Remove damned ancient DOS line endings from Irrlicht. Hopefully I did not go overboard.

1 files changed, 3180 insertions, 3180 deletions

diff --git a/libraries/irrlicht-1.8/source/Irrlicht/libpng/pngwutil.c b/libraries/irrlicht-1.8/source/Irrlicht/libpng/pngwutil.c
index 64888f7..da18e95 100644
--- a/libraries/irrlicht-1.8/source/Irrlicht/libpng/pngwutil.c
+++ b/libraries/irrlicht-1.8/source/Irrlicht/libpng/pngwutil.c
@@ -1,3180 +1,3180 @@
-

-/* pngwutil.c - utilities to write a PNG file

- *

- * Last changed in libpng 1.5.6 [November 3, 2011]

- * Copyright (c) 1998-2011 Glenn Randers-Pehrson

- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

- *

- * This code is released under the libpng license.

- * For conditions of distribution and use, see the disclaimer

- * and license in png.h

- */

-

-#include "pngpriv.h"

-

-#ifdef PNG_WRITE_SUPPORTED

-

-#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED

-/* Place a 32-bit number into a buffer in PNG byte order.  We work

- * with unsigned numbers for convenience, although one supported

- * ancillary chunk uses signed (two's complement) numbers.

- */

-void PNGAPI

-png_save_uint_32(png_bytep buf, png_uint_32 i)

-{

-   buf[0] = (png_byte)((i >> 24) & 0xff);

-   buf[1] = (png_byte)((i >> 16) & 0xff);

-   buf[2] = (png_byte)((i >> 8) & 0xff);

-   buf[3] = (png_byte)(i & 0xff);

-}

-

-#ifdef PNG_SAVE_INT_32_SUPPORTED

-/* The png_save_int_32 function assumes integers are stored in two's

- * complement format.  If this isn't the case, then this routine needs to

- * be modified to write data in two's complement format.  Note that,

- * the following works correctly even if png_int_32 has more than 32 bits

- * (compare the more complex code required on read for sign extention.)

- */

-void PNGAPI

-png_save_int_32(png_bytep buf, png_int_32 i)

-{

-   buf[0] = (png_byte)((i >> 24) & 0xff);

-   buf[1] = (png_byte)((i >> 16) & 0xff);

-   buf[2] = (png_byte)((i >> 8) & 0xff);

-   buf[3] = (png_byte)(i & 0xff);

-}

-#endif

-

-/* Place a 16-bit number into a buffer in PNG byte order.

- * The parameter is declared unsigned int, not png_uint_16,

- * just to avoid potential problems on pre-ANSI C compilers.

- */

-void PNGAPI

-png_save_uint_16(png_bytep buf, unsigned int i)

-{

-   buf[0] = (png_byte)((i >> 8) & 0xff);

-   buf[1] = (png_byte)(i & 0xff);

-}

-#endif

-

-/* Simple function to write the signature.  If we have already written

- * the magic bytes of the signature, or more likely, the PNG stream is

- * being embedded into another stream and doesn't need its own signature,

- * we should call png_set_sig_bytes() to tell libpng how many of the

- * bytes have already been written.

- */

-void PNGAPI

-png_write_sig(png_structp png_ptr)

-{

-   png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};

-

-#ifdef PNG_IO_STATE_SUPPORTED

-   /* Inform the I/O callback that the signature is being written */

-   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;

-#endif

-

-   /* Write the rest of the 8 byte signature */

-   png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],

-      (png_size_t)(8 - png_ptr->sig_bytes));

-

-   if (png_ptr->sig_bytes < 3)

-      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;

-}

-

-/* Write the start of a PNG chunk.  The type is the chunk type.

- * The total_length is the sum of the lengths of all the data you will be

- * passing in png_write_chunk_data().

- */

-static void

-png_write_chunk_header(png_structp png_ptr, png_uint_32 chunk_name,

-    png_uint_32 length)

-{

-   png_byte buf[8];

-

-#if defined(PNG_DEBUG) && (PNG_DEBUG > 0)

-   PNG_CSTRING_FROM_CHUNK(buf, chunk_name);

-   png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);

-#endif

-

-   if (png_ptr == NULL)

-      return;

-

-#ifdef PNG_IO_STATE_SUPPORTED

-   /* Inform the I/O callback that the chunk header is being written.

-    * PNG_IO_CHUNK_HDR requires a single I/O call.

-    */

-   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;

-#endif

-

-   /* Write the length and the chunk name */

-   png_save_uint_32(buf, length);

-   png_save_uint_32(buf + 4, chunk_name);

-   png_write_data(png_ptr, buf, 8);

-

-   /* Put the chunk name into png_ptr->chunk_name */

-   png_ptr->chunk_name = chunk_name;

-

-   /* Reset the crc and run it over the chunk name */

-   png_reset_crc(png_ptr);

-

-   png_calculate_crc(png_ptr, buf + 4, 4);

-

-#ifdef PNG_IO_STATE_SUPPORTED

-   /* Inform the I/O callback that chunk data will (possibly) be written.

-    * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.

-    */

-   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;

-#endif

-}

-

-void PNGAPI

-png_write_chunk_start(png_structp png_ptr, png_const_bytep chunk_string,

-    png_uint_32 length)

-{

-   png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);

-}

-

-/* Write the data of a PNG chunk started with png_write_chunk_header().

- * Note that multiple calls to this function are allowed, and that the

- * sum of the lengths from these calls *must* add up to the total_length

- * given to png_write_chunk_header().

- */

-void PNGAPI

-png_write_chunk_data(png_structp png_ptr, png_const_bytep data,

-    png_size_t length)

-{

-   /* Write the data, and run the CRC over it */

-   if (png_ptr == NULL)

-      return;

-

-   if (data != NULL && length > 0)

-   {

-      png_write_data(png_ptr, data, length);

-

-      /* Update the CRC after writing the data,

-       * in case that the user I/O routine alters it.

-       */

-      png_calculate_crc(png_ptr, data, length);

-   }

-}

-

-/* Finish a chunk started with png_write_chunk_header(). */

-void PNGAPI

-png_write_chunk_end(png_structp png_ptr)

-{

-   png_byte buf[4];

-

-   if (png_ptr == NULL) return;

-

-#ifdef PNG_IO_STATE_SUPPORTED

-   /* Inform the I/O callback that the chunk CRC is being written.

-    * PNG_IO_CHUNK_CRC requires a single I/O function call.

-    */

-   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;

-#endif

-

-   /* Write the crc in a single operation */

-   png_save_uint_32(buf, png_ptr->crc);

-

-   png_write_data(png_ptr, buf, (png_size_t)4);

-}

-

-/* Write a PNG chunk all at once.  The type is an array of ASCII characters

- * representing the chunk name.  The array must be at least 4 bytes in

- * length, and does not need to be null terminated.  To be safe, pass the

- * pre-defined chunk names here, and if you need a new one, define it

- * where the others are defined.  The length is the length of the data.

- * All the data must be present.  If that is not possible, use the

- * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()

- * functions instead.

- */

-static void

-png_write_complete_chunk(png_structp png_ptr, png_uint_32 chunk_name,

-   png_const_bytep data, png_size_t length)

-{

-   if (png_ptr == NULL)

-      return;

-

-   /* On 64 bit architectures 'length' may not fit in a png_uint_32. */

-   if (length > PNG_UINT_32_MAX)

-      png_error(png_ptr, "length exceeds PNG maxima");

-

-   png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);

-   png_write_chunk_data(png_ptr, data, length);

-   png_write_chunk_end(png_ptr);

-}

-

-/* This is the API that calls the internal function above. */

-void PNGAPI

-png_write_chunk(png_structp png_ptr, png_const_bytep chunk_string,

-   png_const_bytep data, png_size_t length)

-{

-   png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,

-      length);

-}

-

-/* Initialize the compressor for the appropriate type of compression. */

-static void

-png_zlib_claim(png_structp png_ptr, png_uint_32 state)

-{

-   if (!(png_ptr->zlib_state & PNG_ZLIB_IN_USE))

-   {

-      /* If already initialized for 'state' do not re-init. */

-      if (png_ptr->zlib_state != state)

-      {

-         int ret = Z_OK;

-         png_const_charp who = "-";

-

-         /* If actually initialized for another state do a deflateEnd. */

-         if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)

-         {

-            ret = deflateEnd(&png_ptr->zstream);

-            who = "end";

-            png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;

-         }

-

-         /* zlib itself detects an incomplete state on deflateEnd */

-         if (ret == Z_OK) switch (state)

-         {

-#           ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED

-               case PNG_ZLIB_FOR_TEXT:

-                  ret = deflateInit2(&png_ptr->zstream,

-                     png_ptr->zlib_text_level, png_ptr->zlib_text_method,

-                     png_ptr->zlib_text_window_bits,

-                     png_ptr->zlib_text_mem_level, png_ptr->zlib_text_strategy);

-                  who = "text";

-                  break;

-#           endif

-

-            case PNG_ZLIB_FOR_IDAT:

-               ret = deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,

-                   png_ptr->zlib_method, png_ptr->zlib_window_bits,

-                   png_ptr->zlib_mem_level, png_ptr->zlib_strategy);

-               who = "IDAT";

-               break;

-

-            default:

-               png_error(png_ptr, "invalid zlib state");

-         }

-

-         if (ret == Z_OK)

-            png_ptr->zlib_state = state;

-

-         else /* an error in deflateEnd or deflateInit2 */

-         {

-            size_t pos = 0;

-            char msg[64];

-

-            pos = png_safecat(msg, sizeof msg, pos,

-               "zlib failed to initialize compressor (");

-            pos = png_safecat(msg, sizeof msg, pos, who);

-

-            switch (ret)

-            {

-               case Z_VERSION_ERROR:

-                  pos = png_safecat(msg, sizeof msg, pos, ") version error");

-                  break;

-

-               case Z_STREAM_ERROR:

-                  pos = png_safecat(msg, sizeof msg, pos, ") stream error");

-                  break;

-

-               case Z_MEM_ERROR:

-                  pos = png_safecat(msg, sizeof msg, pos, ") memory error");

-                  break;

-

-               default:

-                  pos = png_safecat(msg, sizeof msg, pos, ") unknown error");

-                  break;

-            }

-

-            png_error(png_ptr, msg);

-         }

-      }

-

-      /* Here on success, claim the zstream: */

-      png_ptr->zlib_state |= PNG_ZLIB_IN_USE;

-   }

-

-   else

-      png_error(png_ptr, "zstream already in use (internal error)");

-}

-

-/* The opposite: release the stream.  It is also reset, this API will warn on

- * error but will not fail.

- */

-static void

-png_zlib_release(png_structp png_ptr)

-{

-   if (png_ptr->zlib_state & PNG_ZLIB_IN_USE)

-   {

-      int ret = deflateReset(&png_ptr->zstream);

-

-      png_ptr->zlib_state &= ~PNG_ZLIB_IN_USE;

-

-      if (ret != Z_OK)

-      {

-         png_const_charp err;

-         PNG_WARNING_PARAMETERS(p)

-

-         switch (ret)

-         {

-            case Z_VERSION_ERROR:

-               err = "version";

-               break;

-

-            case Z_STREAM_ERROR:

-               err = "stream";

-               break;

-

-            case Z_MEM_ERROR:

-               err = "memory";

-               break;

-

-            default:

-               err = "unknown";

-               break;

-         }

-

-         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, ret);

-         png_warning_parameter(p, 2, err);

-

-         if (png_ptr->zstream.msg)

-            err = png_ptr->zstream.msg;

-         else

-            err = "[no zlib message]";

-

-         png_warning_parameter(p, 3, err);

-

-         png_formatted_warning(png_ptr, p,

-            "zlib failed to reset compressor: @1(@2): @3");

-      }

-   }

-

-   else

-      png_warning(png_ptr, "zstream not in use (internal error)");

-}

-

-#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED

-/* This pair of functions encapsulates the operation of (a) compressing a

- * text string, and (b) issuing it later as a series of chunk data writes.

- * The compression_state structure is shared context for these functions

- * set up by the caller in order to make the whole mess thread-safe.

- */

-

-typedef struct

-{

-   png_const_bytep input;   /* The uncompressed input data */

-   png_size_t input_len;    /* Its length */

-   int num_output_ptr;      /* Number of output pointers used */

-   int max_output_ptr;      /* Size of output_ptr */

-   png_bytep *output_ptr;   /* Array of pointers to output */

-} compression_state;

-

-/* Compress given text into storage in the png_ptr structure */

-static int /* PRIVATE */

-png_text_compress(png_structp png_ptr,

-    png_const_charp text, png_size_t text_len, int compression,

-    compression_state *comp)

-{

-   int ret;

-

-   comp->num_output_ptr = 0;

-   comp->max_output_ptr = 0;

-   comp->output_ptr = NULL;

-   comp->input = NULL;

-   comp->input_len = text_len;

-

-   /* We may just want to pass the text right through */

-   if (compression == PNG_TEXT_COMPRESSION_NONE)

-   {

-      comp->input = (png_const_bytep)text;

-      return((int)text_len);

-   }

-

-   if (compression >= PNG_TEXT_COMPRESSION_LAST)

-   {

-      PNG_WARNING_PARAMETERS(p)

-

-      png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d,

-         compression);

-      png_formatted_warning(png_ptr, p, "Unknown compression type @1");

-   }

-

-   /* We can't write the chunk until we find out how much data we have,

-    * which means we need to run the compressor first and save the

-    * output.  This shouldn't be a problem, as the vast majority of

-    * comments should be reasonable, but we will set up an array of

-    * malloc'd pointers to be sure.

-    *

-    * If we knew the application was well behaved, we could simplify this

-    * greatly by assuming we can always malloc an output buffer large

-    * enough to hold the compressed text ((1001 * text_len / 1000) + 12)

-    * and malloc this directly.  The only time this would be a bad idea is

-    * if we can't malloc more than 64K and we have 64K of random input

-    * data, or if the input string is incredibly large (although this

-    * wouldn't cause a failure, just a slowdown due to swapping).

-    */

-   png_zlib_claim(png_ptr, PNG_ZLIB_FOR_TEXT);

-

-   /* Set up the compression buffers */

-   /* TODO: the following cast hides a potential overflow problem. */

-   png_ptr->zstream.avail_in = (uInt)text_len;

-

-   /* NOTE: assume zlib doesn't overwrite the input */

-   png_ptr->zstream.next_in = (Bytef *)text;

-   png_ptr->zstream.avail_out = png_ptr->zbuf_size;

-   png_ptr->zstream.next_out = png_ptr->zbuf;

-

-   /* This is the same compression loop as in png_write_row() */

-   do

-   {

-      /* Compress the data */

-      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);

-

-      if (ret != Z_OK)

-      {

-         /* Error */

-         if (png_ptr->zstream.msg != NULL)

-            png_error(png_ptr, png_ptr->zstream.msg);

-

-         else

-            png_error(png_ptr, "zlib error");

-      }

-

-      /* Check to see if we need more room */

-      if (!(png_ptr->zstream.avail_out))

-      {

-         /* Make sure the output array has room */

-         if (comp->num_output_ptr >= comp->max_output_ptr)

-         {

-            int old_max;

-

-            old_max = comp->max_output_ptr;

-            comp->max_output_ptr = comp->num_output_ptr + 4;

-            if (comp->output_ptr != NULL)

-            {

-               png_bytepp old_ptr;

-

-               old_ptr = comp->output_ptr;

-

-               comp->output_ptr = (png_bytepp)png_malloc(png_ptr,

-                   (png_alloc_size_t)

-                   (comp->max_output_ptr * png_sizeof(png_charpp)));

-

-               png_memcpy(comp->output_ptr, old_ptr, old_max

-                   * png_sizeof(png_charp));

-

-               png_free(png_ptr, old_ptr);

-            }

-            else

-               comp->output_ptr = (png_bytepp)png_malloc(png_ptr,

-                   (png_alloc_size_t)

-                   (comp->max_output_ptr * png_sizeof(png_charp)));

-         }

-

-         /* Save the data */

-         comp->output_ptr[comp->num_output_ptr] =

-             (png_bytep)png_malloc(png_ptr,

-             (png_alloc_size_t)png_ptr->zbuf_size);

-

-         png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,

-             png_ptr->zbuf_size);

-

-         comp->num_output_ptr++;

-

-         /* and reset the buffer */

-         png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

-         png_ptr->zstream.next_out = png_ptr->zbuf;

-      }

-   /* Continue until we don't have any more to compress */

-   } while (png_ptr->zstream.avail_in);

-

-   /* Finish the compression */

-   do

-   {

-      /* Tell zlib we are finished */

-      ret = deflate(&png_ptr->zstream, Z_FINISH);

-

-      if (ret == Z_OK)

-      {

-         /* Check to see if we need more room */

-         if (!(png_ptr->zstream.avail_out))

-         {

-            /* Check to make sure our output array has room */

-            if (comp->num_output_ptr >= comp->max_output_ptr)

-            {

-               int old_max;

-

-               old_max = comp->max_output_ptr;

-               comp->max_output_ptr = comp->num_output_ptr + 4;

-               if (comp->output_ptr != NULL)

-               {

-                  png_bytepp old_ptr;

-

-                  old_ptr = comp->output_ptr;

-

-                  /* This could be optimized to realloc() */

-                  comp->output_ptr = (png_bytepp)png_malloc(png_ptr,

-                      (png_alloc_size_t)(comp->max_output_ptr *

-                      png_sizeof(png_charp)));

-

-                  png_memcpy(comp->output_ptr, old_ptr,

-                      old_max * png_sizeof(png_charp));

-

-                  png_free(png_ptr, old_ptr);

-               }

-

-               else

-                  comp->output_ptr = (png_bytepp)png_malloc(png_ptr,

-                      (png_alloc_size_t)(comp->max_output_ptr *

-                      png_sizeof(png_charp)));

-            }

-

-            /* Save the data */

-            comp->output_ptr[comp->num_output_ptr] =

-                (png_bytep)png_malloc(png_ptr,

-                (png_alloc_size_t)png_ptr->zbuf_size);

-

-            png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,

-                png_ptr->zbuf_size);

-

-            comp->num_output_ptr++;

-

-            /* and reset the buffer pointers */

-            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

-            png_ptr->zstream.next_out = png_ptr->zbuf;

-         }

-      }

-      else if (ret != Z_STREAM_END)

-      {

-         /* We got an error */

-         if (png_ptr->zstream.msg != NULL)

-            png_error(png_ptr, png_ptr->zstream.msg);

-

-         else

-            png_error(png_ptr, "zlib error");

-      }

-   } while (ret != Z_STREAM_END);

-

-   /* Text length is number of buffers plus last buffer */

-   text_len = png_ptr->zbuf_size * comp->num_output_ptr;

-

-   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)

-      text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;

-

-   return((int)text_len);

-}

-

-/* Ship the compressed text out via chunk writes */

-static void /* PRIVATE */

-png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)

-{

-   int i;

-

-   /* Handle the no-compression case */

-   if (comp->input)

-   {

-      png_write_chunk_data(png_ptr, comp->input, comp->input_len);

-

-      return;

-   }

-

-#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED

-   /* The zbuf_size test is because the code below doesn't work if zbuf_size is

-    * '1'; simply skip it to avoid memory overwrite.

-    */

-   if (comp->input_len >= 2 && comp->input_len < 16384 && png_ptr->zbuf_size > 1)

-   {

-      unsigned int z_cmf;  /* zlib compression method and flags */

-

-      /* Optimize the CMF field in the zlib stream.  This hack of the zlib

-       * stream is compliant to the stream specification.

-       */

-

-      if (comp->num_output_ptr)

-        z_cmf = comp->output_ptr[0][0];

-      else

-        z_cmf = png_ptr->zbuf[0];

-

-      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)

-      {

-         unsigned int z_cinfo;

-         unsigned int half_z_window_size;

-         png_size_t uncompressed_text_size = comp->input_len;

-

-         z_cinfo = z_cmf >> 4;

-         half_z_window_size = 1 << (z_cinfo + 7);

-

-         while (uncompressed_text_size <= half_z_window_size &&

-             half_z_window_size >= 256)

-         {

-            z_cinfo--;

-            half_z_window_size >>= 1;

-         }

-

-         z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);

-

-         if (comp->num_output_ptr)

-         {

-

-           if (comp->output_ptr[0][0] != z_cmf)

-           {

-              int tmp;

-

-              comp->output_ptr[0][0] = (png_byte)z_cmf;

-              tmp = comp->output_ptr[0][1] & 0xe0;

-              tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;

-              comp->output_ptr[0][1] = (png_byte)tmp;

-           }

-         }

-         else

-         {

-            int tmp;

-

-            png_ptr->zbuf[0] = (png_byte)z_cmf;

-            tmp = png_ptr->zbuf[1] & 0xe0;

-            tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;

-            png_ptr->zbuf[1] = (png_byte)tmp;

-         }

-      }

-

-      else

-         png_error(png_ptr,

-             "Invalid zlib compression method or flags in non-IDAT chunk");

-   }

-#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */

-

-   /* Write saved output buffers, if any */

-   for (i = 0; i < comp->num_output_ptr; i++)

-   {

-      png_write_chunk_data(png_ptr, comp->output_ptr[i],

-          (png_size_t)png_ptr->zbuf_size);

-

-      png_free(png_ptr, comp->output_ptr[i]);

-   }

-

-   if (comp->max_output_ptr != 0)

-      png_free(png_ptr, comp->output_ptr);

-

-   /* Write anything left in zbuf */

-   if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)

-      png_write_chunk_data(png_ptr, png_ptr->zbuf,

-          (png_size_t)(png_ptr->zbuf_size - png_ptr->zstream.avail_out));

-

-   /* Reset zlib for another zTXt/iTXt or image data */

-   png_zlib_release(png_ptr);

-}

-#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */

-

-/* Write the IHDR chunk, and update the png_struct with the necessary

- * information.  Note that the rest of this code depends upon this

- * information being correct.

