614 | does not affect images that already have full alpha channels. To add an | 2614 | does not affect images that already have full alpha channels. To add an |
2615 | opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which | 2615 | opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which |
2616 | will generate RGBA pixels. | 2616 | will generate RGBA pixels. |
2617 | 2617 | ||
2618 | Note that png_set_filler() does not change the color type. If you want | 2618 | Note that png_set_filler() does not change the color type. If you want |
2619 | to do that, you can add a true alpha channel with | 2619 | to do that, you can add a true alpha channel with |
2620 | 2620 | ||
2621 | if (color_type == PNG_COLOR_TYPE_RGB || | 2621 | if (color_type == PNG_COLOR_TYPE_RGB || |
2622 | color_type == PNG_COLOR_TYPE_GRAY) | 2622 | color_type == PNG_COLOR_TYPE_GRAY) |
2623 | png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER); | 2623 | png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER); |
2624 | 2624 | ||
2625 | where "filler" contains the alpha value to assign to each pixel. | 2625 | where "filler" contains the alpha value to assign to each pixel. |
2626 | This function was added in libpng-1.2.7. | 2626 | This function was added in libpng-1.2.7. |
2627 | 2627 | ||
2628 | If you are reading an image with an alpha channel, and you need the | 2628 | If you are reading an image with an alpha channel, and you need the |
2629 | data as ARGB instead of the normal PNG format RGBA: | 2629 | data as ARGB instead of the normal PNG format RGBA: |
2630 | 2630 | ||
2631 | if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) | 2631 | if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) |
2632 | png_set_swap_alpha(png_ptr); | 2632 | png_set_swap_alpha(png_ptr); |
2633 | 2633 | ||
2634 | For some uses, you may want a grayscale image to be represented as | 2634 | For some uses, you may want a grayscale image to be represented as |
2635 | RGB. This code will do that conversion: | 2635 | RGB. This code will do that conversion: |
2636 | 2636 | ||
2637 | if (color_type == PNG_COLOR_TYPE_GRAY || | 2637 | if (color_type == PNG_COLOR_TYPE_GRAY || |
2638 | color_type == PNG_COLOR_TYPE_GRAY_ALPHA) | 2638 | color_type == PNG_COLOR_TYPE_GRAY_ALPHA) |
2639 | png_set_gray_to_rgb(png_ptr); | 2639 | png_set_gray_to_rgb(png_ptr); |
2640 | 2640 | ||
2641 | Conversely, you can convert an RGB or RGBA image to grayscale or grayscale | 2641 | Conversely, you can convert an RGB or RGBA image to grayscale or grayscale |
2642 | with alpha. | 2642 | with alpha. |
2643 | 2643 | ||
2644 | if (color_type == PNG_COLOR_TYPE_RGB || | 2644 | if (color_type == PNG_COLOR_TYPE_RGB || |
2645 | color_type == PNG_COLOR_TYPE_RGB_ALPHA) | 2645 | color_type == PNG_COLOR_TYPE_RGB_ALPHA) |
2646 | png_set_rgb_to_gray(png_ptr, error_action, double red_weight, | 2646 | png_set_rgb_to_gray(png_ptr, error_action, double red_weight, |
2647 | double green_weight); | 2647 | double green_weight); |
2648 | 2648 | ||
2649 | error_action = 1: silently do the conversion | 2649 | error_action = 1: silently do the conversion |
2650 | 2650 | ||
2651 | error_action = 2: issue a warning if the original | 2651 | error_action = 2: issue a warning if the original |
2652 | image has any pixel where | 2652 | image has any pixel where |
2653 | red != green or red != blue | 2653 | red != green or red != blue |
2654 | 2654 | ||
2655 | error_action = 3: issue an error and abort the | 2655 | error_action = 3: issue an error and abort the |
2656 | conversion if the original | 2656 | conversion if the original |
2657 | image has any pixel where | 2657 | image has any pixel where |
2658 | red != green or red != blue | 2658 | red != green or red != blue |
2659 | 2659 | ||
2660 | red_weight: weight of red component | 2660 | red_weight: weight of red component |
2661 | 2661 | ||
2662 | green_weight: weight of green component | 2662 | green_weight: weight of green component |
2663 | If either weight is negative, default | 2663 | If either weight is negative, default |
2664 | weights are used. | 2664 | weights are used. |
2665 | 2665 | ||
2666 | In the corresponding fixed point API the red_weight and green_weight values are | 2666 | In the corresponding fixed point API the red_weight and green_weight values are |
2667 | simply scaled by 100,000: | 2667 | simply scaled by 100,000: |
2668 | 2668 | ||
2669 | png_set_rgb_to_gray(png_ptr, error_action, png_fixed_point red_weight, | 2669 | png_set_rgb_to_gray(png_ptr, error_action, png_fixed_point red_weight, |
2670 | png_fixed_point green_weight); | 2670 | png_fixed_point green_weight); |
2671 | 2671 | ||
2672 | If you have set error_action = 1 or 2, you can | 2672 | If you have set error_action = 1 or 2, you can |
2673 | later check whether the image really was gray, after processing | 2673 | later check whether the image really was gray, after processing |
2674 | the image rows, with the png_get_rgb_to_gray_status(png_ptr) function. | 2674 | the image rows, with the png_get_rgb_to_gray_status(png_ptr) function. |
2675 | It will return a png_byte that is zero if the image was gray or | 2675 | It will return a png_byte that is zero if the image was gray or |
2676 | 1 if there were any non-gray pixels. Background and sBIT data | 2676 | 1 if there were any non-gray pixels. Background and sBIT data |
2677 | will be silently converted to grayscale, using the green channel | 2677 | will be silently converted to grayscale, using the green channel |
2678 | data for sBIT, regardless of the error_action setting. | 2678 | data for sBIT, regardless of the error_action setting. |
2679 | 2679 | ||
2680 | The default values come from the PNG file cHRM chunk if present; otherwise, the | 2680 | The default values come from the PNG file cHRM chunk if present; otherwise, the |
2681 | defaults correspond to the ITU-R recommendation 709, and also the sRGB color | 2681 | defaults correspond to the ITU-R recommendation 709, and also the sRGB color |
2682 | space, as recommended in the Charles Poynton's Colour FAQ, | 2682 | space, as recommended in the Charles Poynton's Colour FAQ, |
2683 | <http://www.poynton.com/>, in section 9: | 2683 | <http://www.poynton.com/>, in section 9: |
2684 | 2684 | ||
2685 | <http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9> | 2685 | <http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9> |
2686 | 2686 | ||
2687 | Y = 0.2126 * R + 0.7152 * G + 0.0722 * B | 2687 | Y = 0.2126 * R + 0.7152 * G + 0.0722 * B |
2688 | 2688 | ||
2689 | Previous versions of this document, 1998 through 2002, recommended a slightly | 2689 | Previous versions of this document, 1998 through 2002, recommended a slightly |
2690 | different formula: | 2690 | different formula: |
2691 | 2691 | ||
2692 | Y = 0.212671 * R + 0.715160 * G + 0.072169 * B | 2692 | Y = 0.212671 * R + 0.715160 * G + 0.072169 * B |
2693 | 2693 | ||
2694 | Libpng uses an integer approximation: | 2694 | Libpng uses an integer approximation: |
2695 | 2695 | ||
2696 | Y = (6968 * R + 23434 * G + 2366 * B)/32768 | 2696 | Y = (6968 * R + 23434 * G + 2366 * B)/32768 |
2697 | 2697 | ||
2698 | The calculation is done in a linear colorspace, if the image gamma | 2698 | The calculation is done in a linear colorspace, if the image gamma |
2699 | can be determined. | 2699 | can be determined. |
2700 | 2700 | ||
2701 | The png_set_background() function has been described already; it tells libpng to | 2701 | The png_set_background() function has been described already; it tells libpng to |
2702 | composite images with alpha or simple transparency against the supplied | 2702 | composite images with alpha or simple transparency against the supplied |
2703 | background color. For compatibility with versions of libpng earlier than | 2703 | background color. For compatibility with versions of libpng earlier than |
2704 | libpng-1.5.4 it is recommended that you call the function after reading the file | 2704 | libpng-1.5.4 it is recommended that you call the function after reading the file |
2705 | header, even if you don't want to use the color in a bKGD chunk, if one exists. | 2705 | header, even if you don't want to use the color in a bKGD chunk, if one exists. |
2706 | 2706 | ||
2707 | If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid), | 2707 | If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid), |
2708 | you may use this color, or supply another color more suitable for | 2708 | you may use this color, or supply another color more suitable for |
2709 | the current display (e.g., the background color from a web page). You | 2709 | the current display (e.g., the background color from a web page). You |
2710 | need to tell libpng how the color is represented, both the format of the | 2710 | need to tell libpng how the color is represented, both the format of the |
2711 | component values in the color (the number of bits) and the gamma encoding of the | 2711 | component values in the color (the number of bits) and the gamma encoding of the |
2712 | color. The function takes two arguments, background_gamma_mode and need_expand | 2712 | color. The function takes two arguments, background_gamma_mode and need_expand |
2713 | to convey this information, however only two combinations are likely to be | 2713 | to convey this information, however only two combinations are likely to be |
2714 | useful: | 2714 | useful: |
2715 | 2715 | ||
2716 | png_color_16 my_background; | 2716 | png_color_16 my_background; |
2717 | png_color_16p image_background; | 2717 | png_color_16p image_background; |
2718 | 2718 | ||
2719 | if (png_get_bKGD(png_ptr, info_ptr, &image_background)) | 2719 | if (png_get_bKGD(png_ptr, info_ptr, &image_background)) |
2720 | png_set_background(png_ptr, image_background, | 2720 | png_set_background(png_ptr, image_background, |
2721 | PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1); | 2721 | PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1); |
2722 | else | 2722 | else |
2723 | png_set_background(png_ptr, &my_background, | 2723 | png_set_background(png_ptr, &my_background, |
2724 | PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1); | 2724 | PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1); |
2725 | 2725 | ||
2726 | The second call was described above - my_background is in the format of the | 2726 | The second call was described above - my_background is in the format of the |
2727 | final, display, output produced by libpng. Because you now know the format of | 2727 | final, display, output produced by libpng. Because you now know the format of |
2728 | the PNG it is possible to avoid the need to choose either 8-bit or 16-bit | 2728 | the PNG it is possible to avoid the need to choose either 8-bit or 16-bit |
2729 | output and to retain palette images (the palette colors will be modified | 2729 | output and to retain palette images (the palette colors will be modified |
2730 | appropriately and the tRNS chunk removed.) However, if you are doing this, | 2730 | appropriately and the tRNS chunk removed.) However, if you are doing this, |
2731 | take great care not to ask for transformations without checking first that | 2731 | take great care not to ask for transformations without checking first that |
2732 | they apply! | 2732 | they apply! |
2733 | 2733 | ||
2734 | In the first call the background color has the original bit depth and color type | 2734 | In the first call the background color has the original bit depth and color type |
2735 | of the PNG file. So, for palette images the color is supplied as a palette | 2735 | of the PNG file. So, for palette images the color is supplied as a palette |
2736 | index and for low bit greyscale images the color is a reduced bit value in | 2736 | index and for low bit greyscale images the color is a reduced bit value in |
2737 | image_background->gray. | 2737 | image_background->gray. |
2738 | 2738 | ||
2739 | If you didn't call png_set_gamma() before reading the file header, for example | 2739 | If you didn't call png_set_gamma() before reading the file header, for example |
2740 | if you need your code to remain compatible with older versions of libpng prior | 2740 | if you need your code to remain compatible with older versions of libpng prior |
2741 | to libpng-1.5.4, this is the place to call it. | 2741 | to libpng-1.5.4, this is the place to call it. |
2742 | 2742 | ||
2743 | Do not call it if you called png_set_alpha_mode(); doing so will damage the | 2743 | Do not call it if you called png_set_alpha_mode(); doing so will damage the |
2744 | settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is | 2744 | settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is |
2745 | supported then you can certainly do png_set_gamma() before reading the PNG | 2745 | supported then you can certainly do png_set_gamma() before reading the PNG |
2746 | header.) | 2746 | header.) |
2747 | 2747 | ||
2748 | This API unconditionally sets the screen and file gamma values, so it will | 2748 | This API unconditionally sets the screen and file gamma values, so it will |
2749 | override the value in the PNG file unless it is called before the PNG file | 2749 | override the value in the PNG file unless it is called before the PNG file |
2750 | reading starts. For this reason you must always call it with the PNG file | 2750 | reading starts. For this reason you must always call it with the PNG file |
2751 | value when you call it in this position: | 2751 | value when you call it in this position: |
2752 | 2752 | ||
2753 | if (png_get_gAMA(png_ptr, info_ptr, &file_gamma)) | 2753 | if (png_get_gAMA(png_ptr, info_ptr, &file_gamma)) |
2754 | png_set_gamma(png_ptr, screen_gamma, file_gamma); | 2754 | png_set_gamma(png_ptr, screen_gamma, file_gamma); |
2755 | 2755 | ||
2756 | else | 2756 | else |
2757 | png_set_gamma(png_ptr, screen_gamma, 0.45455); | 2757 | png_set_gamma(png_ptr, screen_gamma, 0.45455); |
2758 | 2758 | ||
2759 | If you need to reduce an RGB file to a paletted file, or if a paletted | 2759 | If you need to reduce an RGB file to a paletted file, or if a paletted |
2760 | file has more entries then will fit on your screen, png_set_quantize() | 2760 | file has more entries then will fit on your screen, png_set_quantize() |
2761 | will do that. Note that this is a simple match quantization that merely | 2761 | will do that. Note that this is a simple match quantization that merely |
2762 | finds the closest color available. This should work fairly well with | 2762 | finds the closest color available. This should work fairly well with |
2763 | optimized palettes, but fairly badly with linear color cubes. If you | 2763 | optimized palettes, but fairly badly with linear color cubes. If you |
2764 | pass a palette that is larger than maximum_colors, the file will | 2764 | pass a palette that is larger than maximum_colors, the file will |
2765 | reduce the number of colors in the palette so it will fit into | 2765 | reduce the number of colors in the palette so it will fit into |
2766 | maximum_colors. If there is a histogram, libpng will use it to make | 2766 | maximum_colors. If there is a histogram, libpng will use it to make |
2767 | more intelligent choices when reducing the palette. If there is no | 2767 | more intelligent choices when reducing the palette. If there is no |
2768 | histogram, it may not do as good a job. | 2768 | histogram, it may not do as good a job. |
2769 | 2769 | ||
2770 | if (color_type & PNG_COLOR_MASK_COLOR) | 2770 | if (color_type & PNG_COLOR_MASK_COLOR) |
2771 | { | 2771 | { |
2772 | if (png_get_valid(png_ptr, info_ptr, | 2772 | if (png_get_valid(png_ptr, info_ptr, |
2773 | PNG_INFO_PLTE)) | 2773 | PNG_INFO_PLTE)) |
2774 | { | 2774 | { |
2775 | png_uint_16p histogram = NULL; | 2775 | png_uint_16p histogram = NULL; |
2776 | 2776 | ||
2777 | png_get_hIST(png_ptr, info_ptr, | 2777 | png_get_hIST(png_ptr, info_ptr, |
2778 | &histogram); | 2778 | &histogram); |
2779 | png_set_quantize(png_ptr, palette, num_palette, | 2779 | png_set_quantize(png_ptr, palette, num_palette, |
2780 | max_screen_colors, histogram, 1); | 2780 | max_screen_colors, histogram, 1); |
2781 | } | 2781 | } |
2782 | 2782 | ||
2783 | else | 2783 | else |
2784 | { | 2784 | { |
2785 | png_color std_color_cube[MAX_SCREEN_COLORS] = | 2785 | png_color std_color_cube[MAX_SCREEN_COLORS] = |
2786 | { ... colors ... }; | 2786 | { ... colors ... }; |
2787 | 2787 | ||
2788 | png_set_quantize(png_ptr, std_color_cube, | 2788 | png_set_quantize(png_ptr, std_color_cube, |
2789 | MAX_SCREEN_COLORS, MAX_SCREEN_COLORS, | 2789 | MAX_SCREEN_COLORS, MAX_SCREEN_COLORS, |
2790 | NULL,0); | 2790 | NULL,0); |
2791 | } | 2791 | } |
2792 | } | 2792 | } |
2793 | 2793 | ||
2794 | PNG files describe monochrome as black being zero and white being one. | 2794 | PNG files describe monochrome as black being zero and white being one. |
2795 | The following code will reverse this (make black be one and white be | 2795 | The following code will reverse this (make black be one and white be |
2796 | zero): | 2796 | zero): |
2797 | 2797 | ||
2798 | if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY) | 2798 | if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY) |
2799 | png_set_invert_mono(png_ptr); | 2799 | png_set_invert_mono(png_ptr); |
2800 | 2800 | ||
2801 | This function can also be used to invert grayscale and gray-alpha images: | 2801 | This function can also be used to invert grayscale and gray-alpha images: |
2802 | 2802 | ||
2803 | if (color_type == PNG_COLOR_TYPE_GRAY || | 2803 | if (color_type == PNG_COLOR_TYPE_GRAY || |
2804 | color_type == PNG_COLOR_TYPE_GRAY_ALPHA) | 2804 | color_type == PNG_COLOR_TYPE_GRAY_ALPHA) |
2805 | png_set_invert_mono(png_ptr); | 2805 | png_set_invert_mono(png_ptr); |
2806 | 2806 | ||
2807 | PNG files store 16-bit pixels in network byte order (big-endian, | 2807 | PNG files store 16-bit pixels in network byte order (big-endian, |
2808 | ie. most significant bits first). This code changes the storage to the | 2808 | ie. most significant bits first). This code changes the storage to the |
2809 | other way (little-endian, i.e. least significant bits first, the | 2809 | other way (little-endian, i.e. least significant bits first, the |
2810 | way PCs store them): | 2810 | way PCs store them): |
2811 | 2811 | ||
2812 | if (bit_depth == 16) | 2812 | if (bit_depth == 16) |
2813 | png_set_swap(png_ptr); | 2813 | png_set_swap(png_ptr); |
2814 | 2814 | ||
2815 | If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you | 2815 | If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you |
2816 | need to change the order the pixels are packed into bytes, you can use: | 2816 | need to change the order the pixels are packed into bytes, you can use: |
2817 | 2817 | ||
2818 | if (bit_depth < 8) | 2818 | if (bit_depth < 8) |
2819 | png_set_packswap(png_ptr); | 2819 | png_set_packswap(png_ptr); |
2820 | 2820 | ||
2821 | Finally, you can write your own transformation function if none of | 2821 | Finally, you can write your own transformation function if none of |
2822 | the existing ones meets your needs. This is done by setting a callback | 2822 | the existing ones meets your needs. This is done by setting a callback |
2823 | with | 2823 | with |
2824 | 2824 | ||
2825 | png_set_read_user_transform_fn(png_ptr, | 2825 | png_set_read_user_transform_fn(png_ptr, |
2826 | read_transform_fn); | 2826 | read_transform_fn); |
2827 | 2827 | ||
2828 | You must supply the function | 2828 | You must supply the function |
2829 | 2829 | ||
2830 | void read_transform_fn(png_structp png_ptr, png_row_infop | 2830 | void read_transform_fn(png_structp png_ptr, png_row_infop |
2831 | row_info, png_bytep data) | 2831 | row_info, png_bytep data) |
2832 | 2832 | ||
2833 | See pngtest.c for a working example. Your function will be called | 2833 | See pngtest.c for a working example. Your function will be called |
2834 | after all of the other transformations have been processed. Take care with | 2834 | after all of the other transformations have been processed. Take care with |
2835 | interlaced images if you do the interlace yourself - the width of the row is the | 2835 | interlaced images if you do the interlace yourself - the width of the row is the |
2836 | width in 'row_info', not the overall image width. | 2836 | width in 'row_info', not the overall image width. |
2837 | 2837 | ||
2838 | If supported, libpng provides two information routines that you can use to find | 2838 | If supported, libpng provides two information routines that you can use to find |
2839 | where you are in processing the image: | 2839 | where you are in processing the image: |
2840 | 2840 | ||
2841 | png_get_current_pass_number(png_structp png_ptr); | 2841 | png_get_current_pass_number(png_structp png_ptr); |
2842 | png_get_current_row_number(png_structp png_ptr); | 2842 | png_get_current_row_number(png_structp png_ptr); |
2843 | 2843 | ||
2844 | Don't try using these outside a transform callback - firstly they are only | 2844 | Don't try using these outside a transform callback - firstly they are only |
2845 | supported if user transforms are supported, secondly they may well return | 2845 | supported if user transforms are supported, secondly they may well return |
2846 | unexpected results unless the row is actually being processed at the moment they | 2846 | unexpected results unless the row is actually being processed at the moment they |
2847 | are called. | 2847 | are called. |
2848 | 2848 | ||
2849 | With interlaced | 2849 | With interlaced |
2850 | images the value returned is the row in the input sub-image image. Use | 2850 | images the value returned is the row in the input sub-image image. Use |
2851 | PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to | 2851 | PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to |
2852 | find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass). | 2852 | find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass). |
2853 | 2853 | ||
2854 | The discussion of interlace handling above contains more information on how to | 2854 | The discussion of interlace handling above contains more information on how to |
2855 | use these values. | 2855 | use these values. |
2856 | 2856 | ||
2857 | You can also set up a pointer to a user structure for use by your | 2857 | You can also set up a pointer to a user structure for use by your |
2858 | callback function, and you can inform libpng that your transform | 2858 | callback function, and you can inform libpng that your transform |
2859 | function will change the number of channels or bit depth with the | 2859 | function will change the number of channels or bit depth with the |
2860 | function | 2860 | function |
2861 | 2861 | ||
2862 | png_set_user_transform_info(png_ptr, user_ptr, | 2862 | png_set_user_transform_info(png_ptr, user_ptr, |
2863 | user_depth, user_channels); | 2863 | user_depth, user_channels); |
2864 | 2864 | ||
2865 | The user's application, not libpng, is responsible for allocating and | 2865 | The user's application, not libpng, is responsible for allocating and |
2866 | freeing any memory required for the user structure. | 2866 | freeing any memory required for the user structure. |
2867 | 2867 | ||
2868 | You can retrieve the pointer via the function | 2868 | You can retrieve the pointer via the function |
2869 | png_get_user_transform_ptr(). For example: | 2869 | png_get_user_transform_ptr(). For example: |
2870 | 2870 | ||
2871 | voidp read_user_transform_ptr = | 2871 | voidp read_user_transform_ptr = |
2872 | png_get_user_transform_ptr(png_ptr); | 2872 | png_get_user_transform_ptr(png_ptr); |
2873 | 2873 | ||
2874 | The last thing to handle is interlacing; this is covered in detail below, | 2874 | The last thing to handle is interlacing; this is covered in detail below, |
2875 | but you must call the function here if you want libpng to handle expansion | 2875 | but you must call the function here if you want libpng to handle expansion |
2876 | of the interlaced image. | 2876 | of the interlaced image. |
2877 | 2877 | ||
2878 | number_of_passes = png_set_interlace_handling(png_ptr); | 2878 | number_of_passes = png_set_interlace_handling(png_ptr); |
2879 | 2879 | ||
2880 | After setting the transformations, libpng can update your png_info | 2880 | After setting the transformations, libpng can update your png_info |
2881 | structure to reflect any transformations you've requested with this | 2881 | structure to reflect any transformations you've requested with this |
2882 | call. | 2882 | call. |
2883 | 2883 | ||
2884 | png_read_update_info(png_ptr, info_ptr); | 2884 | png_read_update_info(png_ptr, info_ptr); |
2885 | 2885 | ||
2886 | This is most useful to update the info structure's rowbytes | 2886 | This is most useful to update the info structure's rowbytes |
2887 | field so you can use it to allocate your image memory. This function | 2887 | field so you can use it to allocate your image memory. This function |
2888 | will also update your palette with the correct screen_gamma and | 2888 | will also update your palette with the correct screen_gamma and |
2889 | background if these have been given with the calls above. You may | 2889 | background if these have been given with the calls above. You may |
2890 | only call png_read_update_info() once with a particular info_ptr. | 2890 | only call png_read_update_info() once with a particular info_ptr. |
2891 | 2891 | ||
2892 | After you call png_read_update_info(), you can allocate any | 2892 | After you call png_read_update_info(), you can allocate any |
2893 | memory you need to hold the image. The row data is simply | 2893 | memory you need to hold the image. The row data is simply |
2894 | raw byte data for all forms of images. As the actual allocation | 2894 | raw byte data for all forms of images. As the actual allocation |
2895 | varies among applications, no example will be given. If you | 2895 | varies among applications, no example will be given. If you |
2896 | are allocating one large chunk, you will need to build an | 2896 | are allocating one large chunk, you will need to build an |
2897 | array of pointers to each row, as it will be needed for some | 2897 | array of pointers to each row, as it will be needed for some |
2898 | of the functions below. | 2898 | of the functions below. |
2899 | 2899 | ||
2900 | Remember: Before you call png_read_update_info(), the png_get_*() | 2900 | Remember: Before you call png_read_update_info(), the png_get_*() |
2901 | functions return the values corresponding to the original PNG image. | 2901 | functions return the values corresponding to the original PNG image. |
2902 | After you call png_read_update_info the values refer to the image | 2902 | After you call png_read_update_info the values refer to the image |
2903 | that libpng will output. Consequently you must call all the png_set_ | 2903 | that libpng will output. Consequently you must call all the png_set_ |
2904 | functions before you call png_read_update_info(). This is particularly | 2904 | functions before you call png_read_update_info(). This is particularly |
2905 | important for png_set_interlace_handling() - if you are going to call | 2905 | important for png_set_interlace_handling() - if you are going to call |
2906 | png_read_update_info() you must call png_set_interlace_handling() before | 2906 | png_read_update_info() you must call png_set_interlace_handling() before |
2907 | it unless you want to receive interlaced output. | 2907 | it unless you want to receive interlaced output. |
2908 | 2908 | ||
2909 | .SS Reading image data | 2909 | .SS Reading image data |
2910 | 2910 | ||
2911 | After you've allocated memory, you can read the image data. | 2911 | After you've allocated memory, you can read the image data. |
2912 | The simplest way to do this is in one function call. If you are | 2912 | The simplest way to do this is in one function call. If you are |
2913 | allocating enough memory to hold the whole image, you can just | 2913 | allocating enough memory to hold the whole image, you can just |
2914 | call png_read_image() and libpng will read in all the image data | 2914 | call png_read_image() and libpng will read in all the image data |
2915 | and put it in the memory area supplied. You will need to pass in | 2915 | and put it in the memory area supplied. You will need to pass in |
2916 | an array of pointers to each row. | 2916 | an array of pointers to each row. |
2917 | 2917 | ||
2918 | This function automatically handles interlacing, so you don't | 2918 | This function automatically handles interlacing, so you don't |
2919 | need to call png_set_interlace_handling() (unless you call | 2919 | need to call png_set_interlace_handling() (unless you call |
2920 | png_read_update_info()) or call this function multiple times, or any | 2920 | png_read_update_info()) or call this function multiple times, or any |
2921 | of that other stuff necessary with png_read_rows(). | 2921 | of that other stuff necessary with png_read_rows(). |
2922 | 2922 | ||
2923 | png_read_image(png_ptr, row_pointers); | 2923 | png_read_image(png_ptr, row_pointers); |
2924 | 2924 | ||
2925 | where row_pointers is: | 2925 | where row_pointers is: |
2926 | 2926 | ||
2927 | png_bytep row_pointers[height]; | 2927 | png_bytep row_pointers[height]; |
2928 | 2928 | ||
2929 | You can point to void or char or whatever you use for pixels. | 2929 | You can point to void or char or whatever you use for pixels. |
2930 | 2930 | ||
2931 | If you don't want to read in the whole image at once, you can | 2931 | If you don't want to read in the whole image at once, you can |
2932 | use png_read_rows() instead. If there is no interlacing (check | 2932 | use png_read_rows() instead. If there is no interlacing (check |
2933 | interlace_type == PNG_INTERLACE_NONE), this is simple: | 2933 | interlace_type == PNG_INTERLACE_NONE), this is simple: |
2934 | 2934 | ||
2935 | png_read_rows(png_ptr, row_pointers, NULL, | 2935 | png_read_rows(png_ptr, row_pointers, NULL, |
2936 | number_of_rows); | 2936 | number_of_rows); |
2937 | 2937 | ||
2938 | where row_pointers is the same as in the png_read_image() call. | 2938 | where row_pointers is the same as in the png_read_image() call. |
2939 | 2939 | ||
2940 | If you are doing this just one row at a time, you can do this with | 2940 | If you are doing this just one row at a time, you can do this with |
2941 | a single row_pointer instead of an array of row_pointers: | 2941 | a single row_pointer instead of an array of row_pointers: |
2942 | 2942 | ||
2943 | png_bytep row_pointer = row; | 2943 | png_bytep row_pointer = row; |
2944 | png_read_row(png_ptr, row_pointer, NULL); | 2944 | png_read_row(png_ptr, row_pointer, NULL); |
2945 | 2945 | ||
2946 | If the file is interlaced (interlace_type != 0 in the IHDR chunk), things | 2946 | If the file is interlaced (interlace_type != 0 in the IHDR chunk), things |
2947 | get somewhat harder. The only current (PNG Specification version 1.2) | 2947 | get somewhat harder. The only current (PNG Specification version 1.2) |
2948 | interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7); | 2948 | interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7); |
2949 | a somewhat complicated 2D interlace scheme, known as Adam7, that | 2949 | a somewhat complicated 2D interlace scheme, known as Adam7, that |
2950 | breaks down an image into seven smaller images of varying size, based | 2950 | breaks down an image into seven smaller images of varying size, based |
2951 | on an 8x8 grid. This number is defined (from libpng 1.5) as | 2951 | on an 8x8 grid. This number is defined (from libpng 1.5) as |
2952 | PNG_INTERLACE_ADAM7_PASSES in png.h | 2952 | PNG_INTERLACE_ADAM7_PASSES in png.h |
2953 | 2953 | ||
2954 | libpng can fill out those images or it can give them to you "as is". | 2954 | libpng can fill out those images or it can give them to you "as is". |
2955 | It is almost always better to have libpng handle the interlacing for you. | 2955 | It is almost always better to have libpng handle the interlacing for you. |
2956 | If you want the images filled out, there are two ways to do that. The one | 2956 | If you want the images filled out, there are two ways to do that. The one |
2957 | mentioned in the PNG specification is to expand each pixel to cover | 2957 | mentioned in the PNG specification is to expand each pixel to cover |
2958 | those pixels that have not been read yet (the "rectangle" method). | 2958 | those pixels that have not been read yet (the "rectangle" method). |
2959 | This results in a blocky image for the first pass, which gradually | 2959 | This results in a blocky image for the first pass, which gradually |
2960 | smooths out as more pixels are read. The other method is the "sparkle" | 2960 | smooths out as more pixels are read. The other method is the "sparkle" |
2961 | method, where pixels are drawn only in their final locations, with the | 2961 | method, where pixels are drawn only in their final locations, with the |
2962 | rest of the image remaining whatever colors they were initialized to | 2962 | rest of the image remaining whatever colors they were initialized to |
2963 | before the start of the read. The first method usually looks better, | 2963 | before the start of the read. The first method usually looks better, |
2964 | but tends to be slower, as there are more pixels to put in the rows. | 2964 | but tends to be slower, as there are more pixels to put in the rows. |
2965 | 2965 | ||
2966 | If, as is likely, you want libpng to expand the images, call this before | 2966 | If, as is likely, you want libpng to expand the images, call this before |
2967 | calling png_start_read_image() or png_read_update_info(): | 2967 | calling png_start_read_image() or png_read_update_info(): |
2968 | 2968 | ||
2969 | if (interlace_type == PNG_INTERLACE_ADAM7) | 2969 | if (interlace_type == PNG_INTERLACE_ADAM7) |
2970 | number_of_passes | 2970 | number_of_passes |
2971 | = png_set_interlace_handling(png_ptr); | 2971 | = png_set_interlace_handling(png_ptr); |
2972 | 2972 | ||
2973 | This will return the number of passes needed. Currently, this is seven, | 2973 | This will return the number of passes needed. Currently, this is seven, |
2974 | but may change if another interlace type is added. This function can be | 2974 | but may change if another interlace type is added. This function can be |
2975 | called even if the file is not interlaced, where it will return one pass. | 2975 | called even if the file is not interlaced, where it will return one pass. |
2976 | You then need to read the whole image 'number_of_passes' times. Each time | 2976 | You then need to read the whole image 'number_of_passes' times. Each time |
2977 | will distribute the pixels from the current pass to the correct place in | 2977 | will distribute the pixels from the current pass to the correct place in |
2978 | the output image, so you need to supply the same rows to png_read_rows in | 2978 | the output image, so you need to supply the same rows to png_read_rows in |
2979 | each pass. | 2979 | each pass. |
2980 | 2980 | ||
2981 | If you are not going to display the image after each pass, but are | 2981 | If you are not going to display the image after each pass, but are |
2982 | going to wait until the entire image is read in, use the sparkle | 2982 | going to wait until the entire image is read in, use the sparkle |
2983 | effect. This effect is faster and the end result of either method | 2983 | effect. This effect is faster and the end result of either method |
2984 | is exactly the same. If you are planning on displaying the image | 2984 | is exactly the same. If you are planning on displaying the image |
2985 | after each pass, the "rectangle" effect is generally considered the | 2985 | after each pass, the "rectangle" effect is generally considered the |
2986 | better looking one. | 2986 | better looking one. |
2987 | 2987 | ||
2988 | If you only want the "sparkle" effect, just call png_read_rows() as | 2988 | If you only want the "sparkle" effect, just call png_read_rows() as |
2989 | normal, with the third parameter NULL. Make sure you make pass over | 2989 | normal, with the third parameter NULL. Make sure you make pass over |
2990 | the image number_of_passes times, and you don't change the data in the | 2990 | the image number_of_passes times, and you don't change the data in the |
2991 | rows between calls. You can change the locations of the data, just | 2991 | rows between calls. You can change the locations of the data, just |
2992 | not the data. Each pass only writes the pixels appropriate for that | 2992 | not the data. Each pass only writes the pixels appropriate for that |
2993 | pass, and assumes the data from previous passes is still valid. | 2993 | pass, and assumes the data from previous passes is still valid. |
2994 | 2994 | ||
2995 | png_read_rows(png_ptr, row_pointers, NULL, | 2995 | png_read_rows(png_ptr, row_pointers, NULL, |
2996 | number_of_rows); | 2996 | number_of_rows); |
2997 | 2997 | ||
2998 | If you only want the first effect (the rectangles), do the same as | 2998 | If you only want the first effect (the rectangles), do the same as |
2999 | before except pass the row buffer in the third parameter, and leave | 2999 | before except pass the row buffer in the third parameter, and leave |
3000 | the second parameter NULL. | 3000 | the second parameter NULL. |
3001 | 3001 | ||
3002 | png_read_rows(png_ptr, NULL, row_pointers, | 3002 | png_read_rows(png_ptr, NULL, row_pointers, |
3003 | number_of_rows); | 3003 | number_of_rows); |
3004 | 3004 | ||
3005 | If you don't want libpng to handle the interlacing details, just call | 3005 | If you don't want libpng to handle the interlacing details, just call |
3006 | png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images. | 3006 | png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images. |
3007 | Each of the images is a valid image by itself, however you will almost | 3007 | Each of the images is a valid image by itself, however you will almost |
3008 | certainly need to distribute the pixels from each sub-image to the | 3008 | certainly need to distribute the pixels from each sub-image to the |
3009 | correct place. This is where everything gets very tricky. | 3009 | correct place. This is where everything gets very tricky. |
3010 | 3010 | ||
3011 | If you want to retrieve the separate images you must pass the correct | 3011 | If you want to retrieve the separate images you must pass the correct |
3012 | number of rows to each successive call of png_read_rows(). The calculation | 3012 | number of rows to each successive call of png_read_rows(). The calculation |
3013 | gets pretty complicated for small images, where some sub-images may | 3013 | gets pretty complicated for small images, where some sub-images may |
3014 | not even exist because either their width or height ends up zero. | 3014 | not even exist because either their width or height ends up zero. |
3015 | libpng provides two macros to help you in 1.5 and later versions: | 3015 | libpng provides two macros to help you in 1.5 and later versions: |
3016 | 3016 | ||
3017 | png_uint_32 width = PNG_PASS_COLS(image_width, pass_number); | 3017 | png_uint_32 width = PNG_PASS_COLS(image_width, pass_number); |
3018 | png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number); | 3018 | png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number); |
3019 | 3019 | ||
