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0f881d62b3
libpng/pngwrite.c
Glenn Randers-Pehrson 0f881d62b3 Imported from libpng-0.99c.tar
2009-04-06 16:04:13 -05:00

950 lines
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/* pngwrite.c - general routines to write a PNG file
*
* libpng 0.99c
* For conditions of distribution and use, see copyright notice in png.h
* Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
* Copyright (c) 1996, 1997 Andreas Dilger
* Copyright (c) 1998, Glenn Randers-Pehrson
* February 7, 1998
*/
/* get internal access to png.h */
#define PNG_INTERNAL
#include "png.h"
/* Writes all the PNG information. This is the suggested way to use the
* library. If you have a new chunk to add, make a function to write it,
* and put it in the correct location here. If you want the chunk written
* after the image data, put it in png_write_end(). I strongly encurage
* you to supply a PNG_INFO_ flag, and check info_ptr->valid before writing
* the chunk, as that will keep the code from breaking if you want to just
* write a plain PNG file. If you have long comments, I suggest writing
* them in png_write_end(), and compressing them.
*/
void
png_write_info(png_structp png_ptr, png_infop info_ptr)
{
#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
int i;
#endif
png_debug(1, "in png_write_info\n");
png_write_sig(png_ptr); /* write PNG signature */
/* write IHDR information. */
png_write_IHDR(png_ptr, info_ptr->width, info_ptr->height,
info_ptr->bit_depth, info_ptr->color_type, info_ptr->compression_type,
info_ptr->filter_type,
#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
info_ptr->interlace_type);
#else
0);
#endif
/* the rest of these check to see if the valid field has the appropriate
flag set, and if it does, writes the chunk. */
#if defined(PNG_WRITE_gAMA_SUPPORTED)
if (info_ptr->valid & PNG_INFO_gAMA)
png_write_gAMA(png_ptr, info_ptr->gamma);
#endif
#if defined(PNG_WRITE_sRGB_SUPPORTED)
if (info_ptr->valid & PNG_INFO_sRGB)
png_write_sRGB(png_ptr, (int)info_ptr->srgb_intent);
#endif
#if defined(PNG_WRITE_sBIT_SUPPORTED)
if (info_ptr->valid & PNG_INFO_sBIT)
png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
#endif
#if defined(PNG_WRITE_cHRM_SUPPORTED)
if (info_ptr->valid & PNG_INFO_cHRM)
png_write_cHRM(png_ptr,
info_ptr->x_white, info_ptr->y_white,
info_ptr->x_red, info_ptr->y_red,
info_ptr->x_green, info_ptr->y_green,
info_ptr->x_blue, info_ptr->y_blue);
#endif
if (info_ptr->valid & PNG_INFO_PLTE)
png_write_PLTE(png_ptr, info_ptr->palette,
(png_uint_32)info_ptr->num_palette);
else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
png_error(png_ptr, "Valid palette required for paletted images\n");
#if defined(PNG_WRITE_tRNS_SUPPORTED)
if (info_ptr->valid & PNG_INFO_tRNS)
{
#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
/* invert the alpha channel (in tRNS) */
if (png_ptr->transformations & PNG_INVERT_ALPHA &&
info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
int j;
for (j=0; j<(int)info_ptr->num_trans; j++)
info_ptr->trans[j] = 255 - info_ptr->trans[j];
}
#endif
png_write_tRNS(png_ptr, info_ptr->trans, &(info_ptr->trans_values),
info_ptr->num_trans, info_ptr->color_type);
}
#endif
#if defined(PNG_WRITE_bKGD_SUPPORTED)
if (info_ptr->valid & PNG_INFO_bKGD)
png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
#endif
#if defined(PNG_WRITE_hIST_SUPPORTED)
if (info_ptr->valid & PNG_INFO_hIST)
png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
#endif
#if defined(PNG_WRITE_oFFs_SUPPORTED)
if (info_ptr->valid & PNG_INFO_oFFs)
png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
info_ptr->offset_unit_type);
#endif
#if defined(PNG_WRITE_pCAL_SUPPORTED)
if (info_ptr->valid & PNG_INFO_pCAL)