- */

-void /* PRIVATE */

-png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,

-    int bit_depth, int color_type, int compression_type, int filter_type,

-    int interlace_type)

-{

-   png_byte buf[13]; /* Buffer to store the IHDR info */

-

-   png_debug(1, "in png_write_IHDR");

-

-   /* Check that we have valid input data from the application info */

-   switch (color_type)

-   {

-      case PNG_COLOR_TYPE_GRAY:

-         switch (bit_depth)

-         {

-            case 1:

-            case 2:

-            case 4:

-            case 8:

-#ifdef PNG_WRITE_16BIT_SUPPORTED

-            case 16:

-#endif

-               png_ptr->channels = 1; break;

-

-            default:

-               png_error(png_ptr,

-                   "Invalid bit depth for grayscale image");

-         }

-         break;

-

-      case PNG_COLOR_TYPE_RGB:

-#ifdef PNG_WRITE_16BIT_SUPPORTED

-         if (bit_depth != 8 && bit_depth != 16)

-#else

-         if (bit_depth != 8)

-#endif

-            png_error(png_ptr, "Invalid bit depth for RGB image");

-

-         png_ptr->channels = 3;

-         break;

-

-      case PNG_COLOR_TYPE_PALETTE:

-         switch (bit_depth)

-         {

-            case 1:

-            case 2:

-            case 4:

-            case 8:

-               png_ptr->channels = 1;

-               break;

-

-            default:

-               png_error(png_ptr, "Invalid bit depth for paletted image");

-         }

-         break;

-

-      case PNG_COLOR_TYPE_GRAY_ALPHA:

-         if (bit_depth != 8 && bit_depth != 16)

-            png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");

-

-         png_ptr->channels = 2;

-         break;

-

-      case PNG_COLOR_TYPE_RGB_ALPHA:

-#ifdef PNG_WRITE_16BIT_SUPPORTED

-         if (bit_depth != 8 && bit_depth != 16)

-#else

-         if (bit_depth != 8)

-#endif

-            png_error(png_ptr, "Invalid bit depth for RGBA image");

-

-         png_ptr->channels = 4;

-         break;

-

-      default:

-         png_error(png_ptr, "Invalid image color type specified");

-   }

-

-   if (compression_type != PNG_COMPRESSION_TYPE_BASE)

-   {

-      png_warning(png_ptr, "Invalid compression type specified");

-      compression_type = PNG_COMPRESSION_TYPE_BASE;

-   }

-

-   /* Write filter_method 64 (intrapixel differencing) only if

-    * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and

-    * 2. Libpng did not write a PNG signature (this filter_method is only

-    *    used in PNG datastreams that are embedded in MNG datastreams) and

-    * 3. The application called png_permit_mng_features with a mask that

-    *    included PNG_FLAG_MNG_FILTER_64 and

-    * 4. The filter_method is 64 and

-    * 5. The color_type is RGB or RGBA

-    */

-   if (

-#ifdef PNG_MNG_FEATURES_SUPPORTED

-       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&

-       ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&

-       (color_type == PNG_COLOR_TYPE_RGB ||

-        color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&

-       (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&

-#endif

-       filter_type != PNG_FILTER_TYPE_BASE)

-   {

-      png_warning(png_ptr, "Invalid filter type specified");

-      filter_type = PNG_FILTER_TYPE_BASE;

-   }

-

-#ifdef PNG_WRITE_INTERLACING_SUPPORTED

-   if (interlace_type != PNG_INTERLACE_NONE &&

-       interlace_type != PNG_INTERLACE_ADAM7)

-   {

-      png_warning(png_ptr, "Invalid interlace type specified");

-      interlace_type = PNG_INTERLACE_ADAM7;

-   }

-#else

-   interlace_type=PNG_INTERLACE_NONE;

-#endif

-

-   /* Save the relevent information */

-   png_ptr->bit_depth = (png_byte)bit_depth;

-   png_ptr->color_type = (png_byte)color_type;

-   png_ptr->interlaced = (png_byte)interlace_type;

-#ifdef PNG_MNG_FEATURES_SUPPORTED

-   png_ptr->filter_type = (png_byte)filter_type;

-#endif

-   png_ptr->compression_type = (png_byte)compression_type;

-   png_ptr->width = width;

-   png_ptr->height = height;

-

-   png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);

-   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);

-   /* Set the usr info, so any transformations can modify it */

-   png_ptr->usr_width = png_ptr->width;

-   png_ptr->usr_bit_depth = png_ptr->bit_depth;

-   png_ptr->usr_channels = png_ptr->channels;

-

-   /* Pack the header information into the buffer */

-   png_save_uint_32(buf, width);

-   png_save_uint_32(buf + 4, height);

-   buf[8] = (png_byte)bit_depth;

-   buf[9] = (png_byte)color_type;

-   buf[10] = (png_byte)compression_type;

-   buf[11] = (png_byte)filter_type;

-   buf[12] = (png_byte)interlace_type;

-

-   /* Write the chunk */

-   png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);

-

-   /* Initialize zlib with PNG info */

-   png_ptr->zstream.zalloc = png_zalloc;

-   png_ptr->zstream.zfree = png_zfree;

-   png_ptr->zstream.opaque = (voidpf)png_ptr;

-

-   if (!(png_ptr->do_filter))

-   {

-      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||

-          png_ptr->bit_depth < 8)

-         png_ptr->do_filter = PNG_FILTER_NONE;

-

-      else

-         png_ptr->do_filter = PNG_ALL_FILTERS;

-   }

-

-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))

-   {

-      if (png_ptr->do_filter != PNG_FILTER_NONE)

-         png_ptr->zlib_strategy = Z_FILTERED;

-

-      else

-         png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;

-   }

-

-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))

-      png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;

-

-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))

-      png_ptr->zlib_mem_level = 8;

-

-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))

-      png_ptr->zlib_window_bits = 15;

-

-   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))

-      png_ptr->zlib_method = 8;

-

-#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED

-#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED

-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_STRATEGY))

-      png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;

-

-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_LEVEL))

-      png_ptr->zlib_text_level = png_ptr->zlib_level;

-

-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL))

-      png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;

-

-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS))

-      png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;

-

-   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_METHOD))

-      png_ptr->zlib_text_method = png_ptr->zlib_method;

-#else

-   png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;

-   png_ptr->zlib_text_level = png_ptr->zlib_level;

-   png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;

-   png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;

-   png_ptr->zlib_text_method = png_ptr->zlib_method;

-#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */

-#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */

-

-   /* Record that the compressor has not yet been initialized. */

-   png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;

-

-   png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */

-}

-

-/* Write the palette.  We are careful not to trust png_color to be in the

- * correct order for PNG, so people can redefine it to any convenient

- * structure.

- */

-void /* PRIVATE */

-png_write_PLTE(png_structp png_ptr, png_const_colorp palette,

-    png_uint_32 num_pal)

-{

-   png_uint_32 i;

-   png_const_colorp pal_ptr;

-   png_byte buf[3];

-

-   png_debug(1, "in png_write_PLTE");

-

-   if ((

-#ifdef PNG_MNG_FEATURES_SUPPORTED

-       !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&

-#endif

-       num_pal == 0) || num_pal > 256)

-   {

-      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)

-      {

-         png_error(png_ptr, "Invalid number of colors in palette");

-      }

-

-      else

-      {

-         png_warning(png_ptr, "Invalid number of colors in palette");

-         return;

-      }

-   }

-

-   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))

-   {

-      png_warning(png_ptr,

-          "Ignoring request to write a PLTE chunk in grayscale PNG");

-

-      return;

-   }

-

-   png_ptr->num_palette = (png_uint_16)num_pal;

-   png_debug1(3, "num_palette = %d", png_ptr->num_palette);

-

-   png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));

-#ifdef PNG_POINTER_INDEXING_SUPPORTED

-

-   for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)

-   {

-      buf[0] = pal_ptr->red;

-      buf[1] = pal_ptr->green;

-      buf[2] = pal_ptr->blue;

-      png_write_chunk_data(png_ptr, buf, (png_size_t)3);

-   }

-

-#else

-   /* This is a little slower but some buggy compilers need to do this

-    * instead

-    */

-   pal_ptr=palette;

-

-   for (i = 0; i < num_pal; i++)

-   {

-      buf[0] = pal_ptr[i].red;

-      buf[1] = pal_ptr[i].green;

-      buf[2] = pal_ptr[i].blue;

-      png_write_chunk_data(png_ptr, buf, (png_size_t)3);

-   }

-

-#endif

-   png_write_chunk_end(png_ptr);

-   png_ptr->mode |= PNG_HAVE_PLTE;

-}

-

-/* Write an IDAT chunk */

-void /* PRIVATE */

-png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)

-{

-   png_debug(1, "in png_write_IDAT");

-

-#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED

-   if (!(png_ptr->mode & PNG_HAVE_IDAT) &&

-       png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)

-   {

-      /* Optimize the CMF field in the zlib stream.  This hack of the zlib

-       * stream is compliant to the stream specification.

-       */

-      unsigned int z_cmf = data[0];  /* zlib compression method and flags */

-

-      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)

-      {

-         /* Avoid memory underflows and multiplication overflows.

-          *

-          * The conditions below are practically always satisfied;

-          * however, they still must be checked.

-          */

-         if (length >= 2 &&

-             png_ptr->height < 16384 && png_ptr->width < 16384)

-         {

-            /* Compute the maximum possible length of the datastream */

-

-            /* Number of pixels, plus for each row a filter byte

-             * and possibly a padding byte, so increase the maximum

-             * size to account for these.

-             */

-            unsigned int z_cinfo;

-            unsigned int half_z_window_size;

-            png_uint_32 uncompressed_idat_size = png_ptr->height *

-                ((png_ptr->width *

-                png_ptr->channels * png_ptr->bit_depth + 15) >> 3);

-

-            /* If it's interlaced, each block of 8 rows is sent as up to

-             * 14 rows, i.e., 6 additional rows, each with a filter byte

-             * and possibly a padding byte

-             */

-            if (png_ptr->interlaced)

-               uncompressed_idat_size += ((png_ptr->height + 7)/8) *

-                   (png_ptr->bit_depth < 8 ? 12 : 6);

-

-            z_cinfo = z_cmf >> 4;

-            half_z_window_size = 1 << (z_cinfo + 7);

-

-            while (uncompressed_idat_size <= half_z_window_size &&

-                half_z_window_size >= 256)

-            {

-               z_cinfo--;

-               half_z_window_size >>= 1;

-            }

-

-            z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);

-

-            if (data[0] != z_cmf)

-            {

-               int tmp;

-               data[0] = (png_byte)z_cmf;

-               tmp = data[1] & 0xe0;

-               tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;

-               data[1] = (png_byte)tmp;

-            }

-         }

-      }

-

-      else

-         png_error(png_ptr,

-             "Invalid zlib compression method or flags in IDAT");

-   }

-#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */

-

-   png_write_complete_chunk(png_ptr, png_IDAT, data, length);

-   png_ptr->mode |= PNG_HAVE_IDAT;

-

-   /* Prior to 1.5.4 this code was replicated in every caller (except at the

-    * end, where it isn't technically necessary).  Since this function has

-    * flushed the data we can safely reset the zlib output buffer here.

-    */

-   png_ptr->zstream.next_out = png_ptr->zbuf;

-   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

-}

-

-/* Write an IEND chunk */

-void /* PRIVATE */

-png_write_IEND(png_structp png_ptr)

-{

-   png_debug(1, "in png_write_IEND");

-

-   png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);

-   png_ptr->mode |= PNG_HAVE_IEND;

-}

-

-#ifdef PNG_WRITE_gAMA_SUPPORTED

-/* Write a gAMA chunk */

-void /* PRIVATE */

-png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)

-{

-   png_byte buf[4];

-

-   png_debug(1, "in png_write_gAMA");

-

-   /* file_gamma is saved in 1/100,000ths */

-   png_save_uint_32(buf, (png_uint_32)file_gamma);

-   png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);

-}

-#endif

-

-#ifdef PNG_WRITE_sRGB_SUPPORTED

-/* Write a sRGB chunk */

-void /* PRIVATE */

-png_write_sRGB(png_structp png_ptr, int srgb_intent)

-{

-   png_byte buf[1];

-

-   png_debug(1, "in png_write_sRGB");

-

-   if (srgb_intent >= PNG_sRGB_INTENT_LAST)

-      png_warning(png_ptr,

-          "Invalid sRGB rendering intent specified");

-

-   buf[0]=(png_byte)srgb_intent;

-   png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);

-}

-#endif

-

-#ifdef PNG_WRITE_iCCP_SUPPORTED

-/* Write an iCCP chunk */

-void /* PRIVATE */

-png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,

-    png_const_charp profile, int profile_len)

-{

-   png_size_t name_len;

-   png_charp new_name;

-   compression_state comp;

-   int embedded_profile_len = 0;

-

-   png_debug(1, "in png_write_iCCP");

-

-   comp.num_output_ptr = 0;

-   comp.max_output_ptr = 0;

-   comp.output_ptr = NULL;

-   comp.input = NULL;

-   comp.input_len = 0;

-

-   if ((name_len = png_check_keyword(png_ptr, name, &new_name)) == 0)

-      return;

-

-   if (compression_type != PNG_COMPRESSION_TYPE_BASE)

-      png_warning(png_ptr, "Unknown compression type in iCCP chunk");

-

-   if (profile == NULL)

-      profile_len = 0;

-

-   if (profile_len > 3)

-      embedded_profile_len =

-          ((*( (png_const_bytep)profile    ))<<24) |

-          ((*( (png_const_bytep)profile + 1))<<16) |

-          ((*( (png_const_bytep)profile + 2))<< 8) |

-          ((*( (png_const_bytep)profile + 3))    );

-

-   if (embedded_profile_len < 0)

-   {

-      png_warning(png_ptr,

-          "Embedded profile length in iCCP chunk is negative");

-

-      png_free(png_ptr, new_name);

-      return;

-   }

-

-   if (profile_len < embedded_profile_len)

-   {

-      png_warning(png_ptr,

-          "Embedded profile length too large in iCCP chunk");

-

-      png_free(png_ptr, new_name);

-      return;

-   }

-

-   if (profile_len > embedded_profile_len)

-   {

-      png_warning(png_ptr,

-          "Truncating profile to actual length in iCCP chunk");

-

-      profile_len = embedded_profile_len;

-   }

-

-   if (profile_len)

-      profile_len = png_text_compress(png_ptr, profile,

-          (png_size_t)profile_len, PNG_COMPRESSION_TYPE_BASE, &comp);

-

-   /* Make sure we include the NULL after the name and the compression type */

-   png_write_chunk_header(png_ptr, png_iCCP,

-       (png_uint_32)(name_len + profile_len + 2));

-

-   new_name[name_len + 1] = 0x00;

-

-   png_write_chunk_data(png_ptr, (png_bytep)new_name,

-       (png_size_t)(name_len + 2));

-

-   if (profile_len)

-   {

-      comp.input_len = profile_len;

-      png_write_compressed_data_out(png_ptr, &comp);

-   }

-

-   png_write_chunk_end(png_ptr);

-   png_free(png_ptr, new_name);

-}

-#endif

-

-#ifdef PNG_WRITE_sPLT_SUPPORTED

-/* Write a sPLT chunk */

-void /* PRIVATE */

-png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)

-{

-   png_size_t name_len;

-   png_charp new_name;

-   png_byte entrybuf[10];

-   png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);

-   png_size_t palette_size = entry_size * spalette->nentries;

-   png_sPLT_entryp ep;

-#ifndef PNG_POINTER_INDEXING_SUPPORTED

-   int i;

-#endif

-

-   png_debug(1, "in png_write_sPLT");

-

-   if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)

-      return;

-

-   /* Make sure we include the NULL after the name */

-   png_write_chunk_header(png_ptr, png_sPLT,

-       (png_uint_32)(name_len + 2 + palette_size));

-

-   png_write_chunk_data(png_ptr, (png_bytep)new_name,

-       (png_size_t)(name_len + 1));

-

-   png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);

-

-   /* Loop through each palette entry, writing appropriately */

-#ifdef PNG_POINTER_INDEXING_SUPPORTED

-   for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)

-   {

-      if (spalette->depth == 8)

-      {

-         entrybuf[0] = (png_byte)ep->red;

-         entrybuf[1] = (png_byte)ep->green;

-         entrybuf[2] = (png_byte)ep->blue;

-         entrybuf[3] = (png_byte)ep->alpha;

-         png_save_uint_16(entrybuf + 4, ep->frequency);

-      }

-

-      else

-      {

-         png_save_uint_16(entrybuf + 0, ep->red);

-         png_save_uint_16(entrybuf + 2, ep->green);

-         png_save_uint_16(entrybuf + 4, ep->blue);

-         png_save_uint_16(entrybuf + 6, ep->alpha);

-         png_save_uint_16(entrybuf + 8, ep->frequency);

-      }

-

-      png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);

-   }

-#else

-   ep=spalette->entries;

-   for (i = 0; i>spalette->nentries; i++)

-   {

-      if (spalette->depth == 8)

-      {

-         entrybuf[0] = (png_byte)ep[i].red;

-         entrybuf[1] = (png_byte)ep[i].green;

-         entrybuf[2] = (png_byte)ep[i].blue;

-         entrybuf[3] = (png_byte)ep[i].alpha;

-         png_save_uint_16(entrybuf + 4, ep[i].frequency);

-      }

-

-      else

-      {

-         png_save_uint_16(entrybuf + 0, ep[i].red);

-         png_save_uint_16(entrybuf + 2, ep[i].green);

-         png_save_uint_16(entrybuf + 4, ep[i].blue);

-         png_save_uint_16(entrybuf + 6, ep[i].alpha);

-         png_save_uint_16(entrybuf + 8, ep[i].frequency);

-      }

-

-      png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);

-   }

-#endif

-

-   png_write_chunk_end(png_ptr);

-   png_free(png_ptr, new_name);

-}

-#endif

-

-#ifdef PNG_WRITE_sBIT_SUPPORTED

-/* Write the sBIT chunk */

-void /* PRIVATE */

-png_write_sBIT(png_structp png_ptr, png_const_color_8p sbit, int color_type)

-{

-   png_byte buf[4];

-   png_size_t size;

-

-   png_debug(1, "in png_write_sBIT");

-

-   /* Make sure we don't depend upon the order of PNG_COLOR_8 */

-   if (color_type & PNG_COLOR_MASK_COLOR)

-   {

-      png_byte maxbits;

-

-      maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :

-          png_ptr->usr_bit_depth);

-

-      if (sbit->red == 0 || sbit->red > maxbits ||

-          sbit->green == 0 || sbit->green > maxbits ||

-          sbit->blue == 0 || sbit->blue > maxbits)

-      {

-         png_warning(png_ptr, "Invalid sBIT depth specified");

-         return;

-      }

-

-      buf[0] = sbit->red;

-      buf[1] = sbit->green;

-      buf[2] = sbit->blue;

-      size = 3;

-   }

-

-   else

-   {

-      if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)

-      {

-         png_warning(png_ptr, "Invalid sBIT depth specified");

-         return;

-      }

-

-      buf[0] = sbit->gray;

-      size = 1;

-   }

-

-   if (color_type & PNG_COLOR_MASK_ALPHA)

-   {

-      if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)

-      {

-         png_warning(png_ptr, "Invalid sBIT depth specified");

-         return;

-      }

-

-      buf[size++] = sbit->alpha;

-   }

-

-   png_write_complete_chunk(png_ptr, png_sBIT, buf, size);

-}

-#endif

-

-#ifdef PNG_WRITE_cHRM_SUPPORTED

-/* Write the cHRM chunk */

-void /* PRIVATE */

-png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,

-    png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,

-    png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,

-    png_fixed_point blue_y)

-{

-   png_byte buf[32];

-

-   png_debug(1, "in png_write_cHRM");

-

-   /* Each value is saved in 1/100,000ths */

-#ifdef PNG_CHECK_cHRM_SUPPORTED

-   if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,

-       green_x, green_y, blue_x, blue_y))

-#endif

-   {

-      png_save_uint_32(buf, (png_uint_32)white_x);

-      png_save_uint_32(buf + 4, (png_uint_32)white_y);

-

-      png_save_uint_32(buf + 8, (png_uint_32)red_x);

-      png_save_uint_32(buf + 12, (png_uint_32)red_y);

-

-      png_save_uint_32(buf + 16, (png_uint_32)green_x);

-      png_save_uint_32(buf + 20, (png_uint_32)green_y);

-

-      png_save_uint_32(buf + 24, (png_uint_32)blue_x);

-      png_save_uint_32(buf + 28, (png_uint_32)blue_y);

-

-      png_write_complete_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);

-   }

-}

-#endif

-

-#ifdef PNG_WRITE_tRNS_SUPPORTED

-/* Write the tRNS chunk */

-void /* PRIVATE */

-png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,

-    png_const_color_16p tran, int num_trans, int color_type)

-{

-   png_byte buf[6];

-

-   png_debug(1, "in png_write_tRNS");

-

-   if (color_type == PNG_COLOR_TYPE_PALETTE)

-   {

-      if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)

-      {

-         png_warning(png_ptr, "Invalid number of transparent colors specified");

-         return;

-      }

-

-      /* Write the chunk out as it is */

-      png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, (png_size_t)num_trans);

-   }

-

-   else if (color_type == PNG_COLOR_TYPE_GRAY)

-   {

-      /* One 16 bit value */

-      if (tran->gray >= (1 << png_ptr->bit_depth))

-      {

-         png_warning(png_ptr,

-             "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");

-

-         return;

-      }

-

-      png_save_uint_16(buf, tran->gray);

-      png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);

-   }

-

-   else if (color_type == PNG_COLOR_TYPE_RGB)

-   {

-      /* Three 16 bit values */

-      png_save_uint_16(buf, tran->red);

-      png_save_uint_16(buf + 2, tran->green);

-      png_save_uint_16(buf + 4, tran->blue);

-#ifdef PNG_WRITE_16BIT_SUPPORTED

-      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))

-#else

-      if (buf[0] | buf[2] | buf[4])

-#endif

-      {

-         png_warning(png_ptr,

-           "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");

-         return;

-      }

-

-      png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);

-   }

-

-   else

-   {

-      png_warning(png_ptr, "Can't write tRNS with an alpha channel");

-   }

-}

-#endif

-

-#ifdef PNG_WRITE_bKGD_SUPPORTED

-/* Write the background chunk */

-void /* PRIVATE */

-png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)

-{

-   png_byte buf[6];

-

-   png_debug(1, "in png_write_bKGD");

-

-   if (color_type == PNG_COLOR_TYPE_PALETTE)

-   {

-      if (

-#ifdef PNG_MNG_FEATURES_SUPPORTED

-          (png_ptr->num_palette ||

-          (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&

-#endif

-         back->index >= png_ptr->num_palette)

-      {

-         png_warning(png_ptr, "Invalid background palette index");

-         return;

-      }

-

-      buf[0] = back->index;

-      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);

-   }

-

-   else if (color_type & PNG_COLOR_MASK_COLOR)

-   {

-      png_save_uint_16(buf, back->red);

-      png_save_uint_16(buf + 2, back->green);

-      png_save_uint_16(buf + 4, back->blue);

-#ifdef PNG_WRITE_16BIT_SUPPORTED

-      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))

-#else

-      if (buf[0] | buf[2] | buf[4])

-#endif

-      {

-         png_warning(png_ptr,

-             "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");

-

-         return;

-      }

-

-      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);

-   }

-

-   else

-   {

-      if (back->gray >= (1 << png_ptr->bit_depth))

-      {

-         png_warning(png_ptr,

-             "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");

-

-         return;

-      }

-

-      png_save_uint_16(buf, back->gray);

-      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);

-   }

-}

-#endif

-

-#ifdef PNG_WRITE_hIST_SUPPORTED

-/* Write the histogram */

-void /* PRIVATE */

-png_write_hIST(png_structp png_ptr, png_const_uint_16p hist, int num_hist)

-{

-   int i;

-   png_byte buf[3];

-

-   png_debug(1, "in png_write_hIST");

-

-   if (num_hist > (int)png_ptr->num_palette)

-   {

-      png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,

-          png_ptr->num_palette);

-

-      png_warning(png_ptr, "Invalid number of histogram entries specified");

-      return;

-   }

-

-   png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));

-

-   for (i = 0; i < num_hist; i++)

-   {

-      png_save_uint_16(buf, hist[i]);

-      png_write_chunk_data(png_ptr, buf, (png_size_t)2);

-   }

-

-   png_write_chunk_end(png_ptr);

-}

-#endif

-

-#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \

-    defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)

-/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,

- * and if invalid, correct the keyword rather than discarding the entire

- * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in

- * length, forbids leading or trailing whitespace, multiple internal spaces,

- * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.