3020 | Respectively these tell you the width and height of the sub-image | 3020 | Respectively these tell you the width and height of the sub-image |
3021 | corresponding to the numbered pass. 'pass' is in in the range 0 to 6 - | 3021 | corresponding to the numbered pass. 'pass' is in in the range 0 to 6 - |
3022 | this can be confusing because the specification refers to the same passes | 3022 | this can be confusing because the specification refers to the same passes |
3023 | as 1 to 7! Be careful, you must check both the width and height before | 3023 | as 1 to 7! Be careful, you must check both the width and height before |
3024 | calling png_read_rows() and not call it for that pass if either is zero. | 3024 | calling png_read_rows() and not call it for that pass if either is zero. |
3025 | 3025 | ||
3026 | You can, of course, read each sub-image row by row. If you want to | 3026 | You can, of course, read each sub-image row by row. If you want to |
3027 | produce optimal code to make a pixel-by-pixel transformation of an | 3027 | produce optimal code to make a pixel-by-pixel transformation of an |
3028 | interlaced image this is the best approach; read each row of each pass, | 3028 | interlaced image this is the best approach; read each row of each pass, |
3029 | transform it, and write it out to a new interlaced image. | 3029 | transform it, and write it out to a new interlaced image. |
3030 | 3030 | ||
3031 | If you want to de-interlace the image yourself libpng provides further | 3031 | If you want to de-interlace the image yourself libpng provides further |
3032 | macros to help that tell you where to place the pixels in the output image. | 3032 | macros to help that tell you where to place the pixels in the output image. |
3033 | Because the interlacing scheme is rectangular - sub-image pixels are always | 3033 | Because the interlacing scheme is rectangular - sub-image pixels are always |
3034 | arranged on a rectangular grid - all you need to know for each pass is the | 3034 | arranged on a rectangular grid - all you need to know for each pass is the |
3035 | starting column and row in the output image of the first pixel plus the | 3035 | starting column and row in the output image of the first pixel plus the |
3036 | spacing between each pixel. As of libpng 1.5 there are four macros to | 3036 | spacing between each pixel. As of libpng 1.5 there are four macros to |
3037 | retrieve this information: | 3037 | retrieve this information: |
3038 | 3038 | ||
3039 | png_uint_32 x = PNG_PASS_START_COL(pass); | 3039 | png_uint_32 x = PNG_PASS_START_COL(pass); |
3040 | png_uint_32 y = PNG_PASS_START_ROW(pass); | 3040 | png_uint_32 y = PNG_PASS_START_ROW(pass); |
3041 | png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass); | 3041 | png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass); |
3042 | png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass); | 3042 | png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass); |
3043 | 3043 | ||
3044 | These allow you to write the obvious loop: | 3044 | These allow you to write the obvious loop: |
3045 | 3045 | ||
3046 | png_uint_32 input_y = 0; | 3046 | png_uint_32 input_y = 0; |
3047 | png_uint_32 output_y = PNG_PASS_START_ROW(pass); | 3047 | png_uint_32 output_y = PNG_PASS_START_ROW(pass); |
3048 | 3048 | ||
3049 | while (output_y < output_image_height) | 3049 | while (output_y < output_image_height) |
3050 | { | 3050 | { |
3051 | png_uint_32 input_x = 0; | 3051 | png_uint_32 input_x = 0; |
3052 | png_uint_32 output_x = PNG_PASS_START_COL(pass); | 3052 | png_uint_32 output_x = PNG_PASS_START_COL(pass); |
3053 | 3053 | ||
3054 | while (output_x < output_image_width) | 3054 | while (output_x < output_image_width) |
3055 | { | 3055 | { |
3056 | image[output_y][output_x] = | 3056 | image[output_y][output_x] = |
3057 | subimage[pass][input_y][input_x++]; | 3057 | subimage[pass][input_y][input_x++]; |
3058 | 3058 | ||
3059 | output_x += xStep; | 3059 | output_x += xStep; |
3060 | } | 3060 | } |
3061 | 3061 | ||
3062 | ++input_y; | 3062 | ++input_y; |
3063 | output_y += yStep; | 3063 | output_y += yStep; |
3064 | } | 3064 | } |
3065 | 3065 | ||
3066 | Notice that the steps between successive output rows and columns are | 3066 | Notice that the steps between successive output rows and columns are |
3067 | returned as shifts. This is possible because the pixels in the subimages | 3067 | returned as shifts. This is possible because the pixels in the subimages |
3068 | are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original | 3068 | are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original |
3069 | image. In practice you may need to directly calculate the output coordinate | 3069 | image. In practice you may need to directly calculate the output coordinate |
3070 | given an input coordinate. libpng provides two further macros for this | 3070 | given an input coordinate. libpng provides two further macros for this |
3071 | purpose: | 3071 | purpose: |
3072 | 3072 | ||
3073 | png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass); | 3073 | png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass); |
3074 | png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass); | 3074 | png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass); |
3075 | 3075 | ||
3076 | Finally a pair of macros are provided to tell you if a particular image | 3076 | Finally a pair of macros are provided to tell you if a particular image |
3077 | row or column appears in a given pass: | 3077 | row or column appears in a given pass: |
3078 | 3078 | ||
3079 | int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass); | 3079 | int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass); |
3080 | int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass); | 3080 | int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass); |
3081 | 3081 | ||
3082 | Bear in mind that you will probably also need to check the width and height | 3082 | Bear in mind that you will probably also need to check the width and height |
3083 | of the pass in addition to the above to be sure the pass even exists! | 3083 | of the pass in addition to the above to be sure the pass even exists! |
3084 | 3084 | ||
3085 | With any luck you are convinced by now that you don't want to do your own | 3085 | With any luck you are convinced by now that you don't want to do your own |
3086 | interlace handling. In reality normally the only good reason for doing this | 3086 | interlace handling. In reality normally the only good reason for doing this |
3087 | is if you are processing PNG files on a pixel-by-pixel basis and don't want | 3087 | is if you are processing PNG files on a pixel-by-pixel basis and don't want |
3088 | to load the whole file into memory when it is interlaced. | 3088 | to load the whole file into memory when it is interlaced. |
3089 | 3089 | ||
3090 | libpng includes a test program, pngvalid, that illustrates reading and | 3090 | libpng includes a test program, pngvalid, that illustrates reading and |
3091 | writing of interlaced images. If you can't get interlacing to work in your | 3091 | writing of interlaced images. If you can't get interlacing to work in your |
3092 | code and don't want to leave it to libpng (the recommended approach), see | 3092 | code and don't want to leave it to libpng (the recommended approach), see |
3093 | how pngvalid.c does it. | 3093 | how pngvalid.c does it. |
3094 | 3094 | ||
3095 | .SS Finishing a sequential read | 3095 | .SS Finishing a sequential read |
3096 | 3096 | ||
3097 | After you are finished reading the image through the | 3097 | After you are finished reading the image through the |
3098 | low-level interface, you can finish reading the file. If you are | 3098 | low-level interface, you can finish reading the file. If you are |
3099 | interested in comments or time, which may be stored either before or | 3099 | interested in comments or time, which may be stored either before or |
3100 | after the image data, you should pass the separate png_info struct if | 3100 | after the image data, you should pass the separate png_info struct if |
3101 | you want to keep the comments from before and after the image | 3101 | you want to keep the comments from before and after the image |
3102 | separate. | 3102 | separate. |
3103 | 3103 | ||
3104 | png_infop end_info = png_create_info_struct(png_ptr); | 3104 | png_infop end_info = png_create_info_struct(png_ptr); |
3105 | 3105 | ||
3106 | if (!end_info) | 3106 | if (!end_info) |
3107 | { | 3107 | { |
3108 | png_destroy_read_struct(&png_ptr, &info_ptr, | 3108 | png_destroy_read_struct(&png_ptr, &info_ptr, |
3109 | (png_infopp)NULL); | 3109 | (png_infopp)NULL); |
3110 | return (ERROR); | 3110 | return (ERROR); |
3111 | } | 3111 | } |
3112 | 3112 | ||
3113 | png_read_end(png_ptr, end_info); | 3113 | png_read_end(png_ptr, end_info); |
3114 | 3114 | ||
3115 | If you are not interested, you should still call png_read_end() | 3115 | If you are not interested, you should still call png_read_end() |
3116 | but you can pass NULL, avoiding the need to create an end_info structure. | 3116 | but you can pass NULL, avoiding the need to create an end_info structure. |
3117 | 3117 | ||
3118 | png_read_end(png_ptr, (png_infop)NULL); | 3118 | png_read_end(png_ptr, (png_infop)NULL); |
3119 | 3119 | ||
3120 | If you don't call png_read_end(), then your file pointer will be | 3120 | If you don't call png_read_end(), then your file pointer will be |
3121 | left pointing to the first chunk after the last IDAT, which is probably | 3121 | left pointing to the first chunk after the last IDAT, which is probably |
3122 | not what you want if you expect to read something beyond the end of | 3122 | not what you want if you expect to read something beyond the end of |
3123 | the PNG datastream. | 3123 | the PNG datastream. |
3124 | 3124 | ||
3125 | When you are done, you can free all memory allocated by libpng like this: | 3125 | When you are done, you can free all memory allocated by libpng like this: |
3126 | 3126 | ||
3127 | png_destroy_read_struct(&png_ptr, &info_ptr, | 3127 | png_destroy_read_struct(&png_ptr, &info_ptr, |
3128 | &end_info); | 3128 | &end_info); |
3129 | 3129 | ||
3130 | or, if you didn't create an end_info structure, | 3130 | or, if you didn't create an end_info structure, |
3131 | 3131 | ||
3132 | png_destroy_read_struct(&png_ptr, &info_ptr, | 3132 | png_destroy_read_struct(&png_ptr, &info_ptr, |
3133 | (png_infopp)NULL); | 3133 | (png_infopp)NULL); |
3134 | 3134 | ||
3135 | It is also possible to individually free the info_ptr members that | 3135 | It is also possible to individually free the info_ptr members that |
3136 | point to libpng-allocated storage with the following function: | 3136 | point to libpng-allocated storage with the following function: |
3137 | 3137 | ||
3138 | png_free_data(png_ptr, info_ptr, mask, seq) | 3138 | png_free_data(png_ptr, info_ptr, mask, seq) |
3139 | 3139 | ||
3140 | mask - identifies data to be freed, a mask | 3140 | mask - identifies data to be freed, a mask |
3141 | containing the bitwise OR of one or | 3141 | containing the bitwise OR of one or |
3142 | more of | 3142 | more of |
3143 | PNG_FREE_PLTE, PNG_FREE_TRNS, | 3143 | PNG_FREE_PLTE, PNG_FREE_TRNS, |
3144 | PNG_FREE_HIST, PNG_FREE_ICCP, | 3144 | PNG_FREE_HIST, PNG_FREE_ICCP, |
3145 | PNG_FREE_PCAL, PNG_FREE_ROWS, | 3145 | PNG_FREE_PCAL, PNG_FREE_ROWS, |
3146 | PNG_FREE_SCAL, PNG_FREE_SPLT, | 3146 | PNG_FREE_SCAL, PNG_FREE_SPLT, |
3147 | PNG_FREE_TEXT, PNG_FREE_UNKN, | 3147 | PNG_FREE_TEXT, PNG_FREE_UNKN, |
3148 | or simply PNG_FREE_ALL | 3148 | or simply PNG_FREE_ALL |
3149 | 3149 | ||
3150 | seq - sequence number of item to be freed | 3150 | seq - sequence number of item to be freed |
3151 | (-1 for all items) | 3151 | (-1 for all items) |
3152 | 3152 | ||
3153 | This function may be safely called when the relevant storage has | 3153 | This function may be safely called when the relevant storage has |
3154 | already been freed, or has not yet been allocated, or was allocated | 3154 | already been freed, or has not yet been allocated, or was allocated |
3155 | by the user and not by libpng, and will in those cases do nothing. | 3155 | by the user and not by libpng, and will in those cases do nothing. |
3156 | The "seq" parameter is ignored if only one item of the selected data | 3156 | The "seq" parameter is ignored if only one item of the selected data |
3157 | type, such as PLTE, is allowed. If "seq" is not -1, and multiple items | 3157 | type, such as PLTE, is allowed. If "seq" is not -1, and multiple items |
3158 | are allowed for the data type identified in the mask, such as text or | 3158 | are allowed for the data type identified in the mask, such as text or |
3159 | sPLT, only the n'th item in the structure is freed, where n is "seq". | 3159 | sPLT, only the n'th item in the structure is freed, where n is "seq". |
3160 | 3160 | ||
3161 | The default behavior is only to free data that was allocated internally | 3161 | The default behavior is only to free data that was allocated internally |
3162 | by libpng. This can be changed, so that libpng will not free the data, | 3162 | by libpng. This can be changed, so that libpng will not free the data, |
3163 | or so that it will free data that was allocated by the user with png_malloc() | 3163 | or so that it will free data that was allocated by the user with png_malloc() |
3164 | or png_zalloc() and passed in via a png_set_*() function, with | 3164 | or png_zalloc() and passed in via a png_set_*() function, with |
3165 | 3165 | ||
3166 | png_data_freer(png_ptr, info_ptr, freer, mask) | 3166 | png_data_freer(png_ptr, info_ptr, freer, mask) |
3167 | 3167 | ||
3168 | freer - one of | 3168 | freer - one of |
3169 | PNG_DESTROY_WILL_FREE_DATA | 3169 | PNG_DESTROY_WILL_FREE_DATA |
3170 | PNG_SET_WILL_FREE_DATA | 3170 | PNG_SET_WILL_FREE_DATA |
3171 | PNG_USER_WILL_FREE_DATA | 3171 | PNG_USER_WILL_FREE_DATA |
3172 | 3172 | ||
3173 | mask - which data elements are affected | 3173 | mask - which data elements are affected |
3174 | same choices as in png_free_data() | 3174 | same choices as in png_free_data() |
3175 | 3175 | ||
3176 | This function only affects data that has already been allocated. | 3176 | This function only affects data that has already been allocated. |
3177 | You can call this function after reading the PNG data but before calling | 3177 | You can call this function after reading the PNG data but before calling |
3178 | any png_set_*() functions, to control whether the user or the png_set_*() | 3178 | any png_set_*() functions, to control whether the user or the png_set_*() |
3179 | function is responsible for freeing any existing data that might be present, | 3179 | function is responsible for freeing any existing data that might be present, |
3180 | and again after the png_set_*() functions to control whether the user | 3180 | and again after the png_set_*() functions to control whether the user |
3181 | or png_destroy_*() is supposed to free the data. When the user assumes | 3181 | or png_destroy_*() is supposed to free the data. When the user assumes |
3182 | responsibility for libpng-allocated data, the application must use | 3182 | responsibility for libpng-allocated data, the application must use |
3183 | png_free() to free it, and when the user transfers responsibility to libpng | 3183 | png_free() to free it, and when the user transfers responsibility to libpng |
3184 | for data that the user has allocated, the user must have used png_malloc() | 3184 | for data that the user has allocated, the user must have used png_malloc() |
3185 | or png_zalloc() to allocate it. | 3185 | or png_zalloc() to allocate it. |
3186 | 3186 | ||
3187 | If you allocated your row_pointers in a single block, as suggested above in | 3187 | If you allocated your row_pointers in a single block, as suggested above in |
3188 | the description of the high level read interface, you must not transfer | 3188 | the description of the high level read interface, you must not transfer |
3189 | responsibility for freeing it to the png_set_rows or png_read_destroy function, | 3189 | responsibility for freeing it to the png_set_rows or png_read_destroy function, |
3190 | because they would also try to free the individual row_pointers[i]. | 3190 | because they would also try to free the individual row_pointers[i]. |
3191 | 3191 | ||
3192 | If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword | 3192 | If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword |
3193 | separately, do not transfer responsibility for freeing text_ptr to libpng, | 3193 | separately, do not transfer responsibility for freeing text_ptr to libpng, |
3194 | because when libpng fills a png_text structure it combines these members with | 3194 | because when libpng fills a png_text structure it combines these members with |
3195 | the key member, and png_free_data() will free only text_ptr.key. Similarly, | 3195 | the key member, and png_free_data() will free only text_ptr.key. Similarly, |
3196 | if you transfer responsibility for free'ing text_ptr from libpng to your | 3196 | if you transfer responsibility for free'ing text_ptr from libpng to your |
3197 | application, your application must not separately free those members. | 3197 | application, your application must not separately free those members. |
3198 | 3198 | ||
3199 | The png_free_data() function will turn off the "valid" flag for anything | 3199 | The png_free_data() function will turn off the "valid" flag for anything |
3200 | it frees. If you need to turn the flag off for a chunk that was freed by | 3200 | it frees. If you need to turn the flag off for a chunk that was freed by |
3201 | your application instead of by libpng, you can use | 3201 | your application instead of by libpng, you can use |
3202 | 3202 | ||
3203 | png_set_invalid(png_ptr, info_ptr, mask); | 3203 | png_set_invalid(png_ptr, info_ptr, mask); |
3204 | 3204 | ||
3205 | mask - identifies the chunks to be made invalid, | 3205 | mask - identifies the chunks to be made invalid, |
3206 | containing the bitwise OR of one or | 3206 | containing the bitwise OR of one or |
3207 | more of | 3207 | more of |
3208 | PNG_INFO_gAMA, PNG_INFO_sBIT, | 3208 | PNG_INFO_gAMA, PNG_INFO_sBIT, |
3209 | PNG_INFO_cHRM, PNG_INFO_PLTE, | 3209 | PNG_INFO_cHRM, PNG_INFO_PLTE, |
3210 | PNG_INFO_tRNS, PNG_INFO_bKGD, | 3210 | PNG_INFO_tRNS, PNG_INFO_bKGD, |
3211 | PNG_INFO_hIST, PNG_INFO_pHYs, | 3211 | PNG_INFO_hIST, PNG_INFO_pHYs, |
3212 | PNG_INFO_oFFs, PNG_INFO_tIME, | 3212 | PNG_INFO_oFFs, PNG_INFO_tIME, |
3213 | PNG_INFO_pCAL, PNG_INFO_sRGB, | 3213 | PNG_INFO_pCAL, PNG_INFO_sRGB, |
3214 | PNG_INFO_iCCP, PNG_INFO_sPLT, | 3214 | PNG_INFO_iCCP, PNG_INFO_sPLT, |
3215 | PNG_INFO_sCAL, PNG_INFO_IDAT | 3215 | PNG_INFO_sCAL, PNG_INFO_IDAT |
3216 | 3216 | ||
3217 | For a more compact example of reading a PNG image, see the file example.c. | 3217 | For a more compact example of reading a PNG image, see the file example.c. |
3218 | 3218 | ||
3219 | .SS Reading PNG files progressively | 3219 | .SS Reading PNG files progressively |
3220 | 3220 | ||
3221 | The progressive reader is slightly different then the non-progressive | 3221 | The progressive reader is slightly different then the non-progressive |
3222 | reader. Instead of calling png_read_info(), png_read_rows(), and | 3222 | reader. Instead of calling png_read_info(), png_read_rows(), and |
3223 | png_read_end(), you make one call to png_process_data(), which calls | 3223 | png_read_end(), you make one call to png_process_data(), which calls |
3224 | callbacks when it has the info, a row, or the end of the image. You | 3224 | callbacks when it has the info, a row, or the end of the image. You |
3225 | set up these callbacks with png_set_progressive_read_fn(). You don't | 3225 | set up these callbacks with png_set_progressive_read_fn(). You don't |
3226 | have to worry about the input/output functions of libpng, as you are | 3226 | have to worry about the input/output functions of libpng, as you are |
3227 | giving the library the data directly in png_process_data(). I will | 3227 | giving the library the data directly in png_process_data(). I will |
3228 | assume that you have read the section on reading PNG files above, | 3228 | assume that you have read the section on reading PNG files above, |
3229 | so I will only highlight the differences (although I will show | 3229 | so I will only highlight the differences (although I will show |
3230 | all of the code). | 3230 | all of the code). |
3231 | 3231 | ||
3232 | png_structp png_ptr; | 3232 | png_structp png_ptr; |
3233 | png_infop info_ptr; | 3233 | png_infop info_ptr; |
3234 | 3234 | ||
3235 | /* An example code fragment of how you would | 3235 | /* An example code fragment of how you would |
3236 | initialize the progressive reader in your | 3236 | initialize the progressive reader in your |
3237 | application. */ | 3237 | application. */ |
3238 | int | 3238 | int |
3239 | initialize_png_reader() | 3239 | initialize_png_reader() |
3240 | { | 3240 | { |
3241 | png_ptr = png_create_read_struct | 3241 | png_ptr = png_create_read_struct |
3242 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, | 3242 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, |
3243 | user_error_fn, user_warning_fn); | 3243 | user_error_fn, user_warning_fn); |
3244 | 3244 | ||
3245 | if (!png_ptr) | 3245 | if (!png_ptr) |
3246 | return (ERROR); | 3246 | return (ERROR); |
3247 | 3247 | ||
3248 | info_ptr = png_create_info_struct(png_ptr); | 3248 | info_ptr = png_create_info_struct(png_ptr); |
3249 | 3249 | ||
3250 | if (!info_ptr) | 3250 | if (!info_ptr) |
3251 | { | 3251 | { |
3252 | png_destroy_read_struct(&png_ptr, | 3252 | png_destroy_read_struct(&png_ptr, |
3253 | (png_infopp)NULL, (png_infopp)NULL); | 3253 | (png_infopp)NULL, (png_infopp)NULL); |
3254 | return (ERROR); | 3254 | return (ERROR); |
3255 | } | 3255 | } |
3256 | 3256 | ||
3257 | if (setjmp(png_jmpbuf(png_ptr))) | 3257 | if (setjmp(png_jmpbuf(png_ptr))) |
3258 | { | 3258 | { |
3259 | png_destroy_read_struct(&png_ptr, &info_ptr, | 3259 | png_destroy_read_struct(&png_ptr, &info_ptr, |
3260 | (png_infopp)NULL); | 3260 | (png_infopp)NULL); |
3261 | return (ERROR); | 3261 | return (ERROR); |
3262 | } | 3262 | } |
3263 | 3263 | ||
3264 | /* This one's new. You can provide functions | 3264 | /* This one's new. You can provide functions |
3265 | to be called when the header info is valid, | 3265 | to be called when the header info is valid, |
3266 | when each row is completed, and when the image | 3266 | when each row is completed, and when the image |
3267 | is finished. If you aren't using all functions, | 3267 | is finished. If you aren't using all functions, |
3268 | you can specify NULL parameters. Even when all | 3268 | you can specify NULL parameters. Even when all |
3269 | three functions are NULL, you need to call | 3269 | three functions are NULL, you need to call |
3270 | png_set_progressive_read_fn(). You can use | 3270 | png_set_progressive_read_fn(). You can use |
3271 | any struct as the user_ptr (cast to a void pointer | 3271 | any struct as the user_ptr (cast to a void pointer |
3272 | for the function call), and retrieve the pointer | 3272 | for the function call), and retrieve the pointer |
3273 | from inside the callbacks using the function | 3273 | from inside the callbacks using the function |
3274 | 3274 | ||
3275 | png_get_progressive_ptr(png_ptr); | 3275 | png_get_progressive_ptr(png_ptr); |
3276 | 3276 | ||
3277 | which will return a void pointer, which you have | 3277 | which will return a void pointer, which you have |
3278 | to cast appropriately. | 3278 | to cast appropriately. |
3279 | */ | 3279 | */ |
3280 | png_set_progressive_read_fn(png_ptr, (void *)user_ptr, | 3280 | png_set_progressive_read_fn(png_ptr, (void *)user_ptr, |
3281 | info_callback, row_callback, end_callback); | 3281 | info_callback, row_callback, end_callback); |
3282 | 3282 | ||
3283 | return 0; | 3283 | return 0; |
3284 | } | 3284 | } |
3285 | 3285 | ||
3286 | /* A code fragment that you call as you receive blocks | 3286 | /* A code fragment that you call as you receive blocks |
3287 | of data */ | 3287 | of data */ |
3288 | int | 3288 | int |
3289 | process_data(png_bytep buffer, png_uint_32 length) | 3289 | process_data(png_bytep buffer, png_uint_32 length) |
3290 | { | 3290 | { |
3291 | if (setjmp(png_jmpbuf(png_ptr))) | 3291 | if (setjmp(png_jmpbuf(png_ptr))) |
3292 | { | 3292 | { |
3293 | png_destroy_read_struct(&png_ptr, &info_ptr, | 3293 | png_destroy_read_struct(&png_ptr, &info_ptr, |
3294 | (png_infopp)NULL); | 3294 | (png_infopp)NULL); |
3295 | return (ERROR); | 3295 | return (ERROR); |
3296 | } | 3296 | } |
3297 | 3297 | ||
3298 | /* This one's new also. Simply give it a chunk | 3298 | /* This one's new also. Simply give it a chunk |
3299 | of data from the file stream (in order, of | 3299 | of data from the file stream (in order, of |
3300 | course). On machines with segmented memory | 3300 | course). On machines with segmented memory |
3301 | models machines, don't give it any more than | 3301 | models machines, don't give it any more than |
3302 | 64K. The library seems to run fine with sizes | 3302 | 64K. The library seems to run fine with sizes |
3303 | of 4K. Although you can give it much less if | 3303 | of 4K. Although you can give it much less if |
3304 | necessary (I assume you can give it chunks of | 3304 | necessary (I assume you can give it chunks of |
3305 | 1 byte, I haven't tried less then 256 bytes | 3305 | 1 byte, I haven't tried less then 256 bytes |
3306 | yet). When this function returns, you may | 3306 | yet). When this function returns, you may |
3307 | want to display any rows that were generated | 3307 | want to display any rows that were generated |
3308 | in the row callback if you don't already do | 3308 | in the row callback if you don't already do |
3309 | so there. | 3309 | so there. |
3310 | */ | 3310 | */ |
3311 | png_process_data(png_ptr, info_ptr, buffer, length); | 3311 | png_process_data(png_ptr, info_ptr, buffer, length); |
3312 | 3312 | ||
3313 | /* At this point you can call png_process_data_skip if | 3313 | /* At this point you can call png_process_data_skip if |
3314 | you want to handle data the library will skip yourself; | 3314 | you want to handle data the library will skip yourself; |
3315 | it simply returns the number of bytes to skip (and stops | 3315 | it simply returns the number of bytes to skip (and stops |
3316 | libpng skipping that number of bytes on the next | 3316 | libpng skipping that number of bytes on the next |
3317 | png_process_data call). | 3317 | png_process_data call). |
3318 | return 0; | 3318 | return 0; |
3319 | } | 3319 | } |
3320 | 3320 | ||
3321 | /* This function is called (as set by | 3321 | /* This function is called (as set by |
3322 | png_set_progressive_read_fn() above) when enough data | 3322 | png_set_progressive_read_fn() above) when enough data |
3323 | has been supplied so all of the header has been | 3323 | has been supplied so all of the header has been |
3324 | read. | 3324 | read. |
3325 | */ | 3325 | */ |
3326 | void | 3326 | void |
3327 | info_callback(png_structp png_ptr, png_infop info) | 3327 | info_callback(png_structp png_ptr, png_infop info) |
3328 | { | 3328 | { |
3329 | /* Do any setup here, including setting any of | 3329 | /* Do any setup here, including setting any of |
3330 | the transformations mentioned in the Reading | 3330 | the transformations mentioned in the Reading |
3331 | PNG files section. For now, you _must_ call | 3331 | PNG files section. For now, you _must_ call |
3332 | either png_start_read_image() or | 3332 | either png_start_read_image() or |
3333 | png_read_update_info() after all the | 3333 | png_read_update_info() after all the |
3334 | transformations are set (even if you don't set | 3334 | transformations are set (even if you don't set |
3335 | any). You may start getting rows before | 3335 | any). You may start getting rows before |
3336 | png_process_data() returns, so this is your | 3336 | png_process_data() returns, so this is your |
3337 | last chance to prepare for that. | 3337 | last chance to prepare for that. |
3338 | 3338 | ||
3339 | This is where you turn on interlace handling, | 3339 | This is where you turn on interlace handling, |
3340 | assuming you don't want to do it yourself. | 3340 | assuming you don't want to do it yourself. |
3341 | 3341 | ||
3342 | If you need to you can stop the processing of | 3342 | If you need to you can stop the processing of |
3343 | your original input data at this point by calling | 3343 | your original input data at this point by calling |
3344 | png_process_data_pause. This returns the number | 3344 | png_process_data_pause. This returns the number |
3345 | of unprocessed bytes from the last png_process_data | 3345 | of unprocessed bytes from the last png_process_data |
3346 | call - it is up to you to ensure that the next call | 3346 | call - it is up to you to ensure that the next call |
3347 | sees these bytes again. If you don't want to bother | 3347 | sees these bytes again. If you don't want to bother |
3348 | with this you can get libpng to cache the unread | 3348 | with this you can get libpng to cache the unread |
3349 | bytes by setting the 'save' parameter (see png.h) but | 3349 | bytes by setting the 'save' parameter (see png.h) but |
3350 | then libpng will have to copy the data internally. | 3350 | then libpng will have to copy the data internally. |
3351 | */ | 3351 | */ |
3352 | } | 3352 | } |
3353 | 3353 | ||
3354 | /* This function is called when each row of image | 3354 | /* This function is called when each row of image |
3355 | data is complete */ | 3355 | data is complete */ |
3356 | void | 3356 | void |
3357 | row_callback(png_structp png_ptr, png_bytep new_row, | 3357 | row_callback(png_structp png_ptr, png_bytep new_row, |
3358 | png_uint_32 row_num, int pass) | 3358 | png_uint_32 row_num, int pass) |
3359 | { | 3359 | { |
3360 | /* If the image is interlaced, and you turned | 3360 | /* If the image is interlaced, and you turned |
3361 | on the interlace handler, this function will | 3361 | on the interlace handler, this function will |
3362 | be called for every row in every pass. Some | 3362 | be called for every row in every pass. Some |
3363 | of these rows will not be changed from the | 3363 | of these rows will not be changed from the |
3364 | previous pass. When the row is not changed, | 3364 | previous pass. When the row is not changed, |
3365 | the new_row variable will be NULL. The rows | 3365 | the new_row variable will be NULL. The rows |
3366 | and passes are called in order, so you don't | 3366 | and passes are called in order, so you don't |
3367 | really need the row_num and pass, but I'm | 3367 | really need the row_num and pass, but I'm |
3368 | supplying them because it may make your life | 3368 | supplying them because it may make your life |
3369 | easier. | 3369 | easier. |
3370 | 3370 | ||
3371 | If you did not turn on interlace handling then | 3371 | If you did not turn on interlace handling then |
3372 | the callback is called for each row of each | 3372 | the callback is called for each row of each |
3373 | sub-image when the image is interlaced. In this | 3373 | sub-image when the image is interlaced. In this |
3374 | case 'row_num' is the row in the sub-image, not | 3374 | case 'row_num' is the row in the sub-image, not |
3375 | the row in the output image as it is in all other | 3375 | the row in the output image as it is in all other |
3376 | cases. | 3376 | cases. |
3377 | 3377 | ||
3378 | For the non-NULL rows of interlaced images when | 3378 | For the non-NULL rows of interlaced images when |
3379 | you have switched on libpng interlace handling, | 3379 | you have switched on libpng interlace handling, |
3380 | you must call png_progressive_combine_row() | 3380 | you must call png_progressive_combine_row() |
3381 | passing in the row and the old row. You can | 3381 | passing in the row and the old row. You can |
3382 | call this function for NULL rows (it will just | 3382 | call this function for NULL rows (it will just |
3383 | return) and for non-interlaced images (it just | 3383 | return) and for non-interlaced images (it just |
3384 | does the memcpy for you) if it will make the | 3384 | does the memcpy for you) if it will make the |
3385 | code easier. Thus, you can just do this for | 3385 | code easier. Thus, you can just do this for |
3386 | all cases if you switch on interlace handling; | 3386 | all cases if you switch on interlace handling; |
3387 | */ | 3387 | */ |
3388 | 3388 | ||
3389 | png_progressive_combine_row(png_ptr, old_row, | 3389 | png_progressive_combine_row(png_ptr, old_row, |
3390 | new_row); | 3390 | new_row); |
3391 | 3391 | ||
3392 | /* where old_row is what was displayed for | 3392 | /* where old_row is what was displayed for |
3393 | previously for the row. Note that the first | 3393 | previously for the row. Note that the first |
3394 | pass (pass == 0, really) will completely cover | 3394 | pass (pass == 0, really) will completely cover |
3395 | the old row, so the rows do not have to be | 3395 | the old row, so the rows do not have to be |
3396 | initialized. After the first pass (and only | 3396 | initialized. After the first pass (and only |
3397 | for interlaced images), you will have to pass | 3397 | for interlaced images), you will have to pass |
3398 | the current row, and the function will combine | 3398 | the current row, and the function will combine |
3399 | the old row and the new row. | 3399 | the old row and the new row. |
3400 | 3400 | ||
3401 | You can also call png_process_data_pause in this | 3401 | You can also call png_process_data_pause in this |
3402 | callback - see above. | 3402 | callback - see above. |
3403 | */ | 3403 | */ |
3404 | } | 3404 | } |
3405 | 3405 | ||
3406 | void | 3406 | void |
3407 | end_callback(png_structp png_ptr, png_infop info) | 3407 | end_callback(png_structp png_ptr, png_infop info) |
3408 | { | 3408 | { |
3409 | /* This function is called after the whole image | 3409 | /* This function is called after the whole image |
3410 | has been read, including any chunks after the | 3410 | has been read, including any chunks after the |
3411 | image (up to and including the IEND). You | 3411 | image (up to and including the IEND). You |
3412 | will usually have the same info chunk as you | 3412 | will usually have the same info chunk as you |
3413 | had in the header, although some data may have | 3413 | had in the header, although some data may have |
3414 | been added to the comments and time fields. | 3414 | been added to the comments and time fields. |
3415 | 3415 | ||
3416 | Most people won't do much here, perhaps setting | 3416 | Most people won't do much here, perhaps setting |
3417 | a flag that marks the image as finished. | 3417 | a flag that marks the image as finished. |
3418 | */ | 3418 | */ |
3419 | } | 3419 | } |
3420 | 3420 | ||
3421 | 3421 | ||
3422 | 3422 | ||
3423 | .SH IV. Writing | 3423 | .SH IV. Writing |
3424 | 3424 | ||
3425 | Much of this is very similar to reading. However, everything of | 3425 | Much of this is very similar to reading. However, everything of |
3426 | importance is repeated here, so you won't have to constantly look | 3426 | importance is repeated here, so you won't have to constantly look |
3427 | back up in the reading section to understand writing. | 3427 | back up in the reading section to understand writing. |
3428 | 3428 | ||
3429 | .SS Setup | 3429 | .SS Setup |
3430 | 3430 | ||
3431 | You will want to do the I/O initialization before you get into libpng, | 3431 | You will want to do the I/O initialization before you get into libpng, |
3432 | so if it doesn't work, you don't have anything to undo. If you are not | 3432 | so if it doesn't work, you don't have anything to undo. If you are not |
3433 | using the standard I/O functions, you will need to replace them with | 3433 | using the standard I/O functions, you will need to replace them with |
3434 | custom writing functions. See the discussion under Customizing libpng. | 3434 | custom writing functions. See the discussion under Customizing libpng. |
3435 | 3435 | ||
3436 | FILE *fp = fopen(file_name, "wb"); | 3436 | FILE *fp = fopen(file_name, "wb"); |
3437 | 3437 | ||
3438 | if (!fp) | 3438 | if (!fp) |
3439 | return (ERROR); | 3439 | return (ERROR); |
3440 | 3440 | ||
3441 | Next, png_struct and png_info need to be allocated and initialized. | 3441 | Next, png_struct and png_info need to be allocated and initialized. |
3442 | As these can be both relatively large, you may not want to store these | 3442 | As these can be both relatively large, you may not want to store these |
3443 | on the stack, unless you have stack space to spare. Of course, you | 3443 | on the stack, unless you have stack space to spare. Of course, you |
3444 | will want to check if they return NULL. If you are also reading, | 3444 | will want to check if they return NULL. If you are also reading, |
3445 | you won't want to name your read structure and your write structure | 3445 | you won't want to name your read structure and your write structure |
3446 | both "png_ptr"; you can call them anything you like, such as | 3446 | both "png_ptr"; you can call them anything you like, such as |
3447 | "read_ptr" and "write_ptr". Look at pngtest.c, for example. | 3447 | "read_ptr" and "write_ptr". Look at pngtest.c, for example. |
3448 | 3448 | ||
3449 | png_structp png_ptr = png_create_write_struct | 3449 | png_structp png_ptr = png_create_write_struct |
3450 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, | 3450 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, |
3451 | user_error_fn, user_warning_fn); | 3451 | user_error_fn, user_warning_fn); |
3452 | 3452 | ||
3453 | if (!png_ptr) | 3453 | if (!png_ptr) |
3454 | return (ERROR); | 3454 | return (ERROR); |
3455 | 3455 | ||
3456 | png_infop info_ptr = png_create_info_struct(png_ptr); | 3456 | png_infop info_ptr = png_create_info_struct(png_ptr); |
3457 | if (!info_ptr) | 3457 | if (!info_ptr) |
3458 | { | 3458 | { |
3459 | png_destroy_write_struct(&png_ptr, | 3459 | png_destroy_write_struct(&png_ptr, |
3460 | (png_infopp)NULL); | 3460 | (png_infopp)NULL); |
3461 | return (ERROR); | 3461 | return (ERROR); |
3462 | } | 3462 | } |
3463 | 3463 | ||
3464 | If you want to use your own memory allocation routines, | 3464 | If you want to use your own memory allocation routines, |
3465 | define PNG_USER_MEM_SUPPORTED and use | 3465 | define PNG_USER_MEM_SUPPORTED and use |
3466 | png_create_write_struct_2() instead of png_create_write_struct(): | 3466 | png_create_write_struct_2() instead of png_create_write_struct(): |
3467 | 3467 | ||
3468 | png_structp png_ptr = png_create_write_struct_2 | 3468 | png_structp png_ptr = png_create_write_struct_2 |
3469 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, | 3469 | (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr, |
3470 | user_error_fn, user_warning_fn, (png_voidp) | 3470 | user_error_fn, user_warning_fn, (png_voidp) |
3471 | user_mem_ptr, user_malloc_fn, user_free_fn); | 3471 | user_mem_ptr, user_malloc_fn, user_free_fn); |
3472 | 3472 | ||
3473 | After you have these structures, you will need to set up the | 3473 | After you have these structures, you will need to set up the |