png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
info_ptr->pcal_units, info_ptr->pcal_params);
#endif
#if defined(PNG_WRITE_pHYs_SUPPORTED)
if (info_ptr->valid & PNG_INFO_pHYs)
png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
#endif
#if defined(PNG_WRITE_tIME_SUPPORTED)
if (info_ptr->valid & PNG_INFO_tIME)
{
png_write_tIME(png_ptr, &(info_ptr->mod_time));
png_ptr->flags |= PNG_FLAG_WROTE_tIME;
}
#endif
#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
/* Check to see if we need to write text chunks */
for (i = 0; i < info_ptr->num_text; i++)
{
png_debug2(2, "Writing header text chunk %d, type %d\n", i,
info_ptr->text[i].compression);
/* If we want a compressed text chunk */
if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
{
#if defined(PNG_WRITE_zTXt_SUPPORTED)
/* write compressed chunk */
png_write_zTXt(png_ptr, info_ptr->text[i].key,
info_ptr->text[i].text, info_ptr->text[i].text_length,
info_ptr->text[i].compression);
#else
png_warning(png_ptr, "Unable to write compressed text\n");
#endif
/* Mark this chunk as written */
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
}
else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
{
#if defined(PNG_WRITE_tEXt_SUPPORTED)
/* write uncompressed chunk */
png_write_tEXt(png_ptr, info_ptr->text[i].key,
info_ptr->text[i].text, info_ptr->text[i].text_length);
#else
png_warning(png_ptr, "Unable to write uncompressed text\n");
#endif
/* Mark this chunk as written */
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
}
}
#endif
}
/* Writes the end of the PNG file. If you don't want to write comments or
* time information, you can pass NULL for info. If you already wrote these
* in png_write_info(), do not write them again here. If you have long
* comments, I suggest writing them here, and compressing them.
*/
void
png_write_end(png_structp png_ptr, png_infop info_ptr)
{
png_debug(1, "in png_write_end\n");
if (!(png_ptr->mode & PNG_HAVE_IDAT))
png_error(png_ptr, "No IDATs written into file");
/* see if user wants us to write information chunks */
if (info_ptr != NULL)
{
#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
int i; /* local index variable */
#endif
#if defined(PNG_WRITE_tIME_SUPPORTED)
/* check to see if user has supplied a time chunk */
if (info_ptr->valid & PNG_INFO_tIME &&
!(png_ptr->flags & PNG_FLAG_WROTE_tIME))
png_write_tIME(png_ptr, &(info_ptr->mod_time));
#endif
#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
/* loop through comment chunks */
for (i = 0; i < info_ptr->num_text; i++)
{
png_debug2(2, "Writing trailer text chunk %d, type %d\n", i,
info_ptr->text[i].compression);
if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
{
#if defined(PNG_WRITE_zTXt_SUPPORTED)
/* write compressed chunk */
png_write_zTXt(png_ptr, info_ptr->text[i].key,
info_ptr->text[i].text, info_ptr->text[i].text_length,
info_ptr->text[i].compression);
#else
png_warning(png_ptr, "Unable to write compressed text\n");
#endif
/* Mark this chunk as written */
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
}
else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
{
#if defined(PNG_WRITE_tEXt_SUPPORTED)
/* write uncompressed chunk */
png_write_tEXt(png_ptr, info_ptr->text[i].key,
info_ptr->text[i].text, info_ptr->text[i].text_length);
#else
png_warning(png_ptr, "Unable to write uncompressed text\n");
#endif
/* Mark this chunk as written */
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
}
}
#endif
}
png_ptr->mode |= PNG_AFTER_IDAT;
/* write end of PNG file */
png_write_IEND(png_ptr);
}
#if defined(PNG_TIME_RFC1123_SUPPORTED)
/* Convert the supplied time into an RFC 1123 string suitable for use in
* a "Creation Time" or other text-based time string.