- *

- * The new_key is allocated to hold the corrected keyword and must be freed

- * by the calling routine.  This avoids problems with trying to write to

- * static keywords without having to have duplicate copies of the strings.

- */

-png_size_t /* PRIVATE */

-png_check_keyword(png_structp png_ptr, png_const_charp key, png_charpp new_key)

-{

-   png_size_t key_len;

-   png_const_charp ikp;

-   png_charp kp, dp;

-   int kflag;

-   int kwarn=0;

-

-   png_debug(1, "in png_check_keyword");

-

-   *new_key = NULL;

-

-   if (key == NULL || (key_len = png_strlen(key)) == 0)

-   {

-      png_warning(png_ptr, "zero length keyword");

-      return ((png_size_t)0);

-   }

-

-   png_debug1(2, "Keyword to be checked is '%s'", key);

-

-   *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));

-

-   if (*new_key == NULL)

-   {

-      png_warning(png_ptr, "Out of memory while procesing keyword");

-      return ((png_size_t)0);

-   }

-

-   /* Replace non-printing characters with a blank and print a warning */

-   for (ikp = key, dp = *new_key; *ikp != '\0'; ikp++, dp++)

-   {

-      if ((png_byte)*ikp < 0x20 ||

-         ((png_byte)*ikp > 0x7E && (png_byte)*ikp < 0xA1))

-      {

-         PNG_WARNING_PARAMETERS(p)

-

-         png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_02x,

-            (png_byte)*ikp);

-         png_formatted_warning(png_ptr, p, "invalid keyword character 0x@1");

-         *dp = ' ';

-      }

-

-      else

-      {

-         *dp = *ikp;

-      }

-   }

-   *dp = '\0';

-

-   /* Remove any trailing white space. */

-   kp = *new_key + key_len - 1;

-   if (*kp == ' ')

-   {

-      png_warning(png_ptr, "trailing spaces removed from keyword");

-

-      while (*kp == ' ')

-      {

-         *(kp--) = '\0';

-         key_len--;

-      }

-   }

-

-   /* Remove any leading white space. */

-   kp = *new_key;

-   if (*kp == ' ')

-   {

-      png_warning(png_ptr, "leading spaces removed from keyword");

-

-      while (*kp == ' ')

-      {

-         kp++;

-         key_len--;

-      }

-   }

-

-   png_debug1(2, "Checking for multiple internal spaces in '%s'", kp);

-

-   /* Remove multiple internal spaces. */

-   for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)

-   {

-      if (*kp == ' ' && kflag == 0)

-      {

-         *(dp++) = *kp;

-         kflag = 1;

-      }

-

-      else if (*kp == ' ')

-      {

-         key_len--;

-         kwarn = 1;

-      }

-

-      else

-      {

-         *(dp++) = *kp;

-         kflag = 0;

-      }

-   }

-   *dp = '\0';

-   if (kwarn)

-      png_warning(png_ptr, "extra interior spaces removed from keyword");

-

-   if (key_len == 0)

-   {

-      png_free(png_ptr, *new_key);

-      png_warning(png_ptr, "Zero length keyword");

-   }

-

-   if (key_len > 79)

-   {

-      png_warning(png_ptr, "keyword length must be 1 - 79 characters");

-      (*new_key)[79] = '\0';

-      key_len = 79;

-   }

-

-   return (key_len);

-}

-#endif

-

-#ifdef PNG_WRITE_tEXt_SUPPORTED

-/* Write a tEXt chunk */

-void /* PRIVATE */

-png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,

-    png_size_t text_len)

-{

-   png_size_t key_len;

-   png_charp new_key;

-

-   png_debug(1, "in png_write_tEXt");

-

-   if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)

-      return;

-

-   if (text == NULL || *text == '\0')

-      text_len = 0;

-

-   else

-      text_len = png_strlen(text);

-

-   /* Make sure we include the 0 after the key */

-   png_write_chunk_header(png_ptr, png_tEXt,

-       (png_uint_32)(key_len + text_len + 1));

-   /*

-    * We leave it to the application to meet PNG-1.0 requirements on the

-    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of

-    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.

-    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.

-    */

-   png_write_chunk_data(png_ptr, (png_bytep)new_key,

-       (png_size_t)(key_len + 1));

-

-   if (text_len)

-      png_write_chunk_data(png_ptr, (png_const_bytep)text,

-          (png_size_t)text_len);

-

-   png_write_chunk_end(png_ptr);

-   png_free(png_ptr, new_key);

-}

-#endif

-

-#ifdef PNG_WRITE_zTXt_SUPPORTED

-/* Write a compressed text chunk */

-void /* PRIVATE */

-png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,

-    png_size_t text_len, int compression)

-{

-   png_size_t key_len;

-   png_byte buf;

-   png_charp new_key;

-   compression_state comp;

-

-   png_debug(1, "in png_write_zTXt");

-

-   comp.num_output_ptr = 0;

-   comp.max_output_ptr = 0;

-   comp.output_ptr = NULL;

-   comp.input = NULL;

-   comp.input_len = 0;

-

-   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)

-   {

-      png_free(png_ptr, new_key);

-      return;

-   }

-

-   if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)

-   {

-      png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);

-      png_free(png_ptr, new_key);

-      return;

-   }

-

-   text_len = png_strlen(text);

-

-   /* Compute the compressed data; do it now for the length */

-   text_len = png_text_compress(png_ptr, text, text_len, compression,

-       &comp);

-

-   /* Write start of chunk */

-   png_write_chunk_header(png_ptr, png_zTXt,

-       (png_uint_32)(key_len+text_len + 2));

-

-   /* Write key */

-   png_write_chunk_data(png_ptr, (png_bytep)new_key,

-       (png_size_t)(key_len + 1));

-

-   png_free(png_ptr, new_key);

-

-   buf = (png_byte)compression;

-

-   /* Write compression */

-   png_write_chunk_data(png_ptr, &buf, (png_size_t)1);

-

-   /* Write the compressed data */

-   comp.input_len = text_len;

-   png_write_compressed_data_out(png_ptr, &comp);

-

-   /* Close the chunk */

-   png_write_chunk_end(png_ptr);

-}

-#endif

-

-#ifdef PNG_WRITE_iTXt_SUPPORTED

-/* Write an iTXt chunk */

-void /* PRIVATE */

-png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,

-    png_const_charp lang, png_const_charp lang_key, png_const_charp text)

-{

-   png_size_t lang_len, key_len, lang_key_len, text_len;

-   png_charp new_lang;

-   png_charp new_key = NULL;

-   png_byte cbuf[2];

-   compression_state comp;

-

-   png_debug(1, "in png_write_iTXt");

-

-   comp.num_output_ptr = 0;

-   comp.max_output_ptr = 0;

-   comp.output_ptr = NULL;

-   comp.input = NULL;

-

-   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)

-      return;

-

-   if ((lang_len = png_check_keyword(png_ptr, lang, &new_lang)) == 0)

-   {

-      png_warning(png_ptr, "Empty language field in iTXt chunk");

-      new_lang = NULL;

-      lang_len = 0;

-   }

-

-   if (lang_key == NULL)

-      lang_key_len = 0;

-

-   else

-      lang_key_len = png_strlen(lang_key);

-

-   if (text == NULL)

-      text_len = 0;

-

-   else

-      text_len = png_strlen(text);

-

-   /* Compute the compressed data; do it now for the length */

-   text_len = png_text_compress(png_ptr, text, text_len, compression - 2,

-       &comp);

-

-

-   /* Make sure we include the compression flag, the compression byte,

-    * and the NULs after the key, lang, and lang_key parts

-    */

-

-   png_write_chunk_header(png_ptr, png_iTXt, (png_uint_32)(

-        5 /* comp byte, comp flag, terminators for key, lang and lang_key */

-        + key_len

-        + lang_len

-        + lang_key_len

-        + text_len));

-

-   /* We leave it to the application to meet PNG-1.0 requirements on the

-    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of

-    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.

-    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.

-    */

-   png_write_chunk_data(png_ptr, (png_bytep)new_key, (png_size_t)(key_len + 1));

-

-   /* Set the compression flag */

-   if (compression == PNG_ITXT_COMPRESSION_NONE ||

-       compression == PNG_TEXT_COMPRESSION_NONE)

-      cbuf[0] = 0;

-

-   else /* compression == PNG_ITXT_COMPRESSION_zTXt */

-      cbuf[0] = 1;

-

-   /* Set the compression method */

-   cbuf[1] = 0;

-

-   png_write_chunk_data(png_ptr, cbuf, (png_size_t)2);

-

-   cbuf[0] = 0;

-   png_write_chunk_data(png_ptr, (new_lang ? (png_const_bytep)new_lang : cbuf),

-       (png_size_t)(lang_len + 1));

-

-   png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf),

-       (png_size_t)(lang_key_len + 1));

-

-   png_write_compressed_data_out(png_ptr, &comp);

-

-   png_write_chunk_end(png_ptr);

-

-   png_free(png_ptr, new_key);

-   png_free(png_ptr, new_lang);

-}

-#endif

-

-#ifdef PNG_WRITE_oFFs_SUPPORTED

-/* Write the oFFs chunk */

-void /* PRIVATE */

-png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,

-    int unit_type)

-{

-   png_byte buf[9];

-

-   png_debug(1, "in png_write_oFFs");

-

-   if (unit_type >= PNG_OFFSET_LAST)

-      png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");

-

-   png_save_int_32(buf, x_offset);

-   png_save_int_32(buf + 4, y_offset);

-   buf[8] = (png_byte)unit_type;

-

-   png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);

-}

-#endif

-#ifdef PNG_WRITE_pCAL_SUPPORTED

-/* Write the pCAL chunk (described in the PNG extensions document) */

-void /* PRIVATE */

-png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,

-    png_int_32 X1, int type, int nparams, png_const_charp units,

-    png_charpp params)

-{

-   png_size_t purpose_len, units_len, total_len;

-   png_size_tp params_len;

-   png_byte buf[10];

-   png_charp new_purpose;

-   int i;

-

-   png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);

-

-   if (type >= PNG_EQUATION_LAST)

-      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");

-

-   purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;

-   png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);

-   units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);

-   png_debug1(3, "pCAL units length = %d", (int)units_len);

-   total_len = purpose_len + units_len + 10;

-

-   params_len = (png_size_tp)png_malloc(png_ptr,

-       (png_alloc_size_t)(nparams * png_sizeof(png_size_t)));

-

-   /* Find the length of each parameter, making sure we don't count the

-    * null terminator for the last parameter.

-    */

-   for (i = 0; i < nparams; i++)

-   {

-      params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);

-      png_debug2(3, "pCAL parameter %d length = %lu", i,

-          (unsigned long)params_len[i]);

-      total_len += params_len[i];

-   }

-

-   png_debug1(3, "pCAL total length = %d", (int)total_len);

-   png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);

-   png_write_chunk_data(png_ptr, (png_const_bytep)new_purpose, purpose_len);

-   png_save_int_32(buf, X0);

-   png_save_int_32(buf + 4, X1);

-   buf[8] = (png_byte)type;

-   buf[9] = (png_byte)nparams;

-   png_write_chunk_data(png_ptr, buf, (png_size_t)10);

-   png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);

-

-   png_free(png_ptr, new_purpose);

-

-   for (i = 0; i < nparams; i++)

-   {

-      png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);

-   }

-

-   png_free(png_ptr, params_len);

-   png_write_chunk_end(png_ptr);

-}

-#endif

-

-#ifdef PNG_WRITE_sCAL_SUPPORTED

-/* Write the sCAL chunk */

-void /* PRIVATE */

-png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,

-    png_const_charp height)

-{

-   png_byte buf[64];

-   png_size_t wlen, hlen, total_len;

-

-   png_debug(1, "in png_write_sCAL_s");

-

-   wlen = png_strlen(width);

-   hlen = png_strlen(height);

-   total_len = wlen + hlen + 2;

-

-   if (total_len > 64)

-   {

-      png_warning(png_ptr, "Can't write sCAL (buffer too small)");

-      return;

-   }

-

-   buf[0] = (png_byte)unit;

-   png_memcpy(buf + 1, width, wlen + 1);      /* Append the '\0' here */

-   png_memcpy(buf + wlen + 2, height, hlen);  /* Do NOT append the '\0' here */

-

-   png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);

-   png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);

-}

-#endif

-

-#ifdef PNG_WRITE_pHYs_SUPPORTED

-/* Write the pHYs chunk */

-void /* PRIVATE */

-png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,

-    png_uint_32 y_pixels_per_unit,

-    int unit_type)

-{

-   png_byte buf[9];

-

-   png_debug(1, "in png_write_pHYs");

-

-   if (unit_type >= PNG_RESOLUTION_LAST)

-      png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");

-

-   png_save_uint_32(buf, x_pixels_per_unit);

-   png_save_uint_32(buf + 4, y_pixels_per_unit);

-   buf[8] = (png_byte)unit_type;

-

-   png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);

-}

-#endif

-

-#ifdef PNG_WRITE_tIME_SUPPORTED

-/* Write the tIME chunk.  Use either png_convert_from_struct_tm()

- * or png_convert_from_time_t(), or fill in the structure yourself.

- */

-void /* PRIVATE */

-png_write_tIME(png_structp png_ptr, png_const_timep mod_time)

-{

-   png_byte buf[7];

-

-   png_debug(1, "in png_write_tIME");

-

-   if (mod_time->month  > 12 || mod_time->month  < 1 ||

-       mod_time->day    > 31 || mod_time->day    < 1 ||

-       mod_time->hour   > 23 || mod_time->second > 60)

-   {

-      png_warning(png_ptr, "Invalid time specified for tIME chunk");

-      return;

-   }

-

-   png_save_uint_16(buf, mod_time->year);

-   buf[2] = mod_time->month;

-   buf[3] = mod_time->day;

-   buf[4] = mod_time->hour;

-   buf[5] = mod_time->minute;

-   buf[6] = mod_time->second;

-

-   png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);

-}

-#endif

-

-/* Initializes the row writing capability of libpng */

-void /* PRIVATE */

-png_write_start_row(png_structp png_ptr)

-{

-#ifdef PNG_WRITE_INTERLACING_SUPPORTED

-   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */

-

-   /* Start of interlace block */

-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};

-

-   /* Offset to next interlace block */

-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};

-

-   /* Start of interlace block in the y direction */

-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};

-

-   /* Offset to next interlace block in the y direction */

-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};

-#endif

-

-   png_alloc_size_t buf_size;

-   int usr_pixel_depth;

-

-   png_debug(1, "in png_write_start_row");

-

-   usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth;

-   buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1;

-

-   /* 1.5.6: added to allow checking in the row write code. */

-   png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;

-   png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;

-

-   /* Set up row buffer */

-   png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size);

-

-   png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;

-

-#ifdef PNG_WRITE_FILTER_SUPPORTED

-   /* Set up filtering buffer, if using this filter */

-   if (png_ptr->do_filter & PNG_FILTER_SUB)

-   {

-      png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);

-

-      png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;

-   }

-

-   /* We only need to keep the previous row if we are using one of these. */

-   if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))

-   {

-      /* Set up previous row buffer */

-      png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size);

-

-      if (png_ptr->do_filter & PNG_FILTER_UP)

-      {

-         png_ptr->up_row = (png_bytep)png_malloc(png_ptr,

-            png_ptr->rowbytes + 1);

-

-         png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;

-      }

-

-      if (png_ptr->do_filter & PNG_FILTER_AVG)

-      {

-         png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,

-             png_ptr->rowbytes + 1);

-

-         png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;

-      }

-

-      if (png_ptr->do_filter & PNG_FILTER_PAETH)

-      {

-         png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,

-             png_ptr->rowbytes + 1);

-

-         png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;

-      }

-   }

-#endif /* PNG_WRITE_FILTER_SUPPORTED */

-

-#ifdef PNG_WRITE_INTERLACING_SUPPORTED

-   /* If interlaced, we need to set up width and height of pass */

-   if (png_ptr->interlaced)

-   {

-      if (!(png_ptr->transformations & PNG_INTERLACE))

-      {

-         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -

-             png_pass_ystart[0]) / png_pass_yinc[0];

-

-         png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -

-             png_pass_start[0]) / png_pass_inc[0];

-      }

-

-      else

-      {

-         png_ptr->num_rows = png_ptr->height;

-         png_ptr->usr_width = png_ptr->width;

-      }

-   }

-

-   else

-#endif

-   {

-      png_ptr->num_rows = png_ptr->height;

-      png_ptr->usr_width = png_ptr->width;

-   }

-

-   png_zlib_claim(png_ptr, PNG_ZLIB_FOR_IDAT);

-   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

-   png_ptr->zstream.next_out = png_ptr->zbuf;

-}

-

-/* Internal use only.  Called when finished processing a row of data. */

-void /* PRIVATE */

-png_write_finish_row(png_structp png_ptr)

-{

-#ifdef PNG_WRITE_INTERLACING_SUPPORTED

-   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */

-

-   /* Start of interlace block */

-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};

-

-   /* Offset to next interlace block */

-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};

-

-   /* Start of interlace block in the y direction */

-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};

-

-   /* Offset to next interlace block in the y direction */

-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};

-#endif

-

-   int ret;

-

-   png_debug(1, "in png_write_finish_row");

-

-   /* Next row */

-   png_ptr->row_number++;

-

-   /* See if we are done */

-   if (png_ptr->row_number < png_ptr->num_rows)

-      return;

-

-#ifdef PNG_WRITE_INTERLACING_SUPPORTED

-   /* If interlaced, go to next pass */

-   if (png_ptr->interlaced)

-   {

-      png_ptr->row_number = 0;

-      if (png_ptr->transformations & PNG_INTERLACE)

-      {

-         png_ptr->pass++;

-      }

-

-      else

-      {

-         /* Loop until we find a non-zero width or height pass */

-         do

-         {

-            png_ptr->pass++;

-

-            if (png_ptr->pass >= 7)

-               break;

-

-            png_ptr->usr_width = (png_ptr->width +

-                png_pass_inc[png_ptr->pass] - 1 -

-                png_pass_start[png_ptr->pass]) /

-                png_pass_inc[png_ptr->pass];

-

-            png_ptr->num_rows = (png_ptr->height +

-                png_pass_yinc[png_ptr->pass] - 1 -

-                png_pass_ystart[png_ptr->pass]) /

-                png_pass_yinc[png_ptr->pass];

-

-            if (png_ptr->transformations & PNG_INTERLACE)

-               break;

-

-         } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);

-

-      }

-

-      /* Reset the row above the image for the next pass */

-      if (png_ptr->pass < 7)

-      {

-         if (png_ptr->prev_row != NULL)

-            png_memset(png_ptr->prev_row, 0,

-                (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*

-                png_ptr->usr_bit_depth, png_ptr->width)) + 1);

-

-         return;

-      }

-   }

-#endif

-

-   /* If we get here, we've just written the last row, so we need

-      to flush the compressor */

-   do

-   {

-      /* Tell the compressor we are done */

-      ret = deflate(&png_ptr->zstream, Z_FINISH);

-

-      /* Check for an error */

-      if (ret == Z_OK)

-      {

-         /* Check to see if we need more room */

-         if (!(png_ptr->zstream.avail_out))

-         {

-            png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);

-            png_ptr->zstream.next_out = png_ptr->zbuf;

-            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

-         }

-      }

-

-      else if (ret != Z_STREAM_END)

-      {

-         if (png_ptr->zstream.msg != NULL)

-            png_error(png_ptr, png_ptr->zstream.msg);

-

-         else

-            png_error(png_ptr, "zlib error");

-      }

-   } while (ret != Z_STREAM_END);

-

-   /* Write any extra space */

-   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)

-   {

-      png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -

-          png_ptr->zstream.avail_out);

-   }

-

-   png_zlib_release(png_ptr);

-   png_ptr->zstream.data_type = Z_BINARY;

-}

-

-#ifdef PNG_WRITE_INTERLACING_SUPPORTED

-/* Pick out the correct pixels for the interlace pass.

