aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/wrgif.c
blob: 13f953b56765fce9efae155ab34454be52a862a2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
/*
 * wrgif.c
 *
 * Copyright (C) 1991-1997, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains routines to write output images in GIF format.
 *
 **************************************************************************
 * NOTE: to avoid entanglements with Unisys' patent on LZW compression,   *
 * this code has been modified to output "uncompressed GIF" files.        *
 * There is no trace of the LZW algorithm in this file.                   *
 **************************************************************************
 *
 * These routines may need modification for non-Unix environments or
 * specialized applications.  As they stand, they assume output to
 * an ordinary stdio stream.
 */

/*
 * This code is loosely based on ppmtogif from the PBMPLUS distribution
 * of Feb. 1991.  That file contains the following copyright notice:
 *    Based on GIFENCODE by David Rowley <mgardi@watdscu.waterloo.edu>.
 *    Lempel-Ziv compression based on "compress" by Spencer W. Thomas et al.
 *    Copyright (C) 1989 by Jef Poskanzer.
 *    Permission to use, copy, modify, and distribute this software and its
 *    documentation for any purpose and without fee is hereby granted, provided
 *    that the above copyright notice appear in all copies and that both that
 *    copyright notice and this permission notice appear in supporting
 *    documentation.  This software is provided "as is" without express or
 *    implied warranty.
 *
 * We are also required to state that
 *    "The Graphics Interchange Format(c) is the Copyright property of
 *    CompuServe Incorporated. GIF(sm) is a Service Mark property of
 *    CompuServe Incorporated."
 */

#include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */

#ifdef GIF_SUPPORTED


/* Private version of data destination object */

typedef struct {
  struct djpeg_dest_struct pub;	/* public fields */

  j_decompress_ptr cinfo;	/* back link saves passing separate parm */

  /* State for packing variable-width codes into a bitstream */
  int n_bits;			/* current number of bits/code */
  int maxcode;			/* maximum code, given n_bits */
  INT32 cur_accum;		/* holds bits not yet output */
  int cur_bits;			/* # of bits in cur_accum */

  /* State for GIF code assignment */
  int ClearCode;		/* clear code (doesn't change) */
  int EOFCode;			/* EOF code (ditto) */
  int code_counter;		/* counts output symbols */

  /* GIF data packet construction buffer */
  int bytesinpkt;		/* # of bytes in current packet */
  char packetbuf[256];		/* workspace for accumulating packet */

} gif_dest_struct;

typedef gif_dest_struct * gif_dest_ptr;

/* Largest value that will fit in N bits */
#define MAXCODE(n_bits)	((1 << (n_bits)) - 1)


/*
 * Routines to package finished data bytes into GIF data blocks.
 * A data block consists of a count byte (1..255) and that many data bytes.
 */

LOCAL(void)
flush_packet (gif_dest_ptr dinfo)
/* flush any accumulated data */
{
  if (dinfo->bytesinpkt > 0) {	/* never write zero-length packet */
    dinfo->packetbuf[0] = (char) dinfo->bytesinpkt++;
    if (JFWRITE(dinfo->pub.output_file, dinfo->packetbuf, dinfo->bytesinpkt)
	!= (size_t) dinfo->bytesinpkt)
      ERREXIT(dinfo->cinfo, JERR_FILE_WRITE);
    dinfo->bytesinpkt = 0;
  }
}


/* Add a character to current packet; flush to disk if necessary */
#define CHAR_OUT(dinfo,c)  \
	{ (dinfo)->packetbuf[++(dinfo)->bytesinpkt] = (char) (c);  \
	    if ((dinfo)->bytesinpkt >= 255)  \
	      flush_packet(dinfo);  \
	}


/* Routine to convert variable-width codes into a byte stream */

LOCAL(void)
output (gif_dest_ptr dinfo, int code)
/* Emit a code of n_bits bits */
/* Uses cur_accum and cur_bits to reblock into 8-bit bytes */
{
  dinfo->cur_accum |= ((INT32) code) << dinfo->cur_bits;
  dinfo->cur_bits += dinfo->n_bits;

  while (dinfo->cur_bits >= 8) {
    CHAR_OUT(dinfo, dinfo->cur_accum & 0xFF);
    dinfo->cur_accum >>= 8;
    dinfo->cur_bits -= 8;
  }
}


/* The pseudo-compression algorithm.
 *
 * In this module we simply output each pixel value as a separate symbol;
 * thus, no compression occurs.  In fact, there is expansion of one bit per
 * pixel, because we use a symbol width one bit wider than the pixel width.
 *
 * GIF ordinarily uses variable-width symbols, and the decoder will expect
 * to ratchet up the symbol width after a fixed number of symbols.
 * To simplify the logic and keep the expansion penalty down, we emit a
 * GIF Clear code to reset the decoder just before the width would ratchet up.
 * Thus, all the symbols in the output file will have the same bit width.
 * Note that emitting the Clear codes at the right times is a mere matter of
 * counting output symbols and is in no way dependent on the LZW patent.
 *
 * With a small basic pixel width (low color count), Clear codes will be
 * needed very frequently, causing the file to expand even more.  So this
 * simplistic approach wouldn't work too well on bilevel images, for example.
 * But for output of JPEG conversions the pixel width will usually be 8 bits
 * (129 to 256 colors), so the overhead added by Clear symbols is only about
 * one symbol in every 256.
 */