*/
png_charp
png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
{
const char *short_months[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
if (png_ptr->time_buffer == NULL)
{
png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
sizeof(char)));
}
#ifdef USE_FAR_KEYWORD
{
char near_time_buf[29];
sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000",
ptime->day % 31, short_months[ptime->month],
ptime->year, ptime->hour % 24, ptime->minute % 60,
ptime->second % 61);
png_memcpy(png_ptr->time_buffer, near_time_buf,
29*sizeof(char));
}
#else
sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000",
ptime->day % 31, short_months[ptime->month],
ptime->year, ptime->hour % 24, ptime->minute % 60,
ptime->second % 61);
#endif
return ((png_charp)png_ptr->time_buffer);
}
#endif /* PNG_TIME_RFC1123_SUPPORTED */
#if defined(PNG_WRITE_tIME_SUPPORTED)
void
png_convert_from_struct_tm(png_timep ptime, struct tm FAR * ttime)
{
png_debug(1, "in png_convert_from_struct_tm\n");
ptime->year = (png_uint_16)(1900 + ttime->tm_year);
ptime->month = (png_byte)(ttime->tm_mon + 1);
ptime->day = (png_byte)ttime->tm_mday;
ptime->hour = (png_byte)ttime->tm_hour;
ptime->minute = (png_byte)ttime->tm_min;
ptime->second = (png_byte)ttime->tm_sec;
}
void
png_convert_from_time_t(png_timep ptime, time_t ttime)
{
struct tm *tbuf;
png_debug(1, "in png_convert_from_time_t\n");
tbuf = gmtime(&ttime);
png_convert_from_struct_tm(ptime, tbuf);
}
#endif
/* Initialize png_ptr structure, and allocate any memory needed */
png_structp
png_create_write_struct(png_const_charp user_png_ver, voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn)
{
png_structp png_ptr;
#ifdef USE_FAR_KEYWORD
jmp_buf jmpbuf;
#endif
png_debug(1, "in png_create_write_struct\n");
if ((png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG)) == NULL)
{
return ((png_structp)NULL);
}
#ifdef USE_FAR_KEYWORD
if (setjmp(jmpbuf))
#else
if (setjmp(png_ptr->jmpbuf))
#endif
{
png_free(png_ptr, png_ptr->zbuf);
png_destroy_struct(png_ptr);
return ((png_structp)NULL);
}
#ifdef USE_FAR_KEYWORD
png_memcpy(png_ptr->jmpbuf,jmpbuf,sizeof(jmp_buf));
#endif
png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
/* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
* we must recompile any applications that use any older library version.
* For versions after libpng 1.0, we will be compatible, so we need
* only check the first digit.
*/
if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
(png_libpng_ver[0] == '0' && user_png_ver[2] < '9'))
{
png_error(png_ptr,
"Incompatible libpng version in application and library");
}
/* initialize zbuf - compression buffer */
png_ptr->zbuf_size = PNG_ZBUF_SIZE;
png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
(png_uint_32)png_ptr->zbuf_size);
png_set_write_fn(png_ptr, NULL, NULL, NULL);
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
1, NULL, NULL);
#endif
return ((png_structp)png_ptr);
}
/* Initialize png_ptr structure, and allocate any memory needed */
void
png_write_init(png_structp png_ptr)
{
jmp_buf tmp_jmp; /* to save current jump buffer */
png_debug(1, "in png_write_init\n");
/* save jump buffer and error functions */
png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf));
/* reset all variables to 0 */
png_memset(png_ptr, 0, sizeof (png_struct));
/* restore jump buffer */
png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf));
/* initialize zbuf - compression buffer */
png_ptr->zbuf_size = PNG_ZBUF_SIZE;
png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
(png_uint_32)png_ptr->zbuf_size);
png_set_write_fn(png_ptr, NULL, NULL, NULL);
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
1, NULL, NULL);
#endif
}
/* Write a few rows of image data. If the image is interlaced,
* either you will have to write the 7 sub images, or, if you
* have called png_set_interlace_handling(), you will have to
* "write" the image seven times.