- * The basic idea here is to go through the row with a source

- * pointer and a destination pointer (sp and dp), and copy the

- * correct pixels for the pass.  As the row gets compacted,

- * sp will always be >= dp, so we should never overwrite anything.

- * See the default: case for the easiest code to understand.

- */

-void /* PRIVATE */

-png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)

-{

-   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */

-

-   /* Start of interlace block */

-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};

-

-   /* Offset to next interlace block */

-   static PNG_CONST png_byte  png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};

-

-   png_debug(1, "in png_do_write_interlace");

-

-   /* We don't have to do anything on the last pass (6) */

-   if (pass < 6)

-   {

-      /* Each pixel depth is handled separately */

-      switch (row_info->pixel_depth)

-      {

-         case 1:

-         {

-            png_bytep sp;

-            png_bytep dp;

-            int shift;

-            int d;

-            int value;

-            png_uint_32 i;

-            png_uint_32 row_width = row_info->width;

-

-            dp = row;

-            d = 0;

-            shift = 7;

-

-            for (i = png_pass_start[pass]; i < row_width;

-               i += png_pass_inc[pass])

-            {

-               sp = row + (png_size_t)(i >> 3);

-               value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;

-               d |= (value << shift);

-

-               if (shift == 0)

-               {

-                  shift = 7;

-                  *dp++ = (png_byte)d;

-                  d = 0;

-               }

-

-               else

-                  shift--;

-

-            }

-            if (shift != 7)

-               *dp = (png_byte)d;

-

-            break;

-         }

-

-         case 2:

-         {

-            png_bytep sp;

-            png_bytep dp;

-            int shift;

-            int d;

-            int value;

-            png_uint_32 i;

-            png_uint_32 row_width = row_info->width;

-

-            dp = row;

-            shift = 6;

-            d = 0;

-

-            for (i = png_pass_start[pass]; i < row_width;

-               i += png_pass_inc[pass])

-            {

-               sp = row + (png_size_t)(i >> 2);

-               value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;

-               d |= (value << shift);

-

-               if (shift == 0)

-               {

-                  shift = 6;

-                  *dp++ = (png_byte)d;

-                  d = 0;

-               }

-

-               else

-                  shift -= 2;

-            }

-            if (shift != 6)

-               *dp = (png_byte)d;

-

-            break;

-         }

-

-         case 4:

-         {

-            png_bytep sp;

-            png_bytep dp;

-            int shift;

-            int d;

-            int value;

-            png_uint_32 i;

-            png_uint_32 row_width = row_info->width;

-

-            dp = row;

-            shift = 4;

-            d = 0;

-            for (i = png_pass_start[pass]; i < row_width;

-                i += png_pass_inc[pass])

-            {

-               sp = row + (png_size_t)(i >> 1);

-               value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;

-               d |= (value << shift);

-

-               if (shift == 0)

-               {

-                  shift = 4;

-                  *dp++ = (png_byte)d;

-                  d = 0;

-               }

-

-               else

-                  shift -= 4;

-            }

-            if (shift != 4)

-               *dp = (png_byte)d;

-

-            break;

-         }

-

-         default:

-         {

-            png_bytep sp;

-            png_bytep dp;

-            png_uint_32 i;

-            png_uint_32 row_width = row_info->width;

-            png_size_t pixel_bytes;

-

-            /* Start at the beginning */

-            dp = row;

-

-            /* Find out how many bytes each pixel takes up */

-            pixel_bytes = (row_info->pixel_depth >> 3);

-

-            /* Loop through the row, only looking at the pixels that matter */

-            for (i = png_pass_start[pass]; i < row_width;

-               i += png_pass_inc[pass])

-            {

-               /* Find out where the original pixel is */

-               sp = row + (png_size_t)i * pixel_bytes;

-

-               /* Move the pixel */

-               if (dp != sp)

-                  png_memcpy(dp, sp, pixel_bytes);

-

-               /* Next pixel */

-               dp += pixel_bytes;

-            }

-            break;

-         }

-      }

-      /* Set new row width */

-      row_info->width = (row_info->width +

-          png_pass_inc[pass] - 1 -

-          png_pass_start[pass]) /

-          png_pass_inc[pass];

-

-      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,

-          row_info->width);

-   }

-}

-#endif

-

-/* This filters the row, chooses which filter to use, if it has not already

- * been specified by the application, and then writes the row out with the

- * chosen filter.

- */

-static void png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,

-   png_size_t row_bytes);

-

-#define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)

-#define PNG_HISHIFT 10

-#define PNG_LOMASK ((png_uint_32)0xffffL)

-#define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))

-void /* PRIVATE */

-png_write_find_filter(png_structp png_ptr, png_row_infop row_info)

-{

-   png_bytep best_row;

-#ifdef PNG_WRITE_FILTER_SUPPORTED

-   png_bytep prev_row, row_buf;

-   png_uint_32 mins, bpp;

-   png_byte filter_to_do = png_ptr->do_filter;

-   png_size_t row_bytes = row_info->rowbytes;

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-   int num_p_filters = png_ptr->num_prev_filters;

-#endif

-

-   png_debug(1, "in png_write_find_filter");

-

-#ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-  if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS)

-  {

-     /* These will never be selected so we need not test them. */

-     filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH);

-  }

-#endif

-

-   /* Find out how many bytes offset each pixel is */

-   bpp = (row_info->pixel_depth + 7) >> 3;

-

-   prev_row = png_ptr->prev_row;

-#endif

-   best_row = png_ptr->row_buf;

-#ifdef PNG_WRITE_FILTER_SUPPORTED

-   row_buf = best_row;

-   mins = PNG_MAXSUM;

-

-   /* The prediction method we use is to find which method provides the

-    * smallest value when summing the absolute values of the distances

-    * from zero, using anything >= 128 as negative numbers.  This is known

-    * as the "minimum sum of absolute differences" heuristic.  Other

-    * heuristics are the "weighted minimum sum of absolute differences"

-    * (experimental and can in theory improve compression), and the "zlib

-    * predictive" method (not implemented yet), which does test compressions

-    * of lines using different filter methods, and then chooses the

-    * (series of) filter(s) that give minimum compressed data size (VERY

-    * computationally expensive).

-    *

-    * GRR 980525:  consider also

-    *

-    *   (1) minimum sum of absolute differences from running average (i.e.,

-    *       keep running sum of non-absolute differences & count of bytes)

-    *       [track dispersion, too?  restart average if dispersion too large?]

-    *

-    *  (1b) minimum sum of absolute differences from sliding average, probably

-    *       with window size <= deflate window (usually 32K)

-    *

-    *   (2) minimum sum of squared differences from zero or running average

-    *       (i.e., ~ root-mean-square approach)

-    */

-

-

-   /* We don't need to test the 'no filter' case if this is the only filter

-    * that has been chosen, as it doesn't actually do anything to the data.

-    */

-   if ((filter_to_do & PNG_FILTER_NONE) && filter_to_do != PNG_FILTER_NONE)

-   {

-      png_bytep rp;

-      png_uint_32 sum = 0;

-      png_size_t i;

-      int v;

-

-      for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)

-      {

-         v = *rp;

-         sum += (v < 128) ? v : 256 - v;

-      }

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         png_uint_32 sumhi, sumlo;

-         int j;

-         sumlo = sum & PNG_LOMASK;

-         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */

-

-         /* Reduce the sum if we match any of the previous rows */

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)

-            {

-               sumlo = (sumlo * png_ptr->filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               sumhi = (sumhi * png_ptr->filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         /* Factor in the cost of this filter (this is here for completeness,

-          * but it makes no sense to have a "cost" for the NONE filter, as

-          * it has the minimum possible computational cost - none).

-          */

-         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>

-             PNG_COST_SHIFT;

-

-         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>

-             PNG_COST_SHIFT;

-

-         if (sumhi > PNG_HIMASK)

-            sum = PNG_MAXSUM;

-

-         else

-            sum = (sumhi << PNG_HISHIFT) + sumlo;

-      }

-#endif

-      mins = sum;

-   }

-

-   /* Sub filter */

-   if (filter_to_do == PNG_FILTER_SUB)

-   /* It's the only filter so no testing is needed */

-   {

-      png_bytep rp, lp, dp;

-      png_size_t i;

-

-      for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;

-           i++, rp++, dp++)

-      {

-         *dp = *rp;

-      }

-

-      for (lp = row_buf + 1; i < row_bytes;

-         i++, rp++, lp++, dp++)

-      {

-         *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);

-      }

-

-      best_row = png_ptr->sub_row;

-   }

-

-   else if (filter_to_do & PNG_FILTER_SUB)

-   {

-      png_bytep rp, dp, lp;

-      png_uint_32 sum = 0, lmins = mins;

-      png_size_t i;

-      int v;

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      /* We temporarily increase the "minimum sum" by the factor we

-       * would reduce the sum of this filter, so that we can do the

-       * early exit comparison without scaling the sum each time.

-       */

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         int j;

-         png_uint_32 lmhi, lmlo;

-         lmlo = lmins & PNG_LOMASK;

-         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;

-

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)

-            {

-               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>

-             PNG_COST_SHIFT;

-

-         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>

-             PNG_COST_SHIFT;

-

-         if (lmhi > PNG_HIMASK)

-            lmins = PNG_MAXSUM;

-

-         else

-            lmins = (lmhi << PNG_HISHIFT) + lmlo;

-      }

-#endif

-

-      for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;

-           i++, rp++, dp++)

-      {

-         v = *dp = *rp;

-

-         sum += (v < 128) ? v : 256 - v;

-      }

-

-      for (lp = row_buf + 1; i < row_bytes;

-         i++, rp++, lp++, dp++)

-      {

-         v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);

-

-         sum += (v < 128) ? v : 256 - v;

-

-         if (sum > lmins)  /* We are already worse, don't continue. */

-            break;

-      }

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         int j;

-         png_uint_32 sumhi, sumlo;

-         sumlo = sum & PNG_LOMASK;

-         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;

-

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)

-            {

-               sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>

-             PNG_COST_SHIFT;

-

-         sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>

-             PNG_COST_SHIFT;

-

-         if (sumhi > PNG_HIMASK)

-            sum = PNG_MAXSUM;

-

-         else

-            sum = (sumhi << PNG_HISHIFT) + sumlo;

-      }

-#endif

-

-      if (sum < mins)

-      {

-         mins = sum;

-         best_row = png_ptr->sub_row;

-      }

-   }

-

-   /* Up filter */

-   if (filter_to_do == PNG_FILTER_UP)

-   {

-      png_bytep rp, dp, pp;

-      png_size_t i;

-

-      for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,

-          pp = prev_row + 1; i < row_bytes;

-          i++, rp++, pp++, dp++)

-      {

-         *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);

-      }

-

-      best_row = png_ptr->up_row;

-   }

-

-   else if (filter_to_do & PNG_FILTER_UP)

-   {

-      png_bytep rp, dp, pp;

-      png_uint_32 sum = 0, lmins = mins;

-      png_size_t i;

-      int v;

-

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         int j;

-         png_uint_32 lmhi, lmlo;

-         lmlo = lmins & PNG_LOMASK;

-         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;

-

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)

-            {

-               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>

-             PNG_COST_SHIFT;

-

-         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>

-             PNG_COST_SHIFT;

-

-         if (lmhi > PNG_HIMASK)

-            lmins = PNG_MAXSUM;

-

-         else

-            lmins = (lmhi << PNG_HISHIFT) + lmlo;

-      }

-#endif

-

-      for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,

-          pp = prev_row + 1; i < row_bytes; i++)

-      {

-         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);

-

-         sum += (v < 128) ? v : 256 - v;

-

-         if (sum > lmins)  /* We are already worse, don't continue. */

-            break;

-      }

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         int j;

-         png_uint_32 sumhi, sumlo;

-         sumlo = sum & PNG_LOMASK;

-         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;

-

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)

-            {

-               sumlo = (sumlo * png_ptr->filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               sumhi = (sumhi * png_ptr->filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>

-             PNG_COST_SHIFT;

-

-         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>

-             PNG_COST_SHIFT;

-

-         if (sumhi > PNG_HIMASK)

-            sum = PNG_MAXSUM;

-

-         else

-            sum = (sumhi << PNG_HISHIFT) + sumlo;

-      }

-#endif

-

-      if (sum < mins)

-      {

-         mins = sum;

-         best_row = png_ptr->up_row;

-      }

-   }

-

-   /* Avg filter */

-   if (filter_to_do == PNG_FILTER_AVG)

-   {

-      png_bytep rp, dp, pp, lp;

-      png_uint_32 i;

-

-      for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,

-           pp = prev_row + 1; i < bpp; i++)

-      {

-         *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);

-      }

-

-      for (lp = row_buf + 1; i < row_bytes; i++)

-      {

-         *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))

-                 & 0xff);

-      }

-      best_row = png_ptr->avg_row;

-   }

-

-   else if (filter_to_do & PNG_FILTER_AVG)

-   {

-      png_bytep rp, dp, pp, lp;

-      png_uint_32 sum = 0, lmins = mins;

-      png_size_t i;

-      int v;

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         int j;

-         png_uint_32 lmhi, lmlo;

-         lmlo = lmins & PNG_LOMASK;

-         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;

-

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)

-            {

-               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>

-             PNG_COST_SHIFT;

-

-         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>

-             PNG_COST_SHIFT;

-

-         if (lmhi > PNG_HIMASK)

-            lmins = PNG_MAXSUM;

-

-         else

-            lmins = (lmhi << PNG_HISHIFT) + lmlo;

-      }

-#endif

-

-      for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,

-           pp = prev_row + 1; i < bpp; i++)

-      {

-         v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);

-

-         sum += (v < 128) ? v : 256 - v;

-      }

-

-      for (lp = row_buf + 1; i < row_bytes; i++)

-      {

-         v = *dp++ =

-             (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);

-

-         sum += (v < 128) ? v : 256 - v;

-

-         if (sum > lmins)  /* We are already worse, don't continue. */

-            break;

-      }

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         int j;

-         png_uint_32 sumhi, sumlo;

-         sumlo = sum & PNG_LOMASK;

-         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;

-

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)

-            {

-               sumlo = (sumlo * png_ptr->filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               sumhi = (sumhi * png_ptr->filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>

-             PNG_COST_SHIFT;

-

-         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>

-             PNG_COST_SHIFT;

-

-         if (sumhi > PNG_HIMASK)

-            sum = PNG_MAXSUM;

-

-         else

-            sum = (sumhi << PNG_HISHIFT) + sumlo;

-      }

-#endif

-

-      if (sum < mins)

-      {

-         mins = sum;

-         best_row = png_ptr->avg_row;

-      }

-   }

-

-   /* Paeth filter */

-   if (filter_to_do == PNG_FILTER_PAETH)

-   {

-      png_bytep rp, dp, pp, cp, lp;

-      png_size_t i;

-

-      for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,

-          pp = prev_row + 1; i < bpp; i++)

-      {

-         *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);

-      }

-

-      for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)

-      {

-         int a, b, c, pa, pb, pc, p;

-

-         b = *pp++;

-         c = *cp++;

-         a = *lp++;

-

-         p = b - c;

-         pc = a - c;

-

-#ifdef PNG_USE_ABS

-         pa = abs(p);

-         pb = abs(pc);

-         pc = abs(p + pc);

-#else

-         pa = p < 0 ? -p : p;

-         pb = pc < 0 ? -pc : pc;

-         pc = (p + pc) < 0 ? -(p + pc) : p + pc;

-#endif

-

-         p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;

-

-         *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);

-      }

-      best_row = png_ptr->paeth_row;

-   }

-

-   else if (filter_to_do & PNG_FILTER_PAETH)

-   {

-      png_bytep rp, dp, pp, cp, lp;

-      png_uint_32 sum = 0, lmins = mins;

-      png_size_t i;

-      int v;

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         int j;

-         png_uint_32 lmhi, lmlo;

-         lmlo = lmins & PNG_LOMASK;

-         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;

-

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)

-            {

-               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>

-             PNG_COST_SHIFT;

-

-         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>

-             PNG_COST_SHIFT;

-

-         if (lmhi > PNG_HIMASK)

-            lmins = PNG_MAXSUM;

-

-         else

-            lmins = (lmhi << PNG_HISHIFT) + lmlo;

-      }

-#endif

-

-      for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,

-          pp = prev_row + 1; i < bpp; i++)

-      {

-         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);

-

-         sum += (v < 128) ? v : 256 - v;

-      }

-

-      for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)

-      {

-         int a, b, c, pa, pb, pc, p;

-

-         b = *pp++;

-         c = *cp++;

-         a = *lp++;

-

-#ifndef PNG_SLOW_PAETH

-         p = b - c;

-         pc = a - c;

-#ifdef PNG_USE_ABS

-         pa = abs(p);

-         pb = abs(pc);

-         pc = abs(p + pc);

-#else

-         pa = p < 0 ? -p : p;

-         pb = pc < 0 ? -pc : pc;

-         pc = (p + pc) < 0 ? -(p + pc) : p + pc;

-#endif

-         p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;

-#else /* PNG_SLOW_PAETH */

-         p = a + b - c;

-         pa = abs(p - a);

-         pb = abs(p - b);

-         pc = abs(p - c);

-

-         if (pa <= pb && pa <= pc)

-            p = a;

-

-         else if (pb <= pc)

-            p = b;

-

-         else

-            p = c;

-#endif /* PNG_SLOW_PAETH */

-

-         v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);

-

-         sum += (v < 128) ? v : 256 - v;

-

-         if (sum > lmins)  /* We are already worse, don't continue. */

-            break;

-      }

-

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)

-      {

-         int j;

-         png_uint_32 sumhi, sumlo;

-         sumlo = sum & PNG_LOMASK;

-         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;

-

-         for (j = 0; j < num_p_filters; j++)

-         {

-            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)

-            {

-               sumlo = (sumlo * png_ptr->filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-

-               sumhi = (sumhi * png_ptr->filter_weights[j]) >>

-                   PNG_WEIGHT_SHIFT;

-            }

-         }

-

-         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>

-             PNG_COST_SHIFT;

-

-         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>

-             PNG_COST_SHIFT;

-

-         if (sumhi > PNG_HIMASK)

-            sum = PNG_MAXSUM;

-

-         else

-            sum = (sumhi << PNG_HISHIFT) + sumlo;

-      }

-#endif

-

-      if (sum < mins)

-      {

-         best_row = png_ptr->paeth_row;

-      }

-   }

-#endif /* PNG_WRITE_FILTER_SUPPORTED */

-

-   /* Do the actual writing of the filtered row data from the chosen filter. */

-   png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);

-

-#ifdef PNG_WRITE_FILTER_SUPPORTED

-#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED

-   /* Save the type of filter we picked this time for future calculations */

-   if (png_ptr->num_prev_filters > 0)

-   {

-      int j;

-

-      for (j = 1; j < num_p_filters; j++)

-      {

-         png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];

-      }

-

-      png_ptr->prev_filters[j] = best_row[0];

-   }

-#endif

-#endif /* PNG_WRITE_FILTER_SUPPORTED */

-}

-

-

-/* Do the actual writing of a previously filtered row. */

-static void

-png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,

-   png_size_t avail/*includes filter byte*/)

-{

-   png_debug(1, "in png_write_filtered_row");

-

-   png_debug1(2, "filter = %d", filtered_row[0]);

-   /* Set up the zlib input buffer */

-

-   png_ptr->zstream.next_in = filtered_row;

-   png_ptr->zstream.avail_in = 0;

-   /* Repeat until we have compressed all the data */

-   do

-   {

-      int ret; /* Return of zlib */

-

-      /* Record the number of bytes available - zlib supports at least 65535

-       * bytes at one step, depending on the size of the zlib type 'uInt', the

-       * maximum size zlib can write at once is ZLIB_IO_MAX (from pngpriv.h).

-       * Use this because on 16 bit systems 'rowbytes' can be up to 65536 (i.e.

-       * one more than 16 bits) and, in this case 'rowbytes+1' can overflow a

-       * uInt.  ZLIB_IO_MAX can be safely reduced to cause zlib to be called

-       * with smaller chunks of data.

