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skia / third_party / libpng / 047737496a77eeb97f9991919dac08ca3c149711 / . / pngwrite.c
blob: 0d4ee9f7ae0ea156f0757d444232ce4df8e2b796 [file] [log] [blame]
/* pngwrite.c - general routines to write a PNG file
*
* Last changed in libpng 1.6.19 [November 12, 2015]
* Copyright (c) 1998-2015 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"
#if defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
# include <errno.h>
#endif
#ifdef PNG_WRITE_SUPPORTED
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
/* Write out all the unknown chunks for the current given location */
static void
write_unknown_chunks(png_structrp png_ptr, png_const_inforp info_ptr,
unsigned int where)
{
if (info_ptr->unknown_chunks_num != 0)
{
png_const_unknown_chunkp up;
png_debug(5, "writing extra chunks");
for (up = info_ptr->unknown_chunks;
up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
++up)
if ((up->location & where) != 0)
{
/* If per-chunk unknown chunk handling is enabled use it, otherwise
* just write the chunks the application has set.
*/
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
int keep = png_handle_as_unknown(png_ptr, up->name);
/* NOTE: this code is radically different from the read side in the
* matter of handling an ancillary unknown chunk. In the read side
* the default behavior is to discard it, in the code below the default
* behavior is to write it. Critical chunks are, however, only
* written if explicitly listed or if the default is set to write all
* unknown chunks.
*
* The default handling is also slightly weird - it is not possible to
* stop the writing of all unsafe-to-copy chunks!
*
* TODO: REVIEW: this would seem to be a bug.
*/
if (keep != PNG_HANDLE_CHUNK_NEVER &&
((up->name[3] & 0x20) /* safe-to-copy overrides everything */ ||
keep == PNG_HANDLE_CHUNK_ALWAYS ||
(keep == PNG_HANDLE_CHUNK_AS_DEFAULT &&
png_ptr->unknown_default == PNG_HANDLE_CHUNK_ALWAYS)))
#endif
{
/* TODO: review, what is wrong with a zero length unknown chunk? */
if (up->size == 0)
png_warning(png_ptr, "Writing zero-length unknown chunk");
png_write_chunk(png_ptr, up->name, up->data, up->size);
}
}
}
}
#endif /* WRITE_UNKNOWN_CHUNKS */
/* 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 encourage
* 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 PNGAPI
png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
{
png_debug(1, "in png_write_info_before_PLTE");
if (png_ptr == NULL || info_ptr == NULL)
return;
if ((png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE) == 0)
{
/* Write PNG signature */
png_write_sig(png_ptr);
#ifdef PNG_MNG_FEATURES_SUPPORTED
if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 && \
png_ptr->mng_features_permitted != 0)
{
png_warning(png_ptr,
"MNG features are not allowed in a PNG datastream");
png_ptr->mng_features_permitted = 0;
}
#endif
/* 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,
#ifdef 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.
*
* 1.6.0: COLORSPACE support controls the writing of these chunks too, and
* the chunks will be written if the WRITE routine is there and
* information * is available in the COLORSPACE. (See
* png_colorspace_sync_info in png.c for where the valid flags get set.)
*
* Under certain circumstances the colorspace can be invalidated without
* syncing the info_struct 'valid' flags; this happens if libpng detects
* an error and calls png_error while the color space is being set, yet
* the application continues writing the PNG. So check the 'invalid'
* flag here too.
*/
#ifdef PNG_GAMMA_SUPPORTED
# ifdef PNG_WRITE_gAMA_SUPPORTED
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
(info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_gAMA) != 0 &&
(info_ptr->valid & PNG_INFO_gAMA) != 0)
png_write_gAMA_fixed(png_ptr, info_ptr->colorspace.gamma);
# endif
#endif
#ifdef PNG_COLORSPACE_SUPPORTED
/* Write only one of sRGB or an ICC profile. If a profile was supplied
* and it matches one of the known sRGB ones issue a warning.