3474 | error handling. When libpng encounters an error, it expects to | 3474 | error handling. When libpng encounters an error, it expects to |
3475 | longjmp() back to your routine. Therefore, you will need to call | 3475 | longjmp() back to your routine. Therefore, you will need to call |
3476 | setjmp() and pass the png_jmpbuf(png_ptr). If you | 3476 | setjmp() and pass the png_jmpbuf(png_ptr). If you |
3477 | write the file from different routines, you will need to update | 3477 | write the file from different routines, you will need to update |
3478 | the png_jmpbuf(png_ptr) every time you enter a new routine that will | 3478 | the png_jmpbuf(png_ptr) every time you enter a new routine that will |
3479 | call a png_*() function. See your documentation of setjmp/longjmp | 3479 | call a png_*() function. See your documentation of setjmp/longjmp |
3480 | for your compiler for more information on setjmp/longjmp. See | 3480 | for your compiler for more information on setjmp/longjmp. See |
3481 | the discussion on libpng error handling in the Customizing Libpng | 3481 | the discussion on libpng error handling in the Customizing Libpng |
3482 | section below for more information on the libpng error handling. | 3482 | section below for more information on the libpng error handling. |
3483 | 3483 | ||
3484 | if (setjmp(png_jmpbuf(png_ptr))) | 3484 | if (setjmp(png_jmpbuf(png_ptr))) |
3485 | { | 3485 | { |
3486 | png_destroy_write_struct(&png_ptr, &info_ptr); | 3486 | png_destroy_write_struct(&png_ptr, &info_ptr); |
3487 | fclose(fp); | 3487 | fclose(fp); |
3488 | return (ERROR); | 3488 | return (ERROR); |
3489 | } | 3489 | } |
3490 | ... | 3490 | ... |
3491 | return; | 3491 | return; |
3492 | 3492 | ||
3493 | If you would rather avoid the complexity of setjmp/longjmp issues, | 3493 | If you would rather avoid the complexity of setjmp/longjmp issues, |
3494 | you can compile libpng with PNG_NO_SETJMP, in which case | 3494 | you can compile libpng with PNG_NO_SETJMP, in which case |
3495 | errors will result in a call to PNG_ABORT() which defaults to abort(). | 3495 | errors will result in a call to PNG_ABORT() which defaults to abort(). |
3496 | 3496 | ||
3497 | You can #define PNG_ABORT() to a function that does something | 3497 | You can #define PNG_ABORT() to a function that does something |
3498 | more useful than abort(), as long as your function does not | 3498 | more useful than abort(), as long as your function does not |
3499 | return. | 3499 | return. |
3500 | 3500 | ||
3501 | Now you need to set up the output code. The default for libpng is to | 3501 | Now you need to set up the output code. The default for libpng is to |
3502 | use the C function fwrite(). If you use this, you will need to pass a | 3502 | use the C function fwrite(). If you use this, you will need to pass a |
3503 | valid FILE * in the function png_init_io(). Be sure that the file is | 3503 | valid FILE * in the function png_init_io(). Be sure that the file is |
3504 | opened in binary mode. Again, if you wish to handle writing data in | 3504 | opened in binary mode. Again, if you wish to handle writing data in |
3505 | another way, see the discussion on libpng I/O handling in the Customizing | 3505 | another way, see the discussion on libpng I/O handling in the Customizing |
3506 | Libpng section below. | 3506 | Libpng section below. |
3507 | 3507 | ||
3508 | png_init_io(png_ptr, fp); | 3508 | png_init_io(png_ptr, fp); |
3509 | 3509 | ||
3510 | If you are embedding your PNG into a datastream such as MNG, and don't | 3510 | If you are embedding your PNG into a datastream such as MNG, and don't |
3511 | want libpng to write the 8-byte signature, or if you have already | 3511 | want libpng to write the 8-byte signature, or if you have already |
3512 | written the signature in your application, use | 3512 | written the signature in your application, use |
3513 | 3513 | ||
3514 | png_set_sig_bytes(png_ptr, 8); | 3514 | png_set_sig_bytes(png_ptr, 8); |
3515 | 3515 | ||
3516 | to inform libpng that it should not write a signature. | 3516 | to inform libpng that it should not write a signature. |
3517 | 3517 | ||
3518 | .SS Write callbacks | 3518 | .SS Write callbacks |
3519 | 3519 | ||
3520 | At this point, you can set up a callback function that will be | 3520 | At this point, you can set up a callback function that will be |
3521 | called after each row has been written, which you can use to control | 3521 | called after each row has been written, which you can use to control |
3522 | a progress meter or the like. It's demonstrated in pngtest.c. | 3522 | a progress meter or the like. It's demonstrated in pngtest.c. |
3523 | You must supply a function | 3523 | You must supply a function |
3524 | 3524 | ||
3525 | void write_row_callback(png_structp png_ptr, png_uint_32 row, | 3525 | void write_row_callback(png_structp png_ptr, png_uint_32 row, |
3526 | int pass); | 3526 | int pass); |
3527 | { | 3527 | { |
3528 | /* put your code here */ | 3528 | /* put your code here */ |
3529 | } | 3529 | } |
3530 | 3530 | ||
3531 | (You can give it another name that you like instead of "write_row_callback") | 3531 | (You can give it another name that you like instead of "write_row_callback") |
3532 | 3532 | ||
3533 | To inform libpng about your function, use | 3533 | To inform libpng about your function, use |
3534 | 3534 | ||
3535 | png_set_write_status_fn(png_ptr, write_row_callback); | 3535 | png_set_write_status_fn(png_ptr, write_row_callback); |
3536 | 3536 | ||
3537 | When this function is called the row has already been completely processed and | 3537 | When this function is called the row has already been completely processed and |
3538 | it has also been written out. The 'row' and 'pass' refer to the next row to be | 3538 | it has also been written out. The 'row' and 'pass' refer to the next row to be |
3539 | handled. For the | 3539 | handled. For the |
3540 | non-interlaced case the row that was just handled is simply one less than the | 3540 | non-interlaced case the row that was just handled is simply one less than the |
3541 | passed in row number, and pass will always be 0. For the interlaced case the | 3541 | passed in row number, and pass will always be 0. For the interlaced case the |
3542 | same applies unless the row value is 0, in which case the row just handled was | 3542 | same applies unless the row value is 0, in which case the row just handled was |
3543 | the last one from one of the preceding passes. Because interlacing may skip a | 3543 | the last one from one of the preceding passes. Because interlacing may skip a |
3544 | pass you cannot be sure that the preceding pass is just 'pass-1', if you really | 3544 | pass you cannot be sure that the preceding pass is just 'pass-1', if you really |
3545 | need to know what the last pass is record (row,pass) from the callback and use | 3545 | need to know what the last pass is record (row,pass) from the callback and use |
3546 | the last recorded value each time. | 3546 | the last recorded value each time. |
3547 | 3547 | ||
3548 | As with the user transform you can find the output row using the | 3548 | As with the user transform you can find the output row using the |
3549 | PNG_ROW_FROM_PASS_ROW macro. | 3549 | PNG_ROW_FROM_PASS_ROW macro. |
3550 | 3550 | ||
3551 | You now have the option of modifying how the compression library will | 3551 | You now have the option of modifying how the compression library will |
3552 | run. The following functions are mainly for testing, but may be useful | 3552 | run. The following functions are mainly for testing, but may be useful |
3553 | in some cases, like if you need to write PNG files extremely fast and | 3553 | in some cases, like if you need to write PNG files extremely fast and |
3554 | are willing to give up some compression, or if you want to get the | 3554 | are willing to give up some compression, or if you want to get the |
3555 | maximum possible compression at the expense of slower writing. If you | 3555 | maximum possible compression at the expense of slower writing. If you |
3556 | have no special needs in this area, let the library do what it wants by | 3556 | have no special needs in this area, let the library do what it wants by |
3557 | not calling this function at all, as it has been tuned to deliver a good | 3557 | not calling this function at all, as it has been tuned to deliver a good |
3558 | speed/compression ratio. The second parameter to png_set_filter() is | 3558 | speed/compression ratio. The second parameter to png_set_filter() is |
3559 | the filter method, for which the only valid values are 0 (as of the | 3559 | the filter method, for which the only valid values are 0 (as of the |
3560 | July 1999 PNG specification, version 1.2) or 64 (if you are writing | 3560 | July 1999 PNG specification, version 1.2) or 64 (if you are writing |
3561 | a PNG datastream that is to be embedded in a MNG datastream). The third | 3561 | a PNG datastream that is to be embedded in a MNG datastream). The third |
3562 | parameter is a flag that indicates which filter type(s) are to be tested | 3562 | parameter is a flag that indicates which filter type(s) are to be tested |
3563 | for each scanline. See the PNG specification for details on the specific | 3563 | for each scanline. See the PNG specification for details on the specific |
3564 | filter types. | 3564 | filter types. |
3565 | 3565 | ||
3566 | 3566 | ||
3567 | /* turn on or off filtering, and/or choose | 3567 | /* turn on or off filtering, and/or choose |
3568 | specific filters. You can use either a single | 3568 | specific filters. You can use either a single |
3569 | PNG_FILTER_VALUE_NAME or the bitwise OR of one | 3569 | PNG_FILTER_VALUE_NAME or the bitwise OR of one |
3570 | or more PNG_FILTER_NAME masks. | 3570 | or more PNG_FILTER_NAME masks. |
3571 | */ | 3571 | */ |
3572 | png_set_filter(png_ptr, 0, | 3572 | png_set_filter(png_ptr, 0, |
3573 | PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE | | 3573 | PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE | |
3574 | PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB | | 3574 | PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB | |
3575 | PNG_FILTER_UP | PNG_FILTER_VALUE_UP | | 3575 | PNG_FILTER_UP | PNG_FILTER_VALUE_UP | |
3576 | PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG | | 3576 | PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG | |
3577 | PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH| | 3577 | PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH| |
3578 | PNG_ALL_FILTERS); | 3578 | PNG_ALL_FILTERS); |
3579 | 3579 | ||
3580 | If an application wants to start and stop using particular filters during | 3580 | If an application wants to start and stop using particular filters during |
3581 | compression, it should start out with all of the filters (to ensure that | 3581 | compression, it should start out with all of the filters (to ensure that |
3582 | the previous row of pixels will be stored in case it's needed later), | 3582 | the previous row of pixels will be stored in case it's needed later), |
3583 | and then add and remove them after the start of compression. | 3583 | and then add and remove them after the start of compression. |
3584 | 3584 | ||
3585 | If you are writing a PNG datastream that is to be embedded in a MNG | 3585 | If you are writing a PNG datastream that is to be embedded in a MNG |
3586 | datastream, the second parameter can be either 0 or 64. | 3586 | datastream, the second parameter can be either 0 or 64. |
3587 | 3587 | ||
3588 | The png_set_compression_*() functions interface to the zlib compression | 3588 | The png_set_compression_*() functions interface to the zlib compression |
3589 | library, and should mostly be ignored unless you really know what you are | 3589 | library, and should mostly be ignored unless you really know what you are |
3590 | doing. The only generally useful call is png_set_compression_level() | 3590 | doing. The only generally useful call is png_set_compression_level() |
3591 | which changes how much time zlib spends on trying to compress the image | 3591 | which changes how much time zlib spends on trying to compress the image |
3592 | data. See the Compression Library (zlib.h and algorithm.txt, distributed | 3592 | data. See the Compression Library (zlib.h and algorithm.txt, distributed |
3593 | with zlib) for details on the compression levels. | 3593 | with zlib) for details on the compression levels. |
3594 | 3594 | ||
3595 | #include zlib.h | 3595 | #include zlib.h |
3596 | 3596 | ||
3597 | /* Set the zlib compression level */ | 3597 | /* Set the zlib compression level */ |
3598 | png_set_compression_level(png_ptr, | 3598 | png_set_compression_level(png_ptr, |
3599 | Z_BEST_COMPRESSION); | 3599 | Z_BEST_COMPRESSION); |
3600 | 3600 | ||
3601 | /* Set other zlib parameters for compressing IDAT */ | 3601 | /* Set other zlib parameters for compressing IDAT */ |
3602 | png_set_compression_mem_level(png_ptr, 8); | 3602 | png_set_compression_mem_level(png_ptr, 8); |
3603 | png_set_compression_strategy(png_ptr, | 3603 | png_set_compression_strategy(png_ptr, |
3604 | Z_DEFAULT_STRATEGY); | 3604 | Z_DEFAULT_STRATEGY); |
3605 | png_set_compression_window_bits(png_ptr, 15); | 3605 | png_set_compression_window_bits(png_ptr, 15); |
3606 | png_set_compression_method(png_ptr, 8); | 3606 | png_set_compression_method(png_ptr, 8); |
3607 | png_set_compression_buffer_size(png_ptr, 8192) | 3607 | png_set_compression_buffer_size(png_ptr, 8192) |
3608 | 3608 | ||
3609 | /* Set zlib parameters for text compression | 3609 | /* Set zlib parameters for text compression |
3610 | * If you don't call these, the parameters | 3610 | * If you don't call these, the parameters |
3611 | * fall back on those defined for IDAT chunks | 3611 | * fall back on those defined for IDAT chunks |
3612 | */ | 3612 | */ |
3613 | png_set_text_compression_mem_level(png_ptr, 8); | 3613 | png_set_text_compression_mem_level(png_ptr, 8); |
3614 | png_set_text_compression_strategy(png_ptr, | 3614 | png_set_text_compression_strategy(png_ptr, |
3615 | Z_DEFAULT_STRATEGY); | 3615 | Z_DEFAULT_STRATEGY); |
3616 | png_set_text_compression_window_bits(png_ptr, 15); | 3616 | png_set_text_compression_window_bits(png_ptr, 15); |
3617 | png_set_text_compression_method(png_ptr, 8); | 3617 | png_set_text_compression_method(png_ptr, 8); |
3618 | 3618 | ||
3619 | .SS Setting the contents of info for output | 3619 | .SS Setting the contents of info for output |
3620 | 3620 | ||
3621 | You now need to fill in the png_info structure with all the data you | 3621 | You now need to fill in the png_info structure with all the data you |
3622 | wish to write before the actual image. Note that the only thing you | 3622 | wish to write before the actual image. Note that the only thing you |
3623 | are allowed to write after the image is the text chunks and the time | 3623 | are allowed to write after the image is the text chunks and the time |
3624 | chunk (as of PNG Specification 1.2, anyway). See png_write_end() and | 3624 | chunk (as of PNG Specification 1.2, anyway). See png_write_end() and |
3625 | the latest PNG specification for more information on that. If you | 3625 | the latest PNG specification for more information on that. If you |
3626 | wish to write them before the image, fill them in now, and flag that | 3626 | wish to write them before the image, fill them in now, and flag that |
3627 | data as being valid. If you want to wait until after the data, don't | 3627 | data as being valid. If you want to wait until after the data, don't |
3628 | fill them until png_write_end(). For all the fields in png_info and | 3628 | fill them until png_write_end(). For all the fields in png_info and |
3629 | their data types, see png.h. For explanations of what the fields | 3629 | their data types, see png.h. For explanations of what the fields |
3630 | contain, see the PNG specification. | 3630 | contain, see the PNG specification. |
3631 | 3631 | ||
3632 | Some of the more important parts of the png_info are: | 3632 | Some of the more important parts of the png_info are: |
3633 | 3633 | ||
3634 | png_set_IHDR(png_ptr, info_ptr, width, height, | 3634 | png_set_IHDR(png_ptr, info_ptr, width, height, |
3635 | bit_depth, color_type, interlace_type, | 3635 | bit_depth, color_type, interlace_type, |
3636 | compression_type, filter_method) | 3636 | compression_type, filter_method) |
3637 | 3637 | ||
3638 | width - holds the width of the image | 3638 | width - holds the width of the image |
3639 | in pixels (up to 2^31). | 3639 | in pixels (up to 2^31). |
3640 | 3640 | ||
3641 | height - holds the height of the image | 3641 | height - holds the height of the image |
3642 | in pixels (up to 2^31). | 3642 | in pixels (up to 2^31). |
3643 | 3643 | ||
3644 | bit_depth - holds the bit depth of one of the | 3644 | bit_depth - holds the bit depth of one of the |
3645 | image channels. | 3645 | image channels. |
3646 | (valid values are 1, 2, 4, 8, 16 | 3646 | (valid values are 1, 2, 4, 8, 16 |
3647 | and depend also on the | 3647 | and depend also on the |
3648 | color_type. See also significant | 3648 | color_type. See also significant |
3649 | bits (sBIT) below). | 3649 | bits (sBIT) below). |
3650 | 3650 | ||
3651 | color_type - describes which color/alpha | 3651 | color_type - describes which color/alpha |
3652 | channels are present. | 3652 | channels are present. |
3653 | PNG_COLOR_TYPE_GRAY | 3653 | PNG_COLOR_TYPE_GRAY |
3654 | (bit depths 1, 2, 4, 8, 16) | 3654 | (bit depths 1, 2, 4, 8, 16) |
3655 | PNG_COLOR_TYPE_GRAY_ALPHA | 3655 | PNG_COLOR_TYPE_GRAY_ALPHA |
3656 | (bit depths 8, 16) | 3656 | (bit depths 8, 16) |
3657 | PNG_COLOR_TYPE_PALETTE | 3657 | PNG_COLOR_TYPE_PALETTE |
3658 | (bit depths 1, 2, 4, 8) | 3658 | (bit depths 1, 2, 4, 8) |
3659 | PNG_COLOR_TYPE_RGB | 3659 | PNG_COLOR_TYPE_RGB |
3660 | (bit_depths 8, 16) | 3660 | (bit_depths 8, 16) |
3661 | PNG_COLOR_TYPE_RGB_ALPHA | 3661 | PNG_COLOR_TYPE_RGB_ALPHA |
3662 | (bit_depths 8, 16) | 3662 | (bit_depths 8, 16) |
3663 | 3663 | ||
3664 | PNG_COLOR_MASK_PALETTE | 3664 | PNG_COLOR_MASK_PALETTE |
3665 | PNG_COLOR_MASK_COLOR | 3665 | PNG_COLOR_MASK_COLOR |
3666 | PNG_COLOR_MASK_ALPHA | 3666 | PNG_COLOR_MASK_ALPHA |
3667 | 3667 | ||
3668 | interlace_type - PNG_INTERLACE_NONE or | 3668 | interlace_type - PNG_INTERLACE_NONE or |
3669 | PNG_INTERLACE_ADAM7 | 3669 | PNG_INTERLACE_ADAM7 |
3670 | 3670 | ||
3671 | compression_type - (must be | 3671 | compression_type - (must be |
3672 | PNG_COMPRESSION_TYPE_DEFAULT) | 3672 | PNG_COMPRESSION_TYPE_DEFAULT) |
3673 | 3673 | ||
3674 | filter_method - (must be PNG_FILTER_TYPE_DEFAULT | 3674 | filter_method - (must be PNG_FILTER_TYPE_DEFAULT |
3675 | or, if you are writing a PNG to | 3675 | or, if you are writing a PNG to |
3676 | be embedded in a MNG datastream, | 3676 | be embedded in a MNG datastream, |
3677 | can also be | 3677 | can also be |
3678 | PNG_INTRAPIXEL_DIFFERENCING) | 3678 | PNG_INTRAPIXEL_DIFFERENCING) |
3679 | 3679 | ||
3680 | If you call png_set_IHDR(), the call must appear before any of the | 3680 | If you call png_set_IHDR(), the call must appear before any of the |
3681 | other png_set_*() functions, because they might require access to some of | 3681 | other png_set_*() functions, because they might require access to some of |
3682 | the IHDR settings. The remaining png_set_*() functions can be called | 3682 | the IHDR settings. The remaining png_set_*() functions can be called |
3683 | in any order. | 3683 | in any order. |
3684 | 3684 | ||
3685 | If you wish, you can reset the compression_type, interlace_type, or | 3685 | If you wish, you can reset the compression_type, interlace_type, or |
3686 | filter_method later by calling png_set_IHDR() again; if you do this, the | 3686 | filter_method later by calling png_set_IHDR() again; if you do this, the |
3687 | width, height, bit_depth, and color_type must be the same in each call. | 3687 | width, height, bit_depth, and color_type must be the same in each call. |
3688 | 3688 | ||
3689 | png_set_PLTE(png_ptr, info_ptr, palette, | 3689 | png_set_PLTE(png_ptr, info_ptr, palette, |
3690 | num_palette); | 3690 | num_palette); |
3691 | 3691 | ||
3692 | palette - the palette for the file | 3692 | palette - the palette for the file |
3693 | (array of png_color) | 3693 | (array of png_color) |
3694 | num_palette - number of entries in the palette | 3694 | num_palette - number of entries in the palette |
3695 | 3695 | ||
3696 | png_set_gAMA(png_ptr, info_ptr, file_gamma); | 3696 | png_set_gAMA(png_ptr, info_ptr, file_gamma); |
3697 | png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma); | 3697 | png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma); |
3698 | 3698 | ||
3699 | file_gamma - the gamma at which the image was | 3699 | file_gamma - the gamma at which the image was |
3700 | created (PNG_INFO_gAMA) | 3700 | created (PNG_INFO_gAMA) |
3701 | 3701 | ||
3702 | int_file_gamma - 100,000 times the gamma at which | 3702 | int_file_gamma - 100,000 times the gamma at which |
3703 | the image was created | 3703 | the image was created |
3704 | 3704 | ||
3705 | png_set_cHRM(png_ptr, info_ptr, white_x, white_y, red_x, red_y, | 3705 | png_set_cHRM(png_ptr, info_ptr, white_x, white_y, red_x, red_y, |
3706 | green_x, green_y, blue_x, blue_y) | 3706 | green_x, green_y, blue_x, blue_y) |
3707 | png_set_cHRM_XYZ(png_ptr, info_ptr, red_X, red_Y, red_Z, green_X, | 3707 | png_set_cHRM_XYZ(png_ptr, info_ptr, red_X, red_Y, red_Z, green_X, |
3708 | green_Y, green_Z, blue_X, blue_Y, blue_Z) | 3708 | green_Y, green_Z, blue_X, blue_Y, blue_Z) |
3709 | png_set_cHRM_fixed(png_ptr, info_ptr, int_white_x, int_white_y, | 3709 | png_set_cHRM_fixed(png_ptr, info_ptr, int_white_x, int_white_y, |
3710 | int_red_x, int_red_y, int_green_x, int_green_y, | 3710 | int_red_x, int_red_y, int_green_x, int_green_y, |
3711 | int_blue_x, int_blue_y) | 3711 | int_blue_x, int_blue_y) |
3712 | png_set_cHRM_XYZ_fixed(png_ptr, info_ptr, int_red_X, int_red_Y, | 3712 | png_set_cHRM_XYZ_fixed(png_ptr, info_ptr, int_red_X, int_red_Y, |
3713 | int_red_Z, int_green_X, int_green_Y, int_green_Z, | 3713 | int_red_Z, int_green_X, int_green_Y, int_green_Z, |
3714 | int_blue_X, int_blue_Y, int_blue_Z) | 3714 | int_blue_X, int_blue_Y, int_blue_Z) |
3715 | 3715 | ||
3716 | {white,red,green,blue}_{x,y} | 3716 | {white,red,green,blue}_{x,y} |
3717 | A color space encoding specified using the chromaticities | 3717 | A color space encoding specified using the chromaticities |
3718 | of the end points and the white point. | 3718 | of the end points and the white point. |
3719 | 3719 | ||
3720 | {red,green,blue}_{X,Y,Z} | 3720 | {red,green,blue}_{X,Y,Z} |
3721 | A color space encoding specified using the encoding end | 3721 | A color space encoding specified using the encoding end |
3722 | points - the CIE tristimulus specification of the intended | 3722 | points - the CIE tristimulus specification of the intended |
3723 | color of the red, green and blue channels in the PNG RGB | 3723 | color of the red, green and blue channels in the PNG RGB |
3724 | data. The white point is simply the sum of the three end | 3724 | data. The white point is simply the sum of the three end |
3725 | points. | 3725 | points. |
3726 | 3726 | ||
3727 | png_set_sRGB(png_ptr, info_ptr, srgb_intent); | 3727 | png_set_sRGB(png_ptr, info_ptr, srgb_intent); |
3728 | 3728 | ||
3729 | srgb_intent - the rendering intent | 3729 | srgb_intent - the rendering intent |
3730 | (PNG_INFO_sRGB) The presence of | 3730 | (PNG_INFO_sRGB) The presence of |
3731 | the sRGB chunk means that the pixel | 3731 | the sRGB chunk means that the pixel |
3732 | data is in the sRGB color space. | 3732 | data is in the sRGB color space. |
3733 | This chunk also implies specific | 3733 | This chunk also implies specific |
3734 | values of gAMA and cHRM. Rendering | 3734 | values of gAMA and cHRM. Rendering |
3735 | intent is the CSS-1 property that | 3735 | intent is the CSS-1 property that |
3736 | has been defined by the International | 3736 | has been defined by the International |
3737 | Color Consortium | 3737 | Color Consortium |
3738 | (http://www.color.org). | 3738 | (http://www.color.org). |
3739 | It can be one of | 3739 | It can be one of |
3740 | PNG_sRGB_INTENT_SATURATION, | 3740 | PNG_sRGB_INTENT_SATURATION, |
3741 | PNG_sRGB_INTENT_PERCEPTUAL, | 3741 | PNG_sRGB_INTENT_PERCEPTUAL, |
3742 | PNG_sRGB_INTENT_ABSOLUTE, or | 3742 | PNG_sRGB_INTENT_ABSOLUTE, or |
3743 | PNG_sRGB_INTENT_RELATIVE. | 3743 | PNG_sRGB_INTENT_RELATIVE. |
3744 | 3744 | ||
3745 | 3745 | ||
3746 | png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, | 3746 | png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, |
3747 | srgb_intent); | 3747 | srgb_intent); |
3748 | 3748 | ||
3749 | srgb_intent - the rendering intent | 3749 | srgb_intent - the rendering intent |
3750 | (PNG_INFO_sRGB) The presence of the | 3750 | (PNG_INFO_sRGB) The presence of the |
3751 | sRGB chunk means that the pixel | 3751 | sRGB chunk means that the pixel |
3752 | data is in the sRGB color space. | 3752 | data is in the sRGB color space. |
3753 | This function also causes gAMA and | 3753 | This function also causes gAMA and |
3754 | cHRM chunks with the specific values | 3754 | cHRM chunks with the specific values |
3755 | that are consistent with sRGB to be | 3755 | that are consistent with sRGB to be |
3756 | written. | 3756 | written. |
3757 | 3757 | ||
3758 | png_set_iCCP(png_ptr, info_ptr, name, compression_type, | 3758 | png_set_iCCP(png_ptr, info_ptr, name, compression_type, |
3759 | profile, proflen); | 3759 | profile, proflen); |
3760 | 3760 | ||
3761 | name - The profile name. | 3761 | name - The profile name. |
3762 | 3762 | ||
3763 | compression_type - The compression type; always | 3763 | compression_type - The compression type; always |
3764 | PNG_COMPRESSION_TYPE_BASE for PNG 1.0. | 3764 | PNG_COMPRESSION_TYPE_BASE for PNG 1.0. |
3765 | You may give NULL to this argument to | 3765 | You may give NULL to this argument to |
3766 | ignore it. | 3766 | ignore it. |
3767 | 3767 | ||
3768 | profile - International Color Consortium color | 3768 | profile - International Color Consortium color |
3769 | profile data. May contain NULs. | 3769 | profile data. May contain NULs. |
3770 | 3770 | ||
3771 | proflen - length of profile data in bytes. | 3771 | proflen - length of profile data in bytes. |
3772 | 3772 | ||
3773 | png_set_sBIT(png_ptr, info_ptr, sig_bit); | 3773 | png_set_sBIT(png_ptr, info_ptr, sig_bit); |
3774 | 3774 | ||
3775 | sig_bit - the number of significant bits for | 3775 | sig_bit - the number of significant bits for |
3776 | (PNG_INFO_sBIT) each of the gray, red, | 3776 | (PNG_INFO_sBIT) each of the gray, red, |
3777 | green, and blue channels, whichever are | 3777 | green, and blue channels, whichever are |
3778 | appropriate for the given color type | 3778 | appropriate for the given color type |
3779 | (png_color_16) | 3779 | (png_color_16) |
3780 | 3780 | ||
3781 | png_set_tRNS(png_ptr, info_ptr, trans_alpha, | 3781 | png_set_tRNS(png_ptr, info_ptr, trans_alpha, |
3782 | num_trans, trans_color); | 3782 | num_trans, trans_color); |
3783 | 3783 | ||
3784 | trans_alpha - array of alpha (transparency) | 3784 | trans_alpha - array of alpha (transparency) |
3785 | entries for palette (PNG_INFO_tRNS) | 3785 | entries for palette (PNG_INFO_tRNS) |
3786 | 3786 | ||
3787 | num_trans - number of transparent entries | 3787 | num_trans - number of transparent entries |
3788 | (PNG_INFO_tRNS) | 3788 | (PNG_INFO_tRNS) |
3789 | 3789 | ||
3790 | trans_color - graylevel or color sample values | 3790 | trans_color - graylevel or color sample values |
3791 | (in order red, green, blue) of the | 3791 | (in order red, green, blue) of the |
3792 | single transparent color for | 3792 | single transparent color for |
3793 | non-paletted images (PNG_INFO_tRNS) | 3793 | non-paletted images (PNG_INFO_tRNS) |
3794 | 3794 | ||
3795 | png_set_hIST(png_ptr, info_ptr, hist); | 3795 | png_set_hIST(png_ptr, info_ptr, hist); |
3796 | 3796 | ||
3797 | hist - histogram of palette (array of | 3797 | hist - histogram of palette (array of |
3798 | png_uint_16) (PNG_INFO_hIST) | 3798 | png_uint_16) (PNG_INFO_hIST) |
3799 | 3799 | ||
3800 | png_set_tIME(png_ptr, info_ptr, mod_time); | 3800 | png_set_tIME(png_ptr, info_ptr, mod_time); |
3801 | 3801 | ||
3802 | mod_time - time image was last modified | 3802 | mod_time - time image was last modified |
3803 | (PNG_VALID_tIME) | 3803 | (PNG_VALID_tIME) |
3804 | 3804 | ||
3805 | png_set_bKGD(png_ptr, info_ptr, background); | 3805 | png_set_bKGD(png_ptr, info_ptr, background); |
3806 | 3806 | ||
3807 | background - background color (of type | 3807 | background - background color (of type |
3808 | png_color_16p) (PNG_VALID_bKGD) | 3808 | png_color_16p) (PNG_VALID_bKGD) |
3809 | 3809 | ||
3810 | png_set_text(png_ptr, info_ptr, text_ptr, num_text); | 3810 | png_set_text(png_ptr, info_ptr, text_ptr, num_text); |
3811 | 3811 | ||
3812 | text_ptr - array of png_text holding image | 3812 | text_ptr - array of png_text holding image |
3813 | comments | 3813 | comments |
3814 | 3814 | ||
3815 | text_ptr[i].compression - type of compression used | 3815 | text_ptr[i].compression - type of compression used |
3816 | on "text" PNG_TEXT_COMPRESSION_NONE | 3816 | on "text" PNG_TEXT_COMPRESSION_NONE |
3817 | PNG_TEXT_COMPRESSION_zTXt | 3817 | PNG_TEXT_COMPRESSION_zTXt |
3818 | PNG_ITXT_COMPRESSION_NONE | 3818 | PNG_ITXT_COMPRESSION_NONE |
3819 | PNG_ITXT_COMPRESSION_zTXt | 3819 | PNG_ITXT_COMPRESSION_zTXt |
3820 | text_ptr[i].key - keyword for comment. Must contain | 3820 | text_ptr[i].key - keyword for comment. Must contain |
3821 | 1-79 characters. | 3821 | 1-79 characters. |
3822 | text_ptr[i].text - text comments for current | 3822 | text_ptr[i].text - text comments for current |
3823 | keyword. Can be NULL or empty. | 3823 | keyword. Can be NULL or empty. |
3824 | text_ptr[i].text_length - length of text string, | 3824 | text_ptr[i].text_length - length of text string, |
3825 | after decompression, 0 for iTXt | 3825 | after decompression, 0 for iTXt |
3826 | text_ptr[i].itxt_length - length of itxt string, | 3826 | text_ptr[i].itxt_length - length of itxt string, |
3827 | after decompression, 0 for tEXt/zTXt | 3827 | after decompression, 0 for tEXt/zTXt |
3828 | text_ptr[i].lang - language of comment (NULL or | 3828 | text_ptr[i].lang - language of comment (NULL or |
3829 | empty for unknown). | 3829 | empty for unknown). |
3830 | text_ptr[i].translated_keyword - keyword in UTF-8 (NULL | 3830 | text_ptr[i].translated_keyword - keyword in UTF-8 (NULL |
3831 | or empty for unknown). | 3831 | or empty for unknown). |
3832 | 3832 | ||
3833 | Note that the itxt_length, lang, and lang_key | 3833 | Note that the itxt_length, lang, and lang_key |
3834 | members of the text_ptr structure only exist when the | 3834 | members of the text_ptr structure only exist when the |
3835 | library is built with iTXt chunk support. Prior to | 3835 | library is built with iTXt chunk support. Prior to |
3836 | libpng-1.4.0 the library was built by default without | 3836 | libpng-1.4.0 the library was built by default without |
3837 | iTXt support. Also note that when iTXt is supported, | 3837 | iTXt support. Also note that when iTXt is supported, |
3838 | they contain NULL pointers when the "compression" | 3838 | they contain NULL pointers when the "compression" |
3839 | field contains PNG_TEXT_COMPRESSION_NONE or | 3839 | field contains PNG_TEXT_COMPRESSION_NONE or |
3840 | PNG_TEXT_COMPRESSION_zTXt. | 3840 | PNG_TEXT_COMPRESSION_zTXt. |
3841 | 3841 | ||
3842 | num_text - number of comments | 3842 | num_text - number of comments |
3843 | 3843 | ||
3844 | png_set_sPLT(png_ptr, info_ptr, &palette_ptr, | 3844 | png_set_sPLT(png_ptr, info_ptr, &palette_ptr, |
3845 | num_spalettes); | 3845 | num_spalettes); |
3846 | 3846 | ||
3847 | palette_ptr - array of png_sPLT_struct structures | 3847 | palette_ptr - array of png_sPLT_struct structures |
3848 | to be added to the list of palettes | 3848 | to be added to the list of palettes |
3849 | in the info structure. | 3849 | in the info structure. |
3850 | num_spalettes - number of palette structures to be | 3850 | num_spalettes - number of palette structures to be |
3851 | added. | 3851 | added. |
3852 | 3852 | ||
3853 | png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, | 3853 | png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, |
3854 | unit_type); | 3854 | unit_type); |
3855 | 3855 | ||
3856 | offset_x - positive offset from the left | 3856 | offset_x - positive offset from the left |
3857 | edge of the screen | 3857 | edge of the screen |
3858 | 3858 | ||
3859 | offset_y - positive offset from the top | 3859 | offset_y - positive offset from the top |
3860 | edge of the screen | 3860 | edge of the screen |
3861 | 3861 | ||
3862 | unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER | 3862 | unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER |
3863 | 3863 | ||
3864 | png_set_pHYs(png_ptr, info_ptr, res_x, res_y, | 3864 | png_set_pHYs(png_ptr, info_ptr, res_x, res_y, |
3865 | unit_type); | 3865 | unit_type); |
3866 | 3866 | ||
3867 | res_x - pixels/unit physical resolution | 3867 | res_x - pixels/unit physical resolution |
3868 | in x direction | 3868 | in x direction |
3869 | 3869 | ||
3870 | res_y - pixels/unit physical resolution | 3870 | res_y - pixels/unit physical resolution |
3871 | in y direction | 3871 | in y direction |
3872 | 3872 | ||
3873 | unit_type - PNG_RESOLUTION_UNKNOWN, | 3873 | unit_type - PNG_RESOLUTION_UNKNOWN, |
3874 | PNG_RESOLUTION_METER | 3874 | PNG_RESOLUTION_METER |
3875 | 3875 | ||
3876 | png_set_sCAL(png_ptr, info_ptr, unit, width, height) | 3876 | png_set_sCAL(png_ptr, info_ptr, unit, width, height) |
3877 | 3877 | ||
3878 | unit - physical scale units (an integer) | 3878 | unit - physical scale units (an integer) |
3879 | 3879 | ||
3880 | width - width of a pixel in physical scale units | 3880 | width - width of a pixel in physical scale units |
3881 | 3881 | ||
3882 | height - height of a pixel in physical scale units | 3882 | height - height of a pixel in physical scale units |
3883 | (width and height are doubles) | 3883 | (width and height are doubles) |
3884 | 3884 | ||
3885 | png_set_sCAL_s(png_ptr, info_ptr, unit, width, height) | 3885 | png_set_sCAL_s(png_ptr, info_ptr, unit, width, height) |
3886 | 3886 | ||
3887 | unit - physical scale units (an integer) | 3887 | unit - physical scale units (an integer) |
3888 | 3888 | ||
3889 | width - width of a pixel in physical scale units | 3889 | width - width of a pixel in physical scale units |
3890 | expressed as a string | 3890 | expressed as a string |
3891 | 3891 | ||
3892 | height - height of a pixel in physical scale units | 3892 | height - height of a pixel in physical scale units |
3893 | (width and height are strings like "2.54") | 3893 | (width and height are strings like "2.54") |
3894 | 3894 | ||
3895 | png_set_unknown_chunks(png_ptr, info_ptr, &unknowns, | 3895 | png_set_unknown_chunks(png_ptr, info_ptr, &unknowns, |
3896 | num_unknowns) | 3896 | num_unknowns) |
3897 | 3897 | ||
3898 | unknowns - array of png_unknown_chunk | 3898 | unknowns - array of png_unknown_chunk |
3899 | structures holding unknown chunks | 3899 | structures holding unknown chunks |
3900 | unknowns[i].name - name of unknown chunk | 3900 | unknowns[i].name - name of unknown chunk |
3901 | unknowns[i].data - data of unknown chunk | 3901 | unknowns[i].data - data of unknown chunk |
3902 | unknowns[i].size - size of unknown chunk's data | 3902 | unknowns[i].size - size of unknown chunk's data |
3903 | unknowns[i].location - position to write chunk in file | 3903 | unknowns[i].location - position to write chunk in file |
3904 | 0: do not write chunk | 3904 | 0: do not write chunk |
3905 | PNG_HAVE_IHDR: before PLTE | 3905 | PNG_HAVE_IHDR: before PLTE |
3906 | PNG_HAVE_PLTE: before IDAT | 3906 | PNG_HAVE_PLTE: before IDAT |
3907 | PNG_AFTER_IDAT: after IDAT | 3907 | PNG_AFTER_IDAT: after IDAT |
3908 | 3908 | ||
3909 | The "location" member is set automatically according to | 3909 | The "location" member is set automatically according to |
3910 | what part of the output file has already been written. | 3910 | what part of the output file has already been written. |
3911 | You can change its value after calling png_set_unknown_chunks() | 3911 | You can change its value after calling png_set_unknown_chunks() |
3912 | as demonstrated in pngtest.c. Within each of the "locations", | 3912 | as demonstrated in pngtest.c. Within each of the "locations", |
3913 | the chunks are sequenced according to their position in the | 3913 | the chunks are sequenced according to their position in the |
3914 | structure (that is, the value of "i", which is the order in which | 3914 | structure (that is, the value of "i", which is the order in which |
3915 | the chunk was either read from the input file or defined with | 3915 | the chunk was either read from the input file or defined with |
3916 | png_set_unknown_chunks). | 3916 | png_set_unknown_chunks). |
3917 | 3917 | ||
3918 | A quick word about text and num_text. text is an array of png_text | 3918 | A quick word about text and num_text. text is an array of png_text |
3919 | structures. num_text is the number of valid structures in the array. | 3919 | structures. num_text is the number of valid structures in the array. |
3920 | Each png_text structure holds a language code, a keyword, a text value, | 3920 | Each png_text structure holds a language code, a keyword, a text value, |
3921 | and a compression type. | 3921 | and a compression type. |
3922 | 3922 | ||
3923 | The compression types have the same valid numbers as the compression | 3923 | The compression types have the same valid numbers as the compression |
3924 | types of the image data. Currently, the only valid number is zero. | 3924 | types of the image data. Currently, the only valid number is zero. |
3925 | However, you can store text either compressed or uncompressed, unlike | 3925 | However, you can store text either compressed or uncompressed, unlike |
3926 | images, which always have to be compressed. So if you don't want the | 3926 | images, which always have to be compressed. So if you don't want the |
3927 | text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE. | 3927 | text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE. |
3928 | Because tEXt and zTXt chunks don't have a language field, if you | 3928 | Because tEXt and zTXt chunks don't have a language field, if you |
3929 | specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt | 3929 | specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt |
3930 | any language code or translated keyword will not be written out. | 3930 | any language code or translated keyword will not be written out. |
3931 | 3931 | ||
3932 | Until text gets around a few hundred bytes, it is not worth compressing it. | 3932 | Until text gets around a few hundred bytes, it is not worth compressing it. |
3933 | After the text has been written out to the file, the compression type | 3933 | After the text has been written out to the file, the compression type |
3934 | is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR, | 3934 | is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR, |