-       */

-      if (png_ptr->zstream.avail_in == 0)

-      {

-         if (avail > ZLIB_IO_MAX)

-         {

-            png_ptr->zstream.avail_in  = ZLIB_IO_MAX;

-            avail -= ZLIB_IO_MAX;

-         }

-

-         else

-         {

-            /* So this will fit in the available uInt space: */

-            png_ptr->zstream.avail_in = (uInt)avail;

-            avail = 0;

-         }

-      }

-

-      /* Compress the data */

-      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);

-

-      /* Check for compression errors */

-      if (ret != Z_OK)

-      {

-         if (png_ptr->zstream.msg != NULL)

-            png_error(png_ptr, png_ptr->zstream.msg);

-

-         else

-            png_error(png_ptr, "zlib error");

-      }

-

-      /* See if it is time to write another IDAT */

-      if (!(png_ptr->zstream.avail_out))

-      {

-         /* Write the IDAT and reset the zlib output buffer */

-         png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);

-      }

-   /* Repeat until all data has been compressed */

-   } while (avail > 0 || png_ptr->zstream.avail_in > 0);

-

-   /* Swap the current and previous rows */

-   if (png_ptr->prev_row != NULL)

-   {

-      png_bytep tptr;

-

-      tptr = png_ptr->prev_row;

-      png_ptr->prev_row = png_ptr->row_buf;

-      png_ptr->row_buf = tptr;

-   }

-

-   /* Finish row - updates counters and flushes zlib if last row */

-   png_write_finish_row(png_ptr);

-

-#ifdef PNG_WRITE_FLUSH_SUPPORTED

-   png_ptr->flush_rows++;

-

-   if (png_ptr->flush_dist > 0 &&

-       png_ptr->flush_rows >= png_ptr->flush_dist)

-   {

-      png_write_flush(png_ptr);