*/
void
png_write_rows(png_structp png_ptr, png_bytepp row,
png_uint_32 num_rows)
{
png_uint_32 i; /* row counter */
png_bytepp rp; /* row pointer */
png_debug(1, "in png_write_rows\n");
/* loop through the rows */
for (i = 0, rp = row; i < num_rows; i++, rp++)
{
png_write_row(png_ptr, *rp);
}
}
/* Write the image. You only need to call this function once, even
* if you are writing an interlaced image.
*/
void
png_write_image(png_structp png_ptr, png_bytepp image)
{
png_uint_32 i; /* row index */
int pass, num_pass; /* pass variables */
png_bytepp rp; /* points to current row */
png_debug(1, "in png_write_image\n");
#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
/* intialize interlace handling. If image is not interlaced,
this will set pass to 1 */
num_pass = png_set_interlace_handling(png_ptr);
#else
num_pass = 1;
#endif
/* loop through passes */
for (pass = 0; pass < num_pass; pass++)
{
/* loop through image */
for (i = 0, rp = image; i < png_ptr->height; i++, rp++)
{
png_write_row(png_ptr, *rp);
}
}
}
/* called by user to write a row of image data */
void
png_write_row(png_structp png_ptr, png_bytep row)
{
png_debug2(1, "in png_write_row (row %ld, pass %d)\n",
png_ptr->row_number, png_ptr->pass);
/* initialize transformations and other stuff if first time */
if (png_ptr->row_number == 0 && png_ptr->pass == 0)
{
png_write_start_row(png_ptr);
}
#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
/* if interlaced and not interested in row, return */
if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
{
switch (png_ptr->pass)
{
case 0:
if (png_ptr->row_number & 7)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 1:
if ((png_ptr->row_number & 7) || png_ptr->width < 5)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 2:
if ((png_ptr->row_number & 7) != 4)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 3:
if ((png_ptr->row_number & 3) || png_ptr->width < 3)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 4:
if ((png_ptr->row_number & 3) != 2)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 5:
if ((png_ptr->row_number & 1) || png_ptr->width < 2)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 6:
if (!(png_ptr->row_number & 1))
{
png_write_finish_row(png_ptr);
return;
}
break;
}
}
#endif
/* set up row info for transformations */
png_ptr->row_info.color_type = png_ptr->color_type;
png_ptr->row_info.width = png_ptr->usr_width;
png_ptr->row_info.channels = png_ptr->usr_channels;
png_ptr->row_info.bit_depth = png_ptr->usr_bit_depth;
png_ptr->row_info.pixel_depth = (png_byte)(png_ptr->row_info.bit_depth *
png_ptr->row_info.channels);
png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *
(png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
png_debug1(3, "row_info->color_type = %d\n", png_ptr->row_info.color_type);
png_debug1(3, "row_info->width = %d\n", png_ptr->row_info.width);
png_debug1(3, "row_info->channels = %d\n", png_ptr->row_info.channels);
png_debug1(3, "row_info->bit_depth = %d\n", png_ptr->row_info.bit_depth);
png_debug1(3, "row_info->pixel_depth = %d\n", png_ptr->row_info.pixel_depth);
png_debug1(3, "row_info->rowbytes = %d\n", png_ptr->row_info.rowbytes);
/* Copy user's row into buffer, leaving room for filter byte. */
png_buffered_memcpy(png_ptr, png_ptr->row_buf + 1, row,
png_ptr->row_info.rowbytes);
#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
/* handle interlacing */
if (png_ptr->interlaced && png_ptr->pass < 6 &&