3935 | so that it isn't written out again at the end (in case you are calling | 3935 | so that it isn't written out again at the end (in case you are calling |
3936 | png_write_end() with the same struct). | 3936 | png_write_end() with the same struct). |
3937 | 3937 | ||
3938 | The keywords that are given in the PNG Specification are: | 3938 | The keywords that are given in the PNG Specification are: |
3939 | 3939 | ||
3940 | Title Short (one line) title or | 3940 | Title Short (one line) title or |
3941 | caption for image | 3941 | caption for image |
3942 | 3942 | ||
3943 | Author Name of image's creator | 3943 | Author Name of image's creator |
3944 | 3944 | ||
3945 | Description Description of image (possibly long) | 3945 | Description Description of image (possibly long) |
3946 | 3946 | ||
3947 | Copyright Copyright notice | 3947 | Copyright Copyright notice |
3948 | 3948 | ||
3949 | Creation Time Time of original image creation | 3949 | Creation Time Time of original image creation |
3950 | (usually RFC 1123 format, see below) | 3950 | (usually RFC 1123 format, see below) |
3951 | 3951 | ||
3952 | Software Software used to create the image | 3952 | Software Software used to create the image |
3953 | 3953 | ||
3954 | Disclaimer Legal disclaimer | 3954 | Disclaimer Legal disclaimer |
3955 | 3955 | ||
3956 | Warning Warning of nature of content | 3956 | Warning Warning of nature of content |
3957 | 3957 | ||
3958 | Source Device used to create the image | 3958 | Source Device used to create the image |
3959 | 3959 | ||
3960 | Comment Miscellaneous comment; conversion | 3960 | Comment Miscellaneous comment; conversion |
3961 | from other image format | 3961 | from other image format |
3962 | 3962 | ||
3963 | The keyword-text pairs work like this. Keywords should be short | 3963 | The keyword-text pairs work like this. Keywords should be short |
3964 | simple descriptions of what the comment is about. Some typical | 3964 | simple descriptions of what the comment is about. Some typical |
3965 | keywords are found in the PNG specification, as is some recommendations | 3965 | keywords are found in the PNG specification, as is some recommendations |
3966 | on keywords. You can repeat keywords in a file. You can even write | 3966 | on keywords. You can repeat keywords in a file. You can even write |
3967 | some text before the image and some after. For example, you may want | 3967 | some text before the image and some after. For example, you may want |
3968 | to put a description of the image before the image, but leave the | 3968 | to put a description of the image before the image, but leave the |
3969 | disclaimer until after, so viewers working over modem connections | 3969 | disclaimer until after, so viewers working over modem connections |
3970 | don't have to wait for the disclaimer to go over the modem before | 3970 | don't have to wait for the disclaimer to go over the modem before |
3971 | they start seeing the image. Finally, keywords should be full | 3971 | they start seeing the image. Finally, keywords should be full |
3972 | words, not abbreviations. Keywords and text are in the ISO 8859-1 | 3972 | words, not abbreviations. Keywords and text are in the ISO 8859-1 |
3973 | (Latin-1) character set (a superset of regular ASCII) and can not | 3973 | (Latin-1) character set (a superset of regular ASCII) and can not |
3974 | contain NUL characters, and should not contain control or other | 3974 | contain NUL characters, and should not contain control or other |
3975 | unprintable characters. To make the comments widely readable, stick | 3975 | unprintable characters. To make the comments widely readable, stick |
3976 | with basic ASCII, and avoid machine specific character set extensions | 3976 | with basic ASCII, and avoid machine specific character set extensions |
3977 | like the IBM-PC character set. The keyword must be present, but | 3977 | like the IBM-PC character set. The keyword must be present, but |
3978 | you can leave off the text string on non-compressed pairs. | 3978 | you can leave off the text string on non-compressed pairs. |
3979 | Compressed pairs must have a text string, as only the text string | 3979 | Compressed pairs must have a text string, as only the text string |
3980 | is compressed anyway, so the compression would be meaningless. | 3980 | is compressed anyway, so the compression would be meaningless. |
3981 | 3981 | ||
3982 | PNG supports modification time via the png_time structure. Two | 3982 | PNG supports modification time via the png_time structure. Two |
3983 | conversion routines are provided, png_convert_from_time_t() for | 3983 | conversion routines are provided, png_convert_from_time_t() for |
3984 | time_t and png_convert_from_struct_tm() for struct tm. The | 3984 | time_t and png_convert_from_struct_tm() for struct tm. The |
3985 | time_t routine uses gmtime(). You don't have to use either of | 3985 | time_t routine uses gmtime(). You don't have to use either of |
3986 | these, but if you wish to fill in the png_time structure directly, | 3986 | these, but if you wish to fill in the png_time structure directly, |
3987 | you should provide the time in universal time (GMT) if possible | 3987 | you should provide the time in universal time (GMT) if possible |
3988 | instead of your local time. Note that the year number is the full | 3988 | instead of your local time. Note that the year number is the full |
3989 | year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and | 3989 | year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and |
3990 | that months start with 1. | 3990 | that months start with 1. |
3991 | 3991 | ||
3992 | If you want to store the time of the original image creation, you should | 3992 | If you want to store the time of the original image creation, you should |
3993 | use a plain tEXt chunk with the "Creation Time" keyword. This is | 3993 | use a plain tEXt chunk with the "Creation Time" keyword. This is |
3994 | necessary because the "creation time" of a PNG image is somewhat vague, | 3994 | necessary because the "creation time" of a PNG image is somewhat vague, |
3995 | depending on whether you mean the PNG file, the time the image was | 3995 | depending on whether you mean the PNG file, the time the image was |
3996 | created in a non-PNG format, a still photo from which the image was | 3996 | created in a non-PNG format, a still photo from which the image was |
3997 | scanned, or possibly the subject matter itself. In order to facilitate | 3997 | scanned, or possibly the subject matter itself. In order to facilitate |
3998 | machine-readable dates, it is recommended that the "Creation Time" | 3998 | machine-readable dates, it is recommended that the "Creation Time" |
3999 | tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"), | 3999 | tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"), |
4000 | although this isn't a requirement. Unlike the tIME chunk, the | 4000 | although this isn't a requirement. Unlike the tIME chunk, the |
4001 | "Creation Time" tEXt chunk is not expected to be automatically changed | 4001 | "Creation Time" tEXt chunk is not expected to be automatically changed |
4002 | by the software. To facilitate the use of RFC 1123 dates, a function | 4002 | by the software. To facilitate the use of RFC 1123 dates, a function |
4003 | png_convert_to_rfc1123(png_timep) is provided to convert from PNG | 4003 | png_convert_to_rfc1123(png_timep) is provided to convert from PNG |
4004 | time to an RFC 1123 format string. | 4004 | time to an RFC 1123 format string. |
4005 | 4005 | ||
4006 | .SS Writing unknown chunks | 4006 | .SS Writing unknown chunks |
4007 | 4007 | ||
4008 | You can use the png_set_unknown_chunks function to queue up chunks | 4008 | You can use the png_set_unknown_chunks function to queue up chunks |
4009 | for writing. You give it a chunk name, raw data, and a size; that's | 4009 | for writing. You give it a chunk name, raw data, and a size; that's |
4010 | all there is to it. The chunks will be written by the next following | 4010 | all there is to it. The chunks will be written by the next following |
4011 | png_write_info_before_PLTE, png_write_info, or png_write_end function. | 4011 | png_write_info_before_PLTE, png_write_info, or png_write_end function. |
4012 | Any chunks previously read into the info structure's unknown-chunk | 4012 | Any chunks previously read into the info structure's unknown-chunk |
4013 | list will also be written out in a sequence that satisfies the PNG | 4013 | list will also be written out in a sequence that satisfies the PNG |
4014 | specification's ordering rules. | 4014 | specification's ordering rules. |
4015 | 4015 | ||
4016 | .SS The high-level write interface | 4016 | .SS The high-level write interface |
4017 | 4017 | ||
4018 | At this point there are two ways to proceed; through the high-level | 4018 | At this point there are two ways to proceed; through the high-level |
4019 | write interface, or through a sequence of low-level write operations. | 4019 | write interface, or through a sequence of low-level write operations. |
4020 | You can use the high-level interface if your image data is present | 4020 | You can use the high-level interface if your image data is present |
4021 | in the info structure. All defined output | 4021 | in the info structure. All defined output |
4022 | transformations are permitted, enabled by the following masks. | 4022 | transformations are permitted, enabled by the following masks. |
4023 | 4023 | ||
4024 | PNG_TRANSFORM_IDENTITY No transformation | 4024 | PNG_TRANSFORM_IDENTITY No transformation |
4025 | PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples | 4025 | PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples |
4026 | PNG_TRANSFORM_PACKSWAP Change order of packed | 4026 | PNG_TRANSFORM_PACKSWAP Change order of packed |
4027 | pixels to LSB first | 4027 | pixels to LSB first |
4028 | PNG_TRANSFORM_INVERT_MONO Invert monochrome images | 4028 | PNG_TRANSFORM_INVERT_MONO Invert monochrome images |
4029 | PNG_TRANSFORM_SHIFT Normalize pixels to the | 4029 | PNG_TRANSFORM_SHIFT Normalize pixels to the |
4030 | sBIT depth | 4030 | sBIT depth |
4031 | PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA | 4031 | PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA |
4032 | to BGRA | 4032 | to BGRA |
4033 | PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA | 4033 | PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA |
4034 | to AG | 4034 | to AG |
4035 | PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity | 4035 | PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity |
4036 | to transparency | 4036 | to transparency |
4037 | PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples | 4037 | PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples |
4038 | PNG_TRANSFORM_STRIP_FILLER Strip out filler | 4038 | PNG_TRANSFORM_STRIP_FILLER Strip out filler |
4039 | bytes (deprecated). | 4039 | bytes (deprecated). |
4040 | PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading | 4040 | PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading |
4041 | filler bytes | 4041 | filler bytes |
4042 | PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing | 4042 | PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing |
4043 | filler bytes | 4043 | filler bytes |
4044 | 4044 | ||
4045 | If you have valid image data in the info structure (you can use | 4045 | If you have valid image data in the info structure (you can use |
4046 | png_set_rows() to put image data in the info structure), simply do this: | 4046 | png_set_rows() to put image data in the info structure), simply do this: |
4047 | 4047 | ||
4048 | png_write_png(png_ptr, info_ptr, png_transforms, NULL) | 4048 | png_write_png(png_ptr, info_ptr, png_transforms, NULL) |
4049 | 4049 | ||
4050 | where png_transforms is an integer containing the bitwise OR of some set of | 4050 | where png_transforms is an integer containing the bitwise OR of some set of |
4051 | transformation flags. This call is equivalent to png_write_info(), | 4051 | transformation flags. This call is equivalent to png_write_info(), |
4052 | followed the set of transformations indicated by the transform mask, | 4052 | followed the set of transformations indicated by the transform mask, |
4053 | then png_write_image(), and finally png_write_end(). | 4053 | then png_write_image(), and finally png_write_end(). |
4054 | 4054 | ||
4055 | (The final parameter of this call is not yet used. Someday it might point | 4055 | (The final parameter of this call is not yet used. Someday it might point |
4056 | to transformation parameters required by some future output transform.) | 4056 | to transformation parameters required by some future output transform.) |
4057 | 4057 | ||
4058 | You must use png_transforms and not call any png_set_transform() functions | 4058 | You must use png_transforms and not call any png_set_transform() functions |
4059 | when you use png_write_png(). | 4059 | when you use png_write_png(). |
4060 | 4060 | ||
4061 | .SS The low-level write interface | 4061 | .SS The low-level write interface |
4062 | 4062 | ||
4063 | If you are going the low-level route instead, you are now ready to | 4063 | If you are going the low-level route instead, you are now ready to |
4064 | write all the file information up to the actual image data. You do | 4064 | write all the file information up to the actual image data. You do |
4065 | this with a call to png_write_info(). | 4065 | this with a call to png_write_info(). |
4066 | 4066 | ||
4067 | png_write_info(png_ptr, info_ptr); | 4067 | png_write_info(png_ptr, info_ptr); |
4068 | 4068 | ||
4069 | Note that there is one transformation you may need to do before | 4069 | Note that there is one transformation you may need to do before |
4070 | png_write_info(). In PNG files, the alpha channel in an image is the | 4070 | png_write_info(). In PNG files, the alpha channel in an image is the |
4071 | level of opacity. If your data is supplied as a level of transparency, | 4071 | level of opacity. If your data is supplied as a level of transparency, |
4072 | you can invert the alpha channel before you write it, so that 0 is | 4072 | you can invert the alpha channel before you write it, so that 0 is |
4073 | fully transparent and 255 (in 8-bit or paletted images) or 65535 | 4073 | fully transparent and 255 (in 8-bit or paletted images) or 65535 |
4074 | (in 16-bit images) is fully opaque, with | 4074 | (in 16-bit images) is fully opaque, with |
4075 | 4075 | ||
4076 | png_set_invert_alpha(png_ptr); | 4076 | png_set_invert_alpha(png_ptr); |
4077 | 4077 | ||
4078 | This must appear before png_write_info() instead of later with the | 4078 | This must appear before png_write_info() instead of later with the |
4079 | other transformations because in the case of paletted images the tRNS | 4079 | other transformations because in the case of paletted images the tRNS |
4080 | chunk data has to be inverted before the tRNS chunk is written. If | 4080 | chunk data has to be inverted before the tRNS chunk is written. If |
4081 | your image is not a paletted image, the tRNS data (which in such cases | 4081 | your image is not a paletted image, the tRNS data (which in such cases |
4082 | represents a single color to be rendered as transparent) won't need to | 4082 | represents a single color to be rendered as transparent) won't need to |
4083 | be changed, and you can safely do this transformation after your | 4083 | be changed, and you can safely do this transformation after your |
4084 | png_write_info() call. | 4084 | png_write_info() call. |
4085 | 4085 | ||
4086 | If you need to write a private chunk that you want to appear before | 4086 | If you need to write a private chunk that you want to appear before |
4087 | the PLTE chunk when PLTE is present, you can write the PNG info in | 4087 | the PLTE chunk when PLTE is present, you can write the PNG info in |
4088 | two steps, and insert code to write your own chunk between them: | 4088 | two steps, and insert code to write your own chunk between them: |
4089 | 4089 | ||
4090 | png_write_info_before_PLTE(png_ptr, info_ptr); | 4090 | png_write_info_before_PLTE(png_ptr, info_ptr); |
4091 | png_set_unknown_chunks(png_ptr, info_ptr, ...); | 4091 | png_set_unknown_chunks(png_ptr, info_ptr, ...); |
4092 | png_write_info(png_ptr, info_ptr); | 4092 | png_write_info(png_ptr, info_ptr); |
4093 | 4093 | ||
4094 | After you've written the file information, you can set up the library | 4094 | After you've written the file information, you can set up the library |
4095 | to handle any special transformations of the image data. The various | 4095 | to handle any special transformations of the image data. The various |
4096 | ways to transform the data will be described in the order that they | 4096 | ways to transform the data will be described in the order that they |
4097 | should occur. This is important, as some of these change the color | 4097 | should occur. This is important, as some of these change the color |
4098 | type and/or bit depth of the data, and some others only work on | 4098 | type and/or bit depth of the data, and some others only work on |
4099 | certain color types and bit depths. Even though each transformation | 4099 | certain color types and bit depths. Even though each transformation |
4100 | checks to see if it has data that it can do something with, you should | 4100 | checks to see if it has data that it can do something with, you should |
4101 | make sure to only enable a transformation if it will be valid for the | 4101 | make sure to only enable a transformation if it will be valid for the |
4102 | data. For example, don't swap red and blue on grayscale data. | 4102 | data. For example, don't swap red and blue on grayscale data. |
4103 | 4103 | ||
4104 | PNG files store RGB pixels packed into 3 or 6 bytes. This code tells | 4104 | PNG files store RGB pixels packed into 3 or 6 bytes. This code tells |
4105 | the library to strip input data that has 4 or 8 bytes per pixel down | 4105 | the library to strip input data that has 4 or 8 bytes per pixel down |
4106 | to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2 | 4106 | to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2 |
4107 | bytes per pixel). | 4107 | bytes per pixel). |
4108 | 4108 | ||
4109 | png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE); | 4109 | png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE); |
4110 | 4110 | ||
4111 | where the 0 is unused, and the location is either PNG_FILLER_BEFORE or | 4111 | where the 0 is unused, and the location is either PNG_FILLER_BEFORE or |
4112 | PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel | 4112 | PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel |
4113 | is stored XRGB or RGBX. | 4113 | is stored XRGB or RGBX. |
4114 | 4114 | ||
4115 | PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as | 4115 | PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as |
4116 | they can, resulting in, for example, 8 pixels per byte for 1 bit files. | 4116 | they can, resulting in, for example, 8 pixels per byte for 1 bit files. |
4117 | If the data is supplied at 1 pixel per byte, use this code, which will | 4117 | If the data is supplied at 1 pixel per byte, use this code, which will |
4118 | correctly pack the pixels into a single byte: | 4118 | correctly pack the pixels into a single byte: |
4119 | 4119 | ||
4120 | png_set_packing(png_ptr); | 4120 | png_set_packing(png_ptr); |
4121 | 4121 | ||
4122 | PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your | 4122 | PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your |
4123 | data is of another bit depth, you can write an sBIT chunk into the | 4123 | data is of another bit depth, you can write an sBIT chunk into the |
4124 | file so that decoders can recover the original data if desired. | 4124 | file so that decoders can recover the original data if desired. |
4125 | 4125 | ||
4126 | /* Set the true bit depth of the image data */ | 4126 | /* Set the true bit depth of the image data */ |
4127 | if (color_type & PNG_COLOR_MASK_COLOR) | 4127 | if (color_type & PNG_COLOR_MASK_COLOR) |
4128 | { | 4128 | { |
4129 | sig_bit.red = true_bit_depth; | 4129 | sig_bit.red = true_bit_depth; |
4130 | sig_bit.green = true_bit_depth; | 4130 | sig_bit.green = true_bit_depth; |
4131 | sig_bit.blue = true_bit_depth; | 4131 | sig_bit.blue = true_bit_depth; |
4132 | } | 4132 | } |
4133 | 4133 | ||
4134 | else | 4134 | else |
4135 | { | 4135 | { |
4136 | sig_bit.gray = true_bit_depth; | 4136 | sig_bit.gray = true_bit_depth; |
4137 | } | 4137 | } |
4138 | 4138 | ||
4139 | if (color_type & PNG_COLOR_MASK_ALPHA) | 4139 | if (color_type & PNG_COLOR_MASK_ALPHA) |
4140 | { | 4140 | { |
4141 | sig_bit.alpha = true_bit_depth; | 4141 | sig_bit.alpha = true_bit_depth; |
4142 | } | 4142 | } |
4143 | 4143 | ||
4144 | png_set_sBIT(png_ptr, info_ptr, &sig_bit); | 4144 | png_set_sBIT(png_ptr, info_ptr, &sig_bit); |
4145 | 4145 | ||
4146 | If the data is stored in the row buffer in a bit depth other than | 4146 | If the data is stored in the row buffer in a bit depth other than |
4147 | one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG), | 4147 | one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG), |
4148 | this will scale the values to appear to be the correct bit depth as | 4148 | this will scale the values to appear to be the correct bit depth as |
4149 | is required by PNG. | 4149 | is required by PNG. |
4150 | 4150 | ||
4151 | png_set_shift(png_ptr, &sig_bit); | 4151 | png_set_shift(png_ptr, &sig_bit); |
4152 | 4152 | ||
4153 | PNG files store 16-bit pixels in network byte order (big-endian, | 4153 | PNG files store 16-bit pixels in network byte order (big-endian, |
4154 | ie. most significant bits first). This code would be used if they are | 4154 | ie. most significant bits first). This code would be used if they are |
4155 | supplied the other way (little-endian, i.e. least significant bits | 4155 | supplied the other way (little-endian, i.e. least significant bits |
4156 | first, the way PCs store them): | 4156 | first, the way PCs store them): |
4157 | 4157 | ||
4158 | if (bit_depth > 8) | 4158 | if (bit_depth > 8) |
4159 | png_set_swap(png_ptr); | 4159 | png_set_swap(png_ptr); |
4160 | 4160 | ||
4161 | If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you | 4161 | If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you |
4162 | need to change the order the pixels are packed into bytes, you can use: | 4162 | need to change the order the pixels are packed into bytes, you can use: |
4163 | 4163 | ||
4164 | if (bit_depth < 8) | 4164 | if (bit_depth < 8) |
4165 | png_set_packswap(png_ptr); | 4165 | png_set_packswap(png_ptr); |
4166 | 4166 | ||
4167 | PNG files store 3 color pixels in red, green, blue order. This code | 4167 | PNG files store 3 color pixels in red, green, blue order. This code |
4168 | would be used if they are supplied as blue, green, red: | 4168 | would be used if they are supplied as blue, green, red: |
4169 | 4169 | ||
4170 | png_set_bgr(png_ptr); | 4170 | png_set_bgr(png_ptr); |
4171 | 4171 | ||
4172 | PNG files describe monochrome as black being zero and white being | 4172 | PNG files describe monochrome as black being zero and white being |
4173 | one. This code would be used if the pixels are supplied with this reversed | 4173 | one. This code would be used if the pixels are supplied with this reversed |
4174 | (black being one and white being zero): | 4174 | (black being one and white being zero): |
4175 | 4175 | ||
4176 | png_set_invert_mono(png_ptr); | 4176 | png_set_invert_mono(png_ptr); |
4177 | 4177 | ||
4178 | Finally, you can write your own transformation function if none of | 4178 | Finally, you can write your own transformation function if none of |
4179 | the existing ones meets your needs. This is done by setting a callback | 4179 | the existing ones meets your needs. This is done by setting a callback |
4180 | with | 4180 | with |
4181 | 4181 | ||
4182 | png_set_write_user_transform_fn(png_ptr, | 4182 | png_set_write_user_transform_fn(png_ptr, |
4183 | write_transform_fn); | 4183 | write_transform_fn); |
4184 | 4184 | ||
4185 | You must supply the function | 4185 | You must supply the function |
4186 | 4186 | ||
4187 | void write_transform_fn(png_structp png_ptr, png_row_infop | 4187 | void write_transform_fn(png_structp png_ptr, png_row_infop |
4188 | row_info, png_bytep data) | 4188 | row_info, png_bytep data) |
4189 | 4189 | ||
4190 | See pngtest.c for a working example. Your function will be called | 4190 | See pngtest.c for a working example. Your function will be called |
4191 | before any of the other transformations are processed. If supported | 4191 | before any of the other transformations are processed. If supported |
4192 | libpng also supplies an information routine that may be called from | 4192 | libpng also supplies an information routine that may be called from |
4193 | your callback: | 4193 | your callback: |
4194 | 4194 | ||
4195 | png_get_current_row_number(png_ptr); | 4195 | png_get_current_row_number(png_ptr); |
4196 | png_get_current_pass_number(png_ptr); | 4196 | png_get_current_pass_number(png_ptr); |
4197 | 4197 | ||
4198 | This returns the current row passed to the transform. With interlaced | 4198 | This returns the current row passed to the transform. With interlaced |
4199 | images the value returned is the row in the input sub-image image. Use | 4199 | images the value returned is the row in the input sub-image image. Use |
4200 | PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to | 4200 | PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to |
4201 | find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass). | 4201 | find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass). |
4202 | 4202 | ||
4203 | The discussion of interlace handling above contains more information on how to | 4203 | The discussion of interlace handling above contains more information on how to |
4204 | use these values. | 4204 | use these values. |
4205 | 4205 | ||
4206 | You can also set up a pointer to a user structure for use by your | 4206 | You can also set up a pointer to a user structure for use by your |
4207 | callback function. | 4207 | callback function. |
4208 | 4208 | ||
4209 | png_set_user_transform_info(png_ptr, user_ptr, 0, 0); | 4209 | png_set_user_transform_info(png_ptr, user_ptr, 0, 0); |
4210 | 4210 | ||
4211 | The user_channels and user_depth parameters of this function are ignored | 4211 | The user_channels and user_depth parameters of this function are ignored |
4212 | when writing; you can set them to zero as shown. | 4212 | when writing; you can set them to zero as shown. |
4213 | 4213 | ||
4214 | You can retrieve the pointer via the function png_get_user_transform_ptr(). | 4214 | You can retrieve the pointer via the function png_get_user_transform_ptr(). |
4215 | For example: | 4215 | For example: |
4216 | 4216 | ||
4217 | voidp write_user_transform_ptr = | 4217 | voidp write_user_transform_ptr = |
4218 | png_get_user_transform_ptr(png_ptr); | 4218 | png_get_user_transform_ptr(png_ptr); |
4219 | 4219 | ||
4220 | It is possible to have libpng flush any pending output, either manually, | 4220 | It is possible to have libpng flush any pending output, either manually, |
4221 | or automatically after a certain number of lines have been written. To | 4221 | or automatically after a certain number of lines have been written. To |
4222 | flush the output stream a single time call: | 4222 | flush the output stream a single time call: |
4223 | 4223 | ||
4224 | png_write_flush(png_ptr); | 4224 | png_write_flush(png_ptr); |
4225 | 4225 | ||
4226 | and to have libpng flush the output stream periodically after a certain | 4226 | and to have libpng flush the output stream periodically after a certain |
4227 | number of scanlines have been written, call: | 4227 | number of scanlines have been written, call: |
4228 | 4228 | ||
4229 | png_set_flush(png_ptr, nrows); | 4229 | png_set_flush(png_ptr, nrows); |
4230 | 4230 | ||
4231 | Note that the distance between rows is from the last time png_write_flush() | 4231 | Note that the distance between rows is from the last time png_write_flush() |
4232 | was called, or the first row of the image if it has never been called. | 4232 | was called, or the first row of the image if it has never been called. |
4233 | So if you write 50 lines, and then png_set_flush 25, it will flush the | 4233 | So if you write 50 lines, and then png_set_flush 25, it will flush the |
4234 | output on the next scanline, and every 25 lines thereafter, unless | 4234 | output on the next scanline, and every 25 lines thereafter, unless |
4235 | png_write_flush() is called before 25 more lines have been written. | 4235 | png_write_flush() is called before 25 more lines have been written. |
4236 | If nrows is too small (less than about 10 lines for a 640 pixel wide | 4236 | If nrows is too small (less than about 10 lines for a 640 pixel wide |
4237 | RGB image) the image compression may decrease noticeably (although this | 4237 | RGB image) the image compression may decrease noticeably (although this |
4238 | may be acceptable for real-time applications). Infrequent flushing will | 4238 | may be acceptable for real-time applications). Infrequent flushing will |
4239 | only degrade the compression performance by a few percent over images | 4239 | only degrade the compression performance by a few percent over images |
4240 | that do not use flushing. | 4240 | that do not use flushing. |
4241 | 4241 | ||
4242 | .SS Writing the image data | 4242 | .SS Writing the image data |
4243 | 4243 | ||
4244 | That's it for the transformations. Now you can write the image data. | 4244 | That's it for the transformations. Now you can write the image data. |
4245 | The simplest way to do this is in one function call. If you have the | 4245 | The simplest way to do this is in one function call. If you have the |
4246 | whole image in memory, you can just call png_write_image() and libpng | 4246 | whole image in memory, you can just call png_write_image() and libpng |
4247 | will write the image. You will need to pass in an array of pointers to | 4247 | will write the image. You will need to pass in an array of pointers to |
4248 | each row. This function automatically handles interlacing, so you don't | 4248 | each row. This function automatically handles interlacing, so you don't |
4249 | need to call png_set_interlace_handling() or call this function multiple | 4249 | need to call png_set_interlace_handling() or call this function multiple |
4250 | times, or any of that other stuff necessary with png_write_rows(). | 4250 | times, or any of that other stuff necessary with png_write_rows(). |
4251 | 4251 | ||
4252 | png_write_image(png_ptr, row_pointers); | 4252 | png_write_image(png_ptr, row_pointers); |
4253 | 4253 | ||
4254 | where row_pointers is: | 4254 | where row_pointers is: |
4255 | 4255 | ||
4256 | png_byte *row_pointers[height]; | 4256 | png_byte *row_pointers[height]; |
4257 | 4257 | ||
4258 | You can point to void or char or whatever you use for pixels. | 4258 | You can point to void or char or whatever you use for pixels. |
4259 | 4259 | ||
4260 | If you don't want to write the whole image at once, you can | 4260 | If you don't want to write the whole image at once, you can |
4261 | use png_write_rows() instead. If the file is not interlaced, | 4261 | use png_write_rows() instead. If the file is not interlaced, |
4262 | this is simple: | 4262 | this is simple: |
4263 | 4263 | ||
4264 | png_write_rows(png_ptr, row_pointers, | 4264 | png_write_rows(png_ptr, row_pointers, |
4265 | number_of_rows); | 4265 | number_of_rows); |
4266 | 4266 | ||
4267 | row_pointers is the same as in the png_write_image() call. | 4267 | row_pointers is the same as in the png_write_image() call. |
4268 | 4268 | ||
4269 | If you are just writing one row at a time, you can do this with | 4269 | If you are just writing one row at a time, you can do this with |
4270 | a single row_pointer instead of an array of row_pointers: | 4270 | a single row_pointer instead of an array of row_pointers: |
4271 | 4271 | ||
4272 | png_bytep row_pointer = row; | 4272 | png_bytep row_pointer = row; |
4273 | 4273 | ||
4274 | png_write_row(png_ptr, row_pointer); | 4274 | png_write_row(png_ptr, row_pointer); |
4275 | 4275 | ||
4276 | When the file is interlaced, things can get a good deal more complicated. | 4276 | When the file is interlaced, things can get a good deal more complicated. |
4277 | The only currently (as of the PNG Specification version 1.2, dated July | 4277 | The only currently (as of the PNG Specification version 1.2, dated July |
4278 | 1999) defined interlacing scheme for PNG files is the "Adam7" interlace | 4278 | 1999) defined interlacing scheme for PNG files is the "Adam7" interlace |
4279 | scheme, that breaks down an image into seven smaller images of varying | 4279 | scheme, that breaks down an image into seven smaller images of varying |
4280 | size. libpng will build these images for you, or you can do them | 4280 | size. libpng will build these images for you, or you can do them |
4281 | yourself. If you want to build them yourself, see the PNG specification | 4281 | yourself. If you want to build them yourself, see the PNG specification |
4282 | for details of which pixels to write when. | 4282 | for details of which pixels to write when. |
4283 | 4283 | ||
4284 | If you don't want libpng to handle the interlacing details, just | 4284 | If you don't want libpng to handle the interlacing details, just |
4285 | use png_set_interlace_handling() and call png_write_rows() the | 4285 | use png_set_interlace_handling() and call png_write_rows() the |
4286 | correct number of times to write all the sub-images | 4286 | correct number of times to write all the sub-images |
4287 | (png_set_interlace_handling() returns the number of sub-images.) | 4287 | (png_set_interlace_handling() returns the number of sub-images.) |
4288 | 4288 | ||
4289 | If you want libpng to build the sub-images, call this before you start | 4289 | If you want libpng to build the sub-images, call this before you start |
4290 | writing any rows: | 4290 | writing any rows: |
4291 | 4291 | ||
4292 | number_of_passes = png_set_interlace_handling(png_ptr); | 4292 | number_of_passes = png_set_interlace_handling(png_ptr); |
4293 | 4293 | ||
4294 | This will return the number of passes needed. Currently, this is seven, | 4294 | This will return the number of passes needed. Currently, this is seven, |
4295 | but may change if another interlace type is added. | 4295 | but may change if another interlace type is added. |
4296 | 4296 | ||
4297 | Then write the complete image number_of_passes times. | 4297 | Then write the complete image number_of_passes times. |
4298 | 4298 | ||
4299 | png_write_rows(png_ptr, row_pointers, number_of_rows); | 4299 | png_write_rows(png_ptr, row_pointers, number_of_rows); |
4300 | 4300 | ||
4301 | Think carefully before you write an interlaced image. Typically code that | 4301 | Think carefully before you write an interlaced image. Typically code that |
4302 | reads such images reads all the image data into memory, uncompressed, before | 4302 | reads such images reads all the image data into memory, uncompressed, before |
4303 | doing any processing. Only code that can display an image on the fly can | 4303 | doing any processing. Only code that can display an image on the fly can |
4304 | take advantage of the interlacing and even then the image has to be exactly | 4304 | take advantage of the interlacing and even then the image has to be exactly |
4305 | the correct size for the output device, because scaling an image requires | 4305 | the correct size for the output device, because scaling an image requires |
4306 | adjacent pixels and these are not available until all the passes have been | 4306 | adjacent pixels and these are not available until all the passes have been |
4307 | read. | 4307 | read. |
4308 | 4308 | ||
4309 | If you do write an interlaced image you will hardly ever need to handle | 4309 | If you do write an interlaced image you will hardly ever need to handle |
4310 | the interlacing yourself. Call png_set_interlace_handling() and use the | 4310 | the interlacing yourself. Call png_set_interlace_handling() and use the |
4311 | approach described above. | 4311 | approach described above. |
4312 | 4312 | ||
4313 | The only time it is conceivable that you will really need to write an | 4313 | The only time it is conceivable that you will really need to write an |
4314 | interlaced image pass-by-pass is when you have read one pass by pass and | 4314 | interlaced image pass-by-pass is when you have read one pass by pass and |
4315 | made some pixel-by-pixel transformation to it, as described in the read | 4315 | made some pixel-by-pixel transformation to it, as described in the read |
4316 | code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros | 4316 | code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros |
4317 | to determine the size of each sub-image in turn and simply write the rows | 4317 | to determine the size of each sub-image in turn and simply write the rows |
4318 | you obtained from the read code. | 4318 | you obtained from the read code. |
4319 | 4319 | ||
4320 | .SS Finishing a sequential write | 4320 | .SS Finishing a sequential write |
4321 | 4321 | ||
4322 | After you are finished writing the image, you should finish writing | 4322 | After you are finished writing the image, you should finish writing |
4323 | the file. If you are interested in writing comments or time, you should | 4323 | the file. If you are interested in writing comments or time, you should |
4324 | pass an appropriately filled png_info pointer. If you are not interested, | 4324 | pass an appropriately filled png_info pointer. If you are not interested, |
4325 | you can pass NULL. | 4325 | you can pass NULL. |
4326 | 4326 | ||
4327 | png_write_end(png_ptr, info_ptr); | 4327 | png_write_end(png_ptr, info_ptr); |
4328 | 4328 | ||
4329 | When you are done, you can free all memory used by libpng like this: | 4329 | When you are done, you can free all memory used by libpng like this: |
4330 | 4330 | ||
4331 | png_destroy_write_struct(&png_ptr, &info_ptr); | 4331 | png_destroy_write_struct(&png_ptr, &info_ptr); |
4332 | 4332 | ||
4333 | It is also possible to individually free the info_ptr members that | 4333 | It is also possible to individually free the info_ptr members that |
4334 | point to libpng-allocated storage with the following function: | 4334 | point to libpng-allocated storage with the following function: |
4335 | 4335 | ||
4336 | png_free_data(png_ptr, info_ptr, mask, seq) | 4336 | png_free_data(png_ptr, info_ptr, mask, seq) |
4337 | 4337 | ||
4338 | mask - identifies data to be freed, a mask | 4338 | mask - identifies data to be freed, a mask |
4339 | containing the bitwise OR of one or | 4339 | containing the bitwise OR of one or |
4340 | more of | 4340 | more of |
4341 | PNG_FREE_PLTE, PNG_FREE_TRNS, | 4341 | PNG_FREE_PLTE, PNG_FREE_TRNS, |
4342 | PNG_FREE_HIST, PNG_FREE_ICCP, | 4342 | PNG_FREE_HIST, PNG_FREE_ICCP, |
4343 | PNG_FREE_PCAL, PNG_FREE_ROWS, | 4343 | PNG_FREE_PCAL, PNG_FREE_ROWS, |
4344 | PNG_FREE_SCAL, PNG_FREE_SPLT, | 4344 | PNG_FREE_SCAL, PNG_FREE_SPLT, |
4345 | PNG_FREE_TEXT, PNG_FREE_UNKN, | 4345 | PNG_FREE_TEXT, PNG_FREE_UNKN, |