-   }

-#endif

-}

-#endif /* PNG_WRITE_SUPPORTED */

+
+/* pngwutil.c - utilities to write a PNG file
+ *
+ * Last changed in libpng 1.5.6 [November 3, 2011]
+ * Copyright (c) 1998-2011 Glenn Randers-Pehrson
+ * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+#include "pngpriv.h"
+
+#ifdef PNG_WRITE_SUPPORTED
+
+#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
+/* Place a 32-bit number into a buffer in PNG byte order.  We work
+ * with unsigned numbers for convenience, although one supported
+ * ancillary chunk uses signed (two's complement) numbers.
+ */
+void PNGAPI
+png_save_uint_32(png_bytep buf, png_uint_32 i)
+{
+   buf[0] = (png_byte)((i >> 24) & 0xff);
+   buf[1] = (png_byte)((i >> 16) & 0xff);
+   buf[2] = (png_byte)((i >> 8) & 0xff);
+   buf[3] = (png_byte)(i & 0xff);
+}
+
+#ifdef PNG_SAVE_INT_32_SUPPORTED
+/* The png_save_int_32 function assumes integers are stored in two's
+ * complement format.  If this isn't the case, then this routine needs to
+ * be modified to write data in two's complement format.  Note that,
+ * the following works correctly even if png_int_32 has more than 32 bits
+ * (compare the more complex code required on read for sign extention.)
+ */
+void PNGAPI
+png_save_int_32(png_bytep buf, png_int_32 i)
+{
+   buf[0] = (png_byte)((i >> 24) & 0xff);
+   buf[1] = (png_byte)((i >> 16) & 0xff);
+   buf[2] = (png_byte)((i >> 8) & 0xff);
+   buf[3] = (png_byte)(i & 0xff);
+}
+#endif
+
+/* Place a 16-bit number into a buffer in PNG byte order.
+ * The parameter is declared unsigned int, not png_uint_16,
+ * just to avoid potential problems on pre-ANSI C compilers.
+ */
+void PNGAPI
+png_save_uint_16(png_bytep buf, unsigned int i)
+{
+   buf[0] = (png_byte)((i >> 8) & 0xff);
+   buf[1] = (png_byte)(i & 0xff);
+}
+#endif
+
+/* Simple function to write the signature.  If we have already written
+ * the magic bytes of the signature, or more likely, the PNG stream is
+ * being embedded into another stream and doesn't need its own signature,
+ * we should call png_set_sig_bytes() to tell libpng how many of the
+ * bytes have already been written.
+ */
+void PNGAPI
+png_write_sig(png_structp png_ptr)
+{
+   png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   /* Inform the I/O callback that the signature is being written */
+   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
+#endif
+
+   /* Write the rest of the 8 byte signature */
+   png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
+      (png_size_t)(8 - png_ptr->sig_bytes));
+
+   if (png_ptr->sig_bytes < 3)
+      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
+}
+
+/* Write the start of a PNG chunk.  The type is the chunk type.
+ * The total_length is the sum of the lengths of all the data you will be
+ * passing in png_write_chunk_data().
+ */
+static void
+png_write_chunk_header(png_structp png_ptr, png_uint_32 chunk_name,
+    png_uint_32 length)
+{
+   png_byte buf[8];
+
+#if defined(PNG_DEBUG) && (PNG_DEBUG > 0)
+   PNG_CSTRING_FROM_CHUNK(buf, chunk_name);
+   png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length);
+#endif
+
+   if (png_ptr == NULL)
+      return;
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   /* Inform the I/O callback that the chunk header is being written.
+    * PNG_IO_CHUNK_HDR requires a single I/O call.
+    */
+   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR;
+#endif
+
+   /* Write the length and the chunk name */
+   png_save_uint_32(buf, length);
+   png_save_uint_32(buf + 4, chunk_name);
+   png_write_data(png_ptr, buf, 8);
+
+   /* Put the chunk name into png_ptr->chunk_name */
+   png_ptr->chunk_name = chunk_name;
+
+   /* Reset the crc and run it over the chunk name */
+   png_reset_crc(png_ptr);
+
+   png_calculate_crc(png_ptr, buf + 4, 4);
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   /* Inform the I/O callback that chunk data will (possibly) be written.
+    * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
+    */
+   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA;
+#endif
+}
+
+void PNGAPI
+png_write_chunk_start(png_structp png_ptr, png_const_bytep chunk_string,
+    png_uint_32 length)
+{
+   png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length);
+}
+
+/* Write the data of a PNG chunk started with png_write_chunk_header().
+ * Note that multiple calls to this function are allowed, and that the
+ * sum of the lengths from these calls *must* add up to the total_length
+ * given to png_write_chunk_header().
+ */
+void PNGAPI
+png_write_chunk_data(png_structp png_ptr, png_const_bytep data,
+    png_size_t length)
+{
+   /* Write the data, and run the CRC over it */
+   if (png_ptr == NULL)
+      return;
+
+   if (data != NULL && length > 0)
+   {
+      png_write_data(png_ptr, data, length);
+
+      /* Update the CRC after writing the data,
+       * in case that the user I/O routine alters it.
+       */
+      png_calculate_crc(png_ptr, data, length);
+   }
+}
+
+/* Finish a chunk started with png_write_chunk_header(). */
+void PNGAPI
+png_write_chunk_end(png_structp png_ptr)
+{
+   png_byte buf[4];
+
+   if (png_ptr == NULL) return;
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   /* Inform the I/O callback that the chunk CRC is being written.
+    * PNG_IO_CHUNK_CRC requires a single I/O function call.
+    */
+   png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC;
+#endif
+
+   /* Write the crc in a single operation */
+   png_save_uint_32(buf, png_ptr->crc);
+
+   png_write_data(png_ptr, buf, (png_size_t)4);
+}
+
+/* Write a PNG chunk all at once.  The type is an array of ASCII characters
+ * representing the chunk name.  The array must be at least 4 bytes in
+ * length, and does not need to be null terminated.  To be safe, pass the
+ * pre-defined chunk names here, and if you need a new one, define it
+ * where the others are defined.  The length is the length of the data.
+ * All the data must be present.  If that is not possible, use the
+ * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
+ * functions instead.
+ */
+static void
+png_write_complete_chunk(png_structp png_ptr, png_uint_32 chunk_name,
+   png_const_bytep data, png_size_t length)
+{
+   if (png_ptr == NULL)
+      return;
+
+   /* On 64 bit architectures 'length' may not fit in a png_uint_32. */
+   if (length > PNG_UINT_32_MAX)
+      png_error(png_ptr, "length exceeds PNG maxima");
+
+   png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length);
+   png_write_chunk_data(png_ptr, data, length);
+   png_write_chunk_end(png_ptr);
+}
+
+/* This is the API that calls the internal function above. */
+void PNGAPI
+png_write_chunk(png_structp png_ptr, png_const_bytep chunk_string,
+   png_const_bytep data, png_size_t length)
+{
+   png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
+      length);
+}
+
+/* Initialize the compressor for the appropriate type of compression. */
+static void
+png_zlib_claim(png_structp png_ptr, png_uint_32 state)
+{
+   if (!(png_ptr->zlib_state & PNG_ZLIB_IN_USE))
+   {
+      /* If already initialized for 'state' do not re-init. */
+      if (png_ptr->zlib_state != state)
+      {
+         int ret = Z_OK;
+         png_const_charp who = "-";
+
+         /* If actually initialized for another state do a deflateEnd. */
+         if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)
+         {
+            ret = deflateEnd(&png_ptr->zstream);
+            who = "end";
+            png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
+         }
+
+         /* zlib itself detects an incomplete state on deflateEnd */
+         if (ret == Z_OK) switch (state)
+         {
+#           ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
+               case PNG_ZLIB_FOR_TEXT:
+                  ret = deflateInit2(&png_ptr->zstream,
+                     png_ptr->zlib_text_level, png_ptr->zlib_text_method,
+                     png_ptr->zlib_text_window_bits,
+                     png_ptr->zlib_text_mem_level, png_ptr->zlib_text_strategy);
+                  who = "text";
+                  break;
+#           endif
+
+            case PNG_ZLIB_FOR_IDAT:
+               ret = deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
+                   png_ptr->zlib_method, png_ptr->zlib_window_bits,
+                   png_ptr->zlib_mem_level, png_ptr->zlib_strategy);
+               who = "IDAT";
+               break;
+
+            default:
+               png_error(png_ptr, "invalid zlib state");
+         }
+
+         if (ret == Z_OK)
+            png_ptr->zlib_state = state;
+
+         else /* an error in deflateEnd or deflateInit2 */
+         {
+            size_t pos = 0;
+            char msg[64];
+
+            pos = png_safecat(msg, sizeof msg, pos,
+               "zlib failed to initialize compressor (");
+            pos = png_safecat(msg, sizeof msg, pos, who);
+
+            switch (ret)
+            {
+               case Z_VERSION_ERROR:
+                  pos = png_safecat(msg, sizeof msg, pos, ") version error");
+                  break;
+
+               case Z_STREAM_ERROR:
+                  pos = png_safecat(msg, sizeof msg, pos, ") stream error");
+                  break;
+
+               case Z_MEM_ERROR:
+                  pos = png_safecat(msg, sizeof msg, pos, ") memory error");
+                  break;
+
+               default:
+                  pos = png_safecat(msg, sizeof msg, pos, ") unknown error");
+                  break;
+            }
+
+            png_error(png_ptr, msg);
+         }
+      }
+
+      /* Here on success, claim the zstream: */
+      png_ptr->zlib_state |= PNG_ZLIB_IN_USE;
+   }
+
+   else
+      png_error(png_ptr, "zstream already in use (internal error)");
+}
+
+/* The opposite: release the stream.  It is also reset, this API will warn on
+ * error but will not fail.
+ */
+static void
+png_zlib_release(png_structp png_ptr)
+{
+   if (png_ptr->zlib_state & PNG_ZLIB_IN_USE)
+   {
+      int ret = deflateReset(&png_ptr->zstream);
+
+      png_ptr->zlib_state &= ~PNG_ZLIB_IN_USE;
+
+      if (ret != Z_OK)
+      {
+         png_const_charp err;
+         PNG_WARNING_PARAMETERS(p)
+
+         switch (ret)
+         {
+            case Z_VERSION_ERROR:
+               err = "version";
+               break;
+
+            case Z_STREAM_ERROR:
+               err = "stream";
+               break;
+
+            case Z_MEM_ERROR:
+               err = "memory";
+               break;
+
+            default:
+               err = "unknown";
+               break;
+         }
+
+         png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d, ret);
+         png_warning_parameter(p, 2, err);
+
+         if (png_ptr->zstream.msg)
+            err = png_ptr->zstream.msg;
+         else
+            err = "[no zlib message]";
+
+         png_warning_parameter(p, 3, err);
+
+         png_formatted_warning(png_ptr, p,
+            "zlib failed to reset compressor: @1(@2): @3");
+      }
+   }
+
+   else
+      png_warning(png_ptr, "zstream not in use (internal error)");
+}
+
+#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
+/* This pair of functions encapsulates the operation of (a) compressing a
+ * text string, and (b) issuing it later as a series of chunk data writes.
+ * The compression_state structure is shared context for these functions
+ * set up by the caller in order to make the whole mess thread-safe.
+ */
+
+typedef struct
+{
+   png_const_bytep input;   /* The uncompressed input data */
+   png_size_t input_len;    /* Its length */
+   int num_output_ptr;      /* Number of output pointers used */
+   int max_output_ptr;      /* Size of output_ptr */
+   png_bytep *output_ptr;   /* Array of pointers to output */
+} compression_state;
+
+/* Compress given text into storage in the png_ptr structure */
+static int /* PRIVATE */
+png_text_compress(png_structp png_ptr,
+    png_const_charp text, png_size_t text_len, int compression,
+    compression_state *comp)
+{
+   int ret;
+
+   comp->num_output_ptr = 0;
+   comp->max_output_ptr = 0;
+   comp->output_ptr = NULL;
+   comp->input = NULL;
+   comp->input_len = text_len;
+
+   /* We may just want to pass the text right through */
+   if (compression == PNG_TEXT_COMPRESSION_NONE)
+   {
+      comp->input = (png_const_bytep)text;
+      return((int)text_len);
+   }
+
+   if (compression >= PNG_TEXT_COMPRESSION_LAST)
+   {
+      PNG_WARNING_PARAMETERS(p)
+
+      png_warning_parameter_signed(p, 1, PNG_NUMBER_FORMAT_d,
+         compression);
+      png_formatted_warning(png_ptr, p, "Unknown compression type @1");
+   }
+
+   /* We can't write the chunk until we find out how much data we have,
+    * which means we need to run the compressor first and save the
+    * output.  This shouldn't be a problem, as the vast majority of
+    * comments should be reasonable, but we will set up an array of
+    * malloc'd pointers to be sure.
+    *
+    * If we knew the application was well behaved, we could simplify this
+    * greatly by assuming we can always malloc an output buffer large
+    * enough to hold the compressed text ((1001 * text_len / 1000) + 12)
+    * and malloc this directly.  The only time this would be a bad idea is
+    * if we can't malloc more than 64K and we have 64K of random input
+    * data, or if the input string is incredibly large (although this
+    * wouldn't cause a failure, just a slowdown due to swapping).
+    */
+   png_zlib_claim(png_ptr, PNG_ZLIB_FOR_TEXT);
+
+   /* Set up the compression buffers */
+   /* TODO: the following cast hides a potential overflow problem. */
+   png_ptr->zstream.avail_in = (uInt)text_len;
+
+   /* NOTE: assume zlib doesn't overwrite the input */
+   png_ptr->zstream.next_in = (Bytef *)text;
+   png_ptr->zstream.avail_out = png_ptr->zbuf_size;
+   png_ptr->zstream.next_out = png_ptr->zbuf;
+
+   /* This is the same compression loop as in png_write_row() */
+   do
+   {
+      /* Compress the data */
+      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
+
+      if (ret != Z_OK)
+      {
+         /* Error */
+         if (png_ptr->zstream.msg != NULL)
+            png_error(png_ptr, png_ptr->zstream.msg);
+
+         else
+            png_error(png_ptr, "zlib error");
+      }
+
+      /* Check to see if we need more room */
+      if (!(png_ptr->zstream.avail_out))
+      {
+         /* Make sure the output array has room */
+         if (comp->num_output_ptr >= comp->max_output_ptr)
+         {
+            int old_max;
+
+            old_max = comp->max_output_ptr;
+            comp->max_output_ptr = comp->num_output_ptr + 4;
+            if (comp->output_ptr != NULL)
+            {
+               png_bytepp old_ptr;
+
+               old_ptr = comp->output_ptr;
+
+               comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
+                   (png_alloc_size_t)
+                   (comp->max_output_ptr * png_sizeof(png_charpp)));
+
+               png_memcpy(comp->output_ptr, old_ptr, old_max
+                   * png_sizeof(png_charp));
+
+               png_free(png_ptr, old_ptr);
+            }
+            else
+               comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
+                   (png_alloc_size_t)
+                   (comp->max_output_ptr * png_sizeof(png_charp)));
+         }
+
+         /* Save the data */
+         comp->output_ptr[comp->num_output_ptr] =
+             (png_bytep)png_malloc(png_ptr,
+             (png_alloc_size_t)png_ptr->zbuf_size);
+
+         png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
+             png_ptr->zbuf_size);
+
+         comp->num_output_ptr++;
+
+         /* and reset the buffer */
+         png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+         png_ptr->zstream.next_out = png_ptr->zbuf;
+      }
+   /* Continue until we don't have any more to compress */
+   } while (png_ptr->zstream.avail_in);
+
+   /* Finish the compression */
+   do
+   {
+      /* Tell zlib we are finished */
+      ret = deflate(&png_ptr->zstream, Z_FINISH);
+
+      if (ret == Z_OK)
+      {
+         /* Check to see if we need more room */
+         if (!(png_ptr->zstream.avail_out))
+         {
+            /* Check to make sure our output array has room */
+            if (comp->num_output_ptr >= comp->max_output_ptr)
+            {
+               int old_max;
+
+               old_max = comp->max_output_ptr;
+               comp->max_output_ptr = comp->num_output_ptr + 4;
+               if (comp->output_ptr != NULL)
+               {
+                  png_bytepp old_ptr;
+
+                  old_ptr = comp->output_ptr;
+
+                  /* This could be optimized to realloc() */
+                  comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
+                      (png_alloc_size_t)(comp->max_output_ptr *
+                      png_sizeof(png_charp)));
+
+                  png_memcpy(comp->output_ptr, old_ptr,
+                      old_max * png_sizeof(png_charp));
+
+                  png_free(png_ptr, old_ptr);
+               }
+
+               else
+                  comp->output_ptr = (png_bytepp)png_malloc(png_ptr,
+                      (png_alloc_size_t)(comp->max_output_ptr *
+                      png_sizeof(png_charp)));
+            }
+
+            /* Save the data */
+            comp->output_ptr[comp->num_output_ptr] =
+                (png_bytep)png_malloc(png_ptr,
+                (png_alloc_size_t)png_ptr->zbuf_size);
+
+            png_memcpy(comp->output_ptr[comp->num_output_ptr], png_ptr->zbuf,
+                png_ptr->zbuf_size);
+
+            comp->num_output_ptr++;
+
+            /* and reset the buffer pointers */
+            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+            png_ptr->zstream.next_out = png_ptr->zbuf;
+         }
+      }
+      else if (ret != Z_STREAM_END)
+      {
+         /* We got an error */
+         if (png_ptr->zstream.msg != NULL)
+            png_error(png_ptr, png_ptr->zstream.msg);
+
+         else
+            png_error(png_ptr, "zlib error");
+      }
+   } while (ret != Z_STREAM_END);
+
+   /* Text length is number of buffers plus last buffer */
+   text_len = png_ptr->zbuf_size * comp->num_output_ptr;
+
+   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
+      text_len += png_ptr->zbuf_size - (png_size_t)png_ptr->zstream.avail_out;
+
+   return((int)text_len);
+}
+
+/* Ship the compressed text out via chunk writes */
+static void /* PRIVATE */
+png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)
+{
+   int i;
+
+   /* Handle the no-compression case */
+   if (comp->input)
+   {
+      png_write_chunk_data(png_ptr, comp->input, comp->input_len);
+
+      return;
+   }
+
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+   /* The zbuf_size test is because the code below doesn't work if zbuf_size is
+    * '1'; simply skip it to avoid memory overwrite.
+    */
+   if (comp->input_len >= 2 && comp->input_len < 16384 && png_ptr->zbuf_size > 1)
+   {
+      unsigned int z_cmf;  /* zlib compression method and flags */
+
+      /* Optimize the CMF field in the zlib stream.  This hack of the zlib
+       * stream is compliant to the stream specification.
+       */
+
+      if (comp->num_output_ptr)
+        z_cmf = comp->output_ptr[0][0];
+      else
+        z_cmf = png_ptr->zbuf[0];
+
+      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
+      {
+         unsigned int z_cinfo;
+         unsigned int half_z_window_size;
+         png_size_t uncompressed_text_size = comp->input_len;
+
+         z_cinfo = z_cmf >> 4;
+         half_z_window_size = 1 << (z_cinfo + 7);
+
+         while (uncompressed_text_size <= half_z_window_size &&
+             half_z_window_size >= 256)
+         {
+            z_cinfo--;
+            half_z_window_size >>= 1;
+         }
+
+         z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
+
+         if (comp->num_output_ptr)
+         {
+
+           if (comp->output_ptr[0][0] != z_cmf)
+           {
+              int tmp;
+
+              comp->output_ptr[0][0] = (png_byte)z_cmf;
+              tmp = comp->output_ptr[0][1] & 0xe0;
+              tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
+              comp->output_ptr[0][1] = (png_byte)tmp;
+           }
+         }
+         else
+         {
+            int tmp;
+
+            png_ptr->zbuf[0] = (png_byte)z_cmf;
+            tmp = png_ptr->zbuf[1] & 0xe0;
+            tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
+            png_ptr->zbuf[1] = (png_byte)tmp;
+         }
+      }
+
+      else
+         png_error(png_ptr,
+             "Invalid zlib compression method or flags in non-IDAT chunk");
+   }
+#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
+
+   /* Write saved output buffers, if any */
+   for (i = 0; i < comp->num_output_ptr; i++)
+   {
+      png_write_chunk_data(png_ptr, comp->output_ptr[i],
+          (png_size_t)png_ptr->zbuf_size);
+
+      png_free(png_ptr, comp->output_ptr[i]);
+   }
+
+   if (comp->max_output_ptr != 0)
+      png_free(png_ptr, comp->output_ptr);
+
+   /* Write anything left in zbuf */
+   if (png_ptr->zstream.avail_out < (png_uint_32)png_ptr->zbuf_size)
+      png_write_chunk_data(png_ptr, png_ptr->zbuf,
+          (png_size_t)(png_ptr->zbuf_size - png_ptr->zstream.avail_out));
+
+   /* Reset zlib for another zTXt/iTXt or image data */
+   png_zlib_release(png_ptr);
+}
+#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
+
+/* Write the IHDR chunk, and update the png_struct with the necessary
+ * information.  Note that the rest of this code depends upon this
+ * information being correct.
+ */
+void /* PRIVATE */
+png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
+    int bit_depth, int color_type, int compression_type, int filter_type,
+    int interlace_type)
+{
+   png_byte buf[13]; /* Buffer to store the IHDR info */
+
+   png_debug(1, "in png_write_IHDR");
+
+   /* Check that we have valid input data from the application info */
+   switch (color_type)
+   {
+      case PNG_COLOR_TYPE_GRAY:
+         switch (bit_depth)
+         {
+            case 1:
+            case 2:
+            case 4:
+            case 8:
+#ifdef PNG_WRITE_16BIT_SUPPORTED
+            case 16:
+#endif
+               png_ptr->channels = 1; break;
+
+            default:
+               png_error(png_ptr,
+                   "Invalid bit depth for grayscale image");
+         }
+         break;
+
+      case PNG_COLOR_TYPE_RGB:
+#ifdef PNG_WRITE_16BIT_SUPPORTED
+         if (bit_depth != 8 && bit_depth != 16)
+#else
+         if (bit_depth != 8)
+#endif
+            png_error(png_ptr, "Invalid bit depth for RGB image");
+
+         png_ptr->channels = 3;
+         break;
+
+      case PNG_COLOR_TYPE_PALETTE:
+         switch (bit_depth)
+         {
+            case 1:
+            case 2:
+            case 4:
+            case 8:
+               png_ptr->channels = 1;
+               break;
+
+            default:
+               png_error(png_ptr, "Invalid bit depth for paletted image");
+         }
+         break;
+
+      case PNG_COLOR_TYPE_GRAY_ALPHA:
+         if (bit_depth != 8 && bit_depth != 16)
+            png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
+
+         png_ptr->channels = 2;
+         break;
+
+      case PNG_COLOR_TYPE_RGB_ALPHA:
+#ifdef PNG_WRITE_16BIT_SUPPORTED
+         if (bit_depth != 8 && bit_depth != 16)
+#else
+         if (bit_depth != 8)
+#endif
+            png_error(png_ptr, "Invalid bit depth for RGBA image");
+
+         png_ptr->channels = 4;
+         break;
+
+      default:
+         png_error(png_ptr, "Invalid image color type specified");
+   }
+
+   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
+   {
+      png_warning(png_ptr, "Invalid compression type specified");
+      compression_type = PNG_COMPRESSION_TYPE_BASE;
+   }
+
+   /* Write filter_method 64 (intrapixel differencing) only if
+    * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
+    * 2. Libpng did not write a PNG signature (this filter_method is only
+    *    used in PNG datastreams that are embedded in MNG datastreams) and
+    * 3. The application called png_permit_mng_features with a mask that
+    *    included PNG_FLAG_MNG_FILTER_64 and
+    * 4. The filter_method is 64 and
+    * 5. The color_type is RGB or RGBA
+    */
+   if (
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+       ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
+       (color_type == PNG_COLOR_TYPE_RGB ||
+        color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
+       (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
+#endif
+       filter_type != PNG_FILTER_TYPE_BASE)
+   {
+      png_warning(png_ptr, "Invalid filter type specified");
+      filter_type = PNG_FILTER_TYPE_BASE;
+   }
+
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+   if (interlace_type != PNG_INTERLACE_NONE &&
+       interlace_type != PNG_INTERLACE_ADAM7)
+   {
+      png_warning(png_ptr, "Invalid interlace type specified");
+      interlace_type = PNG_INTERLACE_ADAM7;
+   }
+#else
+   interlace_type=PNG_INTERLACE_NONE;
+#endif
+
+   /* Save the relevent information */
+   png_ptr->bit_depth = (png_byte)bit_depth;
+   png_ptr->color_type = (png_byte)color_type;
+   png_ptr->interlaced = (png_byte)interlace_type;
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+   png_ptr->filter_type = (png_byte)filter_type;
+#endif
+   png_ptr->compression_type = (png_byte)compression_type;
+   png_ptr->width = width;
+   png_ptr->height = height;
+
+   png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
+   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
+   /* Set the usr info, so any transformations can modify it */
+   png_ptr->usr_width = png_ptr->width;
+   png_ptr->usr_bit_depth = png_ptr->bit_depth;
+   png_ptr->usr_channels = png_ptr->channels;
+
+   /* Pack the header information into the buffer */
+   png_save_uint_32(buf, width);
+   png_save_uint_32(buf + 4, height);
+   buf[8] = (png_byte)bit_depth;
+   buf[9] = (png_byte)color_type;
+   buf[10] = (png_byte)compression_type;
+   buf[11] = (png_byte)filter_type;
+   buf[12] = (png_byte)interlace_type;
+
+   /* Write the chunk */
+   png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
+
+   /* Initialize zlib with PNG info */
+   png_ptr->zstream.zalloc = png_zalloc;
+   png_ptr->zstream.zfree = png_zfree;
+   png_ptr->zstream.opaque = (voidpf)png_ptr;
+
+   if (!(png_ptr->do_filter))
+   {
+      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
+          png_ptr->bit_depth < 8)
+         png_ptr->do_filter = PNG_FILTER_NONE;
+
+      else
+         png_ptr->do_filter = PNG_ALL_FILTERS;
+   }
+
+   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY))
+   {
+      if (png_ptr->do_filter != PNG_FILTER_NONE)
+         png_ptr->zlib_strategy = Z_FILTERED;
+
+      else
+         png_ptr->zlib_strategy = Z_DEFAULT_STRATEGY;
+   }
+
+   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_LEVEL))
+      png_ptr->zlib_level = Z_DEFAULT_COMPRESSION;
+
+   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
+      png_ptr->zlib_mem_level = 8;
+
+   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
+      png_ptr->zlib_window_bits = 15;
+
+   if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
+      png_ptr->zlib_method = 8;
+
+#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
+#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
+   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_STRATEGY))
+      png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
+
+   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_LEVEL))
+      png_ptr->zlib_text_level = png_ptr->zlib_level;
+
+   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL))
+      png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
+
+   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS))
+      png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
+
+   if (!(png_ptr->flags & PNG_FLAG_ZTXT_CUSTOM_METHOD))
+      png_ptr->zlib_text_method = png_ptr->zlib_method;
+#else
+   png_ptr->zlib_text_strategy = Z_DEFAULT_STRATEGY;
+   png_ptr->zlib_text_level = png_ptr->zlib_level;
+   png_ptr->zlib_text_mem_level = png_ptr->zlib_mem_level;
+   png_ptr->zlib_text_window_bits = png_ptr->zlib_window_bits;
+   png_ptr->zlib_text_method = png_ptr->zlib_method;
+#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
+#endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
+
+   /* Record that the compressor has not yet been initialized. */
+   png_ptr->zlib_state = PNG_ZLIB_UNINITIALIZED;
+
+   png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */
+}
+
+/* Write the palette.  We are careful not to trust png_color to be in the
+ * correct order for PNG, so people can redefine it to any convenient
+ * structure.
+ */
+void /* PRIVATE */
+png_write_PLTE(png_structp png_ptr, png_const_colorp palette,
+    png_uint_32 num_pal)
+{
+   png_uint_32 i;
+   png_const_colorp pal_ptr;
+   png_byte buf[3];
+
+   png_debug(1, "in png_write_PLTE");
+
+   if ((
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+       !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
+#endif
+       num_pal == 0) || num_pal > 256)
+   {
+      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+      {
+         png_error(png_ptr, "Invalid number of colors in palette");
+      }
+
+      else
+      {
+         png_warning(png_ptr, "Invalid number of colors in palette");
+         return;
+      }
+   }
+
+   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
+   {
+      png_warning(png_ptr,
+          "Ignoring request to write a PLTE chunk in grayscale PNG");
+
+      return;
+   }
+
+   png_ptr->num_palette = (png_uint_16)num_pal;
+   png_debug1(3, "num_palette = %d", png_ptr->num_palette);
+
+   png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3));
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
+
+   for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
+   {
+      buf[0] = pal_ptr->red;
+      buf[1] = pal_ptr->green;
+      buf[2] = pal_ptr->blue;
+      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
+   }
+
+#else
+   /* This is a little slower but some buggy compilers need to do this
+    * instead
+    */
+   pal_ptr=palette;
+
+   for (i = 0; i < num_pal; i++)
+   {