(png_ptr->transformations & PNG_INTERLACE))
{
png_do_write_interlace(&(png_ptr->row_info),
png_ptr->row_buf + 1, png_ptr->pass);
/* this should always get caught above, but still ... */
if (!(png_ptr->row_info.width))
{
png_write_finish_row(png_ptr);
return;
}
}
#endif
/* handle other transformations */
if (png_ptr->transformations)
png_do_write_transformations(png_ptr);
/* Find a filter if necessary, filter the row and write it out. */
png_write_find_filter(png_ptr, &(png_ptr->row_info));
}
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
/* Set the automatic flush interval or 0 to turn flushing off */
void
png_set_flush(png_structp png_ptr, int nrows)
{
png_debug(1, "in png_set_flush\n");
png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
}
/* flush the current output buffers now */
void
png_write_flush(png_structp png_ptr)
{
int wrote_IDAT;
png_debug(1, "in png_write_flush\n");
/* We have already written out all of the data */
if (png_ptr->row_number >= png_ptr->num_rows)
return;
do
{
int ret;
/* compress the data */
ret = deflate(&png_ptr->zstream, Z_SYNC_FLUSH);
wrote_IDAT = 0;
/* 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");
}
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);
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
wrote_IDAT = 1;
}
} while(wrote_IDAT == 1);
/* If there is any data left to be output, write it into a new IDAT */
if (png_ptr->zbuf_size != 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 - png_ptr->zstream.avail_out);
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
}
png_ptr->flush_rows = 0;
png_flush(png_ptr);
}
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
/* free all memory used by the write */
void
png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
{
png_structp png_ptr = NULL;
png_infop info_ptr = NULL;
png_debug(1, "in png_destroy_write_struct\n");
if (png_ptr_ptr != NULL)
png_ptr = *png_ptr_ptr;
if (info_ptr_ptr != NULL)
info_ptr = *info_ptr_ptr;
if (info_ptr != NULL)
{
#ifdef PNG_WRITE_tEXt_SUPPORTED
png_free(png_ptr, info_ptr->text);
#endif
#if defined(PNG_READ_pCAL_SUPPORTED)
png_free(png_ptr, info_ptr->pcal_purpose);
png_free(png_ptr, info_ptr->pcal_units);
if (info_ptr->pcal_params != NULL)
{
int i;
for (i = 0; i < (int)info_ptr->pcal_nparams; i++)
{
png_free(png_ptr, info_ptr->pcal_params[i]);
}
png_free(png_ptr, info_ptr->pcal_params);
}
#endif
png_destroy_struct((png_voidp)info_ptr);
*info_ptr_ptr = (png_infop)NULL;
}
if (png_ptr != NULL)
{
png_write_destroy(png_ptr);
png_destroy_struct((png_voidp)png_ptr);
*png_ptr_ptr = (png_structp)NULL;
}
}
/* Free any memory used in png_ptr struct (old method) */
void
png_write_destroy(png_structp png_ptr)
{
jmp_buf tmp_jmp; /* save jump buffer */
png_error_ptr error_fn;
png_error_ptr warning_fn;
png_voidp error_ptr;
png_debug(1, "in png_write_destroy\n");
/* free any memory zlib uses */
deflateEnd(&png_ptr->zstream);
/* free our memory. png_free checks NULL for us. */
png_free(png_ptr, png_ptr->zbuf);
png_free(png_ptr, png_ptr->row_buf);
png_free(png_ptr, png_ptr->prev_row);
png_free(png_ptr, png_ptr->sub_row);
png_free(png_ptr, png_ptr->up_row);
png_free(png_ptr, png_ptr->avg_row);
png_free(png_ptr, png_ptr->paeth_row);
#if defined(PNG_TIME_RFC1123_SUPPORTED)
png_free(png_ptr, png_ptr->time_buffer);
#endif /* PNG_TIME_RFC1123_SUPPORTED */
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
png_free(png_ptr, png_ptr->prev_filters);
png_free(png_ptr, png_ptr->filter_weights);