4346 | or simply PNG_FREE_ALL | 4346 | or simply PNG_FREE_ALL |
4347 | 4347 | ||
4348 | seq - sequence number of item to be freed | 4348 | seq - sequence number of item to be freed |
4349 | (-1 for all items) | 4349 | (-1 for all items) |
4350 | 4350 | ||
4351 | This function may be safely called when the relevant storage has | 4351 | This function may be safely called when the relevant storage has |
4352 | already been freed, or has not yet been allocated, or was allocated | 4352 | already been freed, or has not yet been allocated, or was allocated |
4353 | by the user and not by libpng, and will in those cases do nothing. | 4353 | by the user and not by libpng, and will in those cases do nothing. |
4354 | The "seq" parameter is ignored if only one item of the selected data | 4354 | The "seq" parameter is ignored if only one item of the selected data |
4355 | type, such as PLTE, is allowed. If "seq" is not -1, and multiple items | 4355 | type, such as PLTE, is allowed. If "seq" is not -1, and multiple items |
4356 | are allowed for the data type identified in the mask, such as text or | 4356 | are allowed for the data type identified in the mask, such as text or |
4357 | sPLT, only the n'th item in the structure is freed, where n is "seq". | 4357 | sPLT, only the n'th item in the structure is freed, where n is "seq". |
4358 | 4358 | ||
4359 | If you allocated data such as a palette that you passed in to libpng | 4359 | If you allocated data such as a palette that you passed in to libpng |
4360 | with png_set_*, you must not free it until just before the call to | 4360 | with png_set_*, you must not free it until just before the call to |
4361 | png_destroy_write_struct(). | 4361 | png_destroy_write_struct(). |
4362 | 4362 | ||
4363 | The default behavior is only to free data that was allocated internally | 4363 | The default behavior is only to free data that was allocated internally |
4364 | by libpng. This can be changed, so that libpng will not free the data, | 4364 | by libpng. This can be changed, so that libpng will not free the data, |
4365 | or so that it will free data that was allocated by the user with png_malloc() | 4365 | or so that it will free data that was allocated by the user with png_malloc() |
4366 | or png_zalloc() and passed in via a png_set_*() function, with | 4366 | or png_zalloc() and passed in via a png_set_*() function, with |
4367 | 4367 | ||
4368 | png_data_freer(png_ptr, info_ptr, freer, mask) | 4368 | png_data_freer(png_ptr, info_ptr, freer, mask) |
4369 | 4369 | ||
4370 | freer - one of | 4370 | freer - one of |
4371 | PNG_DESTROY_WILL_FREE_DATA | 4371 | PNG_DESTROY_WILL_FREE_DATA |
4372 | PNG_SET_WILL_FREE_DATA | 4372 | PNG_SET_WILL_FREE_DATA |
4373 | PNG_USER_WILL_FREE_DATA | 4373 | PNG_USER_WILL_FREE_DATA |
4374 | 4374 | ||
4375 | mask - which data elements are affected | 4375 | mask - which data elements are affected |
4376 | same choices as in png_free_data() | 4376 | same choices as in png_free_data() |
4377 | 4377 | ||
4378 | For example, to transfer responsibility for some data from a read structure | 4378 | For example, to transfer responsibility for some data from a read structure |
4379 | to a write structure, you could use | 4379 | to a write structure, you could use |
4380 | 4380 | ||
4381 | png_data_freer(read_ptr, read_info_ptr, | 4381 | png_data_freer(read_ptr, read_info_ptr, |
4382 | PNG_USER_WILL_FREE_DATA, | 4382 | PNG_USER_WILL_FREE_DATA, |
4383 | PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST) | 4383 | PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST) |
4384 | 4384 | ||
4385 | png_data_freer(write_ptr, write_info_ptr, | 4385 | png_data_freer(write_ptr, write_info_ptr, |
4386 | PNG_DESTROY_WILL_FREE_DATA, | 4386 | PNG_DESTROY_WILL_FREE_DATA, |
4387 | PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST) | 4387 | PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST) |
4388 | 4388 | ||
4389 | thereby briefly reassigning responsibility for freeing to the user but | 4389 | thereby briefly reassigning responsibility for freeing to the user but |
4390 | immediately afterwards reassigning it once more to the write_destroy | 4390 | immediately afterwards reassigning it once more to the write_destroy |
4391 | function. Having done this, it would then be safe to destroy the read | 4391 | function. Having done this, it would then be safe to destroy the read |
4392 | structure and continue to use the PLTE, tRNS, and hIST data in the write | 4392 | structure and continue to use the PLTE, tRNS, and hIST data in the write |
4393 | structure. | 4393 | structure. |
4394 | 4394 | ||
4395 | This function only affects data that has already been allocated. | 4395 | This function only affects data that has already been allocated. |
4396 | You can call this function before calling after the png_set_*() functions | 4396 | You can call this function before calling after the png_set_*() functions |
4397 | to control whether the user or png_destroy_*() is supposed to free the data. | 4397 | to control whether the user or png_destroy_*() is supposed to free the data. |
4398 | When the user assumes responsibility for libpng-allocated data, the | 4398 | When the user assumes responsibility for libpng-allocated data, the |
4399 | application must use | 4399 | application must use |
4400 | png_free() to free it, and when the user transfers responsibility to libpng | 4400 | png_free() to free it, and when the user transfers responsibility to libpng |
4401 | for data that the user has allocated, the user must have used png_malloc() | 4401 | for data that the user has allocated, the user must have used png_malloc() |
4402 | or png_zalloc() to allocate it. | 4402 | or png_zalloc() to allocate it. |
4403 | 4403 | ||
4404 | If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword | 4404 | If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword |
4405 | separately, do not transfer responsibility for freeing text_ptr to libpng, | 4405 | separately, do not transfer responsibility for freeing text_ptr to libpng, |
4406 | because when libpng fills a png_text structure it combines these members with | 4406 | because when libpng fills a png_text structure it combines these members with |
4407 | the key member, and png_free_data() will free only text_ptr.key. Similarly, | 4407 | the key member, and png_free_data() will free only text_ptr.key. Similarly, |
4408 | if you transfer responsibility for free'ing text_ptr from libpng to your | 4408 | if you transfer responsibility for free'ing text_ptr from libpng to your |
4409 | application, your application must not separately free those members. | 4409 | application, your application must not separately free those members. |
4410 | For a more compact example of writing a PNG image, see the file example.c. | 4410 | For a more compact example of writing a PNG image, see the file example.c. |
4411 | 4411 | ||
4412 | .SH V. Modifying/Customizing libpng: | 4412 | .SH V. Modifying/Customizing libpng: |
4413 | 4413 | ||
4414 | There are two issues here. The first is changing how libpng does | 4414 | There are two issues here. The first is changing how libpng does |
4415 | standard things like memory allocation, input/output, and error handling. | 4415 | standard things like memory allocation, input/output, and error handling. |
4416 | The second deals with more complicated things like adding new chunks, | 4416 | The second deals with more complicated things like adding new chunks, |
4417 | adding new transformations, and generally changing how libpng works. | 4417 | adding new transformations, and generally changing how libpng works. |
4418 | Both of those are compile-time issues; that is, they are generally | 4418 | Both of those are compile-time issues; that is, they are generally |
4419 | determined at the time the code is written, and there is rarely a need | 4419 | determined at the time the code is written, and there is rarely a need |
4420 | to provide the user with a means of changing them. | 4420 | to provide the user with a means of changing them. |
4421 | 4421 | ||
4422 | Memory allocation, input/output, and error handling | 4422 | Memory allocation, input/output, and error handling |
4423 | 4423 | ||
4424 | All of the memory allocation, input/output, and error handling in libpng | 4424 | All of the memory allocation, input/output, and error handling in libpng |
4425 | goes through callbacks that are user-settable. The default routines are | 4425 | goes through callbacks that are user-settable. The default routines are |
4426 | in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change | 4426 | in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change |
4427 | these functions, call the appropriate png_set_*_fn() function. | 4427 | these functions, call the appropriate png_set_*_fn() function. |
4428 | 4428 | ||
4429 | Memory allocation is done through the functions png_malloc(), png_calloc(), | 4429 | Memory allocation is done through the functions png_malloc(), png_calloc(), |
4430 | and png_free(). These currently just call the standard C functions. | 4430 | and png_free(). These currently just call the standard C functions. |
4431 | png_calloc() calls png_malloc() and then clears the newly | 4431 | png_calloc() calls png_malloc() and then clears the newly |
4432 | allocated memory to zero. There is limited support for certain systems | 4432 | allocated memory to zero. There is limited support for certain systems |
4433 | with segmented memory architectures and the types of pointers declared by | 4433 | with segmented memory architectures and the types of pointers declared by |
4434 | png.h match this; you will have to use appropriate pointers in your | 4434 | png.h match this; you will have to use appropriate pointers in your |
4435 | application. Since it is | 4435 | application. Since it is |
4436 | unlikely that the method of handling memory allocation on a platform | 4436 | unlikely that the method of handling memory allocation on a platform |
4437 | will change between applications, these functions must be modified in | 4437 | will change between applications, these functions must be modified in |
4438 | the library at compile time. If you prefer to use a different method | 4438 | the library at compile time. If you prefer to use a different method |
4439 | of allocating and freeing data, you can use png_create_read_struct_2() or | 4439 | of allocating and freeing data, you can use png_create_read_struct_2() or |
4440 | png_create_write_struct_2() to register your own functions as described | 4440 | png_create_write_struct_2() to register your own functions as described |
4441 | above. These functions also provide a void pointer that can be retrieved | 4441 | above. These functions also provide a void pointer that can be retrieved |
4442 | via | 4442 | via |
4443 | 4443 | ||
4444 | mem_ptr=png_get_mem_ptr(png_ptr); | 4444 | mem_ptr=png_get_mem_ptr(png_ptr); |
4445 | 4445 | ||
4446 | Your replacement memory functions must have prototypes as follows: | 4446 | Your replacement memory functions must have prototypes as follows: |
4447 | 4447 | ||
4448 | png_voidp malloc_fn(png_structp png_ptr, | 4448 | png_voidp malloc_fn(png_structp png_ptr, |
4449 | png_alloc_size_t size); | 4449 | png_alloc_size_t size); |
4450 | 4450 | ||
4451 | void free_fn(png_structp png_ptr, png_voidp ptr); | 4451 | void free_fn(png_structp png_ptr, png_voidp ptr); |
4452 | 4452 | ||
4453 | Your malloc_fn() must return NULL in case of failure. The png_malloc() | 4453 | Your malloc_fn() must return NULL in case of failure. The png_malloc() |
4454 | function will normally call png_error() if it receives a NULL from the | 4454 | function will normally call png_error() if it receives a NULL from the |
4455 | system memory allocator or from your replacement malloc_fn(). | 4455 | system memory allocator or from your replacement malloc_fn(). |
4456 | 4456 | ||
4457 | Your free_fn() will never be called with a NULL ptr, since libpng's | 4457 | Your free_fn() will never be called with a NULL ptr, since libpng's |
4458 | png_free() checks for NULL before calling free_fn(). | 4458 | png_free() checks for NULL before calling free_fn(). |
4459 | 4459 | ||
4460 | Input/Output in libpng is done through png_read() and png_write(), | 4460 | Input/Output in libpng is done through png_read() and png_write(), |
4461 | which currently just call fread() and fwrite(). The FILE * is stored in | 4461 | which currently just call fread() and fwrite(). The FILE * is stored in |
4462 | png_struct and is initialized via png_init_io(). If you wish to change | 4462 | png_struct and is initialized via png_init_io(). If you wish to change |
4463 | the method of I/O, the library supplies callbacks that you can set | 4463 | the method of I/O, the library supplies callbacks that you can set |
4464 | through the function png_set_read_fn() and png_set_write_fn() at run | 4464 | through the function png_set_read_fn() and png_set_write_fn() at run |
4465 | time, instead of calling the png_init_io() function. These functions | 4465 | time, instead of calling the png_init_io() function. These functions |
4466 | also provide a void pointer that can be retrieved via the function | 4466 | also provide a void pointer that can be retrieved via the function |
4467 | png_get_io_ptr(). For example: | 4467 | png_get_io_ptr(). For example: |
4468 | 4468 | ||
4469 | png_set_read_fn(png_structp read_ptr, | 4469 | png_set_read_fn(png_structp read_ptr, |
4470 | voidp read_io_ptr, png_rw_ptr read_data_fn) | 4470 | voidp read_io_ptr, png_rw_ptr read_data_fn) |
4471 | 4471 | ||
4472 | png_set_write_fn(png_structp write_ptr, | 4472 | png_set_write_fn(png_structp write_ptr, |
4473 | voidp write_io_ptr, png_rw_ptr write_data_fn, | 4473 | voidp write_io_ptr, png_rw_ptr write_data_fn, |
4474 | png_flush_ptr output_flush_fn); | 4474 | png_flush_ptr output_flush_fn); |
4475 | 4475 | ||
4476 | voidp read_io_ptr = png_get_io_ptr(read_ptr); | 4476 | voidp read_io_ptr = png_get_io_ptr(read_ptr); |
4477 | voidp write_io_ptr = png_get_io_ptr(write_ptr); | 4477 | voidp write_io_ptr = png_get_io_ptr(write_ptr); |
4478 | 4478 | ||
4479 | The replacement I/O functions must have prototypes as follows: | 4479 | The replacement I/O functions must have prototypes as follows: |
4480 | 4480 | ||
4481 | void user_read_data(png_structp png_ptr, | 4481 | void user_read_data(png_structp png_ptr, |
4482 | png_bytep data, png_size_t length); | 4482 | png_bytep data, png_size_t length); |
4483 | 4483 | ||
4484 | void user_write_data(png_structp png_ptr, | 4484 | void user_write_data(png_structp png_ptr, |
4485 | png_bytep data, png_size_t length); | 4485 | png_bytep data, png_size_t length); |
4486 | 4486 | ||
4487 | void user_flush_data(png_structp png_ptr); | 4487 | void user_flush_data(png_structp png_ptr); |
4488 | 4488 | ||
4489 | The user_read_data() function is responsible for detecting and | 4489 | The user_read_data() function is responsible for detecting and |
4490 | handling end-of-data errors. | 4490 | handling end-of-data errors. |
4491 | 4491 | ||
4492 | Supplying NULL for the read, write, or flush functions sets them back | 4492 | Supplying NULL for the read, write, or flush functions sets them back |
4493 | to using the default C stream functions, which expect the io_ptr to | 4493 | to using the default C stream functions, which expect the io_ptr to |
4494 | point to a standard *FILE structure. It is probably a mistake | 4494 | point to a standard *FILE structure. It is probably a mistake |
4495 | to use NULL for one of write_data_fn and output_flush_fn but not both | 4495 | to use NULL for one of write_data_fn and output_flush_fn but not both |
4496 | of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined. | 4496 | of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined. |
4497 | It is an error to read from a write stream, and vice versa. | 4497 | It is an error to read from a write stream, and vice versa. |
4498 | 4498 | ||
4499 | Error handling in libpng is done through png_error() and png_warning(). | 4499 | Error handling in libpng is done through png_error() and png_warning(). |
4500 | Errors handled through png_error() are fatal, meaning that png_error() | 4500 | Errors handled through png_error() are fatal, meaning that png_error() |
4501 | should never return to its caller. Currently, this is handled via | 4501 | should never return to its caller. Currently, this is handled via |
4502 | setjmp() and longjmp() (unless you have compiled libpng with | 4502 | setjmp() and longjmp() (unless you have compiled libpng with |
4503 | PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()), | 4503 | PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()), |
4504 | but you could change this to do things like exit() if you should wish, | 4504 | but you could change this to do things like exit() if you should wish, |
4505 | as long as your function does not return. | 4505 | as long as your function does not return. |
4506 | 4506 | ||
4507 | On non-fatal errors, png_warning() is called | 4507 | On non-fatal errors, png_warning() is called |
4508 | to print a warning message, and then control returns to the calling code. | 4508 | to print a warning message, and then control returns to the calling code. |
4509 | By default png_error() and png_warning() print a message on stderr via | 4509 | By default png_error() and png_warning() print a message on stderr via |
4510 | fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined | 4510 | fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined |
4511 | (because you don't want the messages) or PNG_NO_STDIO defined (because | 4511 | (because you don't want the messages) or PNG_NO_STDIO defined (because |
4512 | fprintf() isn't available). If you wish to change the behavior of the error | 4512 | fprintf() isn't available). If you wish to change the behavior of the error |
4513 | functions, you will need to set up your own message callbacks. These | 4513 | functions, you will need to set up your own message callbacks. These |
4514 | functions are normally supplied at the time that the png_struct is created. | 4514 | functions are normally supplied at the time that the png_struct is created. |
4515 | It is also possible to redirect errors and warnings to your own replacement | 4515 | It is also possible to redirect errors and warnings to your own replacement |
4516 | functions after png_create_*_struct() has been called by calling: | 4516 | functions after png_create_*_struct() has been called by calling: |
4517 | 4517 | ||
4518 | png_set_error_fn(png_structp png_ptr, | 4518 | png_set_error_fn(png_structp png_ptr, |
4519 | png_voidp error_ptr, png_error_ptr error_fn, | 4519 | png_voidp error_ptr, png_error_ptr error_fn, |
4520 | png_error_ptr warning_fn); | 4520 | png_error_ptr warning_fn); |
4521 | 4521 | ||
4522 | png_voidp error_ptr = png_get_error_ptr(png_ptr); | 4522 | png_voidp error_ptr = png_get_error_ptr(png_ptr); |
4523 | 4523 | ||
4524 | If NULL is supplied for either error_fn or warning_fn, then the libpng | 4524 | If NULL is supplied for either error_fn or warning_fn, then the libpng |
4525 | default function will be used, calling fprintf() and/or longjmp() if a | 4525 | default function will be used, calling fprintf() and/or longjmp() if a |
4526 | problem is encountered. The replacement error functions should have | 4526 | problem is encountered. The replacement error functions should have |
4527 | parameters as follows: | 4527 | parameters as follows: |
4528 | 4528 | ||
4529 | void user_error_fn(png_structp png_ptr, | 4529 | void user_error_fn(png_structp png_ptr, |
4530 | png_const_charp error_msg); | 4530 | png_const_charp error_msg); |
4531 | 4531 | ||
4532 | void user_warning_fn(png_structp png_ptr, | 4532 | void user_warning_fn(png_structp png_ptr, |
4533 | png_const_charp warning_msg); | 4533 | png_const_charp warning_msg); |
4534 | 4534 | ||
4535 | The motivation behind using setjmp() and longjmp() is the C++ throw and | 4535 | The motivation behind using setjmp() and longjmp() is the C++ throw and |
4536 | catch exception handling methods. This makes the code much easier to write, | 4536 | catch exception handling methods. This makes the code much easier to write, |
4537 | as there is no need to check every return code of every function call. | 4537 | as there is no need to check every return code of every function call. |
4538 | However, there are some uncertainties about the status of local variables | 4538 | However, there are some uncertainties about the status of local variables |
4539 | after a longjmp, so the user may want to be careful about doing anything | 4539 | after a longjmp, so the user may want to be careful about doing anything |
4540 | after setjmp returns non-zero besides returning itself. Consult your | 4540 | after setjmp returns non-zero besides returning itself. Consult your |
4541 | compiler documentation for more details. For an alternative approach, you | 4541 | compiler documentation for more details. For an alternative approach, you |
4542 | may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net), | 4542 | may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net), |
4543 | which is illustrated in pngvalid.c and in contrib/visupng. | 4543 | which is illustrated in pngvalid.c and in contrib/visupng. |
4544 | 4544 | ||
4545 | .SS Custom chunks | 4545 | .SS Custom chunks |
4546 | 4546 | ||
4547 | If you need to read or write custom chunks, you may need to get deeper | 4547 | If you need to read or write custom chunks, you may need to get deeper |
4548 | into the libpng code. The library now has mechanisms for storing | 4548 | into the libpng code. The library now has mechanisms for storing |
4549 | and writing chunks of unknown type; you can even declare callbacks | 4549 | and writing chunks of unknown type; you can even declare callbacks |
4550 | for custom chunks. However, this may not be good enough if the | 4550 | for custom chunks. However, this may not be good enough if the |
4551 | library code itself needs to know about interactions between your | 4551 | library code itself needs to know about interactions between your |
4552 | chunk and existing `intrinsic' chunks. | 4552 | chunk and existing `intrinsic' chunks. |
4553 | 4553 | ||
4554 | If you need to write a new intrinsic chunk, first read the PNG | 4554 | If you need to write a new intrinsic chunk, first read the PNG |
4555 | specification. Acquire a first level of understanding of how it works. | 4555 | specification. Acquire a first level of understanding of how it works. |
4556 | Pay particular attention to the sections that describe chunk names, | 4556 | Pay particular attention to the sections that describe chunk names, |
4557 | and look at how other chunks were designed, so you can do things | 4557 | and look at how other chunks were designed, so you can do things |
4558 | similarly. Second, check out the sections of libpng that read and | 4558 | similarly. Second, check out the sections of libpng that read and |
4559 | write chunks. Try to find a chunk that is similar to yours and use | 4559 | write chunks. Try to find a chunk that is similar to yours and use |
4560 | it as a template. More details can be found in the comments inside | 4560 | it as a template. More details can be found in the comments inside |
4561 | the code. It is best to handle private or unknown chunks in a generic method, | 4561 | the code. It is best to handle private or unknown chunks in a generic method, |
4562 | via callback functions, instead of by modifying libpng functions. This | 4562 | via callback functions, instead of by modifying libpng functions. This |
4563 | is illustrated in pngtest.c, which uses a callback function to handle a | 4563 | is illustrated in pngtest.c, which uses a callback function to handle a |
4564 | private "vpAg" chunk and the new "sTER" chunk, which are both unknown to | 4564 | private "vpAg" chunk and the new "sTER" chunk, which are both unknown to |
4565 | libpng. | 4565 | libpng. |
4566 | 4566 | ||
4567 | If you wish to write your own transformation for the data, look through | 4567 | If you wish to write your own transformation for the data, look through |
4568 | the part of the code that does the transformations, and check out some of | 4568 | the part of the code that does the transformations, and check out some of |
4569 | the simpler ones to get an idea of how they work. Try to find a similar | 4569 | the simpler ones to get an idea of how they work. Try to find a similar |
4570 | transformation to the one you want to add and copy off of it. More details | 4570 | transformation to the one you want to add and copy off of it. More details |
4571 | can be found in the comments inside the code itself. | 4571 | can be found in the comments inside the code itself. |
4572 | 4572 | ||
4573 | .SS Configuring for 16-bit platforms | 4573 | .SS Configuring for 16-bit platforms |
4574 | 4574 | ||
4575 | You will want to look into zconf.h to tell zlib (and thus libpng) that | 4575 | You will want to look into zconf.h to tell zlib (and thus libpng) that |
4576 | it cannot allocate more then 64K at a time. Even if you can, the memory | 4576 | it cannot allocate more then 64K at a time. Even if you can, the memory |
4577 | won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K. | 4577 | won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K. |
4578 | 4578 | ||
4579 | .SS Configuring for DOS | 4579 | .SS Configuring for DOS |
4580 | 4580 | ||
4581 | For DOS users who only have access to the lower 640K, you will | 4581 | For DOS users who only have access to the lower 640K, you will |
4582 | have to limit zlib's memory usage via a png_set_compression_mem_level() | 4582 | have to limit zlib's memory usage via a png_set_compression_mem_level() |
4583 | call. See zlib.h or zconf.h in the zlib library for more information. | 4583 | call. See zlib.h or zconf.h in the zlib library for more information. |
4584 | 4584 | ||
4585 | .SS Configuring for Medium Model | 4585 | .SS Configuring for Medium Model |
4586 | 4586 | ||
4587 | Libpng's support for medium model has been tested on most of the popular | 4587 | Libpng's support for medium model has been tested on most of the popular |
4588 | compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets | 4588 | compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets |
4589 | defined, and FAR gets defined to far in pngconf.h, and you should be | 4589 | defined, and FAR gets defined to far in pngconf.h, and you should be |
4590 | all set. Everything in the library (except for zlib's structure) is | 4590 | all set. Everything in the library (except for zlib's structure) is |
4591 | expecting far data. You must use the typedefs with the p or pp on | 4591 | expecting far data. You must use the typedefs with the p or pp on |
4592 | the end for pointers (or at least look at them and be careful). Make | 4592 | the end for pointers (or at least look at them and be careful). Make |
4593 | note that the rows of data are defined as png_bytepp, which is | 4593 | note that the rows of data are defined as png_bytepp, which is |
4594 | an "unsigned char far * far *". | 4594 | an "unsigned char far * far *". |
4595 | 4595 | ||
4596 | .SS Configuring for gui/windowing platforms: | 4596 | .SS Configuring for gui/windowing platforms: |
4597 | 4597 | ||
4598 | You will need to write new error and warning functions that use the GUI | 4598 | You will need to write new error and warning functions that use the GUI |
4599 | interface, as described previously, and set them to be the error and | 4599 | interface, as described previously, and set them to be the error and |
4600 | warning functions at the time that png_create_*_struct() is called, | 4600 | warning functions at the time that png_create_*_struct() is called, |
4601 | in order to have them available during the structure initialization. | 4601 | in order to have them available during the structure initialization. |
4602 | They can be changed later via png_set_error_fn(). On some compilers, | 4602 | They can be changed later via png_set_error_fn(). On some compilers, |
4603 | you may also have to change the memory allocators (png_malloc, etc.). | 4603 | you may also have to change the memory allocators (png_malloc, etc.). |
4604 | 4604 | ||
4605 | .SS Configuring for compiler xxx: | 4605 | .SS Configuring for compiler xxx: |
4606 | 4606 | ||
4607 | All includes for libpng are in pngconf.h. If you need to add, change | 4607 | All includes for libpng are in pngconf.h. If you need to add, change |
4608 | or delete an include, this is the place to do it. | 4608 | or delete an include, this is the place to do it. |
4609 | The includes that are not needed outside libpng are placed in pngpriv.h, | 4609 | The includes that are not needed outside libpng are placed in pngpriv.h, |
4610 | which is only used by the routines inside libpng itself. | 4610 | which is only used by the routines inside libpng itself. |
4611 | The files in libpng proper only include pngpriv.h and png.h, which | 4611 | The files in libpng proper only include pngpriv.h and png.h, which |
4612 | %14%in turn includes pngconf.h. | 4612 | %14%in turn includes pngconf.h. |
4613 | in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h. | 4613 | in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h. |
4614 | As of libpng-1.5.0, pngpriv.h also includes three other private header | 4614 | As of libpng-1.5.0, pngpriv.h also includes three other private header |
4615 | files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material | 4615 | files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material |
4616 | that previously appeared in the public headers. | 4616 | that previously appeared in the public headers. |
4617 | 4617 | ||
4618 | .SS Configuring zlib: | 4618 | .SS Configuring zlib: |
4619 | 4619 | ||
4620 | There are special functions to configure the compression. Perhaps the | 4620 | There are special functions to configure the compression. Perhaps the |
4621 | most useful one changes the compression level, which currently uses | 4621 | most useful one changes the compression level, which currently uses |
4622 | input compression values in the range 0 - 9. The library normally | 4622 | input compression values in the range 0 - 9. The library normally |
4623 | uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests | 4623 | uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests |
4624 | have shown that for a large majority of images, compression values in | 4624 | have shown that for a large majority of images, compression values in |
4625 | the range 3-6 compress nearly as well as higher levels, and do so much | 4625 | the range 3-6 compress nearly as well as higher levels, and do so much |
4626 | faster. For online applications it may be desirable to have maximum speed | 4626 | faster. For online applications it may be desirable to have maximum speed |
4627 | (Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also | 4627 | (Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also |
4628 | specify no compression (Z_NO_COMPRESSION = 0), but this would create | 4628 | specify no compression (Z_NO_COMPRESSION = 0), but this would create |
4629 | files larger than just storing the raw bitmap. You can specify the | 4629 | files larger than just storing the raw bitmap. You can specify the |
4630 | compression level by calling: | 4630 | compression level by calling: |
4631 | 4631 | ||
4632 | #include zlib.h | 4632 | #include zlib.h |
4633 | png_set_compression_level(png_ptr, level); | 4633 | png_set_compression_level(png_ptr, level); |
4634 | 4634 | ||
4635 | Another useful one is to reduce the memory level used by the library. | 4635 | Another useful one is to reduce the memory level used by the library. |
4636 | The memory level defaults to 8, but it can be lowered if you are | 4636 | The memory level defaults to 8, but it can be lowered if you are |
4637 | short on memory (running DOS, for example, where you only have 640K). | 4637 | short on memory (running DOS, for example, where you only have 640K). |
4638 | Note that the memory level does have an effect on compression; among | 4638 | Note that the memory level does have an effect on compression; among |
4639 | other things, lower levels will result in sections of incompressible | 4639 | other things, lower levels will result in sections of incompressible |
4640 | data being emitted in smaller stored blocks, with a correspondingly | 4640 | data being emitted in smaller stored blocks, with a correspondingly |
4641 | larger relative overhead of up to 15% in the worst case. | 4641 | larger relative overhead of up to 15% in the worst case. |
4642 | 4642 | ||
4643 | #include zlib.h | 4643 | #include zlib.h |
4644 | png_set_compression_mem_level(png_ptr, level); | 4644 | png_set_compression_mem_level(png_ptr, level); |
4645 | 4645 | ||
4646 | The other functions are for configuring zlib. They are not recommended | 4646 | The other functions are for configuring zlib. They are not recommended |
4647 | for normal use and may result in writing an invalid PNG file. See | 4647 | for normal use and may result in writing an invalid PNG file. See |
4648 | zlib.h for more information on what these mean. | 4648 | zlib.h for more information on what these mean. |
4649 | 4649 | ||
4650 | #include zlib.h | 4650 | #include zlib.h |
4651 | png_set_compression_strategy(png_ptr, | 4651 | png_set_compression_strategy(png_ptr, |
4652 | strategy); | 4652 | strategy); |
4653 | 4653 | ||
4654 | png_set_compression_window_bits(png_ptr, | 4654 | png_set_compression_window_bits(png_ptr, |
4655 | window_bits); | 4655 | window_bits); |
4656 | 4656 | ||
4657 | png_set_compression_method(png_ptr, method); | 4657 | png_set_compression_method(png_ptr, method); |
4658 | 4658 | ||
4659 | png_set_compression_buffer_size(png_ptr, size); | 4659 | png_set_compression_buffer_size(png_ptr, size); |
4660 | 4660 | ||
4661 | As of libpng version 1.5.4, additional APIs became | 4661 | As of libpng version 1.5.4, additional APIs became |
4662 | available to set these separately for non-IDAT | 4662 | available to set these separately for non-IDAT |
4663 | compressed chunks such as zTXt, iTXt, and iCCP: | 4663 | compressed chunks such as zTXt, iTXt, and iCCP: |
4664 | 4664 | ||
4665 | #include zlib.h | 4665 | #include zlib.h |
4666 | #if PNG_LIBPNG_VER <= 10504 | 4666 | #if PNG_LIBPNG_VER <= 10504 |
4667 | png_set_text_compression_level(png_ptr, level); | 4667 | png_set_text_compression_level(png_ptr, level); |
4668 | 4668 | ||
4669 | png_set_text_compression_mem_level(png_ptr, level); | 4669 | png_set_text_compression_mem_level(png_ptr, level); |
4670 | 4670 | ||
4671 | png_set_text_compression_strategy(png_ptr, | 4671 | png_set_text_compression_strategy(png_ptr, |
4672 | strategy); | 4672 | strategy); |
4673 | 4673 | ||
4674 | png_set_text_compression_window_bits(png_ptr, | 4674 | png_set_text_compression_window_bits(png_ptr, |
4675 | window_bits); | 4675 | window_bits); |
4676 | 4676 | ||
4677 | png_set_text_compression_method(png_ptr, method); | 4677 | png_set_text_compression_method(png_ptr, method); |
4678 | #endif | 4678 | #endif |
4679 | 4679 | ||
4680 | .SS Controlling row filtering | 4680 | .SS Controlling row filtering |
4681 | 4681 | ||
4682 | If you want to control whether libpng uses filtering or not, which | 4682 | If you want to control whether libpng uses filtering or not, which |
4683 | filters are used, and how it goes about picking row filters, you | 4683 | filters are used, and how it goes about picking row filters, you |
4684 | can call one of these functions. The selection and configuration | 4684 | can call one of these functions. The selection and configuration |
4685 | of row filters can have a significant impact on the size and | 4685 | of row filters can have a significant impact on the size and |
4686 | encoding speed and a somewhat lesser impact on the decoding speed | 4686 | encoding speed and a somewhat lesser impact on the decoding speed |
4687 | of an image. Filtering is enabled by default for RGB and grayscale | 4687 | of an image. Filtering is enabled by default for RGB and grayscale |
4688 | images (with and without alpha), but not for paletted images nor | 4688 | images (with and without alpha), but not for paletted images nor |
4689 | for any images with bit depths less than 8 bits/pixel. | 4689 | for any images with bit depths less than 8 bits/pixel. |
4690 | 4690 | ||
4691 | The 'method' parameter sets the main filtering method, which is | 4691 | The 'method' parameter sets the main filtering method, which is |
4692 | currently only '0' in the PNG 1.2 specification. The 'filters' | 4692 | currently only '0' in the PNG 1.2 specification. The 'filters' |
4693 | parameter sets which filter(s), if any, should be used for each | 4693 | parameter sets which filter(s), if any, should be used for each |
4694 | scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS | 4694 | scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS |
4695 | to turn filtering on and off, respectively. | 4695 | to turn filtering on and off, respectively. |
4696 | 4696 | ||
4697 | Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB, | 4697 | Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB, |
4698 | PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise | 4698 | PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise |
4699 | ORed together with '|' to specify one or more filters to use. | 4699 | ORed together with '|' to specify one or more filters to use. |
4700 | These filters are described in more detail in the PNG specification. | 4700 | These filters are described in more detail in the PNG specification. |
4701 | If you intend to change the filter type during the course of writing | 4701 | If you intend to change the filter type during the course of writing |
4702 | the image, you should start with flags set for all of the filters | 4702 | the image, you should start with flags set for all of the filters |
4703 | you intend to use so that libpng can initialize its internal | 4703 | you intend to use so that libpng can initialize its internal |
4704 | structures appropriately for all of the filter types. (Note that this | 4704 | structures appropriately for all of the filter types. (Note that this |
4705 | means the first row must always be adaptively filtered, because libpng | 4705 | means the first row must always be adaptively filtered, because libpng |
4706 | currently does not allocate the filter buffers until png_write_row() | 4706 | currently does not allocate the filter buffers until png_write_row() |
4707 | is called for the first time.) | 4707 | is called for the first time.) |
4708 | 4708 | ||
4709 | filters = PNG_FILTER_NONE | PNG_FILTER_SUB | 4709 | filters = PNG_FILTER_NONE | PNG_FILTER_SUB |
4710 | PNG_FILTER_UP | PNG_FILTER_AVG | | 4710 | PNG_FILTER_UP | PNG_FILTER_AVG | |
4711 | PNG_FILTER_PAETH | PNG_ALL_FILTERS; | 4711 | PNG_FILTER_PAETH | PNG_ALL_FILTERS; |
4712 | 4712 | ||
4713 | png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, | 4713 | png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, |
4714 | filters); | 4714 | filters); |
4715 | The second parameter can also be | 4715 | The second parameter can also be |
4716 | PNG_INTRAPIXEL_DIFFERENCING if you are | 4716 | PNG_INTRAPIXEL_DIFFERENCING if you are |