+      buf[0] = pal_ptr[i].red;
+      buf[1] = pal_ptr[i].green;
+      buf[2] = pal_ptr[i].blue;
+      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
+   }
+
+#endif
+   png_write_chunk_end(png_ptr);
+   png_ptr->mode |= PNG_HAVE_PLTE;
+}
+
+/* Write an IDAT chunk */
+void /* PRIVATE */
+png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+   png_debug(1, "in png_write_IDAT");
+
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+   if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
+       png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
+   {
+      /* Optimize the CMF field in the zlib stream.  This hack of the zlib
+       * stream is compliant to the stream specification.
+       */
+      unsigned int z_cmf = data[0];  /* zlib compression method and flags */
+
+      if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
+      {
+         /* Avoid memory underflows and multiplication overflows.
+          *
+          * The conditions below are practically always satisfied;
+          * however, they still must be checked.
+          */
+         if (length >= 2 &&
+             png_ptr->height < 16384 && png_ptr->width < 16384)
+         {
+            /* Compute the maximum possible length of the datastream */
+
+            /* Number of pixels, plus for each row a filter byte
+             * and possibly a padding byte, so increase the maximum
+             * size to account for these.
+             */
+            unsigned int z_cinfo;
+            unsigned int half_z_window_size;
+            png_uint_32 uncompressed_idat_size = png_ptr->height *
+                ((png_ptr->width *
+                png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
+
+            /* If it's interlaced, each block of 8 rows is sent as up to
+             * 14 rows, i.e., 6 additional rows, each with a filter byte
+             * and possibly a padding byte
+             */
+            if (png_ptr->interlaced)
+               uncompressed_idat_size += ((png_ptr->height + 7)/8) *
+                   (png_ptr->bit_depth < 8 ? 12 : 6);
+
+            z_cinfo = z_cmf >> 4;
+            half_z_window_size = 1 << (z_cinfo + 7);
+
+            while (uncompressed_idat_size <= half_z_window_size &&
+                half_z_window_size >= 256)
+            {
+               z_cinfo--;
+               half_z_window_size >>= 1;
+            }
+
+            z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
+
+            if (data[0] != z_cmf)
+            {
+               int tmp;
+               data[0] = (png_byte)z_cmf;
+               tmp = data[1] & 0xe0;
+               tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
+               data[1] = (png_byte)tmp;
+            }
+         }
+      }
+
+      else
+         png_error(png_ptr,
+             "Invalid zlib compression method or flags in IDAT");
+   }
+#endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */
+
+   png_write_complete_chunk(png_ptr, png_IDAT, data, length);
+   png_ptr->mode |= PNG_HAVE_IDAT;
+
+   /* Prior to 1.5.4 this code was replicated in every caller (except at the
+    * end, where it isn't technically necessary).  Since this function has
+    * flushed the data we can safely reset the zlib output buffer here.
+    */
+   png_ptr->zstream.next_out = png_ptr->zbuf;
+   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+}
+
+/* Write an IEND chunk */
+void /* PRIVATE */
+png_write_IEND(png_structp png_ptr)
+{
+   png_debug(1, "in png_write_IEND");
+
+   png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
+   png_ptr->mode |= PNG_HAVE_IEND;
+}
+
+#ifdef PNG_WRITE_gAMA_SUPPORTED
+/* Write a gAMA chunk */
+void /* PRIVATE */
+png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
+{
+   png_byte buf[4];
+
+   png_debug(1, "in png_write_gAMA");
+
+   /* file_gamma is saved in 1/100,000ths */
+   png_save_uint_32(buf, (png_uint_32)file_gamma);
+   png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
+}
+#endif
+
+#ifdef PNG_WRITE_sRGB_SUPPORTED
+/* Write a sRGB chunk */
+void /* PRIVATE */
+png_write_sRGB(png_structp png_ptr, int srgb_intent)
+{
+   png_byte buf[1];
+
+   png_debug(1, "in png_write_sRGB");
+
+   if (srgb_intent >= PNG_sRGB_INTENT_LAST)
+      png_warning(png_ptr,
+          "Invalid sRGB rendering intent specified");
+
+   buf[0]=(png_byte)srgb_intent;
+   png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
+}
+#endif
+
+#ifdef PNG_WRITE_iCCP_SUPPORTED
+/* Write an iCCP chunk */
+void /* PRIVATE */
+png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
+    png_const_charp profile, int profile_len)
+{
+   png_size_t name_len;
+   png_charp new_name;
+   compression_state comp;
+   int embedded_profile_len = 0;
+
+   png_debug(1, "in png_write_iCCP");
+
+   comp.num_output_ptr = 0;
+   comp.max_output_ptr = 0;
+   comp.output_ptr = NULL;
+   comp.input = NULL;
+   comp.input_len = 0;
+
+   if ((name_len = png_check_keyword(png_ptr, name, &new_name)) == 0)
+      return;
+
+   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
+      png_warning(png_ptr, "Unknown compression type in iCCP chunk");
+
+   if (profile == NULL)
+      profile_len = 0;
+
+   if (profile_len > 3)
+      embedded_profile_len =
+          ((*( (png_const_bytep)profile    ))<<24) |
+          ((*( (png_const_bytep)profile + 1))<<16) |
+          ((*( (png_const_bytep)profile + 2))<< 8) |
+          ((*( (png_const_bytep)profile + 3))    );
+
+   if (embedded_profile_len < 0)
+   {
+      png_warning(png_ptr,
+          "Embedded profile length in iCCP chunk is negative");
+
+      png_free(png_ptr, new_name);
+      return;
+   }
+
+   if (profile_len < embedded_profile_len)
+   {
+      png_warning(png_ptr,
+          "Embedded profile length too large in iCCP chunk");
+
+      png_free(png_ptr, new_name);
+      return;
+   }
+
+   if (profile_len > embedded_profile_len)
+   {
+      png_warning(png_ptr,
+          "Truncating profile to actual length in iCCP chunk");
+
+      profile_len = embedded_profile_len;
+   }
+
+   if (profile_len)
+      profile_len = png_text_compress(png_ptr, profile,
+          (png_size_t)profile_len, PNG_COMPRESSION_TYPE_BASE, &comp);
+
+   /* Make sure we include the NULL after the name and the compression type */
+   png_write_chunk_header(png_ptr, png_iCCP,
+       (png_uint_32)(name_len + profile_len + 2));
+
+   new_name[name_len + 1] = 0x00;
+
+   png_write_chunk_data(png_ptr, (png_bytep)new_name,
+       (png_size_t)(name_len + 2));
+
+   if (profile_len)
+   {
+      comp.input_len = profile_len;
+      png_write_compressed_data_out(png_ptr, &comp);
+   }
+
+   png_write_chunk_end(png_ptr);
+   png_free(png_ptr, new_name);
+}
+#endif
+
+#ifdef PNG_WRITE_sPLT_SUPPORTED
+/* Write a sPLT chunk */
+void /* PRIVATE */
+png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
+{
+   png_size_t name_len;
+   png_charp new_name;
+   png_byte entrybuf[10];
+   png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
+   png_size_t palette_size = entry_size * spalette->nentries;
+   png_sPLT_entryp ep;
+#ifndef PNG_POINTER_INDEXING_SUPPORTED
+   int i;
+#endif
+
+   png_debug(1, "in png_write_sPLT");
+
+   if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)
+      return;
+
+   /* Make sure we include the NULL after the name */
+   png_write_chunk_header(png_ptr, png_sPLT,
+       (png_uint_32)(name_len + 2 + palette_size));
+
+   png_write_chunk_data(png_ptr, (png_bytep)new_name,
+       (png_size_t)(name_len + 1));
+
+   png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
+
+   /* Loop through each palette entry, writing appropriately */
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
+   for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
+   {
+      if (spalette->depth == 8)
+      {
+         entrybuf[0] = (png_byte)ep->red;
+         entrybuf[1] = (png_byte)ep->green;
+         entrybuf[2] = (png_byte)ep->blue;
+         entrybuf[3] = (png_byte)ep->alpha;
+         png_save_uint_16(entrybuf + 4, ep->frequency);
+      }
+
+      else
+      {
+         png_save_uint_16(entrybuf + 0, ep->red);
+         png_save_uint_16(entrybuf + 2, ep->green);
+         png_save_uint_16(entrybuf + 4, ep->blue);
+         png_save_uint_16(entrybuf + 6, ep->alpha);
+         png_save_uint_16(entrybuf + 8, ep->frequency);
+      }
+
+      png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
+   }
+#else
+   ep=spalette->entries;
+   for (i = 0; i>spalette->nentries; i++)
+   {
+      if (spalette->depth == 8)
+      {
+         entrybuf[0] = (png_byte)ep[i].red;
+         entrybuf[1] = (png_byte)ep[i].green;
+         entrybuf[2] = (png_byte)ep[i].blue;
+         entrybuf[3] = (png_byte)ep[i].alpha;
+         png_save_uint_16(entrybuf + 4, ep[i].frequency);
+      }
+
+      else
+      {
+         png_save_uint_16(entrybuf + 0, ep[i].red);
+         png_save_uint_16(entrybuf + 2, ep[i].green);
+         png_save_uint_16(entrybuf + 4, ep[i].blue);
+         png_save_uint_16(entrybuf + 6, ep[i].alpha);
+         png_save_uint_16(entrybuf + 8, ep[i].frequency);
+      }
+
+      png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
+   }
+#endif
+
+   png_write_chunk_end(png_ptr);
+   png_free(png_ptr, new_name);
+}
+#endif
+
+#ifdef PNG_WRITE_sBIT_SUPPORTED
+/* Write the sBIT chunk */
+void /* PRIVATE */
+png_write_sBIT(png_structp png_ptr, png_const_color_8p sbit, int color_type)
+{
+   png_byte buf[4];
+   png_size_t size;
+
+   png_debug(1, "in png_write_sBIT");
+
+   /* Make sure we don't depend upon the order of PNG_COLOR_8 */
+   if (color_type & PNG_COLOR_MASK_COLOR)
+   {
+      png_byte maxbits;
+
+      maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
+          png_ptr->usr_bit_depth);
+
+      if (sbit->red == 0 || sbit->red > maxbits ||
+          sbit->green == 0 || sbit->green > maxbits ||
+          sbit->blue == 0 || sbit->blue > maxbits)
+      {
+         png_warning(png_ptr, "Invalid sBIT depth specified");
+         return;
+      }
+
+      buf[0] = sbit->red;
+      buf[1] = sbit->green;
+      buf[2] = sbit->blue;
+      size = 3;
+   }
+
+   else
+   {
+      if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth)
+      {
+         png_warning(png_ptr, "Invalid sBIT depth specified");
+         return;
+      }
+
+      buf[0] = sbit->gray;
+      size = 1;
+   }
+
+   if (color_type & PNG_COLOR_MASK_ALPHA)
+   {
+      if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
+      {
+         png_warning(png_ptr, "Invalid sBIT depth specified");
+         return;
+      }
+
+      buf[size++] = sbit->alpha;
+   }
+
+   png_write_complete_chunk(png_ptr, png_sBIT, buf, size);
+}
+#endif
+
+#ifdef PNG_WRITE_cHRM_SUPPORTED
+/* Write the cHRM chunk */
+void /* PRIVATE */
+png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
+    png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
+    png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
+    png_fixed_point blue_y)
+{
+   png_byte buf[32];
+
+   png_debug(1, "in png_write_cHRM");
+
+   /* Each value is saved in 1/100,000ths */
+#ifdef PNG_CHECK_cHRM_SUPPORTED
+   if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,
+       green_x, green_y, blue_x, blue_y))
+#endif
+   {
+      png_save_uint_32(buf, (png_uint_32)white_x);
+      png_save_uint_32(buf + 4, (png_uint_32)white_y);
+
+      png_save_uint_32(buf + 8, (png_uint_32)red_x);
+      png_save_uint_32(buf + 12, (png_uint_32)red_y);
+
+      png_save_uint_32(buf + 16, (png_uint_32)green_x);
+      png_save_uint_32(buf + 20, (png_uint_32)green_y);
+
+      png_save_uint_32(buf + 24, (png_uint_32)blue_x);
+      png_save_uint_32(buf + 28, (png_uint_32)blue_y);
+
+      png_write_complete_chunk(png_ptr, png_cHRM, buf, (png_size_t)32);
+   }
+}
+#endif
+
+#ifdef PNG_WRITE_tRNS_SUPPORTED
+/* Write the tRNS chunk */
+void /* PRIVATE */
+png_write_tRNS(png_structp png_ptr, png_const_bytep trans_alpha,
+    png_const_color_16p tran, int num_trans, int color_type)
+{
+   png_byte buf[6];
+
+   png_debug(1, "in png_write_tRNS");
+
+   if (color_type == PNG_COLOR_TYPE_PALETTE)
+   {
+      if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
+      {
+         png_warning(png_ptr, "Invalid number of transparent colors specified");
+         return;
+      }
+
+      /* Write the chunk out as it is */
+      png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, (png_size_t)num_trans);
+   }
+
+   else if (color_type == PNG_COLOR_TYPE_GRAY)
+   {
+      /* One 16 bit value */
+      if (tran->gray >= (1 << png_ptr->bit_depth))
+      {
+         png_warning(png_ptr,
+             "Ignoring attempt to write tRNS chunk out-of-range for bit_depth");
+
+         return;
+      }
+
+      png_save_uint_16(buf, tran->gray);
+      png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
+   }
+
+   else if (color_type == PNG_COLOR_TYPE_RGB)
+   {
+      /* Three 16 bit values */
+      png_save_uint_16(buf, tran->red);
+      png_save_uint_16(buf + 2, tran->green);
+      png_save_uint_16(buf + 4, tran->blue);
+#ifdef PNG_WRITE_16BIT_SUPPORTED
+      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
+#else
+      if (buf[0] | buf[2] | buf[4])
+#endif
+      {
+         png_warning(png_ptr,
+           "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8");
+         return;
+      }
+
+      png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
+   }
+
+   else
+   {
+      png_warning(png_ptr, "Can't write tRNS with an alpha channel");
+   }
+}
+#endif
+
+#ifdef PNG_WRITE_bKGD_SUPPORTED
+/* Write the background chunk */
+void /* PRIVATE */
+png_write_bKGD(png_structp png_ptr, png_const_color_16p back, int color_type)
+{
+   png_byte buf[6];
+
+   png_debug(1, "in png_write_bKGD");
+
+   if (color_type == PNG_COLOR_TYPE_PALETTE)
+   {
+      if (
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+          (png_ptr->num_palette ||
+          (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
+#endif
+         back->index >= png_ptr->num_palette)
+      {
+         png_warning(png_ptr, "Invalid background palette index");
+         return;
+      }
+
+      buf[0] = back->index;
+      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
+   }
+
+   else if (color_type & PNG_COLOR_MASK_COLOR)
+   {
+      png_save_uint_16(buf, back->red);
+      png_save_uint_16(buf + 2, back->green);
+      png_save_uint_16(buf + 4, back->blue);
+#ifdef PNG_WRITE_16BIT_SUPPORTED
+      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
+#else
+      if (buf[0] | buf[2] | buf[4])
+#endif
+      {
+         png_warning(png_ptr,
+             "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
+
+         return;
+      }
+
+      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
+   }
+
+   else
+   {
+      if (back->gray >= (1 << png_ptr->bit_depth))
+      {
+         png_warning(png_ptr,
+             "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
+
+         return;
+      }
+
+      png_save_uint_16(buf, back->gray);
+      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
+   }
+}
+#endif
+
+#ifdef PNG_WRITE_hIST_SUPPORTED
+/* Write the histogram */
+void /* PRIVATE */
+png_write_hIST(png_structp png_ptr, png_const_uint_16p hist, int num_hist)
+{
+   int i;
+   png_byte buf[3];
+
+   png_debug(1, "in png_write_hIST");
+
+   if (num_hist > (int)png_ptr->num_palette)
+   {
+      png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
+          png_ptr->num_palette);
+
+      png_warning(png_ptr, "Invalid number of histogram entries specified");
+      return;
+   }
+
+   png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2));
+
+   for (i = 0; i < num_hist; i++)
+   {
+      png_save_uint_16(buf, hist[i]);
+      png_write_chunk_data(png_ptr, buf, (png_size_t)2);
+   }
+
+   png_write_chunk_end(png_ptr);
+}
+#endif
+
+#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
+    defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
+/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
+ * and if invalid, correct the keyword rather than discarding the entire
+ * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in
+ * length, forbids leading or trailing whitespace, multiple internal spaces,
+ * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.
+ *
+ * The new_key is allocated to hold the corrected keyword and must be freed
+ * by the calling routine.  This avoids problems with trying to write to
+ * static keywords without having to have duplicate copies of the strings.
+ */
+png_size_t /* PRIVATE */
+png_check_keyword(png_structp png_ptr, png_const_charp key, png_charpp new_key)
+{
+   png_size_t key_len;
+   png_const_charp ikp;
+   png_charp kp, dp;
+   int kflag;
+   int kwarn=0;
+
+   png_debug(1, "in png_check_keyword");
+
+   *new_key = NULL;
+
+   if (key == NULL || (key_len = png_strlen(key)) == 0)
+   {
+      png_warning(png_ptr, "zero length keyword");
+      return ((png_size_t)0);
+   }
+
+   png_debug1(2, "Keyword to be checked is '%s'", key);
+
+   *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
+
+   if (*new_key == NULL)
+   {
+      png_warning(png_ptr, "Out of memory while procesing keyword");
+      return ((png_size_t)0);
+   }
+
+   /* Replace non-printing characters with a blank and print a warning */
+   for (ikp = key, dp = *new_key; *ikp != '\0'; ikp++, dp++)
+   {
+      if ((png_byte)*ikp < 0x20 ||
+         ((png_byte)*ikp > 0x7E && (png_byte)*ikp < 0xA1))
+      {
+         PNG_WARNING_PARAMETERS(p)
+
+         png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_02x,
+            (png_byte)*ikp);
+         png_formatted_warning(png_ptr, p, "invalid keyword character 0x@1");
+         *dp = ' ';
+      }
+
+      else
+      {
+         *dp = *ikp;
+      }
+   }
+   *dp = '\0';
+
+   /* Remove any trailing white space. */
+   kp = *new_key + key_len - 1;
+   if (*kp == ' ')
+   {
+      png_warning(png_ptr, "trailing spaces removed from keyword");
+
+      while (*kp == ' ')
+      {
+         *(kp--) = '\0';
+         key_len--;
+      }
+   }
+
+   /* Remove any leading white space. */
+   kp = *new_key;
+   if (*kp == ' ')
+   {
+      png_warning(png_ptr, "leading spaces removed from keyword");
+
+      while (*kp == ' ')
+      {
+         kp++;
+         key_len--;
+      }
+   }
+
+   png_debug1(2, "Checking for multiple internal spaces in '%s'", kp);
+
+   /* Remove multiple internal spaces. */
+   for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
+   {
+      if (*kp == ' ' && kflag == 0)
+      {
+         *(dp++) = *kp;
+         kflag = 1;
+      }
+
+      else if (*kp == ' ')
+      {
+         key_len--;
+         kwarn = 1;
+      }
+
+      else
+      {
+         *(dp++) = *kp;
+         kflag = 0;
+      }
+   }
+   *dp = '\0';
+   if (kwarn)
+      png_warning(png_ptr, "extra interior spaces removed from keyword");
+
+   if (key_len == 0)
+   {
+      png_free(png_ptr, *new_key);
+      png_warning(png_ptr, "Zero length keyword");
+   }
+
+   if (key_len > 79)
+   {
+      png_warning(png_ptr, "keyword length must be 1 - 79 characters");
+      (*new_key)[79] = '\0';
+      key_len = 79;
+   }
+
+   return (key_len);
+}
+#endif
+
+#ifdef PNG_WRITE_tEXt_SUPPORTED
+/* Write a tEXt chunk */
+void /* PRIVATE */
+png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
+    png_size_t text_len)
+{
+   png_size_t key_len;
+   png_charp new_key;
+
+   png_debug(1, "in png_write_tEXt");
+
+   if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)
+      return;
+
+   if (text == NULL || *text == '\0')
+      text_len = 0;
+
+   else
+      text_len = png_strlen(text);
+
+   /* Make sure we include the 0 after the key */
+   png_write_chunk_header(png_ptr, png_tEXt,
+       (png_uint_32)(key_len + text_len + 1));
+   /*
+    * We leave it to the application to meet PNG-1.0 requirements on the
+    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
+    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
+    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
+    */
+   png_write_chunk_data(png_ptr, (png_bytep)new_key,
+       (png_size_t)(key_len + 1));
+
+   if (text_len)
+      png_write_chunk_data(png_ptr, (png_const_bytep)text,
+          (png_size_t)text_len);
+
+   png_write_chunk_end(png_ptr);
+   png_free(png_ptr, new_key);
+}
+#endif
+
+#ifdef PNG_WRITE_zTXt_SUPPORTED
+/* Write a compressed text chunk */
+void /* PRIVATE */
+png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
+    png_size_t text_len, int compression)
+{
+   png_size_t key_len;
+   png_byte buf;
+   png_charp new_key;
+   compression_state comp;
+
+   png_debug(1, "in png_write_zTXt");
+
+   comp.num_output_ptr = 0;
+   comp.max_output_ptr = 0;
+   comp.output_ptr = NULL;
+   comp.input = NULL;
+   comp.input_len = 0;
+
+   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
+   {
+      png_free(png_ptr, new_key);
+      return;
+   }
+
+   if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
+   {
+      png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
+      png_free(png_ptr, new_key);
+      return;
+   }
+
+   text_len = png_strlen(text);
+
+   /* Compute the compressed data; do it now for the length */
+   text_len = png_text_compress(png_ptr, text, text_len, compression,
+       &comp);
+
+   /* Write start of chunk */
+   png_write_chunk_header(png_ptr, png_zTXt,
+       (png_uint_32)(key_len+text_len + 2));
+
+   /* Write key */
+   png_write_chunk_data(png_ptr, (png_bytep)new_key,
+       (png_size_t)(key_len + 1));
+
+   png_free(png_ptr, new_key);
+
+   buf = (png_byte)compression;
+
+   /* Write compression */
+   png_write_chunk_data(png_ptr, &buf, (png_size_t)1);
+
+   /* Write the compressed data */
+   comp.input_len = text_len;
+   png_write_compressed_data_out(png_ptr, &comp);
+
+   /* Close the chunk */
+   png_write_chunk_end(png_ptr);
+}
+#endif
+
+#ifdef PNG_WRITE_iTXt_SUPPORTED
+/* Write an iTXt chunk */
+void /* PRIVATE */
+png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
+    png_const_charp lang, png_const_charp lang_key, png_const_charp text)
+{
+   png_size_t lang_len, key_len, lang_key_len, text_len;
+   png_charp new_lang;
+   png_charp new_key = NULL;
+   png_byte cbuf[2];
+   compression_state comp;
+
+   png_debug(1, "in png_write_iTXt");
+
+   comp.num_output_ptr = 0;
+   comp.max_output_ptr = 0;
+   comp.output_ptr = NULL;
+   comp.input = NULL;
+
+   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
+      return;
+
+   if ((lang_len = png_check_keyword(png_ptr, lang, &new_lang)) == 0)
+   {
+      png_warning(png_ptr, "Empty language field in iTXt chunk");
+      new_lang = NULL;
+      lang_len = 0;
+   }
+
+   if (lang_key == NULL)
+      lang_key_len = 0;
+
+   else
+      lang_key_len = png_strlen(lang_key);
+
+   if (text == NULL)
+      text_len = 0;
+
+   else
+      text_len = png_strlen(text);
+
+   /* Compute the compressed data; do it now for the length */
+   text_len = png_text_compress(png_ptr, text, text_len, compression - 2,
+       &comp);
+
+
+   /* Make sure we include the compression flag, the compression byte,
+    * and the NULs after the key, lang, and lang_key parts
+    */
+
+   png_write_chunk_header(png_ptr, png_iTXt, (png_uint_32)(
+        5 /* comp byte, comp flag, terminators for key, lang and lang_key */
+        + key_len
+        + lang_len
+        + lang_key_len
+        + text_len));
+
+   /* We leave it to the application to meet PNG-1.0 requirements on the
+    * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
+    * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
+    * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
+    */
+   png_write_chunk_data(png_ptr, (png_bytep)new_key, (png_size_t)(key_len + 1));
+
+   /* Set the compression flag */
+   if (compression == PNG_ITXT_COMPRESSION_NONE ||
+       compression == PNG_TEXT_COMPRESSION_NONE)
+      cbuf[0] = 0;
+
+   else /* compression == PNG_ITXT_COMPRESSION_zTXt */
+      cbuf[0] = 1;
+
+   /* Set the compression method */
+   cbuf[1] = 0;
+
+   png_write_chunk_data(png_ptr, cbuf, (png_size_t)2);
+
+   cbuf[0] = 0;
+   png_write_chunk_data(png_ptr, (new_lang ? (png_const_bytep)new_lang : cbuf),
+       (png_size_t)(lang_len + 1));
+
+   png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf),
+       (png_size_t)(lang_key_len + 1));
+
+   png_write_compressed_data_out(png_ptr, &comp);
+
+   png_write_chunk_end(png_ptr);
+
+   png_free(png_ptr, new_key);
+   png_free(png_ptr, new_lang);
+}
+#endif
+
+#ifdef PNG_WRITE_oFFs_SUPPORTED
+/* Write the oFFs chunk */
+void /* PRIVATE */
+png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
+    int unit_type)
+{
+   png_byte buf[9];
+
+   png_debug(1, "in png_write_oFFs");
+
+   if (unit_type >= PNG_OFFSET_LAST)
+      png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
+
+   png_save_int_32(buf, x_offset);
+   png_save_int_32(buf + 4, y_offset);
+   buf[8] = (png_byte)unit_type;
+
+   png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
+}
+#endif
+#ifdef PNG_WRITE_pCAL_SUPPORTED
+/* Write the pCAL chunk (described in the PNG extensions document) */
+void /* PRIVATE */
+png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
+    png_int_32 X1, int type, int nparams, png_const_charp units,
+    png_charpp params)
+{
+   png_size_t purpose_len, units_len, total_len;
+   png_size_tp params_len;
+   png_byte buf[10];
+   png_charp new_purpose;
+   int i;
+
+   png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
+
+   if (type >= PNG_EQUATION_LAST)
+      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
+
+   purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
+   png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
+   units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
+   png_debug1(3, "pCAL units length = %d", (int)units_len);
+   total_len = purpose_len + units_len + 10;
+
+   params_len = (png_size_tp)png_malloc(png_ptr,
+       (png_alloc_size_t)(nparams * png_sizeof(png_size_t)));
+
+   /* Find the length of each parameter, making sure we don't count the
+    * null terminator for the last parameter.
+    */
+   for (i = 0; i < nparams; i++)
+   {
+      params_len[i] = png_strlen(params[i]) + (i == nparams - 1 ? 0 : 1);
+      png_debug2(3, "pCAL parameter %d length = %lu", i,
+          (unsigned long)params_len[i]);
+      total_len += params_len[i];
+   }
+
+   png_debug1(3, "pCAL total length = %d", (int)total_len);
+   png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
+   png_write_chunk_data(png_ptr, (png_const_bytep)new_purpose, purpose_len);
+   png_save_int_32(buf, X0);
+   png_save_int_32(buf + 4, X1);
+   buf[8] = (png_byte)type;
+   buf[9] = (png_byte)nparams;
+   png_write_chunk_data(png_ptr, buf, (png_size_t)10);
+   png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
+
+   png_free(png_ptr, new_purpose);
+
+   for (i = 0; i < nparams; i++)
+   {
+      png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);
+   }
+
+   png_free(png_ptr, params_len);
+   png_write_chunk_end(png_ptr);
+}
+#endif
+
+#ifdef PNG_WRITE_sCAL_SUPPORTED
+/* Write the sCAL chunk */
+void /* PRIVATE */
+png_write_sCAL_s(png_structp png_ptr, int unit, png_const_charp width,
+    png_const_charp height)
+{
+   png_byte buf[64];
+   png_size_t wlen, hlen, total_len;
+
+   png_debug(1, "in png_write_sCAL_s");
+
+   wlen = png_strlen(width);
+   hlen = png_strlen(height);
+   total_len = wlen + hlen + 2;
+
+   if (total_len > 64)
+   {
+      png_warning(png_ptr, "Can't write sCAL (buffer too small)");
+      return;
+   }
+
+   buf[0] = (png_byte)unit;
+   png_memcpy(buf + 1, width, wlen + 1);      /* Append the '\0' here */
+   png_memcpy(buf + wlen + 2, height, hlen);  /* Do NOT append the '\0' here */
+
+   png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
+   png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len);
+}
+#endif
+
+#ifdef PNG_WRITE_pHYs_SUPPORTED
+/* Write the pHYs chunk */
+void /* PRIVATE */
+png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
+    png_uint_32 y_pixels_per_unit,
+    int unit_type)
+{
+   png_byte buf[9];
+
+   png_debug(1, "in png_write_pHYs");
+
+   if (unit_type >= PNG_RESOLUTION_LAST)
+      png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
+
+   png_save_uint_32(buf, x_pixels_per_unit);
+   png_save_uint_32(buf + 4, y_pixels_per_unit);
+   buf[8] = (png_byte)unit_type;
+
+   png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
+}
+#endif
+
+#ifdef PNG_WRITE_tIME_SUPPORTED
+/* Write the tIME chunk.  Use either png_convert_from_struct_tm()
+ * or png_convert_from_time_t(), or fill in the structure yourself.
+ */
+void /* PRIVATE */
+png_write_tIME(png_structp png_ptr, png_const_timep mod_time)
+{
+   png_byte buf[7];
+
+   png_debug(1, "in png_write_tIME");
+
+   if (mod_time->month  > 12 || mod_time->month  < 1 ||
+       mod_time->day    > 31 || mod_time->day    < 1 ||
+       mod_time->hour   > 23 || mod_time->second > 60)
+   {
+      png_warning(png_ptr, "Invalid time specified for tIME chunk");
+      return;
+   }
+
+   png_save_uint_16(buf, mod_time->year);
+   buf[2] = mod_time->month;
+   buf[3] = mod_time->day;
+   buf[4] = mod_time->hour;
+   buf[5] = mod_time->minute;
+   buf[6] = mod_time->second;
+
+   png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
+}
+#endif
+
+/* Initializes the row writing capability of libpng */
+void /* PRIVATE */
+png_write_start_row(png_structp png_ptr)
+{
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+
+   /* Start of interlace block */
+   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+
+   /* Offset to next interlace block */
+   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+
+   /* Start of interlace block in the y direction */
+   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+
+   /* Offset to next interlace block in the y direction */
+   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+#endif
+
+   png_alloc_size_t buf_size;
+   int usr_pixel_depth;
+
+   png_debug(1, "in png_write_start_row");
+
+   usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth;
+   buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1;
+
+   /* 1.5.6: added to allow checking in the row write code. */
+   png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;
+   png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;
+