png_free(png_ptr, png_ptr->inv_filter_weights);
png_free(png_ptr, png_ptr->filter_costs);
png_free(png_ptr, png_ptr->inv_filter_costs);
#endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
/* reset structure */
png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf));
error_fn = png_ptr->error_fn;
warning_fn = png_ptr->warning_fn;
error_ptr = png_ptr->error_ptr;
png_memset(png_ptr, 0, sizeof (png_struct));
png_ptr->error_fn = error_fn;
png_ptr->warning_fn = warning_fn;
png_ptr->error_ptr = error_ptr;
png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf));
}
/* Allow the application to select one or more row filters to use. */
void
png_set_filter(png_structp png_ptr, int method, int filters)
{
png_debug(1, "in png_set_filter\n");
/* We allow 'method' only for future expansion of the base filter method. */
if (method == PNG_FILTER_TYPE_BASE)
{
switch (filters & (PNG_ALL_FILTERS | 0x07))
{
case 5:
case 6:
case 7: png_warning(png_ptr, "Unknown row filter for method 0");
case PNG_FILTER_VALUE_NONE: png_ptr->do_filter=PNG_FILTER_NONE; break;
case PNG_FILTER_VALUE_SUB: png_ptr->do_filter=PNG_FILTER_SUB; break;
case PNG_FILTER_VALUE_UP: png_ptr->do_filter=PNG_FILTER_UP; break;
case PNG_FILTER_VALUE_AVG: png_ptr->do_filter=PNG_FILTER_AVG; break;
case PNG_FILTER_VALUE_PAETH: png_ptr->do_filter=PNG_FILTER_PAETH;break;
default: png_ptr->do_filter = (png_byte)filters; break;
}
/* If we have allocated the row_buf, this means we have already started
* with the image and we should have allocated all of the filter buffers
* that have been selected. If prev_row isn't already allocated, then
* it is too late to start using the filters that need it, since we
* will be missing the data in the previous row. If an application
* wants to start and stop using particular filters during compression,
* it should start out with all of the filters, and then add and
* remove them after the start of compression.
*/
if (png_ptr->row_buf != NULL)
{
if (png_ptr->do_filter & PNG_FILTER_SUB && png_ptr->sub_row == NULL)
{
png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
(png_ptr->rowbytes + 1));
png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
}
if (png_ptr->do_filter & PNG_FILTER_UP && png_ptr->up_row == NULL)
{
if (png_ptr->prev_row == NULL)
{
png_warning(png_ptr, "Can't add Up filter after starting");
png_ptr->do_filter &= ~PNG_FILTER_UP;
}
else
{
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 == NULL)
{
if (png_ptr->prev_row == NULL)
{
png_warning(png_ptr, "Can't add Average filter after starting");
png_ptr->do_filter &= ~PNG_FILTER_AVG;
}
else
{
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 == NULL)
{
if (png_ptr->prev_row == NULL)
{
png_warning(png_ptr, "Can't add Paeth filter after starting");
png_ptr->do_filter &= ~PNG_FILTER_PAETH;
}
else
{
png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
(png_ptr->rowbytes + 1));
png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
}
}
if (png_ptr->do_filter == PNG_NO_FILTERS)
png_ptr->do_filter = PNG_FILTER_NONE;
}
}
else
png_error(png_ptr, "Unknown custom filter method");
}
/* This allows us to influence the way in which libpng chooses the "best"
* filter for the current scanline. While the "minimum-sum-of-absolute-
* differences metric is relatively fast and effective, there is some
* question as to whether it can be improved upon by trying to keep the
* filtered data going to zlib more consistent, hopefully resulting in
* better compression.