LOCAL(void)
compress_init (gif_dest_ptr dinfo, int i_bits)
/* Initialize pseudo-compressor */
{
  /* init all the state variables */
  dinfo->n_bits = i_bits;
  dinfo->maxcode = MAXCODE(dinfo->n_bits);
  dinfo->ClearCode = (1 << (i_bits - 1));
  dinfo->EOFCode = dinfo->ClearCode + 1;
  dinfo->code_counter = dinfo->ClearCode + 2;
  /* init output buffering vars */
  dinfo->bytesinpkt = 0;
  dinfo->cur_accum = 0;
  dinfo->cur_bits = 0;
  /* GIF specifies an initial Clear code */
  output(dinfo, dinfo->ClearCode);
}


LOCAL(void)
compress_pixel (gif_dest_ptr dinfo, int c)
/* Accept and "compress" one pixel value.
 * The given value must be less than n_bits wide.
 */
{
  /* Output the given pixel value as a symbol. */
  output(dinfo, c);
  /* Issue Clear codes often enough to keep the reader from ratcheting up
   * its symbol size.
   */
  if (dinfo->code_counter < dinfo->maxcode) {
    dinfo->code_counter++;
  } else {
    output(dinfo, dinfo->ClearCode);
    dinfo->code_counter = dinfo->ClearCode + 2;	/* reset the counter */
  }
}


LOCAL(void)
compress_term (gif_dest_ptr dinfo)
/* Clean up at end */
{
  /* Send an EOF code */
  output(dinfo, dinfo->EOFCode);
  /* Flush the bit-packing buffer */
  if (dinfo->cur_bits > 0) {
    CHAR_OUT(dinfo, dinfo->cur_accum & 0xFF);
  }
  /* Flush the packet buffer */
  flush_packet(dinfo);
}


/* GIF header construction */


LOCAL(void)
put_word (gif_dest_ptr dinfo, unsigned int w)
/* Emit a 16-bit word, LSB first */
{
  putc(w & 0xFF, dinfo->pub.output_file);
  putc((w >> 8) & 0xFF, dinfo->pub.output_file);
}


LOCAL(void)
put_3bytes (gif_dest_ptr dinfo, int val)
/* Emit 3 copies of same byte value --- handy subr for colormap construction */
{
  putc(val, dinfo->pub.output_file);
  putc(val, dinfo->pub.output_file);
  putc(val, dinfo->pub.output_file);
}


LOCAL(void)
emit_header (gif_dest_ptr dinfo, int num_colors, JSAMPARRAY colormap)
/* Output the GIF file header, including color map */
/* If colormap==NULL, synthesize a gray-scale colormap */
{
  int BitsPerPixel, ColorMapSize, InitCodeSize, FlagByte;
  int cshift = dinfo->cinfo->data_precision - 8;
  int i;

  if (num_colors > 256)
    ERREXIT1(dinfo->cinfo, JERR_TOO_MANY_COLORS, num_colors);
  /* Compute bits/pixel and related values */
  BitsPerPixel = 1;
  while (num_colors > (1 << BitsPerPixel))
    BitsPerPixel++;
  ColorMapSize = 1 << BitsPerPixel;
  if (BitsPerPixel <= 1)
    InitCodeSize = 2;
  else
    InitCodeSize = BitsPerPixel;
  /*
   * Write the GIF header.
   * Note that we generate a plain GIF87 header for maximum compatibility.
   */
  putc('G', dinfo->pub.output_file);
  putc('I', dinfo->pub.output_file);
  putc('F', dinfo->pub.output_file);
  putc('8', dinfo->pub.output_file);
  putc('7', dinfo->pub.output_file);
  putc('a', dinfo->pub.output_file);
  /* Write the Logical Screen Descriptor */
  put_word(dinfo, (unsigned int) dinfo->cinfo->output_width);
  put_word(dinfo, (unsigned int) dinfo->cinfo->output_height);
  FlagByte = 0x80;		/* Yes, there is a global color table */
  FlagByte |= (BitsPerPixel-1) << 4; /* color resolution */
  FlagByte |= (BitsPerPixel-1);	/* size of global color table */
  putc(FlagByte, dinfo->pub.output_file);
  putc(0, dinfo->pub.output_file); /* Background color index */
  putc(0, dinfo->pub.output_file); /* Reserved (aspect ratio in GIF89) */
  /* Write the Global Color Map */
  /* If the color map is more than 8 bits precision, */
  /* we reduce it to 8 bits by shifting */
  for (i=0; i < ColorMapSize; i++) {
    if (i < num_colors) {
      if (colormap != NULL) {
	if (dinfo->cinfo->out_color_space == JCS_RGB) {
	  /* Normal case: RGB color map */
	  putc(GETJSAMPLE(colormap[0][i]) >> cshift, dinfo->pub.output_file);
	  putc(GETJSAMPLE(colormap[1][i]) >> cshift, dinfo->pub.output_file);
	  putc(GETJSAMPLE(colormap[2][i]) >> cshift, dinfo->pub.output_file);
	} else {
	  /* Grayscale "color map": possible if quantizing grayscale image */
	  put_3bytes(dinfo, GETJSAMPLE(colormap[0][i]) >> cshift);
	}
      } else {
	/* Create a gray-scale map of num_colors values, range 0..255 */
	put_3bytes(dinfo, (i * 255 + (num_colors-1)/2) / (num_colors-1));
      }
    } else {
      /* fill out the map to a power of 2 */
      put_3bytes(dinfo, 0);
    }
  }
  /* Write image separator and Image Descriptor */
  putc(',', dinfo->pub.output_file); /* separator */
  put_word(dinfo, 0);		/* left/top offset */
  put_word(dinfo, 0);
  put_word(dinfo, (unsigned int) dinfo->cinfo->output_width); /* image size */
  put_word(dinfo, (unsigned int) dinfo->cinfo->output_height);
  /* flag byte: not interlaced, no local color map */
  putc(0x00, dinfo->pub.output_file);
  /* Write Initial Code Size byte */
  putc(InitCodeSize, dinfo->pub.output_file);