4717 | writing a PNG to be embedded in a MNG | 4717 | writing a PNG to be embedded in a MNG |
4718 | datastream. This parameter must be the | 4718 | datastream. This parameter must be the |
4719 | same as the value of filter_method used | 4719 | same as the value of filter_method used |
4720 | in png_set_IHDR(). | 4720 | in png_set_IHDR(). |
4721 | 4721 | ||
4722 | It is also possible to influence how libpng chooses from among the | 4722 | It is also possible to influence how libpng chooses from among the |
4723 | available filters. This is done in one or both of two ways - by | 4723 | available filters. This is done in one or both of two ways - by |
4724 | telling it how important it is to keep the same filter for successive | 4724 | telling it how important it is to keep the same filter for successive |
4725 | rows, and by telling it the relative computational costs of the filters. | 4725 | rows, and by telling it the relative computational costs of the filters. |
4726 | 4726 | ||
4727 | double weights[3] = {1.5, 1.3, 1.1}, | 4727 | double weights[3] = {1.5, 1.3, 1.1}, |
4728 | costs[PNG_FILTER_VALUE_LAST] = | 4728 | costs[PNG_FILTER_VALUE_LAST] = |
4729 | {1.0, 1.3, 1.3, 1.5, 1.7}; | 4729 | {1.0, 1.3, 1.3, 1.5, 1.7}; |
4730 | 4730 | ||
4731 | png_set_filter_heuristics(png_ptr, | 4731 | png_set_filter_heuristics(png_ptr, |
4732 | PNG_FILTER_HEURISTIC_WEIGHTED, 3, | 4732 | PNG_FILTER_HEURISTIC_WEIGHTED, 3, |
4733 | weights, costs); | 4733 | weights, costs); |
4734 | 4734 | ||
4735 | The weights are multiplying factors that indicate to libpng that the | 4735 | The weights are multiplying factors that indicate to libpng that the |
4736 | row filter should be the same for successive rows unless another row filter | 4736 | row filter should be the same for successive rows unless another row filter |
4737 | is that many times better than the previous filter. In the above example, | 4737 | is that many times better than the previous filter. In the above example, |
4738 | if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a | 4738 | if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a |
4739 | "sum of absolute differences" 1.5 x 1.3 times higher than other filters | 4739 | "sum of absolute differences" 1.5 x 1.3 times higher than other filters |
4740 | and still be chosen, while the NONE filter could have a sum 1.1 times | 4740 | and still be chosen, while the NONE filter could have a sum 1.1 times |
4741 | higher than other filters and still be chosen. Unspecified weights are | 4741 | higher than other filters and still be chosen. Unspecified weights are |
4742 | taken to be 1.0, and the specified weights should probably be declining | 4742 | taken to be 1.0, and the specified weights should probably be declining |
4743 | like those above in order to emphasize recent filters over older filters. | 4743 | like those above in order to emphasize recent filters over older filters. |
4744 | 4744 | ||
4745 | The filter costs specify for each filter type a relative decoding cost | 4745 | The filter costs specify for each filter type a relative decoding cost |
4746 | to be considered when selecting row filters. This means that filters | 4746 | to be considered when selecting row filters. This means that filters |
4747 | with higher costs are less likely to be chosen over filters with lower | 4747 | with higher costs are less likely to be chosen over filters with lower |
4748 | costs, unless their "sum of absolute differences" is that much smaller. | 4748 | costs, unless their "sum of absolute differences" is that much smaller. |
4749 | The costs do not necessarily reflect the exact computational speeds of | 4749 | The costs do not necessarily reflect the exact computational speeds of |
4750 | the various filters, since this would unduly influence the final image | 4750 | the various filters, since this would unduly influence the final image |
4751 | size. | 4751 | size. |
4752 | 4752 | ||
4753 | Note that the numbers above were invented purely for this example and | 4753 | Note that the numbers above were invented purely for this example and |
4754 | are given only to help explain the function usage. Little testing has | 4754 | are given only to help explain the function usage. Little testing has |
4755 | been done to find optimum values for either the costs or the weights. | 4755 | been done to find optimum values for either the costs or the weights. |
4756 | 4756 | ||
4757 | .SS Removing unwanted object code | 4757 | .SS Removing unwanted object code |
4758 | 4758 | ||
4759 | There are a bunch of #define's in pngconf.h that control what parts of | 4759 | There are a bunch of #define's in pngconf.h that control what parts of |
4760 | libpng are compiled. All the defines end in _SUPPORTED. If you are | 4760 | libpng are compiled. All the defines end in _SUPPORTED. If you are |
4761 | never going to use a capability, you can change the #define to #undef | 4761 | never going to use a capability, you can change the #define to #undef |
4762 | before recompiling libpng and save yourself code and data space, or | 4762 | before recompiling libpng and save yourself code and data space, or |
4763 | you can turn off individual capabilities with defines that begin with | 4763 | you can turn off individual capabilities with defines that begin with |
4764 | PNG_NO_. | 4764 | PNG_NO_. |
4765 | 4765 | ||
4766 | In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead. | 4766 | In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead. |
4767 | 4767 | ||
4768 | You can also turn all of the transforms and ancillary chunk capabilities | 4768 | You can also turn all of the transforms and ancillary chunk capabilities |
4769 | off en masse with compiler directives that define | 4769 | off en masse with compiler directives that define |
4770 | PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS, | 4770 | PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS, |
4771 | or all four, | 4771 | or all four, |
4772 | along with directives to turn on any of the capabilities that you do | 4772 | along with directives to turn on any of the capabilities that you do |
4773 | want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the extra | 4773 | want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the extra |
4774 | transformations but still leave the library fully capable of reading | 4774 | transformations but still leave the library fully capable of reading |
4775 | and writing PNG files with all known public chunks. Use of the | 4775 | and writing PNG files with all known public chunks. Use of the |
4776 | PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library | 4776 | PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library |
4777 | that is incapable of reading or writing ancillary chunks. If you are | 4777 | that is incapable of reading or writing ancillary chunks. If you are |
4778 | not using the progressive reading capability, you can turn that off | 4778 | not using the progressive reading capability, you can turn that off |
4779 | with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING | 4779 | with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING |
4780 | capability, which you'll still have). | 4780 | capability, which you'll still have). |
4781 | 4781 | ||
4782 | All the reading and writing specific code are in separate files, so the | 4782 | All the reading and writing specific code are in separate files, so the |
4783 | linker should only grab the files it needs. However, if you want to | 4783 | linker should only grab the files it needs. However, if you want to |
4784 | make sure, or if you are building a stand alone library, all the | 4784 | make sure, or if you are building a stand alone library, all the |
4785 | reading files start with "pngr" and all the writing files start with "pngw". | 4785 | reading files start with "pngr" and all the writing files start with "pngw". |
4786 | The files that don't match either (like png.c, pngtrans.c, etc.) | 4786 | The files that don't match either (like png.c, pngtrans.c, etc.) |
4787 | are used for both reading and writing, and always need to be included. | 4787 | are used for both reading and writing, and always need to be included. |
4788 | The progressive reader is in pngpread.c | 4788 | The progressive reader is in pngpread.c |
4789 | 4789 | ||
4790 | If you are creating or distributing a dynamically linked library (a .so | 4790 | If you are creating or distributing a dynamically linked library (a .so |
4791 | or DLL file), you should not remove or disable any parts of the library, | 4791 | or DLL file), you should not remove or disable any parts of the library, |
4792 | as this will cause applications linked with different versions of the | 4792 | as this will cause applications linked with different versions of the |
4793 | library to fail if they call functions not available in your library. | 4793 | library to fail if they call functions not available in your library. |
4794 | The size of the library itself should not be an issue, because only | 4794 | The size of the library itself should not be an issue, because only |
4795 | those sections that are actually used will be loaded into memory. | 4795 | those sections that are actually used will be loaded into memory. |
4796 | 4796 | ||
4797 | .SS Requesting debug printout | 4797 | .SS Requesting debug printout |
4798 | 4798 | ||
4799 | The macro definition PNG_DEBUG can be used to request debugging | 4799 | The macro definition PNG_DEBUG can be used to request debugging |
4800 | printout. Set it to an integer value in the range 0 to 3. Higher | 4800 | printout. Set it to an integer value in the range 0 to 3. Higher |
4801 | numbers result in increasing amounts of debugging information. The | 4801 | numbers result in increasing amounts of debugging information. The |
4802 | information is printed to the "stderr" file, unless another file | 4802 | information is printed to the "stderr" file, unless another file |
4803 | name is specified in the PNG_DEBUG_FILE macro definition. | 4803 | name is specified in the PNG_DEBUG_FILE macro definition. |
4804 | 4804 | ||
4805 | When PNG_DEBUG > 0, the following functions (macros) become available: | 4805 | When PNG_DEBUG > 0, the following functions (macros) become available: |
4806 | 4806 | ||
4807 | png_debug(level, message) | 4807 | png_debug(level, message) |
4808 | png_debug1(level, message, p1) | 4808 | png_debug1(level, message, p1) |
4809 | png_debug2(level, message, p1, p2) | 4809 | png_debug2(level, message, p1, p2) |
4810 | 4810 | ||
4811 | in which "level" is compared to PNG_DEBUG to decide whether to print | 4811 | in which "level" is compared to PNG_DEBUG to decide whether to print |
4812 | the message, "message" is the formatted string to be printed, | 4812 | the message, "message" is the formatted string to be printed, |
4813 | and p1 and p2 are parameters that are to be embedded in the string | 4813 | and p1 and p2 are parameters that are to be embedded in the string |
4814 | according to printf-style formatting directives. For example, | 4814 | according to printf-style formatting directives. For example, |
4815 | 4815 | ||
4816 | png_debug1(2, "foo=%d\n", foo); | 4816 | png_debug1(2, "foo=%d\n", foo); |
4817 | 4817 | ||
4818 | is expanded to | 4818 | is expanded to |
4819 | 4819 | ||
4820 | if (PNG_DEBUG > 2) | 4820 | if (PNG_DEBUG > 2) |
4821 | fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo); | 4821 | fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo); |
4822 | 4822 | ||
4823 | When PNG_DEBUG is defined but is zero, the macros aren't defined, but you | 4823 | When PNG_DEBUG is defined but is zero, the macros aren't defined, but you |
4824 | can still use PNG_DEBUG to control your own debugging: | 4824 | can still use PNG_DEBUG to control your own debugging: |
4825 | 4825 | ||
4826 | #ifdef PNG_DEBUG | 4826 | #ifdef PNG_DEBUG |
4827 | fprintf(stderr, ... | 4827 | fprintf(stderr, ... |
4828 | #endif | 4828 | #endif |
4829 | 4829 | ||
4830 | When PNG_DEBUG = 1, the macros are defined, but only png_debug statements | 4830 | When PNG_DEBUG = 1, the macros are defined, but only png_debug statements |
4831 | having level = 0 will be printed. There aren't any such statements in | 4831 | having level = 0 will be printed. There aren't any such statements in |
4832 | this version of libpng, but if you insert some they will be printed. | 4832 | this version of libpng, but if you insert some they will be printed. |
4833 | 4833 | ||
4834 | .SH VI. MNG support | 4834 | .SH VI. MNG support |
4835 | 4835 | ||
4836 | The MNG specification (available at http://www.libpng.org/pub/mng) allows | 4836 | The MNG specification (available at http://www.libpng.org/pub/mng) allows |
4837 | certain extensions to PNG for PNG images that are embedded in MNG datastreams. | 4837 | certain extensions to PNG for PNG images that are embedded in MNG datastreams. |
4838 | Libpng can support some of these extensions. To enable them, use the | 4838 | Libpng can support some of these extensions. To enable them, use the |
4839 | png_permit_mng_features() function: | 4839 | png_permit_mng_features() function: |
4840 | 4840 | ||
4841 | feature_set = png_permit_mng_features(png_ptr, mask) | 4841 | feature_set = png_permit_mng_features(png_ptr, mask) |
4842 | 4842 | ||
4843 | mask is a png_uint_32 containing the bitwise OR of the | 4843 | mask is a png_uint_32 containing the bitwise OR of the |
4844 | features you want to enable. These include | 4844 | features you want to enable. These include |
4845 | PNG_FLAG_MNG_EMPTY_PLTE | 4845 | PNG_FLAG_MNG_EMPTY_PLTE |
4846 | PNG_FLAG_MNG_FILTER_64 | 4846 | PNG_FLAG_MNG_FILTER_64 |
4847 | PNG_ALL_MNG_FEATURES | 4847 | PNG_ALL_MNG_FEATURES |
4848 | 4848 | ||
4849 | feature_set is a png_uint_32 that is the bitwise AND of | 4849 | feature_set is a png_uint_32 that is the bitwise AND of |
4850 | your mask with the set of MNG features that is | 4850 | your mask with the set of MNG features that is |
4851 | supported by the version of libpng that you are using. | 4851 | supported by the version of libpng that you are using. |
4852 | 4852 | ||
4853 | It is an error to use this function when reading or writing a standalone | 4853 | It is an error to use this function when reading or writing a standalone |
4854 | PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped | 4854 | PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped |
4855 | in a MNG datastream. As a minimum, it must have the MNG 8-byte signature | 4855 | in a MNG datastream. As a minimum, it must have the MNG 8-byte signature |
4856 | and the MHDR and MEND chunks. Libpng does not provide support for these | 4856 | and the MHDR and MEND chunks. Libpng does not provide support for these |
4857 | or any other MNG chunks; your application must provide its own support for | 4857 | or any other MNG chunks; your application must provide its own support for |
4858 | them. You may wish to consider using libmng (available at | 4858 | them. You may wish to consider using libmng (available at |
4859 | http://www.libmng.com) instead. | 4859 | http://www.libmng.com) instead. |
4860 | 4860 | ||
4861 | .SH VII. Changes to Libpng from version 0.88 | 4861 | .SH VII. Changes to Libpng from version 0.88 |
4862 | 4862 | ||
4863 | It should be noted that versions of libpng later than 0.96 are not | 4863 | It should be noted that versions of libpng later than 0.96 are not |
4864 | distributed by the original libpng author, Guy Schalnat, nor by | 4864 | distributed by the original libpng author, Guy Schalnat, nor by |
4865 | Andreas Dilger, who had taken over from Guy during 1996 and 1997, and | 4865 | Andreas Dilger, who had taken over from Guy during 1996 and 1997, and |
4866 | distributed versions 0.89 through 0.96, but rather by another member | 4866 | distributed versions 0.89 through 0.96, but rather by another member |
4867 | of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are | 4867 | of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are |
4868 | still alive and well, but they have moved on to other things. | 4868 | still alive and well, but they have moved on to other things. |
4869 | 4869 | ||
4870 | The old libpng functions png_read_init(), png_write_init(), | 4870 | The old libpng functions png_read_init(), png_write_init(), |
4871 | png_info_init(), png_read_destroy(), and png_write_destroy() have been | 4871 | png_info_init(), png_read_destroy(), and png_write_destroy() have been |
4872 | moved to PNG_INTERNAL in version 0.95 to discourage their use. These | 4872 | moved to PNG_INTERNAL in version 0.95 to discourage their use. These |
4873 | functions will be removed from libpng version 1.4.0. | 4873 | functions will be removed from libpng version 1.4.0. |
4874 | 4874 | ||
4875 | The preferred method of creating and initializing the libpng structures is | 4875 | The preferred method of creating and initializing the libpng structures is |
4876 | via the png_create_read_struct(), png_create_write_struct(), and | 4876 | via the png_create_read_struct(), png_create_write_struct(), and |
4877 | png_create_info_struct() because they isolate the size of the structures | 4877 | png_create_info_struct() because they isolate the size of the structures |
4878 | from the application, allow version error checking, and also allow the | 4878 | from the application, allow version error checking, and also allow the |
4879 | use of custom error handling routines during the initialization, which | 4879 | use of custom error handling routines during the initialization, which |
4880 | the old functions do not. The functions png_read_destroy() and | 4880 | the old functions do not. The functions png_read_destroy() and |
4881 | png_write_destroy() do not actually free the memory that libpng | 4881 | png_write_destroy() do not actually free the memory that libpng |
4882 | allocated for these structs, but just reset the data structures, so they | 4882 | allocated for these structs, but just reset the data structures, so they |
4883 | can be used instead of png_destroy_read_struct() and | 4883 | can be used instead of png_destroy_read_struct() and |
4884 | png_destroy_write_struct() if you feel there is too much system overhead | 4884 | png_destroy_write_struct() if you feel there is too much system overhead |
4885 | allocating and freeing the png_struct for each image read. | 4885 | allocating and freeing the png_struct for each image read. |
4886 | 4886 | ||
4887 | Setting the error callbacks via png_set_message_fn() before | 4887 | Setting the error callbacks via png_set_message_fn() before |
4888 | png_read_init() as was suggested in libpng-0.88 is no longer supported | 4888 | png_read_init() as was suggested in libpng-0.88 is no longer supported |
4889 | because this caused applications that do not use custom error functions | 4889 | because this caused applications that do not use custom error functions |
4890 | to fail if the png_ptr was not initialized to zero. It is still possible | 4890 | to fail if the png_ptr was not initialized to zero. It is still possible |
4891 | to set the error callbacks AFTER png_read_init(), or to change them with | 4891 | to set the error callbacks AFTER png_read_init(), or to change them with |
4892 | png_set_error_fn(), which is essentially the same function, but with a new | 4892 | png_set_error_fn(), which is essentially the same function, but with a new |
4893 | name to force compilation errors with applications that try to use the old | 4893 | name to force compilation errors with applications that try to use the old |
4894 | method. | 4894 | method. |
4895 | 4895 | ||
4896 | Starting with version 1.0.7, you can find out which version of the library | 4896 | Starting with version 1.0.7, you can find out which version of the library |
4897 | you are using at run-time: | 4897 | you are using at run-time: |
4898 | 4898 | ||
4899 | png_uint_32 libpng_vn = png_access_version_number(); | 4899 | png_uint_32 libpng_vn = png_access_version_number(); |
4900 | 4900 | ||
4901 | The number libpng_vn is constructed from the major version, minor | 4901 | The number libpng_vn is constructed from the major version, minor |
4902 | version with leading zero, and release number with leading zero, | 4902 | version with leading zero, and release number with leading zero, |
4903 | (e.g., libpng_vn for version 1.0.7 is 10007). | 4903 | (e.g., libpng_vn for version 1.0.7 is 10007). |
4904 | 4904 | ||
4905 | Note that this function does not take a png_ptr, so you can call it | 4905 | Note that this function does not take a png_ptr, so you can call it |
4906 | before you've created one. | 4906 | before you've created one. |
4907 | 4907 | ||
4908 | You can also check which version of png.h you used when compiling your | 4908 | You can also check which version of png.h you used when compiling your |
4909 | application: | 4909 | application: |
4910 | 4910 | ||
4911 | png_uint_32 application_vn = PNG_LIBPNG_VER; | 4911 | png_uint_32 application_vn = PNG_LIBPNG_VER; |
4912 | 4912 | ||
4913 | .SH VIII. Changes to Libpng from version 1.0.x to 1.2.x | 4913 | .SH VIII. Changes to Libpng from version 1.0.x to 1.2.x |
4914 | 4914 | ||
4915 | Support for user memory management was enabled by default. To | 4915 | Support for user memory management was enabled by default. To |
4916 | accomplish this, the functions png_create_read_struct_2(), | 4916 | accomplish this, the functions png_create_read_struct_2(), |
4917 | png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(), | 4917 | png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(), |
4918 | png_malloc_default(), and png_free_default() were added. | 4918 | png_malloc_default(), and png_free_default() were added. |
4919 | 4919 | ||
4920 | Support for the iTXt chunk has been enabled by default as of | 4920 | Support for the iTXt chunk has been enabled by default as of |
4921 | version 1.2.41. | 4921 | version 1.2.41. |
4922 | 4922 | ||
4923 | Support for certain MNG features was enabled. | 4923 | Support for certain MNG features was enabled. |
4924 | 4924 | ||
4925 | Support for numbered error messages was added. However, we never got | 4925 | Support for numbered error messages was added. However, we never got |
4926 | around to actually numbering the error messages. The function | 4926 | around to actually numbering the error messages. The function |
4927 | png_set_strip_error_numbers() was added (Note: the prototype for this | 4927 | png_set_strip_error_numbers() was added (Note: the prototype for this |
4928 | function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE | 4928 | function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE |
4929 | builds of libpng-1.2.15. It was restored in libpng-1.2.36). | 4929 | builds of libpng-1.2.15. It was restored in libpng-1.2.36). |
4930 | 4930 | ||
4931 | The png_malloc_warn() function was added at libpng-1.2.3. This issues | 4931 | The png_malloc_warn() function was added at libpng-1.2.3. This issues |
4932 | a png_warning and returns NULL instead of aborting when it fails to | 4932 | a png_warning and returns NULL instead of aborting when it fails to |
4933 | acquire the requested memory allocation. | 4933 | acquire the requested memory allocation. |
4934 | 4934 | ||
4935 | Support for setting user limits on image width and height was enabled | 4935 | Support for setting user limits on image width and height was enabled |
4936 | by default. The functions png_set_user_limits(), png_get_user_width_max(), | 4936 | by default. The functions png_set_user_limits(), png_get_user_width_max(), |
4937 | and png_get_user_height_max() were added at libpng-1.2.6. | 4937 | and png_get_user_height_max() were added at libpng-1.2.6. |
4938 | 4938 | ||
4939 | The png_set_add_alpha() function was added at libpng-1.2.7. | 4939 | The png_set_add_alpha() function was added at libpng-1.2.7. |
4940 | 4940 | ||
4941 | The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9. | 4941 | The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9. |
4942 | Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the | 4942 | Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the |
4943 | tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is | 4943 | tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is |
4944 | deprecated. | 4944 | deprecated. |
4945 | 4945 | ||
4946 | A number of macro definitions in support of runtime selection of | 4946 | A number of macro definitions in support of runtime selection of |
4947 | assembler code features (especially Intel MMX code support) were | 4947 | assembler code features (especially Intel MMX code support) were |
4948 | added at libpng-1.2.0: | 4948 | added at libpng-1.2.0: |
4949 | 4949 | ||
4950 | PNG_ASM_FLAG_MMX_SUPPORT_COMPILED | 4950 | PNG_ASM_FLAG_MMX_SUPPORT_COMPILED |
4951 | PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU | 4951 | PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU |
4952 | PNG_ASM_FLAG_MMX_READ_COMBINE_ROW | 4952 | PNG_ASM_FLAG_MMX_READ_COMBINE_ROW |
4953 | PNG_ASM_FLAG_MMX_READ_INTERLACE | 4953 | PNG_ASM_FLAG_MMX_READ_INTERLACE |
4954 | PNG_ASM_FLAG_MMX_READ_FILTER_SUB | 4954 | PNG_ASM_FLAG_MMX_READ_FILTER_SUB |
4955 | PNG_ASM_FLAG_MMX_READ_FILTER_UP | 4955 | PNG_ASM_FLAG_MMX_READ_FILTER_UP |
4956 | PNG_ASM_FLAG_MMX_READ_FILTER_AVG | 4956 | PNG_ASM_FLAG_MMX_READ_FILTER_AVG |
4957 | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH | 4957 | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH |
4958 | PNG_ASM_FLAGS_INITIALIZED | 4958 | PNG_ASM_FLAGS_INITIALIZED |
4959 | PNG_MMX_READ_FLAGS | 4959 | PNG_MMX_READ_FLAGS |
4960 | PNG_MMX_FLAGS | 4960 | PNG_MMX_FLAGS |
4961 | PNG_MMX_WRITE_FLAGS | 4961 | PNG_MMX_WRITE_FLAGS |
4962 | PNG_MMX_FLAGS | 4962 | PNG_MMX_FLAGS |
4963 | 4963 | ||
4964 | We added the following functions in support of runtime | 4964 | We added the following functions in support of runtime |
4965 | selection of assembler code features: | 4965 | selection of assembler code features: |
4966 | 4966 | ||
4967 | png_get_mmx_flagmask() | 4967 | png_get_mmx_flagmask() |
4968 | png_set_mmx_thresholds() | 4968 | png_set_mmx_thresholds() |
4969 | png_get_asm_flags() | 4969 | png_get_asm_flags() |
4970 | png_get_mmx_bitdepth_threshold() | 4970 | png_get_mmx_bitdepth_threshold() |
4971 | png_get_mmx_rowbytes_threshold() | 4971 | png_get_mmx_rowbytes_threshold() |
4972 | png_set_asm_flags() | 4972 | png_set_asm_flags() |
4973 | 4973 | ||
4974 | We replaced all of these functions with simple stubs in libpng-1.2.20, | 4974 | We replaced all of these functions with simple stubs in libpng-1.2.20, |
4975 | when the Intel assembler code was removed due to a licensing issue. | 4975 | when the Intel assembler code was removed due to a licensing issue. |
4976 | 4976 | ||
4977 | These macros are deprecated: | 4977 | These macros are deprecated: |
4978 | 4978 | ||
4979 | PNG_READ_TRANSFORMS_NOT_SUPPORTED | 4979 | PNG_READ_TRANSFORMS_NOT_SUPPORTED |
4980 | PNG_PROGRESSIVE_READ_NOT_SUPPORTED | 4980 | PNG_PROGRESSIVE_READ_NOT_SUPPORTED |
4981 | PNG_NO_SEQUENTIAL_READ_SUPPORTED | 4981 | PNG_NO_SEQUENTIAL_READ_SUPPORTED |
4982 | PNG_WRITE_TRANSFORMS_NOT_SUPPORTED | 4982 | PNG_WRITE_TRANSFORMS_NOT_SUPPORTED |
4983 | PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED | 4983 | PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED |
4984 | PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED | 4984 | PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED |
4985 | 4985 | ||
4986 | They have been replaced, respectively, by: | 4986 | They have been replaced, respectively, by: |
4987 | 4987 | ||
4988 | PNG_NO_READ_TRANSFORMS | 4988 | PNG_NO_READ_TRANSFORMS |
4989 | PNG_NO_PROGRESSIVE_READ | 4989 | PNG_NO_PROGRESSIVE_READ |
4990 | PNG_NO_SEQUENTIAL_READ | 4990 | PNG_NO_SEQUENTIAL_READ |
4991 | PNG_NO_WRITE_TRANSFORMS | 4991 | PNG_NO_WRITE_TRANSFORMS |
4992 | PNG_NO_READ_ANCILLARY_CHUNKS | 4992 | PNG_NO_READ_ANCILLARY_CHUNKS |
4993 | PNG_NO_WRITE_ANCILLARY_CHUNKS | 4993 | PNG_NO_WRITE_ANCILLARY_CHUNKS |
4994 | 4994 | ||
4995 | PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been | 4995 | PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been |
4996 | deprecated since libpng-1.0.16 and libpng-1.2.6. | 4996 | deprecated since libpng-1.0.16 and libpng-1.2.6. |
4997 | 4997 | ||
4998 | The function | 4998 | The function |
4999 | png_check_sig(sig, num) | 4999 | png_check_sig(sig, num) |
5000 | was replaced with | 5000 | was replaced with |
5001 | !png_sig_cmp(sig, 0, num) | 5001 | !png_sig_cmp(sig, 0, num) |
5002 | It has been deprecated since libpng-0.90. | 5002 | It has been deprecated since libpng-0.90. |
5003 | 5003 | ||
5004 | The function | 5004 | The function |
5005 | png_set_gray_1_2_4_to_8() | 5005 | png_set_gray_1_2_4_to_8() |
5006 | which also expands tRNS to alpha was replaced with | 5006 | which also expands tRNS to alpha was replaced with |
5007 | png_set_expand_gray_1_2_4_to_8() | 5007 | png_set_expand_gray_1_2_4_to_8() |
5008 | which does not. It has been deprecated since libpng-1.0.18 and 1.2.9. | 5008 | which does not. It has been deprecated since libpng-1.0.18 and 1.2.9. |
5009 | 5009 | ||
5010 | .SH IX. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x | 5010 | .SH IX. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x |
5011 | 5011 | ||
5012 | Private libpng prototypes and macro definitions were moved from | 5012 | Private libpng prototypes and macro definitions were moved from |
5013 | png.h and pngconf.h into a new pngpriv.h header file. | 5013 | png.h and pngconf.h into a new pngpriv.h header file. |
5014 | 5014 | ||
5015 | Functions png_set_benign_errors(), png_benign_error(), and | 5015 | Functions png_set_benign_errors(), png_benign_error(), and |
5016 | png_chunk_benign_error() were added. | 5016 | png_chunk_benign_error() were added. |
5017 | 5017 | ||
5018 | Support for setting the maximum amount of memory that the application | 5018 | Support for setting the maximum amount of memory that the application |
5019 | will allocate for reading chunks was added, as a security measure. | 5019 | will allocate for reading chunks was added, as a security measure. |
5020 | The functions png_set_chunk_cache_max() and png_get_chunk_cache_max() | 5020 | The functions png_set_chunk_cache_max() and png_get_chunk_cache_max() |
5021 | were added to the library. | 5021 | were added to the library. |
5022 | 5022 | ||
5023 | We implemented support for I/O states by adding png_ptr member io_state | 5023 | We implemented support for I/O states by adding png_ptr member io_state |
5024 | and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c | 5024 | and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c |
5025 | 5025 | ||
5026 | We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level | 5026 | We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level |
5027 | input transforms. | 5027 | input transforms. |
5028 | 5028 | ||
5029 | Checking for and reporting of errors in the IHDR chunk is more thorough. | 5029 | Checking for and reporting of errors in the IHDR chunk is more thorough. |
5030 | 5030 | ||
5031 | Support for global arrays was removed, to improve thread safety. | 5031 | Support for global arrays was removed, to improve thread safety. |
5032 | 5032 | ||
5033 | Some obsolete/deprecated macros and functions have been removed. | 5033 | Some obsolete/deprecated macros and functions have been removed. |
5034 | 5034 | ||
5035 | Typecasted NULL definitions such as | 5035 | Typecasted NULL definitions such as |
5036 | #define png_voidp_NULL (png_voidp)NULL | 5036 | #define png_voidp_NULL (png_voidp)NULL |
5037 | were eliminated. If you used these in your application, just use | 5037 | were eliminated. If you used these in your application, just use |
5038 | NULL instead. | 5038 | NULL instead. |
5039 | 5039 | ||
5040 | The png_struct and info_struct members "trans" and "trans_values" were | 5040 | The png_struct and info_struct members "trans" and "trans_values" were |
5041 | changed to "trans_alpha" and "trans_color", respectively. | 5041 | changed to "trans_alpha" and "trans_color", respectively. |
5042 | 5042 | ||
5043 | The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles | 5043 | The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles |
5044 | were removed. | 5044 | were removed. |
5045 | 5045 | ||
5046 | The PNG_1_0_X and PNG_1_2_X macros were eliminated. | 5046 | The PNG_1_0_X and PNG_1_2_X macros were eliminated. |
5047 | 5047 | ||
5048 | The PNG_LEGACY_SUPPORTED macro was eliminated. | 5048 | The PNG_LEGACY_SUPPORTED macro was eliminated. |
5049 | 5049 | ||
5050 | Many WIN32_WCE #ifdefs were removed. | 5050 | Many WIN32_WCE #ifdefs were removed. |
5051 | 5051 | ||
5052 | The functions png_read_init(info_ptr), png_write_init(info_ptr), | 5052 | The functions png_read_init(info_ptr), png_write_init(info_ptr), |
5053 | png_info_init(info_ptr), png_read_destroy(), and png_write_destroy() | 5053 | png_info_init(info_ptr), png_read_destroy(), and png_write_destroy() |
5054 | have been removed. They have been deprecated since libpng-0.95. | 5054 | have been removed. They have been deprecated since libpng-0.95. |
5055 | 5055 | ||
5056 | The png_permit_empty_plte() was removed. It has been deprecated | 5056 | The png_permit_empty_plte() was removed. It has been deprecated |
5057 | since libpng-1.0.9. Use png_permit_mng_features() instead. | 5057 | since libpng-1.0.9. Use png_permit_mng_features() instead. |
5058 | 5058 | ||
5059 | We removed the obsolete stub functions png_get_mmx_flagmask(), | 5059 | We removed the obsolete stub functions png_get_mmx_flagmask(), |
5060 | png_set_mmx_thresholds(), png_get_asm_flags(), | 5060 | png_set_mmx_thresholds(), png_get_asm_flags(), |
5061 | png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(), | 5061 | png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(), |
5062 | png_set_asm_flags(), and png_mmx_supported() | 5062 | png_set_asm_flags(), and png_mmx_supported() |
5063 | 5063 | ||
5064 | We removed the obsolete png_check_sig(), png_memcpy_check(), and | 5064 | We removed the obsolete png_check_sig(), png_memcpy_check(), and |
5065 | png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(), | 5065 | png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(), |
5066 | and memset(), respectively. | 5066 | and memset(), respectively. |
5067 | 5067 | ||
5068 | The function png_set_gray_1_2_4_to_8() was removed. It has been | 5068 | The function png_set_gray_1_2_4_to_8() was removed. It has been |
5069 | deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with | 5069 | deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with |
5070 | png_set_expand_gray_1_2_4_to_8() because the former function also | 5070 | png_set_expand_gray_1_2_4_to_8() because the former function also |
5071 | expanded any tRNS chunk to an alpha channel. | 5071 | expanded any tRNS chunk to an alpha channel. |
5072 | 5072 | ||
5073 | Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32 | 5073 | Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32 |
5074 | were added and are used by default instead of the corresponding | 5074 | were added and are used by default instead of the corresponding |
5075 | functions. Unfortunately, | 5075 | functions. Unfortunately, |
5076 | from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the | 5076 | from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the |
5077 | function) incorrectly returned a value of type png_uint_32. | 5077 | function) incorrectly returned a value of type png_uint_32. |
5078 | 5078 | ||
5079 | We changed the prototype for png_malloc() from | 5079 | We changed the prototype for png_malloc() from |
5080 | png_malloc(png_structp png_ptr, png_uint_32 size) | 5080 | png_malloc(png_structp png_ptr, png_uint_32 size) |
5081 | to | 5081 | to |
5082 | png_malloc(png_structp png_ptr, png_alloc_size_t size) | 5082 | png_malloc(png_structp png_ptr, png_alloc_size_t size) |
5083 | 5083 | ||
5084 | This also applies to the prototype for the user replacement malloc_fn(). | 5084 | This also applies to the prototype for the user replacement malloc_fn(). |
5085 | 5085 | ||
5086 | The png_calloc() function was added and is used in place of | 5086 | The png_calloc() function was added and is used in place of |
5087 | of "png_malloc(); memset();" except in the case in png_read_png() | 5087 | of "png_malloc(); memset();" except in the case in png_read_png() |
5088 | where the array consists of pointers; in this case a "for" loop is used | 5088 | where the array consists of pointers; in this case a "for" loop is used |
5089 | after the png_malloc() to set the pointers to NULL, to give robust. | 5089 | after the png_malloc() to set the pointers to NULL, to give robust. |
5090 | behavior in case the application runs out of memory part-way through | 5090 | behavior in case the application runs out of memory part-way through |
5091 | the process. | 5091 | the process. |
5092 | 5092 | ||
5093 | We changed the prototypes of png_get_compression_buffer_size() and | 5093 | We changed the prototypes of png_get_compression_buffer_size() and |
5094 | png_set_compression_buffer_size() to work with png_size_t instead of | 5094 | png_set_compression_buffer_size() to work with png_size_t instead of |
5095 | png_uint_32. | 5095 | png_uint_32. |
5096 | 5096 | ||
5097 | Support for numbered error messages was removed by default, since we | 5097 | Support for numbered error messages was removed by default, since we |
5098 | never got around to actually numbering the error messages. The function | 5098 | never got around to actually numbering the error messages. The function |
5099 | png_set_strip_error_numbers() was removed from the library by default. | 5099 | png_set_strip_error_numbers() was removed from the library by default. |
5100 | 5100 | ||
5101 | The png_zalloc() and png_zfree() functions are no longer exported. | 5101 | The png_zalloc() and png_zfree() functions are no longer exported. |
5102 | The png_zalloc() function no longer zeroes out the memory that it | 5102 | The png_zalloc() function no longer zeroes out the memory that it |
5103 | allocates. | 5103 | allocates. |
5104 | 5104 | ||
5105 | Support for dithering was disabled by default in libpng-1.4.0, because | 5105 | Support for dithering was disabled by default in libpng-1.4.0, because |
5106 | it has not been well tested and doesn't actually "dither". | 5106 | it has not been well tested and doesn't actually "dither". |
5107 | The code was not | 5107 | The code was not |
5108 | removed, however, and could be enabled by building libpng with | 5108 | removed, however, and could be enabled by building libpng with |
5109 | PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support | 5109 | PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support |
5110 | was reenabled, but the function was renamed png_set_quantize() to | 5110 | was reenabled, but the function was renamed png_set_quantize() to |
5111 | reflect more accurately what it actually does. At the same time, | 5111 | reflect more accurately what it actually does. At the same time, |
5112 | the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to | 5112 | the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to |
5113 | PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED | 5113 | PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED |
5114 | was renamed to PNG_READ_QUANTIZE_SUPPORTED. | 5114 | was renamed to PNG_READ_QUANTIZE_SUPPORTED. |
5115 | 5115 | ||