*/
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) /* GRR 970116 */
void
png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
int num_weights, png_doublep filter_weights,
png_doublep filter_costs)
{
#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
int i;
#endif
png_debug(1, "in png_set_filter_heuristics\n");
if (heuristic_method >= PNG_FILTER_HEURISTIC_LAST)
{
png_warning(png_ptr, "Unknown filter heuristic method");
return;
}
if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT)
{
heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
}
if (num_weights < 0 || filter_weights == NULL ||
heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
{
num_weights = 0;
}
png_ptr->num_prev_filters = num_weights;
png_ptr->heuristic_method = heuristic_method;
if (num_weights > 0)
{
if (png_ptr->prev_filters == NULL)
{
png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
(png_uint_32)(sizeof(png_byte) * num_weights));
/* To make sure that the weighting starts out fairly */
for (i = 0; i < num_weights; i++)
{
png_ptr->prev_filters[i] = 255;
}
}
if (png_ptr->filter_weights == NULL)
{
png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)(sizeof(png_uint_16) * num_weights));
png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)(sizeof(png_uint_16) * num_weights));
for (i = 0; i < num_weights; i++)
{
png_ptr->inv_filter_weights[i] =
png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
}
}
for (i = 0; i < num_weights; i++)
{
if (filter_weights[i] < 0.0)
{
png_ptr->inv_filter_weights[i] =
png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
}
else
{
png_ptr->inv_filter_weights[i] =
(png_uint_16)((double)PNG_WEIGHT_FACTOR*filter_weights[i]+0.5);
png_ptr->filter_weights[i] =
(png_uint_16)((double)PNG_WEIGHT_FACTOR/filter_weights[i]+0.5);
}
}
}
/* If, in the future, there are other filter methods, this would
* need to be based on png_ptr->filter.
*/
if (png_ptr->filter_costs == NULL)
{
png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)(sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));
png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)(sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));
for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
{
png_ptr->inv_filter_costs[i] =
png_ptr->filter_costs[i] = PNG_COST_FACTOR;
}
}
/* Here is where we set the relative costs of the different filters. We
* should take the desired compression level into account when setting
* the costs, so that Paeth, for instance, has a high relative cost at low
* compression levels, while it has a lower relative cost at higher
* compression settings. The filter types are in order of increasing
* relative cost, so it would be possible to do this with an algorithm.
*/
for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
{
if (filter_costs == NULL || filter_costs[i] < 0.0)
{
png_ptr->inv_filter_costs[i] =
png_ptr->filter_costs[i] = PNG_COST_FACTOR;
}
else if (filter_costs[i] >= 1.0)
{
png_ptr->inv_filter_costs[i] =
(png_uint_16)((double)PNG_COST_FACTOR / filter_costs[i] + 0.5);
png_ptr->filter_costs[i] =
(png_uint_16)((double)PNG_COST_FACTOR * filter_costs[i] + 0.5);
}
}
}
#endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
void
png_set_compression_level(png_structp png_ptr, int level)
{
png_debug(1, "in png_set_compression_level\n");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_LEVEL;
png_ptr->zlib_level = level;
}
void
png_set_compression_mem_level(png_structp png_ptr, int mem_level)
{
png_debug(1, "in png_set_compression_mem_level\n");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL;
png_ptr->zlib_mem_level = mem_level;
}
void
png_set_compression_strategy(png_structp png_ptr, int strategy)
{
png_debug(1, "in png_set_compression_strategy\n");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
png_ptr->zlib_strategy = strategy;
}
void
png_set_compression_window_bits(png_structp png_ptr, int window_bits)
{
if (window_bits > 15)
png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS;
png_ptr->zlib_window_bits = window_bits;
}
void
png_set_compression_method(png_structp png_ptr, int method)
{
png_debug(1, "in png_set_compression_method\n");
if (method != 8)
png_warning(png_ptr, "Only compression method 8 is supported by PNG");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_METHOD;
png_ptr->zlib_method = method;
}
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