+   /* Set up row buffer */
+   png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size);
+
+   png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
+
+#ifdef PNG_WRITE_FILTER_SUPPORTED
+   /* Set up filtering buffer, if using this filter */
+   if (png_ptr->do_filter & PNG_FILTER_SUB)
+   {
+      png_ptr->sub_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);
+
+      png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
+   }
+
+   /* We only need to keep the previous row if we are using one of these. */
+   if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
+   {
+      /* Set up previous row buffer */
+      png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size);
+
+      if (png_ptr->do_filter & PNG_FILTER_UP)
+      {
+         png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
+            png_ptr->rowbytes + 1);
+
+         png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
+      }
+
+      if (png_ptr->do_filter & PNG_FILTER_AVG)
+      {
+         png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
+             png_ptr->rowbytes + 1);
+
+         png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
+      }
+
+      if (png_ptr->do_filter & PNG_FILTER_PAETH)
+      {
+         png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
+             png_ptr->rowbytes + 1);
+
+         png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
+      }
+   }
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
+
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+   /* If interlaced, we need to set up width and height of pass */
+   if (png_ptr->interlaced)
+   {
+      if (!(png_ptr->transformations & PNG_INTERLACE))
+      {
+         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
+             png_pass_ystart[0]) / png_pass_yinc[0];
+
+         png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
+             png_pass_start[0]) / png_pass_inc[0];
+      }
+
+      else
+      {
+         png_ptr->num_rows = png_ptr->height;
+         png_ptr->usr_width = png_ptr->width;
+      }
+   }
+
+   else
+#endif
+   {
+      png_ptr->num_rows = png_ptr->height;
+      png_ptr->usr_width = png_ptr->width;
+   }
+
+   png_zlib_claim(png_ptr, PNG_ZLIB_FOR_IDAT);
+   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+   png_ptr->zstream.next_out = png_ptr->zbuf;
+}
+
+/* Internal use only.  Called when finished processing a row of data. */
+void /* PRIVATE */
+png_write_finish_row(png_structp png_ptr)
+{
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+
+   /* Start of interlace block */
+   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+
+   /* Offset to next interlace block */
+   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+
+   /* Start of interlace block in the y direction */
+   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+
+   /* Offset to next interlace block in the y direction */
+   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+#endif
+
+   int ret;
+
+   png_debug(1, "in png_write_finish_row");
+
+   /* Next row */
+   png_ptr->row_number++;
+
+   /* See if we are done */
+   if (png_ptr->row_number < png_ptr->num_rows)
+      return;
+
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+   /* If interlaced, go to next pass */
+   if (png_ptr->interlaced)
+   {
+      png_ptr->row_number = 0;
+      if (png_ptr->transformations & PNG_INTERLACE)
+      {
+         png_ptr->pass++;
+      }
+
+      else
+      {
+         /* Loop until we find a non-zero width or height pass */
+         do
+         {
+            png_ptr->pass++;
+
+            if (png_ptr->pass >= 7)
+               break;
+
+            png_ptr->usr_width = (png_ptr->width +
+                png_pass_inc[png_ptr->pass] - 1 -
+                png_pass_start[png_ptr->pass]) /
+                png_pass_inc[png_ptr->pass];
+
+            png_ptr->num_rows = (png_ptr->height +
+                png_pass_yinc[png_ptr->pass] - 1 -
+                png_pass_ystart[png_ptr->pass]) /
+                png_pass_yinc[png_ptr->pass];
+
+            if (png_ptr->transformations & PNG_INTERLACE)
+               break;
+
+         } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
+
+      }
+
+      /* Reset the row above the image for the next pass */
+      if (png_ptr->pass < 7)
+      {
+         if (png_ptr->prev_row != NULL)
+            png_memset(png_ptr->prev_row, 0,
+                (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
+                png_ptr->usr_bit_depth, png_ptr->width)) + 1);
+
+         return;
+      }
+   }
+#endif
+
+   /* If we get here, we've just written the last row, so we need
+      to flush the compressor */
+   do
+   {
+      /* Tell the compressor we are done */
+      ret = deflate(&png_ptr->zstream, Z_FINISH);
+
+      /* Check for an error */
+      if (ret == Z_OK)
+      {
+         /* Check to see if we need more room */
+         if (!(png_ptr->zstream.avail_out))
+         {
+            png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
+            png_ptr->zstream.next_out = png_ptr->zbuf;
+            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+         }
+      }
+
+      else if (ret != Z_STREAM_END)
+      {
+         if (png_ptr->zstream.msg != NULL)
+            png_error(png_ptr, png_ptr->zstream.msg);
+
+         else
+            png_error(png_ptr, "zlib error");
+      }
+   } while (ret != Z_STREAM_END);
+
+   /* Write any extra space */
+   if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
+   {
+      png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
+          png_ptr->zstream.avail_out);
+   }
+
+   png_zlib_release(png_ptr);
+   png_ptr->zstream.data_type = Z_BINARY;
+}
+
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+/* Pick out the correct pixels for the interlace pass.
+ * The basic idea here is to go through the row with a source
+ * pointer and a destination pointer (sp and dp), and copy the
+ * correct pixels for the pass.  As the row gets compacted,
+ * sp will always be >= dp, so we should never overwrite anything.
+ * See the default: case for the easiest code to understand.
+ */
+void /* PRIVATE */
+png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
+{
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+
+   /* Start of interlace block */
+   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+
+   /* Offset to next interlace block */
+   static PNG_CONST png_byte  png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+
+   png_debug(1, "in png_do_write_interlace");
+
+   /* We don't have to do anything on the last pass (6) */
+   if (pass < 6)
+   {
+      /* Each pixel depth is handled separately */
+      switch (row_info->pixel_depth)
+      {
+         case 1:
+         {
+            png_bytep sp;
+            png_bytep dp;
+            int shift;
+            int d;
+            int value;
+            png_uint_32 i;
+            png_uint_32 row_width = row_info->width;
+
+            dp = row;
+            d = 0;
+            shift = 7;
+
+            for (i = png_pass_start[pass]; i < row_width;
+               i += png_pass_inc[pass])
+            {
+               sp = row + (png_size_t)(i >> 3);
+               value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
+               d |= (value << shift);
+
+               if (shift == 0)
+               {
+                  shift = 7;
+                  *dp++ = (png_byte)d;
+                  d = 0;
+               }
+
+               else
+                  shift--;
+
+            }
+            if (shift != 7)
+               *dp = (png_byte)d;
+
+            break;
+         }
+
+         case 2:
+         {
+            png_bytep sp;
+            png_bytep dp;
+            int shift;
+            int d;
+            int value;
+            png_uint_32 i;
+            png_uint_32 row_width = row_info->width;
+
+            dp = row;
+            shift = 6;
+            d = 0;
+
+            for (i = png_pass_start[pass]; i < row_width;
+               i += png_pass_inc[pass])
+            {
+               sp = row + (png_size_t)(i >> 2);
+               value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
+               d |= (value << shift);
+
+               if (shift == 0)
+               {
+                  shift = 6;
+                  *dp++ = (png_byte)d;
+                  d = 0;
+               }
+
+               else
+                  shift -= 2;
+            }
+            if (shift != 6)
+               *dp = (png_byte)d;
+
+            break;
+         }
+
+         case 4:
+         {
+            png_bytep sp;
+            png_bytep dp;
+            int shift;
+            int d;
+            int value;
+            png_uint_32 i;
+            png_uint_32 row_width = row_info->width;
+
+            dp = row;
+            shift = 4;
+            d = 0;
+            for (i = png_pass_start[pass]; i < row_width;
+                i += png_pass_inc[pass])
+            {
+               sp = row + (png_size_t)(i >> 1);
+               value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
+               d |= (value << shift);
+
+               if (shift == 0)
+               {
+                  shift = 4;
+                  *dp++ = (png_byte)d;
+                  d = 0;
+               }
+
+               else
+                  shift -= 4;
+            }
+            if (shift != 4)
+               *dp = (png_byte)d;
+
+            break;
+         }
+
+         default:
+         {
+            png_bytep sp;
+            png_bytep dp;
+            png_uint_32 i;
+            png_uint_32 row_width = row_info->width;
+            png_size_t pixel_bytes;
+
+            /* Start at the beginning */
+            dp = row;
+
+            /* Find out how many bytes each pixel takes up */
+            pixel_bytes = (row_info->pixel_depth >> 3);
+
+            /* Loop through the row, only looking at the pixels that matter */
+            for (i = png_pass_start[pass]; i < row_width;
+               i += png_pass_inc[pass])
+            {
+               /* Find out where the original pixel is */
+               sp = row + (png_size_t)i * pixel_bytes;
+
+               /* Move the pixel */
+               if (dp != sp)
+                  png_memcpy(dp, sp, pixel_bytes);
+
+               /* Next pixel */
+               dp += pixel_bytes;
+            }
+            break;
+         }
+      }
+      /* Set new row width */
+      row_info->width = (row_info->width +
+          png_pass_inc[pass] - 1 -
+          png_pass_start[pass]) /
+          png_pass_inc[pass];
+
+      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
+          row_info->width);
+   }
+}
+#endif
+
+/* This filters the row, chooses which filter to use, if it has not already
+ * been specified by the application, and then writes the row out with the
+ * chosen filter.
+ */
+static void png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
+   png_size_t row_bytes);
+
+#define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
+#define PNG_HISHIFT 10
+#define PNG_LOMASK ((png_uint_32)0xffffL)
+#define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
+void /* PRIVATE */
+png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
+{
+   png_bytep best_row;
+#ifdef PNG_WRITE_FILTER_SUPPORTED
+   png_bytep prev_row, row_buf;
+   png_uint_32 mins, bpp;
+   png_byte filter_to_do = png_ptr->do_filter;
+   png_size_t row_bytes = row_info->rowbytes;
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+   int num_p_filters = png_ptr->num_prev_filters;
+#endif
+
+   png_debug(1, "in png_write_find_filter");
+
+#ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+  if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS)
+  {
+     /* These will never be selected so we need not test them. */
+     filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH);
+  }
+#endif
+
+   /* Find out how many bytes offset each pixel is */
+   bpp = (row_info->pixel_depth + 7) >> 3;
+
+   prev_row = png_ptr->prev_row;
+#endif
+   best_row = png_ptr->row_buf;
+#ifdef PNG_WRITE_FILTER_SUPPORTED
+   row_buf = best_row;
+   mins = PNG_MAXSUM;
+
+   /* The prediction method we use is to find which method provides the
+    * smallest value when summing the absolute values of the distances
+    * from zero, using anything >= 128 as negative numbers.  This is known
+    * as the "minimum sum of absolute differences" heuristic.  Other
+    * heuristics are the "weighted minimum sum of absolute differences"
+    * (experimental and can in theory improve compression), and the "zlib
+    * predictive" method (not implemented yet), which does test compressions
+    * of lines using different filter methods, and then chooses the
+    * (series of) filter(s) that give minimum compressed data size (VERY
+    * computationally expensive).
+    *
+    * GRR 980525:  consider also
+    *
+    *   (1) minimum sum of absolute differences from running average (i.e.,
+    *       keep running sum of non-absolute differences & count of bytes)
+    *       [track dispersion, too?  restart average if dispersion too large?]
+    *
+    *  (1b) minimum sum of absolute differences from sliding average, probably
+    *       with window size <= deflate window (usually 32K)
+    *
+    *   (2) minimum sum of squared differences from zero or running average
+    *       (i.e., ~ root-mean-square approach)
+    */
+
+
+   /* We don't need to test the 'no filter' case if this is the only filter
+    * that has been chosen, as it doesn't actually do anything to the data.
+    */
+   if ((filter_to_do & PNG_FILTER_NONE) && filter_to_do != PNG_FILTER_NONE)
+   {
+      png_bytep rp;
+      png_uint_32 sum = 0;
+      png_size_t i;
+      int v;
+
+      for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
+      {
+         v = *rp;
+         sum += (v < 128) ? v : 256 - v;
+      }
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         png_uint_32 sumhi, sumlo;
+         int j;
+         sumlo = sum & PNG_LOMASK;
+         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
+
+         /* Reduce the sum if we match any of the previous rows */
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
+            {
+               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         /* Factor in the cost of this filter (this is here for completeness,
+          * but it makes no sense to have a "cost" for the NONE filter, as
+          * it has the minimum possible computational cost - none).
+          */
+         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
+             PNG_COST_SHIFT;
+
+         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_NONE]) >>
+             PNG_COST_SHIFT;
+
+         if (sumhi > PNG_HIMASK)
+            sum = PNG_MAXSUM;
+
+         else
+            sum = (sumhi << PNG_HISHIFT) + sumlo;
+      }
+#endif
+      mins = sum;
+   }
+
+   /* Sub filter */
+   if (filter_to_do == PNG_FILTER_SUB)
+   /* It's the only filter so no testing is needed */
+   {
+      png_bytep rp, lp, dp;
+      png_size_t i;
+
+      for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
+           i++, rp++, dp++)
+      {
+         *dp = *rp;
+      }
+
+      for (lp = row_buf + 1; i < row_bytes;
+         i++, rp++, lp++, dp++)
+      {
+         *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
+      }
+
+      best_row = png_ptr->sub_row;
+   }
+
+   else if (filter_to_do & PNG_FILTER_SUB)
+   {
+      png_bytep rp, dp, lp;
+      png_uint_32 sum = 0, lmins = mins;
+      png_size_t i;
+      int v;
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      /* We temporarily increase the "minimum sum" by the factor we
+       * would reduce the sum of this filter, so that we can do the
+       * early exit comparison without scaling the sum each time.
+       */
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         int j;
+         png_uint_32 lmhi, lmlo;
+         lmlo = lmins & PNG_LOMASK;
+         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
+
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
+            {
+               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
+             PNG_COST_SHIFT;
+
+         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
+             PNG_COST_SHIFT;
+
+         if (lmhi > PNG_HIMASK)
+            lmins = PNG_MAXSUM;
+
+         else
+            lmins = (lmhi << PNG_HISHIFT) + lmlo;
+      }
+#endif
+
+      for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
+           i++, rp++, dp++)
+      {
+         v = *dp = *rp;
+
+         sum += (v < 128) ? v : 256 - v;
+      }
+
+      for (lp = row_buf + 1; i < row_bytes;
+         i++, rp++, lp++, dp++)
+      {
+         v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
+
+         sum += (v < 128) ? v : 256 - v;
+
+         if (sum > lmins)  /* We are already worse, don't continue. */
+            break;
+      }
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         int j;
+         png_uint_32 sumhi, sumlo;
+         sumlo = sum & PNG_LOMASK;
+         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
+
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
+            {
+               sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         sumlo = (sumlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
+             PNG_COST_SHIFT;
+
+         sumhi = (sumhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_SUB]) >>
+             PNG_COST_SHIFT;
+
+         if (sumhi > PNG_HIMASK)
+            sum = PNG_MAXSUM;
+
+         else
+            sum = (sumhi << PNG_HISHIFT) + sumlo;
+      }
+#endif
+
+      if (sum < mins)
+      {
+         mins = sum;
+         best_row = png_ptr->sub_row;
+      }
+   }
+
+   /* Up filter */
+   if (filter_to_do == PNG_FILTER_UP)
+   {
+      png_bytep rp, dp, pp;
+      png_size_t i;
+
+      for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
+          pp = prev_row + 1; i < row_bytes;
+          i++, rp++, pp++, dp++)
+      {
+         *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
+      }
+
+      best_row = png_ptr->up_row;
+   }
+
+   else if (filter_to_do & PNG_FILTER_UP)
+   {
+      png_bytep rp, dp, pp;
+      png_uint_32 sum = 0, lmins = mins;
+      png_size_t i;
+      int v;
+
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         int j;
+         png_uint_32 lmhi, lmlo;
+         lmlo = lmins & PNG_LOMASK;
+         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
+
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
+            {
+               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
+             PNG_COST_SHIFT;
+
+         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_UP]) >>
+             PNG_COST_SHIFT;
+
+         if (lmhi > PNG_HIMASK)
+            lmins = PNG_MAXSUM;
+
+         else
+            lmins = (lmhi << PNG_HISHIFT) + lmlo;
+      }
+#endif
+
+      for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
+          pp = prev_row + 1; i < row_bytes; i++)
+      {
+         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+
+         sum += (v < 128) ? v : 256 - v;
+
+         if (sum > lmins)  /* We are already worse, don't continue. */
+            break;
+      }
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         int j;
+         png_uint_32 sumhi, sumlo;
+         sumlo = sum & PNG_LOMASK;
+         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
+
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
+            {
+               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
+             PNG_COST_SHIFT;
+
+         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_UP]) >>
+             PNG_COST_SHIFT;
+
+         if (sumhi > PNG_HIMASK)
+            sum = PNG_MAXSUM;
+
+         else
+            sum = (sumhi << PNG_HISHIFT) + sumlo;
+      }
+#endif
+
+      if (sum < mins)
+      {
+         mins = sum;
+         best_row = png_ptr->up_row;
+      }
+   }
+
+   /* Avg filter */
+   if (filter_to_do == PNG_FILTER_AVG)
+   {
+      png_bytep rp, dp, pp, lp;
+      png_uint_32 i;
+
+      for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
+           pp = prev_row + 1; i < bpp; i++)
+      {
+         *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
+      }
+
+      for (lp = row_buf + 1; i < row_bytes; i++)
+      {
+         *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
+                 & 0xff);
+      }
+      best_row = png_ptr->avg_row;
+   }
+
+   else if (filter_to_do & PNG_FILTER_AVG)
+   {
+      png_bytep rp, dp, pp, lp;
+      png_uint_32 sum = 0, lmins = mins;
+      png_size_t i;
+      int v;
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         int j;
+         png_uint_32 lmhi, lmlo;
+         lmlo = lmins & PNG_LOMASK;
+         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
+
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
+            {
+               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
+             PNG_COST_SHIFT;
+
+         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_AVG]) >>
+             PNG_COST_SHIFT;
+
+         if (lmhi > PNG_HIMASK)
+            lmins = PNG_MAXSUM;
+
+         else
+            lmins = (lmhi << PNG_HISHIFT) + lmlo;
+      }
+#endif
+
+      for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
+           pp = prev_row + 1; i < bpp; i++)
+      {
+         v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
+
+         sum += (v < 128) ? v : 256 - v;
+      }
+
+      for (lp = row_buf + 1; i < row_bytes; i++)
+      {
+         v = *dp++ =
+             (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
+
+         sum += (v < 128) ? v : 256 - v;
+
+         if (sum > lmins)  /* We are already worse, don't continue. */
+            break;
+      }
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         int j;
+         png_uint_32 sumhi, sumlo;
+         sumlo = sum & PNG_LOMASK;
+         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
+
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
+            {
+               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
+             PNG_COST_SHIFT;
+
+         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_AVG]) >>
+             PNG_COST_SHIFT;
+
+         if (sumhi > PNG_HIMASK)
+            sum = PNG_MAXSUM;
+
+         else
+            sum = (sumhi << PNG_HISHIFT) + sumlo;
+      }
+#endif
+
+      if (sum < mins)
+      {
+         mins = sum;
+         best_row = png_ptr->avg_row;
+      }
+   }
+
+   /* Paeth filter */
+   if (filter_to_do == PNG_FILTER_PAETH)
+   {
+      png_bytep rp, dp, pp, cp, lp;
+      png_size_t i;
+
+      for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
+          pp = prev_row + 1; i < bpp; i++)
+      {
+         *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+      }
+
+      for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
+      {
+         int a, b, c, pa, pb, pc, p;
+
+         b = *pp++;
+         c = *cp++;
+         a = *lp++;
+
+         p = b - c;
+         pc = a - c;
+
+#ifdef PNG_USE_ABS
+         pa = abs(p);
+         pb = abs(pc);
+         pc = abs(p + pc);
+#else
+         pa = p < 0 ? -p : p;
+         pb = pc < 0 ? -pc : pc;
+         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+#endif
+
+         p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
+
+         *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
+      }
+      best_row = png_ptr->paeth_row;
+   }
+
+   else if (filter_to_do & PNG_FILTER_PAETH)
+   {
+      png_bytep rp, dp, pp, cp, lp;
+      png_uint_32 sum = 0, lmins = mins;
+      png_size_t i;
+      int v;
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         int j;
+         png_uint_32 lmhi, lmlo;
+         lmlo = lmins & PNG_LOMASK;
+         lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
+
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
+            {
+               lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         lmlo = (lmlo * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
+             PNG_COST_SHIFT;
+
+         lmhi = (lmhi * png_ptr->inv_filter_costs[PNG_FILTER_VALUE_PAETH]) >>
+             PNG_COST_SHIFT;
+
+         if (lmhi > PNG_HIMASK)
+            lmins = PNG_MAXSUM;
+
+         else
+            lmins = (lmhi << PNG_HISHIFT) + lmlo;
+      }
+#endif
+
+      for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
+          pp = prev_row + 1; i < bpp; i++)
+      {
+         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+
+         sum += (v < 128) ? v : 256 - v;
+      }
+
+      for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
+      {
+         int a, b, c, pa, pb, pc, p;
+
+         b = *pp++;
+         c = *cp++;
+         a = *lp++;
+
+#ifndef PNG_SLOW_PAETH
+         p = b - c;
+         pc = a - c;
+#ifdef PNG_USE_ABS
+         pa = abs(p);
+         pb = abs(pc);
+         pc = abs(p + pc);
+#else
+         pa = p < 0 ? -p : p;
+         pb = pc < 0 ? -pc : pc;
+         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+#endif
+         p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
+#else /* PNG_SLOW_PAETH */
+         p = a + b - c;
+         pa = abs(p - a);
+         pb = abs(p - b);
+         pc = abs(p - c);
+
+         if (pa <= pb && pa <= pc)
+            p = a;
+
+         else if (pb <= pc)
+            p = b;
+
+         else
+            p = c;
+#endif /* PNG_SLOW_PAETH */
+
+         v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
+
+         sum += (v < 128) ? v : 256 - v;
+
+         if (sum > lmins)  /* We are already worse, don't continue. */
+            break;
+      }
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+      if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+      {
+         int j;
+         png_uint_32 sumhi, sumlo;
+         sumlo = sum & PNG_LOMASK;
+         sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
+
+         for (j = 0; j < num_p_filters; j++)
+         {
+            if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
+            {
+               sumlo = (sumlo * png_ptr->filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+
+               sumhi = (sumhi * png_ptr->filter_weights[j]) >>
+                   PNG_WEIGHT_SHIFT;
+            }
+         }
+
+         sumlo = (sumlo * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
+             PNG_COST_SHIFT;
+
+         sumhi = (sumhi * png_ptr->filter_costs[PNG_FILTER_VALUE_PAETH]) >>
+             PNG_COST_SHIFT;
+
+         if (sumhi > PNG_HIMASK)
+            sum = PNG_MAXSUM;
+
+         else
+            sum = (sumhi << PNG_HISHIFT) + sumlo;
+      }
+#endif
+
+      if (sum < mins)
+      {
+         best_row = png_ptr->paeth_row;
+      }
+   }
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
+
+   /* Do the actual writing of the filtered row data from the chosen filter. */
+   png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1);
+
+#ifdef PNG_WRITE_FILTER_SUPPORTED
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+   /* Save the type of filter we picked this time for future calculations */
+   if (png_ptr->num_prev_filters > 0)
+   {
+      int j;
+
+      for (j = 1; j < num_p_filters; j++)
+      {
+         png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
+      }
+
+      png_ptr->prev_filters[j] = best_row[0];
+   }
+#endif
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
+}
+
+
+/* Do the actual writing of a previously filtered row. */
+static void
+png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row,
+   png_size_t avail/*includes filter byte*/)
+{
+   png_debug(1, "in png_write_filtered_row");
+
+   png_debug1(2, "filter = %d", filtered_row[0]);
+   /* Set up the zlib input buffer */
+
+   png_ptr->zstream.next_in = filtered_row;
+   png_ptr->zstream.avail_in = 0;
+   /* Repeat until we have compressed all the data */
+   do
+   {
+      int ret; /* Return of zlib */
+
+      /* Record the number of bytes available - zlib supports at least 65535
+       * bytes at one step, depending on the size of the zlib type 'uInt', the
+       * maximum size zlib can write at once is ZLIB_IO_MAX (from pngpriv.h).
+       * Use this because on 16 bit systems 'rowbytes' can be up to 65536 (i.e.
+       * one more than 16 bits) and, in this case 'rowbytes+1' can overflow a
+       * uInt.  ZLIB_IO_MAX can be safely reduced to cause zlib to be called
+       * with smaller chunks of data.
+       */
+      if (png_ptr->zstream.avail_in == 0)
+      {
+         if (avail > ZLIB_IO_MAX)
+         {
+            png_ptr->zstream.avail_in  = ZLIB_IO_MAX;
+            avail -= ZLIB_IO_MAX;
+         }
+
+         else
+         {
+            /* So this will fit in the available uInt space: */
+            png_ptr->zstream.avail_in = (uInt)avail;
+            avail = 0;
+         }
+      }
+
+      /* Compress the data */
+      ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
+
+      /* Check for compression errors */
+      if (ret != Z_OK)
+      {
+         if (png_ptr->zstream.msg != NULL)
+            png_error(png_ptr, png_ptr->zstream.msg);
+
+         else
+            png_error(png_ptr, "zlib error");
+      }
+
+      /* See if it is time to write another IDAT */
+      if (!(png_ptr->zstream.avail_out))
+      {
+         /* Write the IDAT and reset the zlib output buffer */
+         png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
+      }
+   /* Repeat until all data has been compressed */
+   } while (avail > 0 || png_ptr->zstream.avail_in > 0);
+
+   /* Swap the current and previous rows */
+   if (png_ptr->prev_row != NULL)
+   {
+      png_bytep tptr;
+
+      tptr = png_ptr->prev_row;
+      png_ptr->prev_row = png_ptr->row_buf;
+      png_ptr->row_buf = tptr;
+   }
+
+   /* Finish row - updates counters and flushes zlib if last row */
+   png_write_finish_row(png_ptr);
+
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
+   png_ptr->flush_rows++;
+
+   if (png_ptr->flush_dist > 0 &&
+       png_ptr->flush_rows >= png_ptr->flush_dist)
+   {
+      png_write_flush(png_ptr);
+   }
+#endif
+}
+#endif /* PNG_WRITE_SUPPORTED */