5116 | We removed the trailing '.' from the warning and error messages. | 5116 | We removed the trailing '.' from the warning and error messages. |
5117 | 5117 | ||
5118 | .SH X. Changes to Libpng from version 1.4.x to 1.5.x | 5118 | .SH X. Changes to Libpng from version 1.4.x to 1.5.x |
5119 | 5119 | ||
5120 | From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the | 5120 | From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the |
5121 | function) incorrectly returned a value of type png_uint_32. | 5121 | function) incorrectly returned a value of type png_uint_32. |
5122 | 5122 | ||
5123 | A. Changes that affect users of libpng | 5123 | A. Changes that affect users of libpng |
5124 | 5124 | ||
5125 | There are no substantial API changes between the non-deprecated parts of | 5125 | There are no substantial API changes between the non-deprecated parts of |
5126 | the 1.4.5 API and the 1.5.0 API, however the ability to directly access | 5126 | the 1.4.5 API and the 1.5.0 API, however the ability to directly access |
5127 | the main libpng control structures, png_struct and png_info, deprecated | 5127 | the main libpng control structures, png_struct and png_info, deprecated |
5128 | in earlier versions of libpng, has been completely removed from | 5128 | in earlier versions of libpng, has been completely removed from |
5129 | libpng 1.5. | 5129 | libpng 1.5. |
5130 | 5130 | ||
5131 | We no longer include zlib.h in png.h. Applications that need access | 5131 | We no longer include zlib.h in png.h. Applications that need access |
5132 | to information in zlib.h will need to add the '#include "zlib.h"' | 5132 | to information in zlib.h will need to add the '#include "zlib.h"' |
5133 | directive. It does not matter whether it is placed prior to or after | 5133 | directive. It does not matter whether it is placed prior to or after |
5134 | the '"#include png.h"' directive. | 5134 | the '"#include png.h"' directive. |
5135 | 5135 | ||
5136 | We moved the png_strcpy(), png_strncpy(), png_strlen(), png_memcpy(), | 5136 | We moved the png_strcpy(), png_strncpy(), png_strlen(), png_memcpy(), |
5137 | png_memcmp(), png_sprintf, and png_memcpy() macros into a private | 5137 | png_memcmp(), png_sprintf, and png_memcpy() macros into a private |
5138 | header file (pngpriv.h) that is not accessible to applications. | 5138 | header file (pngpriv.h) that is not accessible to applications. |
5139 | 5139 | ||
5140 | In png_get_iCCP, the type of "profile" was changed from png_charpp | 5140 | In png_get_iCCP, the type of "profile" was changed from png_charpp |
5141 | to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep. | 5141 | to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep. |
5142 | 5142 | ||
5143 | There are changes of form in png.h, including new and changed macros to | 5143 | There are changes of form in png.h, including new and changed macros to |
5144 | declare parts of the API. Some API functions with arguments that are | 5144 | declare parts of the API. Some API functions with arguments that are |
5145 | pointers to data not modified within the function have been corrected to | 5145 | pointers to data not modified within the function have been corrected to |
5146 | declare these arguments with PNG_CONST. | 5146 | declare these arguments with PNG_CONST. |
5147 | 5147 | ||
5148 | Much of the internal use of C macros to control the library build has also | 5148 | Much of the internal use of C macros to control the library build has also |
5149 | changed and some of this is visible in the exported header files, in | 5149 | changed and some of this is visible in the exported header files, in |
5150 | particular the use of macros to control data and API elements visible | 5150 | particular the use of macros to control data and API elements visible |
5151 | during application compilation may require significant revision to | 5151 | during application compilation may require significant revision to |
5152 | application code. (It is extremely rare for an application to do this.) | 5152 | application code. (It is extremely rare for an application to do this.) |
5153 | 5153 | ||
5154 | Any program that compiled against libpng 1.4 and did not use deprecated | 5154 | Any program that compiled against libpng 1.4 and did not use deprecated |
5155 | features or access internal library structures should compile and work | 5155 | features or access internal library structures should compile and work |
5156 | against libpng 1.5, except for the change in the prototype for | 5156 | against libpng 1.5, except for the change in the prototype for |
5157 | png_get_iCCP() and png_set_iCCP() API functions mentioned above. | 5157 | png_get_iCCP() and png_set_iCCP() API functions mentioned above. |
5158 | 5158 | ||
5159 | libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of | 5159 | libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of |
5160 | interlaced images. The macros return the number of rows and columns in | 5160 | interlaced images. The macros return the number of rows and columns in |
5161 | each pass and information that can be used to de-interlace and (if | 5161 | each pass and information that can be used to de-interlace and (if |
5162 | absolutely necessary) interlace an image. | 5162 | absolutely necessary) interlace an image. |
5163 | 5163 | ||
5164 | libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls | 5164 | libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls |
5165 | the application-provided png_longjmp_ptr on the internal, but application | 5165 | the application-provided png_longjmp_ptr on the internal, but application |
5166 | initialized, longjmp buffer. It is provided as a convenience to avoid | 5166 | initialized, longjmp buffer. It is provided as a convenience to avoid |
5167 | the need to use the png_jmpbuf macro, which had the unnecessary side | 5167 | the need to use the png_jmpbuf macro, which had the unnecessary side |
5168 | effect of resetting the internal png_longjmp_ptr value. | 5168 | effect of resetting the internal png_longjmp_ptr value. |
5169 | 5169 | ||
5170 | libpng 1.5.0 includes a complete fixed point API. By default this is | 5170 | libpng 1.5.0 includes a complete fixed point API. By default this is |
5171 | present along with the corresponding floating point API. In general the | 5171 | present along with the corresponding floating point API. In general the |
5172 | fixed point API is faster and smaller than the floating point one because | 5172 | fixed point API is faster and smaller than the floating point one because |
5173 | the PNG file format used fixed point, not floating point. This applies | 5173 | the PNG file format used fixed point, not floating point. This applies |
5174 | even if the library uses floating point in internal calculations. A new | 5174 | even if the library uses floating point in internal calculations. A new |
5175 | macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library | 5175 | macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library |
5176 | uses floating point arithmetic (the default) or fixed point arithmetic | 5176 | uses floating point arithmetic (the default) or fixed point arithmetic |
5177 | internally for performance critical calculations such as gamma correction. | 5177 | internally for performance critical calculations such as gamma correction. |
5178 | In some cases, the gamma calculations may produce slightly different | 5178 | In some cases, the gamma calculations may produce slightly different |
5179 | results. This has changed the results in png_rgb_to_gray and in alpha | 5179 | results. This has changed the results in png_rgb_to_gray and in alpha |
5180 | composition (png_set_background for example). This applies even if the | 5180 | composition (png_set_background for example). This applies even if the |
5181 | original image was already linear (gamma == 1.0) and, therefore, it is | 5181 | original image was already linear (gamma == 1.0) and, therefore, it is |
5182 | not necessary to linearize the image. This is because libpng has *not* | 5182 | not necessary to linearize the image. This is because libpng has *not* |
5183 | been changed to optimize that case correctly, yet. | 5183 | been changed to optimize that case correctly, yet. |
5184 | 5184 | ||
5185 | Fixed point support for the sCAL chunk comes with an important caveat; | 5185 | Fixed point support for the sCAL chunk comes with an important caveat; |
5186 | the sCAL specification uses a decimal encoding of floating point values | 5186 | the sCAL specification uses a decimal encoding of floating point values |
5187 | and the accuracy of PNG fixed point values is insufficient for | 5187 | and the accuracy of PNG fixed point values is insufficient for |
5188 | representation of these values. Consequently a "string" API | 5188 | representation of these values. Consequently a "string" API |
5189 | (png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading | 5189 | (png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading |
5190 | arbitrary sCAL chunks in the absence of either the floating point API or | 5190 | arbitrary sCAL chunks in the absence of either the floating point API or |
5191 | internal floating point calculations. | 5191 | internal floating point calculations. |
5192 | 5192 | ||
5193 | Applications no longer need to include the optional distribution header | 5193 | Applications no longer need to include the optional distribution header |
5194 | file pngusr.h or define the corresponding macros during application | 5194 | file pngusr.h or define the corresponding macros during application |
5195 | build in order to see the correct variant of the libpng API. From 1.5.0 | 5195 | build in order to see the correct variant of the libpng API. From 1.5.0 |
5196 | application code can check for the corresponding _SUPPORTED macro: | 5196 | application code can check for the corresponding _SUPPORTED macro: |
5197 | 5197 | ||
5198 | #ifdef PNG_INCH_CONVERSIONS_SUPPORTED | 5198 | #ifdef PNG_INCH_CONVERSIONS_SUPPORTED |
5199 | /* code that uses the inch conversion APIs. */ | 5199 | /* code that uses the inch conversion APIs. */ |
5200 | #endif | 5200 | #endif |
5201 | 5201 | ||
5202 | This macro will only be defined if the inch conversion functions have been | 5202 | This macro will only be defined if the inch conversion functions have been |
5203 | compiled into libpng. The full set of macros, and whether or not support | 5203 | compiled into libpng. The full set of macros, and whether or not support |
5204 | has been compiled in, are available in the header file pnglibconf.h. | 5204 | has been compiled in, are available in the header file pnglibconf.h. |
5205 | This header file is specific to the libpng build. Notice that prior to | 5205 | This header file is specific to the libpng build. Notice that prior to |
5206 | 1.5.0 the _SUPPORTED macros would always have the default definition unless | 5206 | 1.5.0 the _SUPPORTED macros would always have the default definition unless |
5207 | reset by pngusr.h or by explicit settings on the compiler command line. | 5207 | reset by pngusr.h or by explicit settings on the compiler command line. |
5208 | These settings may produce compiler warnings or errors in 1.5.0 because | 5208 | These settings may produce compiler warnings or errors in 1.5.0 because |
5209 | of macro redefinition. | 5209 | of macro redefinition. |
5210 | 5210 | ||
5211 | From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the | 5211 | From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the |
5212 | function) incorrectly returned a value of type png_uint_32. libpng 1.5.0 | 5212 | function) incorrectly returned a value of type png_uint_32. libpng 1.5.0 |
5213 | is consistent with the implementation in 1.4.5 and 1.2.x (where the macro | 5213 | is consistent with the implementation in 1.4.5 and 1.2.x (where the macro |
5214 | did not exist.) | 5214 | did not exist.) |
5215 | 5215 | ||
5216 | Applications can now choose whether to use these macros or to call the | 5216 | Applications can now choose whether to use these macros or to call the |
5217 | corresponding function by defining PNG_USE_READ_MACROS or | 5217 | corresponding function by defining PNG_USE_READ_MACROS or |
5218 | PNG_NO_USE_READ_MACROS before including png.h. Notice that this is | 5218 | PNG_NO_USE_READ_MACROS before including png.h. Notice that this is |
5219 | only supported from 1.5.0 -defining PNG_NO_USE_READ_MACROS prior to 1.5.0 | 5219 | only supported from 1.5.0 -defining PNG_NO_USE_READ_MACROS prior to 1.5.0 |
5220 | will lead to a link failure. | 5220 | will lead to a link failure. |
5221 | 5221 | ||
5222 | Prior to libpng-1.5.4, the zlib compressor used the same set of parameters | 5222 | Prior to libpng-1.5.4, the zlib compressor used the same set of parameters |
5223 | when compressing the IDAT data and textual data such as zTXt and iCCP. | 5223 | when compressing the IDAT data and textual data such as zTXt and iCCP. |
5224 | In libpng-1.5.4 we reinitialized the zlib stream for each type of data. | 5224 | In libpng-1.5.4 we reinitialized the zlib stream for each type of data. |
5225 | We added five png_set_text_*() functions for setting the parameters to | 5225 | We added five png_set_text_*() functions for setting the parameters to |
5226 | use with textual data. | 5226 | use with textual data. |
5227 | 5227 | ||
5228 | Prior to libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED | 5228 | Prior to libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED |
5229 | option was off by default, and slightly inaccurate scaling occurred. | 5229 | option was off by default, and slightly inaccurate scaling occurred. |
5230 | This option can no longer be turned off, and the choice of accurate | 5230 | This option can no longer be turned off, and the choice of accurate |
5231 | or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8() | 5231 | or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8() |
5232 | API for accurate scaling or the old png_set_strip_16_to_8() API for simple | 5232 | API for accurate scaling or the old png_set_strip_16_to_8() API for simple |
5233 | chopping. | 5233 | chopping. |
5234 | 5234 | ||
5235 | Prior to libpng-1.5.4, the png_set_user_limits() function could only be | 5235 | Prior to libpng-1.5.4, the png_set_user_limits() function could only be |
5236 | used to reduce the width and height limits from the value of | 5236 | used to reduce the width and height limits from the value of |
5237 | PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said | 5237 | PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said |
5238 | that it could be used to override them. Now this function will reduce or | 5238 | that it could be used to override them. Now this function will reduce or |
5239 | increase the limits. | 5239 | increase the limits. |
5240 | 5240 | ||
5241 | B. Changes to the build and configuration of libpng | 5241 | B. Changes to the build and configuration of libpng |
5242 | 5242 | ||
5243 | Details of internal changes to the library code can be found in the CHANGES | 5243 | Details of internal changes to the library code can be found in the CHANGES |
5244 | file and in the GIT repository logs. These will be of no concern to the vast | 5244 | file and in the GIT repository logs. These will be of no concern to the vast |
5245 | majority of library users or builders, however the few who configure libpng | 5245 | majority of library users or builders, however the few who configure libpng |
5246 | to a non-default feature set may need to change how this is done. | 5246 | to a non-default feature set may need to change how this is done. |
5247 | 5247 | ||
5248 | There should be no need for library builders to alter build scripts if | 5248 | There should be no need for library builders to alter build scripts if |
5249 | these use the distributed build support - configure or the makefiles - | 5249 | these use the distributed build support - configure or the makefiles - |
5250 | however users of the makefiles may care to update their build scripts | 5250 | however users of the makefiles may care to update their build scripts |
5251 | to build pnglibconf.h where the corresponding makefile does not do so. | 5251 | to build pnglibconf.h where the corresponding makefile does not do so. |
5252 | 5252 | ||
5253 | Building libpng with a non-default configuration has changed completely. | 5253 | Building libpng with a non-default configuration has changed completely. |
5254 | The old method using pngusr.h should still work correctly even though the | 5254 | The old method using pngusr.h should still work correctly even though the |
5255 | way pngusr.h is used in the build has been changed; however, library | 5255 | way pngusr.h is used in the build has been changed; however, library |
5256 | builders will probably want to examine the changes to take advantage of | 5256 | builders will probably want to examine the changes to take advantage of |
5257 | new capabilities and to simplify their build system. | 5257 | new capabilities and to simplify their build system. |
5258 | 5258 | ||
5259 | B.1 Specific changes to library configuration capabilities | 5259 | B.1 Specific changes to library configuration capabilities |
5260 | 5260 | ||
5261 | The library now supports a complete fixed point implementation and can | 5261 | The library now supports a complete fixed point implementation and can |
5262 | thus be used on systems that have no floating point support or very | 5262 | thus be used on systems that have no floating point support or very |
5263 | limited or slow support. Previously gamma correction, an essential part | 5263 | limited or slow support. Previously gamma correction, an essential part |
5264 | of complete PNG support, required reasonably fast floating point. | 5264 | of complete PNG support, required reasonably fast floating point. |
5265 | 5265 | ||
5266 | As part of this the choice of internal implementation has been made | 5266 | As part of this the choice of internal implementation has been made |
5267 | independent of the choice of fixed versus floating point APIs and all the | 5267 | independent of the choice of fixed versus floating point APIs and all the |
5268 | missing fixed point APIs have been implemented. | 5268 | missing fixed point APIs have been implemented. |
5269 | 5269 | ||
5270 | The exact mechanism used to control attributes of API functions has | 5270 | The exact mechanism used to control attributes of API functions has |
5271 | changed. A single set of operating system independent macro definitions | 5271 | changed. A single set of operating system independent macro definitions |
5272 | is used and operating system specific directives are defined in | 5272 | is used and operating system specific directives are defined in |
5273 | pnglibconf.h | 5273 | pnglibconf.h |
5274 | 5274 | ||
5275 | As part of this the mechanism used to choose procedure call standards on | 5275 | As part of this the mechanism used to choose procedure call standards on |
5276 | those systems that allow a choice has been changed. At present this only | 5276 | those systems that allow a choice has been changed. At present this only |
5277 | affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems | 5277 | affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems |
5278 | running on Intel processors. As before, PNGAPI is defined where required | 5278 | running on Intel processors. As before, PNGAPI is defined where required |
5279 | to control the exported API functions; however, two new macros, PNGCBAPI | 5279 | to control the exported API functions; however, two new macros, PNGCBAPI |
5280 | and PNGCAPI, are used instead for callback functions (PNGCBAPI) and | 5280 | and PNGCAPI, are used instead for callback functions (PNGCBAPI) and |
5281 | (PNGCAPI) for functions that must match a C library prototype (currently | 5281 | (PNGCAPI) for functions that must match a C library prototype (currently |
5282 | only png_longjmp_ptr, which must match the C longjmp function.) The new | 5282 | only png_longjmp_ptr, which must match the C longjmp function.) The new |
5283 | approach is documented in pngconf.h | 5283 | approach is documented in pngconf.h |
5284 | 5284 | ||
5285 | Despite these changes, libpng 1.5.0 only supports the native C function | 5285 | Despite these changes, libpng 1.5.0 only supports the native C function |
5286 | calling standard on those platforms tested so far (__cdecl on Microsoft | 5286 | calling standard on those platforms tested so far (__cdecl on Microsoft |
5287 | Windows). This is because the support requirements for alternative | 5287 | Windows). This is because the support requirements for alternative |
5288 | calling conventions seem to no longer exist. Developers who find it | 5288 | calling conventions seem to no longer exist. Developers who find it |
5289 | necessary to set PNG_API_RULE to 1 should advise the mailing list | 5289 | necessary to set PNG_API_RULE to 1 should advise the mailing list |
5290 | (png-mng-implement) of this and library builders who use Openwatcom and | 5290 | (png-mng-implement) of this and library builders who use Openwatcom and |
5291 | therefore set PNG_API_RULE to 2 should also contact the mailing list. | 5291 | therefore set PNG_API_RULE to 2 should also contact the mailing list. |
5292 | 5292 | ||
5293 | A new test program, pngvalid, is provided in addition to pngtest. | 5293 | A new test program, pngvalid, is provided in addition to pngtest. |
5294 | pngvalid validates the arithmetic accuracy of the gamma correction | 5294 | pngvalid validates the arithmetic accuracy of the gamma correction |
5295 | calculations and includes a number of validations of the file format. | 5295 | calculations and includes a number of validations of the file format. |
5296 | A subset of the full range of tests is run when "make check" is done | 5296 | A subset of the full range of tests is run when "make check" is done |
5297 | (in the 'configure' build.) pngvalid also allows total allocated memory | 5297 | (in the 'configure' build.) pngvalid also allows total allocated memory |
5298 | usage to be evaluated and performs additional memory overwrite validation. | 5298 | usage to be evaluated and performs additional memory overwrite validation. |
5299 | 5299 | ||
5300 | Many changes to individual feature macros have been made. The following | 5300 | Many changes to individual feature macros have been made. The following |
5301 | are the changes most likely to be noticed by library builders who | 5301 | are the changes most likely to be noticed by library builders who |
5302 | configure libpng: | 5302 | configure libpng: |
5303 | 5303 | ||
5304 | 1) All feature macros now have consistent naming: | 5304 | 1) All feature macros now have consistent naming: |
5305 | 5305 | ||
5306 | #define PNG_NO_feature turns the feature off | 5306 | #define PNG_NO_feature turns the feature off |
5307 | #define PNG_feature_SUPPORTED turns the feature on | 5307 | #define PNG_feature_SUPPORTED turns the feature on |
5308 | 5308 | ||
5309 | pnglibconf.h contains one line for each feature macro which is either: | 5309 | pnglibconf.h contains one line for each feature macro which is either: |
5310 | 5310 | ||
5311 | #define PNG_feature_SUPPORTED | 5311 | #define PNG_feature_SUPPORTED |
5312 | 5312 | ||
5313 | if the feature is supported or: | 5313 | if the feature is supported or: |
5314 | 5314 | ||
5315 | /*#undef PNG_feature_SUPPORTED*/ | 5315 | /*#undef PNG_feature_SUPPORTED*/ |
5316 | 5316 | ||
5317 | if it is not. Library code consistently checks for the 'SUPPORTED' macro. | 5317 | if it is not. Library code consistently checks for the 'SUPPORTED' macro. |
5318 | It does not, and libpng applications should not, check for the 'NO' macro | 5318 | It does not, and libpng applications should not, check for the 'NO' macro |
5319 | which will not normally be defined even if the feature is not supported. | 5319 | which will not normally be defined even if the feature is not supported. |
5320 | The 'NO' macros are only used internally for setting or not setting the | 5320 | The 'NO' macros are only used internally for setting or not setting the |
5321 | corresponding 'SUPPORTED' macros. | 5321 | corresponding 'SUPPORTED' macros. |
5322 | 5322 | ||
5323 | Compatibility with the old names is provided as follows: | 5323 | Compatibility with the old names is provided as follows: |
5324 | 5324 | ||
5325 | PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED | 5325 | PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED |
5326 | 5326 | ||
5327 | And the following definitions disable the corresponding feature: | 5327 | And the following definitions disable the corresponding feature: |
5328 | 5328 | ||
5329 | PNG_SETJMP_NOT_SUPPORTED disables SETJMP | 5329 | PNG_SETJMP_NOT_SUPPORTED disables SETJMP |
5330 | PNG_READ_TRANSFORMS_NOT_SUPPORTED disables READ_TRANSFORMS | 5330 | PNG_READ_TRANSFORMS_NOT_SUPPORTED disables READ_TRANSFORMS |
5331 | PNG_NO_READ_COMPOSITED_NODIV disables READ_COMPOSITE_NODIV | 5331 | PNG_NO_READ_COMPOSITED_NODIV disables READ_COMPOSITE_NODIV |
5332 | PNG_WRITE_TRANSFORMS_NOT_SUPPORTED disables WRITE_TRANSFORMS | 5332 | PNG_WRITE_TRANSFORMS_NOT_SUPPORTED disables WRITE_TRANSFORMS |
5333 | PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED disables READ_ANCILLARY_CHUNKS | 5333 | PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED disables READ_ANCILLARY_CHUNKS |
5334 | PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED disables WRITE_ANCILLARY_CHUNKS | 5334 | PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED disables WRITE_ANCILLARY_CHUNKS |
5335 | 5335 | ||
5336 | Library builders should remove use of the above, inconsistent, names. | 5336 | Library builders should remove use of the above, inconsistent, names. |
5337 | 5337 | ||
5338 | 2) Warning and error message formatting was previously conditional on | 5338 | 2) Warning and error message formatting was previously conditional on |
5339 | the STDIO feature. The library has been changed to use the | 5339 | the STDIO feature. The library has been changed to use the |
5340 | CONSOLE_IO feature instead. This means that if CONSOLE_IO is disabled | 5340 | CONSOLE_IO feature instead. This means that if CONSOLE_IO is disabled |
5341 | the library no longer uses the printf(3) functions, even though the | 5341 | the library no longer uses the printf(3) functions, even though the |
5342 | default read/write implementations use (FILE) style stdio.h functions. | 5342 | default read/write implementations use (FILE) style stdio.h functions. |
5343 | 5343 | ||
5344 | 3) Three feature macros now control the fixed/floating point decisions: | 5344 | 3) Three feature macros now control the fixed/floating point decisions: |
5345 | 5345 | ||
5346 | PNG_FLOATING_POINT_SUPPORTED enables the floating point APIs | 5346 | PNG_FLOATING_POINT_SUPPORTED enables the floating point APIs |
5347 | 5347 | ||
5348 | PNG_FIXED_POINT_SUPPORTED enables the fixed point APIs; however, in | 5348 | PNG_FIXED_POINT_SUPPORTED enables the fixed point APIs; however, in |
5349 | practice these are normally required internally anyway (because the PNG | 5349 | practice these are normally required internally anyway (because the PNG |
5350 | file format is fixed point), therefore in most cases PNG_NO_FIXED_POINT | 5350 | file format is fixed point), therefore in most cases PNG_NO_FIXED_POINT |
5351 | merely stops the function from being exported. | 5351 | merely stops the function from being exported. |
5352 | 5352 | ||
5353 | PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating | 5353 | PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating |
5354 | point implementation or the fixed point one. Typically the fixed point | 5354 | point implementation or the fixed point one. Typically the fixed point |
5355 | implementation is larger and slower than the floating point implementation | 5355 | implementation is larger and slower than the floating point implementation |
5356 | on a system that supports floating point, however it may be faster on a | 5356 | on a system that supports floating point, however it may be faster on a |
5357 | system which lacks floating point hardware and therefore uses a software | 5357 | system which lacks floating point hardware and therefore uses a software |
5358 | emulation. | 5358 | emulation. |
5359 | 5359 | ||
5360 | 4) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the | 5360 | 4) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the |
5361 | functions to read and write ints to be disabled independently of | 5361 | functions to read and write ints to be disabled independently of |
5362 | PNG_USE_READ_MACROS, which allows libpng to be built with the functions | 5362 | PNG_USE_READ_MACROS, which allows libpng to be built with the functions |
5363 | even though the default is to use the macros - this allows applications | 5363 | even though the default is to use the macros - this allows applications |
5364 | to choose at app buildtime whether or not to use macros (previously | 5364 | to choose at app buildtime whether or not to use macros (previously |
5365 | impossible because the functions weren't in the default build.) | 5365 | impossible because the functions weren't in the default build.) |
5366 | 5366 | ||
5367 | B.2 Changes to the configuration mechanism | 5367 | B.2 Changes to the configuration mechanism |
5368 | 5368 | ||
5369 | Prior to libpng-1.5.0 library builders who needed to configure libpng | 5369 | Prior to libpng-1.5.0 library builders who needed to configure libpng |
5370 | had either to modify the exported pngconf.h header file to add system | 5370 | had either to modify the exported pngconf.h header file to add system |
5371 | specific configuration or had to write feature selection macros into | 5371 | specific configuration or had to write feature selection macros into |
5372 | pngusr.h and cause this to be included into pngconf.h by defining | 5372 | pngusr.h and cause this to be included into pngconf.h by defining |
5373 | PNG_USER_CONFIG. The latter mechanism had the disadvantage that an | 5373 | PNG_USER_CONFIG. The latter mechanism had the disadvantage that an |
5374 | application built without PNG_USER_CONFIG defined would see the | 5374 | application built without PNG_USER_CONFIG defined would see the |
5375 | unmodified, default, libpng API and thus would probably fail to link. | 5375 | unmodified, default, libpng API and thus would probably fail to link. |
5376 | 5376 | ||
5377 | These mechanisms still work in the configure build and in any makefile | 5377 | These mechanisms still work in the configure build and in any makefile |
5378 | build that builds pnglibconf.h, although the feature selection macros | 5378 | build that builds pnglibconf.h, although the feature selection macros |
5379 | have changed somewhat as described above. In 1.5.0, however, pngusr.h is | 5379 | have changed somewhat as described above. In 1.5.0, however, pngusr.h is |
5380 | processed only once, when the exported header file pnglibconf.h is built. | 5380 | processed only once, when the exported header file pnglibconf.h is built. |
5381 | pngconf.h no longer includes pngusr.h, therefore pngusr.h is ignored after the | 5381 | pngconf.h no longer includes pngusr.h, therefore pngusr.h is ignored after the |
5382 | build of pnglibconf.h and it is never included in an application build. | 5382 | build of pnglibconf.h and it is never included in an application build. |
5383 | 5383 | ||
5384 | The rarely used alternative of adding a list of feature macros to the | 5384 | The rarely used alternative of adding a list of feature macros to the |
5385 | CFLAGS setting in the build also still works, however the macros will be | 5385 | CFLAGS setting in the build also still works, however the macros will be |
5386 | copied to pnglibconf.h and this may produce macro redefinition warnings | 5386 | copied to pnglibconf.h and this may produce macro redefinition warnings |
5387 | when the individual C files are compiled. | 5387 | when the individual C files are compiled. |
5388 | 5388 | ||
5389 | All configuration now only works if pnglibconf.h is built from | 5389 | All configuration now only works if pnglibconf.h is built from |
5390 | scripts/pnglibconf.dfa. This requires the program awk. Brian Kernighan | 5390 | scripts/pnglibconf.dfa. This requires the program awk. Brian Kernighan |
5391 | (the original author of awk) maintains C source code of that awk and this | 5391 | (the original author of awk) maintains C source code of that awk and this |
5392 | and all known later implementations (often called by subtly different | 5392 | and all known later implementations (often called by subtly different |
5393 | names - nawk and gawk for example) are adequate to build pnglibconf.h. | 5393 | names - nawk and gawk for example) are adequate to build pnglibconf.h. |
5394 | The Sun Microsystems (now Oracle) program 'awk' is an earlier version | 5394 | The Sun Microsystems (now Oracle) program 'awk' is an earlier version |
5395 | and does not work; this may also apply to other systems that have a | 5395 | and does not work; this may also apply to other systems that have a |
5396 | functioning awk called 'nawk'. | 5396 | functioning awk called 'nawk'. |
5397 | 5397 | ||
5398 | Configuration options are now documented in scripts/pnglibconf.dfa. This | 5398 | Configuration options are now documented in scripts/pnglibconf.dfa. This |
5399 | file also includes dependency information that ensures a configuration is | 5399 | file also includes dependency information that ensures a configuration is |
5400 | consistent; that is, if a feature is switched off dependent features are | 5400 | consistent; that is, if a feature is switched off dependent features are |
5401 | also removed. As a recommended alternative to using feature macros in | 5401 | also removed. As a recommended alternative to using feature macros in |
5402 | pngusr.h a system builder may also define equivalent options in pngusr.dfa | 5402 | pngusr.h a system builder may also define equivalent options in pngusr.dfa |
5403 | (or, indeed, any file) and add that to the configuration by setting | 5403 | (or, indeed, any file) and add that to the configuration by setting |
5404 | DFA_XTRA to the file name. The makefiles in contrib/pngminim illustrate | 5404 | DFA_XTRA to the file name. The makefiles in contrib/pngminim illustrate |
5405 | how to do this, and a case where pngusr.h is still required. | 5405 | how to do this, and a case where pngusr.h is still required. |
5406 | 5406 | ||
5407 | .SH XI. Detecting libpng | 5407 | .SH XI. Detecting libpng |
5408 | 5408 | ||
5409 | The png_get_io_ptr() function has been present since libpng-0.88, has never | 5409 | The png_get_io_ptr() function has been present since libpng-0.88, has never |
5410 | changed, and is unaffected by conditional compilation macros. It is the | 5410 | changed, and is unaffected by conditional compilation macros. It is the |
5411 | best choice for use in configure scripts for detecting the presence of any | 5411 | best choice for use in configure scripts for detecting the presence of any |
5412 | libpng version since 0.88. In an autoconf "configure.in" you could use | 5412 | libpng version since 0.88. In an autoconf "configure.in" you could use |
5413 | 5413 | ||
5414 | AC_CHECK_LIB(png, png_get_io_ptr, ... | 5414 | AC_CHECK_LIB(png, png_get_io_ptr, ... |
5415 | 5415 | ||
5416 | .SH XII. Source code repository | 5416 | .SH XII. Source code repository |
5417 | 5417 | ||
5418 | Since about February 2009, version 1.2.34, libpng has been under "git" source | 5418 | Since about February 2009, version 1.2.34, libpng has been under "git" source |
5419 | control. The git repository was built from old libpng-x.y.z.tar.gz files | 5419 | control. The git repository was built from old libpng-x.y.z.tar.gz files |
5420 | going back to version 0.70. You can access the git repository (read only) | 5420 | going back to version 0.70. You can access the git repository (read only) |
5421 | at | 5421 | at |
5422 | 5422 | ||
5423 | git://libpng.git.sourceforge.net/gitroot/libpng | 5423 | git://libpng.git.sourceforge.net/gitroot/libpng |
5424 | 5424 | ||
5425 | or you can browse it via "gitweb" at | 5425 | or you can browse it via "gitweb" at |
5426 | 5426 | ||
5427 | http://libpng.git.sourceforge.net/git/gitweb.cgi?p=libpng | 5427 | http://libpng.git.sourceforge.net/git/gitweb.cgi?p=libpng |
5428 | 5428 | ||
5429 | Patches can be sent to glennrp at users.sourceforge.net or to | 5429 | Patches can be sent to glennrp at users.sourceforge.net or to |
5430 | png-mng-implement at lists.sourceforge.net or you can upload them to | 5430 | png-mng-implement at lists.sourceforge.net or you can upload them to |
5431 | the libpng bug tracker at | 5431 | the libpng bug tracker at |
5432 | 5432 | ||
5433 | http://libpng.sourceforge.net | 5433 | http://libpng.sourceforge.net |
5434 | 5434 | ||
5435 | We also accept patches built from the tar or zip distributions, and | 5435 | We also accept patches built from the tar or zip distributions, and |
5436 | simple verbal discriptions of bug fixes, reported either to the | 5436 | simple verbal discriptions of bug fixes, reported either to the |
5437 | SourceForge bug tracker, to the png-mng-implement at lists.sf.net | 5437 | SourceForge bug tracker, to the png-mng-implement at lists.sf.net |
5438 | mailing list, or directly to glennrp. | 5438 | mailing list, or directly to glennrp. |
5439 | 5439 | ||
5440 | .SH XIII. Coding style | 5440 | .SH XIII. Coding style |
5441 | 5441 | ||
5442 | Our coding style is similar to the "Allman" style, with curly | 5442 | Our coding style is similar to the "Allman" style, with curly |
5443 | braces on separate lines: | 5443 | braces on separate lines: |
5444 | 5444 | ||
5445 | if (condition) | 5445 | if (condition) |
5446 | { | 5446 | { |
5447 | action; | 5447 | action; |
5448 | } | 5448 | } |
5449 | 5449 | ||
5450 | else if (another condition) | 5450 | else if (another condition) |
5451 | { | 5451 | { |
5452 | another action; | 5452 | another action; |
5453 | } | 5453 | } |
5454 | 5454 | ||
5455 | The braces can be omitted from simple one-line actions: | 5455 | The braces can be omitted from simple one-line actions: |
5456 | 5456 | ||
5457 | if (condition) | 5457 | if (condition) |
5458 | return (0); | 5458 | return (0); |
5459 | 5459 | ||
5460 | We use 3-space indentation, except for continued statements which | 5460 | We use 3-space indentation, except for continued statements which |
5461 | are usually indented the same as the first line of the statement | 5461 | are usually indented the same as the first line of the statement |
5462 | plus four more spaces. | 5462 | plus four more spaces. |
5463 | 5463 | ||
5464 | For macro definitions we use 2-space indentation, always leaving the "#" | 5464 | For macro definitions we use 2-space indentation, always leaving the "#" |
5465 | in the first column. | 5465 | in the first column. |
5466 | 5466 | ||
5467 | #ifndef PNG_NO_FEATURE | 5467 | #ifndef PNG_NO_FEATURE |
5468 | # ifndef PNG_FEATURE_SUPPORTED | 5468 | # ifndef PNG_FEATURE_SUPPORTED |
5469 | # define PNG_FEATURE_SUPPORTED | 5469 | # define PNG_FEATURE_SUPPORTED |
5470 | # endif | 5470 | # endif |
5471 | #endif | 5471 | #endif |
5472 | 5472 | ||