  /* Initialize for "compression" of image data */
  compress_init(dinfo, InitCodeSize+1);
}


/*
 * Startup: write the file header.
 */

METHODDEF(void)
start_output_gif (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
{
  gif_dest_ptr dest = (gif_dest_ptr) dinfo;

  if (cinfo->quantize_colors)
    emit_header(dest, cinfo->actual_number_of_colors, cinfo->colormap);
  else
    emit_header(dest, 256, (JSAMPARRAY) NULL);
}


/*
 * Write some pixel data.
 * In this module rows_supplied will always be 1.
 */

METHODDEF(void)
put_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
		JDIMENSION rows_supplied)
{
  gif_dest_ptr dest = (gif_dest_ptr) dinfo;
  register JSAMPROW ptr;
  register JDIMENSION col;

  ptr = dest->pub.buffer[0];
  for (col = cinfo->output_width; col > 0; col--) {
    compress_pixel(dest, GETJSAMPLE(*ptr++));
  }
}


/*
 * Finish up at the end of the file.
 */

METHODDEF(void)
finish_output_gif (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
{
  gif_dest_ptr dest = (gif_dest_ptr) dinfo;

  /* Flush "compression" mechanism */
  compress_term(dest);
  /* Write a zero-length data block to end the series */
  putc(0, dest->pub.output_file);
  /* Write the GIF terminator mark */
  putc(';', dest->pub.output_file);
  /* Make sure we wrote the output file OK */
  fflush(dest->pub.output_file);
  if (ferror(dest->pub.output_file))
    ERREXIT(cinfo, JERR_FILE_WRITE);
}


/*
 * The module selection routine for GIF format output.
 */

GLOBAL(djpeg_dest_ptr)
jinit_write_gif (j_decompress_ptr cinfo)
{
  gif_dest_ptr dest;

  /* Create module interface object, fill in method pointers */
  dest = (gif_dest_ptr)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				  SIZEOF(gif_dest_struct));
  dest->cinfo = cinfo;		/* make back link for subroutines */
  dest->pub.start_output = start_output_gif;
  dest->pub.put_pixel_rows = put_pixel_rows;
  dest->pub.finish_output = finish_output_gif;

  if (cinfo->out_color_space != JCS_GRAYSCALE &&
      cinfo->out_color_space != JCS_RGB)
    ERREXIT(cinfo, JERR_GIF_COLORSPACE);

  /* Force quantization if color or if > 8 bits input */
  if (cinfo->out_color_space != JCS_GRAYSCALE || cinfo->data_precision > 8) {
    /* Force quantization to at most 256 colors */
    cinfo->quantize_colors = TRUE;
    if (cinfo->desired_number_of_colors > 256)
      cinfo->desired_number_of_colors = 256;
  }

  /* Calculate output image dimensions so we can allocate space */
  jpeg_calc_output_dimensions(cinfo);

  if (cinfo->output_components != 1) /* safety check: just one component? */
    ERREXIT(cinfo, JERR_GIF_BUG);

  /* Create decompressor output buffer. */
  dest->pub.buffer = (*cinfo->mem->alloc_sarray)
    ((j_common_ptr) cinfo, JPOOL_IMAGE, cinfo->output_width, (JDIMENSION) 1);
  dest->pub.buffer_height = 1;

  return (djpeg_dest_ptr) dest;
}

#endif /* GIF_SUPPORTED */