5473 | Comments appear with the leading "/*" at the same indentation as | 5473 | Comments appear with the leading "/*" at the same indentation as |
5474 | the statement that follows the comment: | 5474 | the statement that follows the comment: |
5475 | 5475 | ||
5476 | /* Single-line comment */ | 5476 | /* Single-line comment */ |
5477 | statement; | 5477 | statement; |
5478 | 5478 | ||
5479 | /* This is a multiple-line | 5479 | /* This is a multiple-line |
5480 | * comment. | 5480 | * comment. |
5481 | */ | 5481 | */ |
5482 | statement; | 5482 | statement; |
5483 | 5483 | ||
5484 | Very short comments can be placed after the end of the statement | 5484 | Very short comments can be placed after the end of the statement |
5485 | to which they pertain: | 5485 | to which they pertain: |
5486 | 5486 | ||
5487 | statement; /* comment */ | 5487 | statement; /* comment */ |
5488 | 5488 | ||
5489 | We don't use C++ style ("//") comments. We have, however, | 5489 | We don't use C++ style ("//") comments. We have, however, |
5490 | used them in the past in some now-abandoned MMX assembler | 5490 | used them in the past in some now-abandoned MMX assembler |
5491 | code. | 5491 | code. |
5492 | 5492 | ||
5493 | Functions and their curly braces are not indented, and | 5493 | Functions and their curly braces are not indented, and |
5494 | exported functions are marked with PNGAPI: | 5494 | exported functions are marked with PNGAPI: |
5495 | 5495 | ||
5496 | /* This is a public function that is visible to | 5496 | /* This is a public function that is visible to |
5497 | * application programmers. It does thus-and-so. | 5497 | * application programmers. It does thus-and-so. |
5498 | */ | 5498 | */ |
5499 | void PNGAPI | 5499 | void PNGAPI |
5500 | png_exported_function(png_ptr, png_info, foo) | 5500 | png_exported_function(png_ptr, png_info, foo) |
5501 | { | 5501 | { |
5502 | body; | 5502 | body; |
5503 | } | 5503 | } |
5504 | 5504 | ||
5505 | The prototypes for all exported functions appear in png.h, | 5505 | The prototypes for all exported functions appear in png.h, |
5506 | above the comment that says | 5506 | above the comment that says |
5507 | 5507 | ||
5508 | /* Maintainer: Put new public prototypes here ... */ | 5508 | /* Maintainer: Put new public prototypes here ... */ |
5509 | 5509 | ||
5510 | We mark all non-exported functions with "/* PRIVATE */"": | 5510 | We mark all non-exported functions with "/* PRIVATE */"": |
5511 | 5511 | ||
5512 | void /* PRIVATE */ | 5512 | void /* PRIVATE */ |
5513 | png_non_exported_function(png_ptr, png_info, foo) | 5513 | png_non_exported_function(png_ptr, png_info, foo) |
5514 | { | 5514 | { |
5515 | body; | 5515 | body; |
5516 | } | 5516 | } |
5517 | 5517 | ||
5518 | The prototypes for non-exported functions (except for those in | 5518 | The prototypes for non-exported functions (except for those in |
5519 | pngtest) appear in | 5519 | pngtest) appear in |
5520 | pngpriv.h | 5520 | pngpriv.h |
5521 | above the comment that says | 5521 | above the comment that says |
5522 | 5522 | ||
5523 | /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */ | 5523 | /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */ |
5524 | 5524 | ||
5525 | To avoid polluting the global namespace, the names of all exported | 5525 | To avoid polluting the global namespace, the names of all exported |
5526 | functions and variables begin with "png_", and all publicly visible C | 5526 | functions and variables begin with "png_", and all publicly visible C |
5527 | preprocessor macros begin with "PNG_". We request that applications that | 5527 | preprocessor macros begin with "PNG_". We request that applications that |
5528 | use libpng *not* begin any of their own symbols with either of these strings. | 5528 | use libpng *not* begin any of their own symbols with either of these strings. |
5529 | 5529 | ||
5530 | We put a space after each comma and after each semicolon | 5530 | We put a space after each comma and after each semicolon |
5531 | in "for" statements, and we put spaces before and after each | 5531 | in "for" statements, and we put spaces before and after each |
5532 | C binary operator and after "for" or "while", and before | 5532 | C binary operator and after "for" or "while", and before |
5533 | "?". We don't put a space between a typecast and the expression | 5533 | "?". We don't put a space between a typecast and the expression |
5534 | being cast, nor do we put one between a function name and the | 5534 | being cast, nor do we put one between a function name and the |
5535 | left parenthesis that follows it: | 5535 | left parenthesis that follows it: |
5536 | 5536 | ||
5537 | for (i = 2; i > 0; --i) | 5537 | for (i = 2; i > 0; --i) |
5538 | y[i] = a(x) + (int)b; | 5538 | y[i] = a(x) + (int)b; |
5539 | 5539 | ||
5540 | We prefer #ifdef and #ifndef to #if defined() and if !defined() | 5540 | We prefer #ifdef and #ifndef to #if defined() and if !defined() |
5541 | when there is only one macro being tested. | 5541 | when there is only one macro being tested. |
5542 | 5542 | ||
5543 | We prefer to express integers that are used as bit masks in hex format, | 5543 | We prefer to express integers that are used as bit masks in hex format, |
5544 | with an even number of lower-case hex digits (e.g., 0x00, 0xff, 0x0100). | 5544 | with an even number of lower-case hex digits (e.g., 0x00, 0xff, 0x0100). |
5545 | 5545 | ||
5546 | We do not use the TAB character for indentation in the C sources. | 5546 | We do not use the TAB character for indentation in the C sources. |
5547 | 5547 | ||
5548 | Lines do not exceed 80 characters. | 5548 | Lines do not exceed 80 characters. |
5549 | 5549 | ||
5550 | Other rules can be inferred by inspecting the libpng source. | 5550 | Other rules can be inferred by inspecting the libpng source. |
5551 | 5551 | ||
5552 | .SH XIV. Y2K Compliance in libpng | 5552 | .SH XIV. Y2K Compliance in libpng |
5553 | 5553 | ||
5554 | February 18, 2012 | 5554 | February 18, 2012 |
5555 | 5555 | ||
5556 | Since the PNG Development group is an ad-hoc body, we can't make | 5556 | Since the PNG Development group is an ad-hoc body, we can't make |
5557 | an official declaration. | 5557 | an official declaration. |
5558 | 5558 | ||
5559 | This is your unofficial assurance that libpng from version 0.71 and | 5559 | This is your unofficial assurance that libpng from version 0.71 and |
5560 | upward through 1.5.9 are Y2K compliant. It is my belief that earlier | 5560 | upward through 1.5.9 are Y2K compliant. It is my belief that earlier |
5561 | versions were also Y2K compliant. | 5561 | versions were also Y2K compliant. |
5562 | 5562 | ||
5563 | Libpng only has three year fields. One is a 2-byte unsigned integer that | 5563 | Libpng only has three year fields. One is a 2-byte unsigned integer that |
5564 | will hold years up to 65535. The other two hold the date in text | 5564 | will hold years up to 65535. The other two hold the date in text |
5565 | format, and will hold years up to 9999. | 5565 | format, and will hold years up to 9999. |
5566 | 5566 | ||
5567 | The integer is | 5567 | The integer is |
5568 | "png_uint_16 year" in png_time_struct. | 5568 | "png_uint_16 year" in png_time_struct. |
5569 | 5569 | ||
5570 | The strings are | 5570 | The strings are |
5571 | "png_charp time_buffer" in png_struct and | 5571 | "png_charp time_buffer" in png_struct and |
5572 | "near_time_buffer", which is a local character string in png.c. | 5572 | "near_time_buffer", which is a local character string in png.c. |
5573 | 5573 | ||
5574 | There are seven time-related functions: | 5574 | There are seven time-related functions: |
5575 | 5575 | ||
5576 | png_convert_to_rfc_1123() in png.c | 5576 | png_convert_to_rfc_1123() in png.c |
5577 | (formerly png_convert_to_rfc_1152() in error) | 5577 | (formerly png_convert_to_rfc_1152() in error) |
5578 | png_convert_from_struct_tm() in pngwrite.c, called | 5578 | png_convert_from_struct_tm() in pngwrite.c, called |
5579 | in pngwrite.c | 5579 | in pngwrite.c |
5580 | png_convert_from_time_t() in pngwrite.c | 5580 | png_convert_from_time_t() in pngwrite.c |
5581 | png_get_tIME() in pngget.c | 5581 | png_get_tIME() in pngget.c |
5582 | png_handle_tIME() in pngrutil.c, called in pngread.c | 5582 | png_handle_tIME() in pngrutil.c, called in pngread.c |
5583 | png_set_tIME() in pngset.c | 5583 | png_set_tIME() in pngset.c |
5584 | png_write_tIME() in pngwutil.c, called in pngwrite.c | 5584 | png_write_tIME() in pngwutil.c, called in pngwrite.c |
5585 | 5585 | ||
5586 | All appear to handle dates properly in a Y2K environment. The | 5586 | All appear to handle dates properly in a Y2K environment. The |
5587 | png_convert_from_time_t() function calls gmtime() to convert from system | 5587 | png_convert_from_time_t() function calls gmtime() to convert from system |
5588 | clock time, which returns (year - 1900), which we properly convert to | 5588 | clock time, which returns (year - 1900), which we properly convert to |
5589 | the full 4-digit year. There is a possibility that applications using | 5589 | the full 4-digit year. There is a possibility that applications using |
5590 | libpng are not passing 4-digit years into the png_convert_to_rfc_1123() | 5590 | libpng are not passing 4-digit years into the png_convert_to_rfc_1123() |
5591 | function, or that they are incorrectly passing only a 2-digit year | 5591 | function, or that they are incorrectly passing only a 2-digit year |
5592 | instead of "year - 1900" into the png_convert_from_struct_tm() function, | 5592 | instead of "year - 1900" into the png_convert_from_struct_tm() function, |
5593 | but this is not under our control. The libpng documentation has always | 5593 | but this is not under our control. The libpng documentation has always |
5594 | stated that it works with 4-digit years, and the APIs have been | 5594 | stated that it works with 4-digit years, and the APIs have been |
5595 | documented as such. | 5595 | documented as such. |
5596 | 5596 | ||
5597 | The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned | 5597 | The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned |
5598 | integer to hold the year, and can hold years as large as 65535. | 5598 | integer to hold the year, and can hold years as large as 65535. |
5599 | 5599 | ||
5600 | zlib, upon which libpng depends, is also Y2K compliant. It contains | 5600 | zlib, upon which libpng depends, is also Y2K compliant. It contains |
5601 | no date-related code. | 5601 | no date-related code. |
5602 | 5602 | ||
5603 | 5603 | ||
5604 | Glenn Randers-Pehrson | 5604 | Glenn Randers-Pehrson |
5605 | libpng maintainer | 5605 | libpng maintainer |
5606 | PNG Development Group | 5606 | PNG Development Group |
5607 | 5607 | ||
5608 | .SH NOTE | 5608 | .SH NOTE |
5609 | 5609 | ||
5610 | Note about libpng version numbers: | 5610 | Note about libpng version numbers: |
5611 | 5611 | ||
5612 | Due to various miscommunications, unforeseen code incompatibilities | 5612 | Due to various miscommunications, unforeseen code incompatibilities |
5613 | and occasional factors outside the authors' control, version numbering | 5613 | and occasional factors outside the authors' control, version numbering |
5614 | on the library has not always been consistent and straightforward. | 5614 | on the library has not always been consistent and straightforward. |
5615 | The following table summarizes matters since version 0.89c, which was | 5615 | The following table summarizes matters since version 0.89c, which was |
5616 | the first widely used release: | 5616 | the first widely used release: |
5617 | 5617 | ||
5618 | source png.h png.h shared-lib | 5618 | source png.h png.h shared-lib |
5619 | version string int version | 5619 | version string int version |
5620 | ------- ------ ----- ---------- | 5620 | ------- ------ ----- ---------- |
5621 | 0.89c ("beta 3") 0.89 89 1.0.89 | 5621 | 0.89c ("beta 3") 0.89 89 1.0.89 |
5622 | 0.90 ("beta 4") 0.90 90 0.90 | 5622 | 0.90 ("beta 4") 0.90 90 0.90 |
5623 | 0.95 ("beta 5") 0.95 95 0.95 | 5623 | 0.95 ("beta 5") 0.95 95 0.95 |
5624 | 0.96 ("beta 6") 0.96 96 0.96 | 5624 | 0.96 ("beta 6") 0.96 96 0.96 |
5625 | 0.97b ("beta 7") 1.00.97 97 1.0.1 | 5625 | 0.97b ("beta 7") 1.00.97 97 1.0.1 |
5626 | 0.97c 0.97 97 2.0.97 | 5626 | 0.97c 0.97 97 2.0.97 |
5627 | 0.98 0.98 98 2.0.98 | 5627 | 0.98 0.98 98 2.0.98 |
5628 | 0.99 0.99 98 2.0.99 | 5628 | 0.99 0.99 98 2.0.99 |
5629 | 0.99a-m 0.99 99 2.0.99 | 5629 | 0.99a-m 0.99 99 2.0.99 |
5630 | 1.00 1.00 100 2.1.0 | 5630 | 1.00 1.00 100 2.1.0 |
5631 | 1.0.0 1.0.0 100 2.1.0 | 5631 | 1.0.0 1.0.0 100 2.1.0 |
5632 | 1.0.0 (from here on, the 100 2.1.0 | 5632 | 1.0.0 (from here on, the 100 2.1.0 |
5633 | 1.0.1 png.h string is 10001 2.1.0 | 5633 | 1.0.1 png.h string is 10001 2.1.0 |
5634 | 1.0.1a-e identical to the 10002 from here on, the | 5634 | 1.0.1a-e identical to the 10002 from here on, the |
5635 | 1.0.2 source version) 10002 shared library is 2.V | 5635 | 1.0.2 source version) 10002 shared library is 2.V |
5636 | 1.0.2a-b 10003 where V is the source | 5636 | 1.0.2a-b 10003 where V is the source |
5637 | 1.0.1 10001 code version except as | 5637 | 1.0.1 10001 code version except as |
5638 | 1.0.1a-e 10002 2.1.0.1a-e noted. | 5638 | 1.0.1a-e 10002 2.1.0.1a-e noted. |
5639 | 1.0.2 10002 2.1.0.2 | 5639 | 1.0.2 10002 2.1.0.2 |
5640 | 1.0.2a-b 10003 2.1.0.2a-b | 5640 | 1.0.2a-b 10003 2.1.0.2a-b |
5641 | 1.0.3 10003 2.1.0.3 | 5641 | 1.0.3 10003 2.1.0.3 |
5642 | 1.0.3a-d 10004 2.1.0.3a-d | 5642 | 1.0.3a-d 10004 2.1.0.3a-d |
5643 | 1.0.4 10004 2.1.0.4 | 5643 | 1.0.4 10004 2.1.0.4 |
5644 | 1.0.4a-f 10005 2.1.0.4a-f | 5644 | 1.0.4a-f 10005 2.1.0.4a-f |
5645 | 1.0.5 (+ 2 patches) 10005 2.1.0.5 | 5645 | 1.0.5 (+ 2 patches) 10005 2.1.0.5 |
5646 | 1.0.5a-d 10006 2.1.0.5a-d | 5646 | 1.0.5a-d 10006 2.1.0.5a-d |
5647 | 1.0.5e-r 10100 2.1.0.5e-r | 5647 | 1.0.5e-r 10100 2.1.0.5e-r |
5648 | 1.0.5s-v 10006 2.1.0.5s-v | 5648 | 1.0.5s-v 10006 2.1.0.5s-v |
5649 | 1.0.6 (+ 3 patches) 10006 2.1.0.6 | 5649 | 1.0.6 (+ 3 patches) 10006 2.1.0.6 |
5650 | 1.0.6d-g 10007 2.1.0.6d-g | 5650 | 1.0.6d-g 10007 2.1.0.6d-g |
5651 | 1.0.6h 10007 10.6h | 5651 | 1.0.6h 10007 10.6h |
5652 | 1.0.6i 10007 10.6i | 5652 | 1.0.6i 10007 10.6i |
5653 | 1.0.6j 10007 2.1.0.6j | 5653 | 1.0.6j 10007 2.1.0.6j |
5654 | 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14 | 5654 | 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14 |
5655 | 1.0.7beta15-18 1 10007 2.1.0.7beta15-18 | 5655 | 1.0.7beta15-18 1 10007 2.1.0.7beta15-18 |
5656 | 1.0.7rc1-2 1 10007 2.1.0.7rc1-2 | 5656 | 1.0.7rc1-2 1 10007 2.1.0.7rc1-2 |
5657 | 1.0.7 1 10007 2.1.0.7 | 5657 | 1.0.7 1 10007 2.1.0.7 |
5658 | 1.0.8beta1-4 1 10008 2.1.0.8beta1-4 | 5658 | 1.0.8beta1-4 1 10008 2.1.0.8beta1-4 |
5659 | 1.0.8rc1 1 10008 2.1.0.8rc1 | 5659 | 1.0.8rc1 1 10008 2.1.0.8rc1 |
5660 | 1.0.8 1 10008 2.1.0.8 | 5660 | 1.0.8 1 10008 2.1.0.8 |
5661 | 1.0.9beta1-6 1 10009 2.1.0.9beta1-6 | 5661 | 1.0.9beta1-6 1 10009 2.1.0.9beta1-6 |
5662 | 1.0.9rc1 1 10009 2.1.0.9rc1 | 5662 | 1.0.9rc1 1 10009 2.1.0.9rc1 |
5663 | 1.0.9beta7-10 1 10009 2.1.0.9beta7-10 | 5663 | 1.0.9beta7-10 1 10009 2.1.0.9beta7-10 |
5664 | 1.0.9rc2 1 10009 2.1.0.9rc2 | 5664 | 1.0.9rc2 1 10009 2.1.0.9rc2 |
5665 | 1.0.9 1 10009 2.1.0.9 | 5665 | 1.0.9 1 10009 2.1.0.9 |
5666 | 1.0.10beta1 1 10010 2.1.0.10beta1 | 5666 | 1.0.10beta1 1 10010 2.1.0.10beta1 |
5667 | 1.0.10rc1 1 10010 2.1.0.10rc1 | 5667 | 1.0.10rc1 1 10010 2.1.0.10rc1 |
5668 | 1.0.10 1 10010 2.1.0.10 | 5668 | 1.0.10 1 10010 2.1.0.10 |
5669 | 1.0.11beta1-3 1 10011 2.1.0.11beta1-3 | 5669 | 1.0.11beta1-3 1 10011 2.1.0.11beta1-3 |
5670 | 1.0.11rc1 1 10011 2.1.0.11rc1 | 5670 | 1.0.11rc1 1 10011 2.1.0.11rc1 |
5671 | 1.0.11 1 10011 2.1.0.11 | 5671 | 1.0.11 1 10011 2.1.0.11 |
5672 | 1.0.12beta1-2 2 10012 2.1.0.12beta1-2 | 5672 | 1.0.12beta1-2 2 10012 2.1.0.12beta1-2 |
5673 | 1.0.12rc1 2 10012 2.1.0.12rc1 | 5673 | 1.0.12rc1 2 10012 2.1.0.12rc1 |
5674 | 1.0.12 2 10012 2.1.0.12 | 5674 | 1.0.12 2 10012 2.1.0.12 |
5675 | 1.1.0a-f - 10100 2.1.1.0a-f abandoned | 5675 | 1.1.0a-f - 10100 2.1.1.0a-f abandoned |
5676 | 1.2.0beta1-2 2 10200 2.1.2.0beta1-2 | 5676 | 1.2.0beta1-2 2 10200 2.1.2.0beta1-2 |
5677 | 1.2.0beta3-5 3 10200 3.1.2.0beta3-5 | 5677 | 1.2.0beta3-5 3 10200 3.1.2.0beta3-5 |
5678 | 1.2.0rc1 3 10200 3.1.2.0rc1 | 5678 | 1.2.0rc1 3 10200 3.1.2.0rc1 |
5679 | 1.2.0 3 10200 3.1.2.0 | 5679 | 1.2.0 3 10200 3.1.2.0 |
5680 | 1.2.1beta-4 3 10201 3.1.2.1beta1-4 | 5680 | 1.2.1beta-4 3 10201 3.1.2.1beta1-4 |
5681 | 1.2.1rc1-2 3 10201 3.1.2.1rc1-2 | 5681 | 1.2.1rc1-2 3 10201 3.1.2.1rc1-2 |
5682 | 1.2.1 3 10201 3.1.2.1 | 5682 | 1.2.1 3 10201 3.1.2.1 |
5683 | 1.2.2beta1-6 12 10202 12.so.0.1.2.2beta1-6 | 5683 | 1.2.2beta1-6 12 10202 12.so.0.1.2.2beta1-6 |
5684 | 1.0.13beta1 10 10013 10.so.0.1.0.13beta1 | 5684 | 1.0.13beta1 10 10013 10.so.0.1.0.13beta1 |
5685 | 1.0.13rc1 10 10013 10.so.0.1.0.13rc1 | 5685 | 1.0.13rc1 10 10013 10.so.0.1.0.13rc1 |
5686 | 1.2.2rc1 12 10202 12.so.0.1.2.2rc1 | 5686 | 1.2.2rc1 12 10202 12.so.0.1.2.2rc1 |
5687 | 1.0.13 10 10013 10.so.0.1.0.13 | 5687 | 1.0.13 10 10013 10.so.0.1.0.13 |
5688 | 1.2.2 12 10202 12.so.0.1.2.2 | 5688 | 1.2.2 12 10202 12.so.0.1.2.2 |
5689 | 1.2.3rc1-6 12 10203 12.so.0.1.2.3rc1-6 | 5689 | 1.2.3rc1-6 12 10203 12.so.0.1.2.3rc1-6 |
5690 | 1.2.3 12 10203 12.so.0.1.2.3 | 5690 | 1.2.3 12 10203 12.so.0.1.2.3 |
5691 | 1.2.4beta1-3 13 10204 12.so.0.1.2.4beta1-3 | 5691 | 1.2.4beta1-3 13 10204 12.so.0.1.2.4beta1-3 |
5692 | 1.2.4rc1 13 10204 12.so.0.1.2.4rc1 | 5692 | 1.2.4rc1 13 10204 12.so.0.1.2.4rc1 |
5693 | 1.0.14 10 10014 10.so.0.1.0.14 | 5693 | 1.0.14 10 10014 10.so.0.1.0.14 |
5694 | 1.2.4 13 10204 12.so.0.1.2.4 | 5694 | 1.2.4 13 10204 12.so.0.1.2.4 |
5695 | 1.2.5beta1-2 13 10205 12.so.0.1.2.5beta1-2 | 5695 | 1.2.5beta1-2 13 10205 12.so.0.1.2.5beta1-2 |
5696 | 1.0.15rc1 10 10015 10.so.0.1.0.15rc1 | 5696 | 1.0.15rc1 10 10015 10.so.0.1.0.15rc1 |
5697 | 1.0.15 10 10015 10.so.0.1.0.15 | 5697 | 1.0.15 10 10015 10.so.0.1.0.15 |
5698 | 1.2.5 13 10205 12.so.0.1.2.5 | 5698 | 1.2.5 13 10205 12.so.0.1.2.5 |
5699 | 1.2.6beta1-4 13 10206 12.so.0.1.2.6beta1-4 | 5699 | 1.2.6beta1-4 13 10206 12.so.0.1.2.6beta1-4 |
5700 | 1.2.6rc1-5 13 10206 12.so.0.1.2.6rc1-5 | 5700 | 1.2.6rc1-5 13 10206 12.so.0.1.2.6rc1-5 |
5701 | 1.0.16 10 10016 10.so.0.1.0.16 | 5701 | 1.0.16 10 10016 10.so.0.1.0.16 |
5702 | 1.2.6 13 10206 12.so.0.1.2.6 | 5702 | 1.2.6 13 10206 12.so.0.1.2.6 |
5703 | 1.2.7beta1-2 13 10207 12.so.0.1.2.7beta1-2 | 5703 | 1.2.7beta1-2 13 10207 12.so.0.1.2.7beta1-2 |
5704 | 1.0.17rc1 10 10017 12.so.0.1.0.17rc1 | 5704 | 1.0.17rc1 10 10017 12.so.0.1.0.17rc1 |
5705 | 1.2.7rc1 13 10207 12.so.0.1.2.7rc1 | 5705 | 1.2.7rc1 13 10207 12.so.0.1.2.7rc1 |
5706 | 1.0.17 10 10017 12.so.0.1.0.17 | 5706 | 1.0.17 10 10017 12.so.0.1.0.17 |
5707 | 1.2.7 13 10207 12.so.0.1.2.7 | 5707 | 1.2.7 13 10207 12.so.0.1.2.7 |
5708 | 1.2.8beta1-5 13 10208 12.so.0.1.2.8beta1-5 | 5708 | 1.2.8beta1-5 13 10208 12.so.0.1.2.8beta1-5 |
5709 | 1.0.18rc1-5 10 10018 12.so.0.1.0.18rc1-5 | 5709 | 1.0.18rc1-5 10 10018 12.so.0.1.0.18rc1-5 |
5710 | 1.2.8rc1-5 13 10208 12.so.0.1.2.8rc1-5 | 5710 | 1.2.8rc1-5 13 10208 12.so.0.1.2.8rc1-5 |
5711 | 1.0.18 10 10018 12.so.0.1.0.18 | 5711 | 1.0.18 10 10018 12.so.0.1.0.18 |
5712 | 1.2.8 13 10208 12.so.0.1.2.8 | 5712 | 1.2.8 13 10208 12.so.0.1.2.8 |
5713 | 1.2.9beta1-3 13 10209 12.so.0.1.2.9beta1-3 | 5713 | 1.2.9beta1-3 13 10209 12.so.0.1.2.9beta1-3 |
5714 | 1.2.9beta4-11 13 10209 12.so.0.9[.0] | 5714 | 1.2.9beta4-11 13 10209 12.so.0.9[.0] |
5715 | 1.2.9rc1 13 10209 12.so.0.9[.0] | 5715 | 1.2.9rc1 13 10209 12.so.0.9[.0] |
5716 | 1.2.9 13 10209 12.so.0.9[.0] | 5716 | 1.2.9 13 10209 12.so.0.9[.0] |
5717 | 1.2.10beta1-7 13 10210 12.so.0.10[.0] | 5717 | 1.2.10beta1-7 13 10210 12.so.0.10[.0] |
5718 | 1.2.10rc1-2 13 10210 12.so.0.10[.0] | 5718 | 1.2.10rc1-2 13 10210 12.so.0.10[.0] |
5719 | 1.2.10 13 10210 12.so.0.10[.0] | 5719 | 1.2.10 13 10210 12.so.0.10[.0] |
5720 | 1.4.0beta1-6 14 10400 14.so.0.0[.0] | 5720 | 1.4.0beta1-6 14 10400 14.so.0.0[.0] |
5721 | 1.2.11beta1-4 13 10210 12.so.0.11[.0] | 5721 | 1.2.11beta1-4 13 10210 12.so.0.11[.0] |
5722 | 1.4.0beta7-8 14 10400 14.so.0.0[.0] | 5722 | 1.4.0beta7-8 14 10400 14.so.0.0[.0] |
5723 | 1.2.11 13 10211 12.so.0.11[.0] | 5723 | 1.2.11 13 10211 12.so.0.11[.0] |
5724 | 1.2.12 13 10212 12.so.0.12[.0] | 5724 | 1.2.12 13 10212 12.so.0.12[.0] |
5725 | 1.4.0beta9-14 14 10400 14.so.0.0[.0] | 5725 | 1.4.0beta9-14 14 10400 14.so.0.0[.0] |
5726 | 1.2.13 13 10213 12.so.0.13[.0] | 5726 | 1.2.13 13 10213 12.so.0.13[.0] |
5727 | 1.4.0beta15-36 14 10400 14.so.0.0[.0] | 5727 | 1.4.0beta15-36 14 10400 14.so.0.0[.0] |
5728 | 1.4.0beta37-87 14 10400 14.so.14.0[.0] | 5728 | 1.4.0beta37-87 14 10400 14.so.14.0[.0] |
5729 | 1.4.0rc01 14 10400 14.so.14.0[.0] | 5729 | 1.4.0rc01 14 10400 14.so.14.0[.0] |
5730 | 1.4.0beta88-109 14 10400 14.so.14.0[.0] | 5730 | 1.4.0beta88-109 14 10400 14.so.14.0[.0] |
5731 | 1.4.0rc02-08 14 10400 14.so.14.0[.0] | 5731 | 1.4.0rc02-08 14 10400 14.so.14.0[.0] |
5732 | 1.4.0 14 10400 14.so.14.0[.0] | 5732 | 1.4.0 14 10400 14.so.14.0[.0] |
5733 | 1.4.1beta01-03 14 10401 14.so.14.1[.0] | 5733 | 1.4.1beta01-03 14 10401 14.so.14.1[.0] |
5734 | 1.4.1rc01 14 10401 14.so.14.1[.0] | 5734 | 1.4.1rc01 14 10401 14.so.14.1[.0] |
5735 | 1.4.1beta04-12 14 10401 14.so.14.1[.0] | 5735 | 1.4.1beta04-12 14 10401 14.so.14.1[.0] |
5736 | 1.4.1 14 10401 14.so.14.1[.0] | 5736 | 1.4.1 14 10401 14.so.14.1[.0] |
5737 | 1.4.2 14 10402 14.so.14.2[.0] | 5737 | 1.4.2 14 10402 14.so.14.2[.0] |
5738 | 1.4.3 14 10403 14.so.14.3[.0] | 5738 | 1.4.3 14 10403 14.so.14.3[.0] |
5739 | 1.4.4 14 10404 14.so.14.4[.0] | 5739 | 1.4.4 14 10404 14.so.14.4[.0] |
5740 | 1.5.0beta01-58 15 10500 15.so.15.0[.0] | 5740 | 1.5.0beta01-58 15 10500 15.so.15.0[.0] |
5741 | 1.5.0rc01-07 15 10500 15.so.15.0[.0] | 5741 | 1.5.0rc01-07 15 10500 15.so.15.0[.0] |
5742 | 1.5.0 15 10500 15.so.15.0[.0] | 5742 | 1.5.0 15 10500 15.so.15.0[.0] |
5743 | 1.5.1beta01-11 15 10501 15.so.15.1[.0] | 5743 | 1.5.1beta01-11 15 10501 15.so.15.1[.0] |
5744 | 1.5.1rc01-02 15 10501 15.so.15.1[.0] | 5744 | 1.5.1rc01-02 15 10501 15.so.15.1[.0] |
5745 | 1.5.1 15 10501 15.so.15.1[.0] | 5745 | 1.5.1 15 10501 15.so.15.1[.0] |
5746 | 1.5.2beta01-03 15 10502 15.so.15.2[.0] | 5746 | 1.5.2beta01-03 15 10502 15.so.15.2[.0] |
5747 | 1.5.2rc01-03 15 10502 15.so.15.2[.0] | 5747 | 1.5.2rc01-03 15 10502 15.so.15.2[.0] |
5748 | 1.5.2 15 10502 15.so.15.2[.0] | 5748 | 1.5.2 15 10502 15.so.15.2[.0] |
5749 | 1.5.3beta01-10 15 10503 15.so.15.3[.0] | 5749 | 1.5.3beta01-10 15 10503 15.so.15.3[.0] |
5750 | 1.5.3rc01-02 15 10503 15.so.15.3[.0] | 5750 | 1.5.3rc01-02 15 10503 15.so.15.3[.0] |
5751 | 1.5.3beta11 15 10503 15.so.15.3[.0] | 5751 | 1.5.3beta11 15 10503 15.so.15.3[.0] |
5752 | 1.5.3 [omitted] | 5752 | 1.5.3 [omitted] |
5753 | 1.5.4beta01-08 15 10504 15.so.15.4[.0] | 5753 | 1.5.4beta01-08 15 10504 15.so.15.4[.0] |
5754 | 1.5.4rc01 15 10504 15.so.15.4[.0] | 5754 | 1.5.4rc01 15 10504 15.so.15.4[.0] |
5755 | 1.5.4 15 10504 15.so.15.4[.0] | 5755 | 1.5.4 15 10504 15.so.15.4[.0] |
5756 | 1.5.5beta01-08 15 10505 15.so.15.5[.0] | 5756 | 1.5.5beta01-08 15 10505 15.so.15.5[.0] |
5757 | 1.5.5rc01 15 10505 15.so.15.5[.0] | 5757 | 1.5.5rc01 15 10505 15.so.15.5[.0] |
5758 | 1.5.5 15 10505 15.so.15.5[.0] | 5758 | 1.5.5 15 10505 15.so.15.5[.0] |
5759 | 1.5.6beta01-07 15 10506 15.so.15.6[.0] | 5759 | 1.5.6beta01-07 15 10506 15.so.15.6[.0] |
5760 | 1.5.6rc01-03 15 10506 15.so.15.6[.0] | 5760 | 1.5.6rc01-03 15 10506 15.so.15.6[.0] |
5761 | 1.5.6 15 10506 15.so.15.6[.0] | 5761 | 1.5.6 15 10506 15.so.15.6[.0] |
5762 | 1.5.7beta01-05 15 10507 15.so.15.7[.0] | 5762 | 1.5.7beta01-05 15 10507 15.so.15.7[.0] |
5763 | 1.5.7rc01-03 15 10507 15.so.15.7[.0] | 5763 | 1.5.7rc01-03 15 10507 15.so.15.7[.0] |
5764 | 1.5.7 15 10507 15.so.15.7[.0] | 5764 | 1.5.7 15 10507 15.so.15.7[.0] |
5765 | 1.5.8beta01 15 10508 15.so.15.8[.0] | 5765 | 1.5.8beta01 15 10508 15.so.15.8[.0] |
5766 | 1.5.8rc01 15 10508 15.so.15.8[.0] | 5766 | 1.5.8rc01 15 10508 15.so.15.8[.0] |
5767 | 1.5.8 15 10508 15.so.15.8[.0] | 5767 | 1.5.8 15 10508 15.so.15.8[.0] |
5768 | 1.5.9beta01-02 15 10509 15.so.15.9[.0] | 5768 | 1.5.9beta01-02 15 10509 15.so.15.9[.0] |
5769 | 1.5.9rc01 15 10509 15.so.15.9[.0] | 5769 | 1.5.9rc01 15 10509 15.so.15.9[.0] |
5770 | 1.5.9 15 10509 15.so.15.9[.0] | 5770 | 1.5.9 15 10509 15.so.15.9[.0] |
5771 | 5771 | ||
5772 | Henceforth the source version will match the shared-library minor | 5772 | Henceforth the source version will match the shared-library minor |
5773 | and patch numbers; the shared-library major version number will be | 5773 | and patch numbers; the shared-library major version number will be |
5774 | used for changes in backward compatibility, as it is intended. The | 5774 | used for changes in backward compatibility, as it is intended. The |
5775 | PNG_PNGLIB_VER macro, which is not used within libpng but is available | 5775 | PNG_PNGLIB_VER macro, which is not used within libpng but is available |
5776 | for applications, is an unsigned integer of the form xyyzz corresponding | 5776 | for applications, is an unsigned integer of the form xyyzz corresponding |
5777 | to the source version x.y.z (leading zeros in y and z). Beta versions | 5777 | to the source version x.y.z (leading zeros in y and z). Beta versions |
5778 | were given the previous public release number plus a letter, until | 5778 | were given the previous public release number plus a letter, until |
5779 | version 1.0.6j; from then on they were given the upcoming public | 5779 | version 1.0.6j; from then on they were given the upcoming public |
5780 | release number plus "betaNN" or "rcN". | 5780 | release number plus "betaNN" or "rcN". |
5781 | 5781 | ||
5782 | .SH "SEE ALSO" | 5782 | .SH "SEE ALSO" |
5783 | .BR "png"(5), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5) | 5783 | .BR "png"(5), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5) |
5784 | 5784 | ||
5785 | .LP | 5785 | .LP |
5786 | .IR libpng : | 5786 | .IR libpng : |
5787 | .IP | 5787 | .IP |
5788 | http://libpng.sourceforge.net (follow the [DOWNLOAD] link) | 5788 | http://libpng.sourceforge.net (follow the [DOWNLOAD] link) |
5789 | http://www.libpng.org/pub/png | 5789 | http://www.libpng.org/pub/png |
5790 | 5790 | ||
5791 | .LP | 5791 | .LP |
5792 | .IR zlib : | 5792 | .IR zlib : |
5793 | .IP | 5793 | .IP |
5794 | (generally) at the same location as | 5794 | (generally) at the same location as |
5795 | .I libpng | 5795 | .I libpng |
5796 | or at | 5796 | or at |
5797 | .br | 5797 | .br |
5798 | ftp://ftp.info-zip.org/pub/infozip/zlib | 5798 | ftp://ftp.info-zip.org/pub/infozip/zlib |
5799 | 5799 | ||
5800 | .LP | 5800 | .LP |
5801 | .IR PNG specification: RFC 2083 | 5801 | .IR PNG specification: RFC 2083 |
5802 | .IP | 5802 | .IP |
5803 | (generally) at the same location as | 5803 | (generally) at the same location as |
5804 | .I libpng | 5804 | .I libpng |
5805 | or at | 5805 | or at |
5806 | .br | 5806 | .br |
5807 | ftp://ds.internic.net/rfc/rfc2083.txt | 5807 | ftp://ds.internic.net/rfc/rfc2083.txt |
5808 | .br | 5808 | .br |
5809 | or (as a W3C Recommendation) at | 5809 | or (as a W3C Recommendation) at |
5810 | .br | 5810 | .br |
5811 | http://www.w3.org/TR/REC-png.html | 5811 | http://www.w3.org/TR/REC-png.html |
5812 | 5812 | ||
5813 | .LP | 5813 | .LP |
5814 | In the case of any inconsistency between the PNG specification | 5814 | In the case of any inconsistency between the PNG specification |
5815 | and this library, the specification takes precedence. | 5815 | and this library, the specification takes precedence. |
5816 | 5816 | ||
5817 | .SH AUTHORS | 5817 | .SH AUTHORS |
5818 | This man page: Glenn Randers-Pehrson | 5818 | This man page: Glenn Randers-Pehrson |
5819 | <glennrp at users.sourceforge.net> | 5819 | <glennrp at users.sourceforge.net> |
5820 | 5820 | ||
5821 | The contributing authors would like to thank all those who helped | 5821 | The contributing authors would like to thank all those who helped |
5822 | with testing, bug fixes, and patience. This wouldn't have been | 5822 | with testing, bug fixes, and patience. This wouldn't have been |
5823 | possible without all of you. | 5823 | possible without all of you. |
5824 | 5824 | ||
5825 | Thanks to Frank J. T. Wojcik for helping with the documentation. | 5825 | Thanks to Frank J. T. Wojcik for helping with the documentation. |
5826 | 5826 | ||
5827 | Libpng version 1.5.9 - February 18, 2012: | 5827 | Libpng version 1.5.9 - February 18, 2012: |
5828 | Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc. | 5828 | Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc. |
5829 | Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net). | 5829 | Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net). |
5830 | 5830 | ||
5831 | Supported by the PNG development group | 5831 | Supported by the PNG development group |
5832 | .br | 5832 | .br |
5833 | png-mng-implement at lists.sf.net | 5833 | png-mng-implement at lists.sf.net |
5834 | (subscription required; visit | 5834 | (subscription required; visit |
5835 | png-mng-implement at lists.sourceforge.net (subscription required; visit | 5835 | png-mng-implement at lists.sourceforge.net (subscription required; visit |
5836 | https://lists.sourceforge.net/lists/listinfo/png-mng-implement | 5836 | https://lists.sourceforge.net/lists/listinfo/png-mng-implement |
5837 | to subscribe). | 5837 | to subscribe). |
5838 | 5838 | ||
5839 | .SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE: | 5839 | .SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE: |
5840 | 5840 | ||
5841 | (This copy of the libpng notices is provided for your convenience. In case of | 5841 | (This copy of the libpng notices is provided for your convenience. In case of |
5842 | any discrepancy between this copy and the notices in the file png.h that is | 5842 | any discrepancy between this copy and the notices in the file png.h that is |
5843 | included in the libpng distribution, the latter shall prevail.) | 5843 | included in the libpng distribution, the latter shall prevail.) |
5844 | 5844 | ||
5845 | If you modify libpng you may insert additional notices immediately following | 5845 | If you modify libpng you may insert additional notices immediately following |
5846 | this sentence. | 5846 | this sentence. |
5847 | 5847 | ||
5848 | This code is released under the libpng license. | 5848 | This code is released under the libpng license. |
5849 | 5849 | ||
5850 | libpng versions 1.2.6, August 15, 2004, through 1.5.9, February 18, 2012, are | 5850 | libpng versions 1.2.6, August 15, 2004, through 1.5.9, February 18, 2012, are |
5851 | Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are | 5851 | Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are |
5852 | distributed according to the same disclaimer and license as libpng-1.2.5 | 5852 | distributed according to the same disclaimer and license as libpng-1.2.5 |
5853 | with the following individual added to the list of Contributing Authors | 5853 | with the following individual added to the list of Contributing Authors |
5854 | 5854 | ||
5855 | Cosmin Truta | 5855 | Cosmin Truta |
5856 | 5856 | ||
5857 | libpng versions 1.0.7, July 1, 2000, through 1.2.5 - October 3, 2002, are | 5857 | libpng versions 1.0.7, July 1, 2000, through 1.2.5 - October 3, 2002, are |
5858 | Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are | 5858 | Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are |
5859 | distributed according to the same disclaimer and license as libpng-1.0.6 | 5859 | distributed according to the same disclaimer and license as libpng-1.0.6 |
5860 | with the following individuals added to the list of Contributing Authors | 5860 | with the following individuals added to the list of Contributing Authors |
5861 | 5861 | ||
5862 | Simon-Pierre Cadieux | 5862 | Simon-Pierre Cadieux |
5863 | Eric S. Raymond | 5863 | Eric S. Raymond |
5864 | Gilles Vollant | 5864 | Gilles Vollant |
5865 | 5865 | ||
5866 | and with the following additions to the disclaimer: | 5866 | and with the following additions to the disclaimer: |
5867 | 5867 | ||
5868 | There is no warranty against interference with your | 5868 | There is no warranty against interference with your |
5869 | enjoyment of the library or against infringement. | 5869 | enjoyment of the library or against infringement. |
5870 | There is no warranty that our efforts or the library | 5870 | There is no warranty that our efforts or the library |
5871 | will fulfill any of your particular purposes or needs. | 5871 | will fulfill any of your particular purposes or needs. |
5872 | This library is provided with all faults, and the entire | 5872 | This library is provided with all faults, and the entire |
5873 | risk of satisfactory quality, performance, accuracy, and | 5873 | risk of satisfactory quality, performance, accuracy, and |
5874 | effort is with the user. | 5874 | effort is with the user. |
5875 | 5875 | ||
5876 | libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are | 5876 | libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are |
5877 | Copyright (c) 1998, 1999 Glenn Randers-Pehrson | 5877 | Copyright (c) 1998, 1999 Glenn Randers-Pehrson |
5878 | Distributed according to the same disclaimer and license as libpng-0.96, | 5878 | Distributed according to the same disclaimer and license as libpng-0.96, |
5879 | with the following individuals added to the list of Contributing Authors: | 5879 | with the following individuals added to the list of Contributing Authors: |
5880 | 5880 | ||
5881 | Tom Lane | 5881 | Tom Lane |
5882 | Glenn Randers-Pehrson | 5882 | Glenn Randers-Pehrson |
5883 | Willem van Schaik | 5883 | Willem van Schaik |
5884 | 5884 | ||
5885 | libpng versions 0.89, June 1996, through 0.96, May 1997, are | 5885 | libpng versions 0.89, June 1996, through 0.96, May 1997, are |
5886 | Copyright (c) 1996, 1997 Andreas Dilger | 5886 | Copyright (c) 1996, 1997 Andreas Dilger |
5887 | Distributed according to the same disclaimer and license as libpng-0.88, | 5887 | Distributed according to the same disclaimer and license as libpng-0.88, |
5888 | with the following individuals added to the list of Contributing Authors: | 5888 | with the following individuals added to the list of Contributing Authors: |
5889 | 5889 | ||
5890 | John Bowler | 5890 | John Bowler |
5891 | Kevin Bracey | 5891 | Kevin Bracey |
5892 | Sam Bushell | 5892 | Sam Bushell |
5893 | Magnus Holmgren | 5893 | Magnus Holmgren |
5894 | Greg Roelofs | 5894 | Greg Roelofs |
5895 | Tom Tanner | 5895 | Tom Tanner |
5896 | 5896 | ||
5897 | libpng versions 0.5, May 1995, through 0.88, January 1996, are | 5897 | libpng versions 0.5, May 1995, through 0.88, January 1996, are |
5898 | Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. | 5898 | Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. |
5899 | 5899 | ||
5900 | For the purposes of this copyright and license, "Contributing Authors" | 5900 | For the purposes of this copyright and license, "Contributing Authors" |
5901 | is defined as the following set of individuals: | 5901 | is defined as the following set of individuals: |
5902 | 5902 | ||
5903 | Andreas Dilger | 5903 | Andreas Dilger |
5904 | Dave Martindale | 5904 | Dave Martindale |
5905 | Guy Eric Schalnat | 5905 | Guy Eric Schalnat |
5906 | Paul Schmidt | 5906 | Paul Schmidt |
5907 | Tim Wegner | 5907 | Tim Wegner |
5908 | 5908 | ||
5909 | The PNG Reference Library is supplied "AS IS". The Contributing Authors | 5909 | The PNG Reference Library is supplied "AS IS". The Contributing Authors |
5910 | and Group 42, Inc. disclaim all warranties, expressed or implied, | 5910 | and Group 42, Inc. disclaim all warranties, expressed or implied, |
5911 | including, without limitation, the warranties of merchantability and of | 5911 | including, without limitation, the warranties of merchantability and of |
5912 | fitness for any purpose. The Contributing Authors and Group 42, Inc. | 5912 | fitness for any purpose. The Contributing Authors and Group 42, Inc. |
5913 | assume no liability for direct, indirect, incidental, special, exemplary, | 5913 | assume no liability for direct, indirect, incidental, special, exemplary, |
5914 | or consequential damages, which may result from the use of the PNG | 5914 | or consequential damages, which may result from the use of the PNG |
5915 | Reference Library, even if advised of the possibility of such damage. | 5915 | Reference Library, even if advised of the possibility of such damage. |
5916 | 5916 | ||
5917 | Permission is hereby granted to use, copy, modify, and distribute this | 5917 | Permission is hereby granted to use, copy, modify, and distribute this |
5918 | source code, or portions hereof, for any purpose, without fee, subject | 5918 | source code, or portions hereof, for any purpose, without fee, subject |
5919 | to the following restrictions: | 5919 | to the following restrictions: |
5920 | 5920 | ||
5921 | 1. The origin of this source code must not be misrepresented. | 5921 | 1. The origin of this source code must not be misrepresented. |
5922 | 5922 | ||
5923 | 2. Altered versions must be plainly marked as such and | 5923 | 2. Altered versions must be plainly marked as such and |
5924 | must not be misrepresented as being the original source. | 5924 | must not be misrepresented as being the original source. |
5925 | 5925 | ||
5926 | 3. This Copyright notice may not be removed or altered from | 5926 | 3. This Copyright notice may not be removed or altered from |
5927 | any source or altered source distribution. | 5927 | any source or altered source distribution. |
5928 | 5928 | ||
5929 | The Contributing Authors and Group 42, Inc. specifically permit, without | 5929 | The Contributing Authors and Group 42, Inc. specifically permit, without |
5930 | fee, and encourage the use of this source code as a component to | 5930 | fee, and encourage the use of this source code as a component to |
5931 | supporting the PNG file format in commercial products. If you use this | 5931 | supporting the PNG file format in commercial products. If you use this |
5932 | source code in a product, acknowledgment is not required but would be | 5932 | source code in a product, acknowledgment is not required but would be |
5933 | appreciated. | 5933 | appreciated. |
5934 | 5934 | ||
5935 | 5935 | ||
5936 | A "png_get_copyright" function is available, for convenient use in "about" | 5936 | A "png_get_copyright" function is available, for convenient use in "about" |
5937 | boxes and the like: | 5937 | boxes and the like: |
5938 | 5938 | ||
5939 | printf("%s",png_get_copyright(NULL)); | 5939 | printf("%s",png_get_copyright(NULL)); |
5940 | 5940 | ||
5941 | Also, the PNG logo (in PNG format, of course) is supplied in the | 5941 | Also, the PNG logo (in PNG format, of course) is supplied in the |
5942 | files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31). | 5942 | files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31). |
5943 | 5943 | ||
5944 | Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a | 5944 | Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a |
5945 | certification mark of the Open Source Initiative. | 5945 | certification mark of the Open Source Initiative. |
5946 | 5946 | ||
5947 | Glenn Randers-Pehrson | 5947 | Glenn Randers-Pehrson |
5948 | glennrp at users.sourceforge.net | 5948 | glennrp at users.sourceforge.net |
5949 | February 18, 2012 | 5949 | February 18, 2012 |
5950 | 5950 | ||
5951 | .\" end of man page | 5951 | .\" end of man page |
5952 | 5952 | ||