*/
# ifdef PNG_WRITE_iCCP_SUPPORTED
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
(info_ptr->valid & PNG_INFO_iCCP) != 0)
{
# ifdef PNG_WRITE_sRGB_SUPPORTED
if ((info_ptr->valid & PNG_INFO_sRGB) != 0)
png_app_warning(png_ptr,
"profile matches sRGB but writing iCCP instead");
# endif
png_write_iCCP(png_ptr, info_ptr->iccp_name,
info_ptr->iccp_profile);
}
# ifdef PNG_WRITE_sRGB_SUPPORTED
else
# endif
# endif
# ifdef PNG_WRITE_sRGB_SUPPORTED
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
(info_ptr->valid & PNG_INFO_sRGB) != 0)
png_write_sRGB(png_ptr, info_ptr->colorspace.rendering_intent);
# endif /* WRITE_sRGB */
#endif /* COLORSPACE */
#ifdef PNG_WRITE_sBIT_SUPPORTED
if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
#endif
#ifdef PNG_COLORSPACE_SUPPORTED
# ifdef PNG_WRITE_cHRM_SUPPORTED
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
(info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0 &&
(info_ptr->valid & PNG_INFO_cHRM) != 0)
png_write_cHRM_fixed(png_ptr, &info_ptr->colorspace.end_points_xy);
# endif
#endif
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_IHDR);
#endif
png_ptr->mode |= PNG_WROTE_INFO_BEFORE_PLTE;
}
}
void PNGAPI
png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
{
#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
int i;
#endif
png_debug(1, "in png_write_info");
if (png_ptr == NULL || info_ptr == NULL)
return;
png_write_info_before_PLTE(png_ptr, info_ptr);
if ((info_ptr->valid & PNG_INFO_PLTE) != 0)
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");
#ifdef PNG_WRITE_tRNS_SUPPORTED
if ((info_ptr->valid & PNG_INFO_tRNS) !=0)
{
#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
/* Invert the alpha channel (in tRNS) */
if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0 &&
info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
int j, jend;
jend = info_ptr->num_trans;
if (jend > PNG_MAX_PALETTE_LENGTH)
jend = PNG_MAX_PALETTE_LENGTH;
for (j = 0; j<jend; ++j)
info_ptr->trans_alpha[j] =
(png_byte)(255 - info_ptr->trans_alpha[j]);
}
#endif
png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
info_ptr->num_trans, info_ptr->color_type);
}
#endif
#ifdef PNG_WRITE_bKGD_SUPPORTED
if ((info_ptr->valid & PNG_INFO_bKGD) != 0)
png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
#endif
#ifdef PNG_WRITE_hIST_SUPPORTED
if ((info_ptr->valid & PNG_INFO_hIST) != 0)
png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
#endif
#ifdef PNG_WRITE_oFFs_SUPPORTED
if ((info_ptr->valid & PNG_INFO_oFFs) != 0)
png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
info_ptr->offset_unit_type);
#endif
#ifdef PNG_WRITE_pCAL_SUPPORTED
if ((info_ptr->valid & PNG_INFO_pCAL) != 0)
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
#ifdef PNG_WRITE_sCAL_SUPPORTED
if ((info_ptr->valid & PNG_INFO_sCAL) != 0)
png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
info_ptr->scal_s_width, info_ptr->scal_s_height);
#endif /* sCAL */
#ifdef PNG_WRITE_pHYs_SUPPORTED
if ((info_ptr->valid & PNG_INFO_pHYs) != 0)
png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
#endif /* pHYs */
#ifdef PNG_WRITE_tIME_SUPPORTED
if ((info_ptr->valid & PNG_INFO_tIME) != 0)
{
png_write_tIME(png_ptr, &(info_ptr->mod_time));
png_ptr->mode |= PNG_WROTE_tIME;
}
#endif /* tIME */
#ifdef PNG_WRITE_sPLT_SUPPORTED
if ((info_ptr->valid & PNG_INFO_sPLT) != 0)
for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
png_write_sPLT(png_ptr, info_ptr->splt_palettes + i);
#endif /* sPLT */
#ifdef PNG_WRITE_TEXT_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", i,
info_ptr->text[i].compression);
/* An internationalized chunk? */
if (info_ptr->text[i].compression > 0)
{
#ifdef PNG_WRITE_iTXt_SUPPORTED
/* Write international chunk */
png_write_iTXt(png_ptr,
info_ptr->text[i].compression,
info_ptr->text[i].key,
info_ptr->text[i].lang,
info_ptr->text[i].lang_key,
info_ptr->text[i].text);
/* Mark this chunk as written */
if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
else
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
#else
png_warning(png_ptr, "Unable to write international text");
#endif
}
/* If we want a compressed text chunk */
else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt)
{
#ifdef 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].compression);
/* Mark this chunk as written */
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
#else
png_warning(png_ptr, "Unable to write compressed text");
#endif
}
else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
{
#ifdef PNG_WRITE_tEXt_SUPPORTED
/* Write uncompressed chunk */
png_write_tEXt(png_ptr, info_ptr->text[i].key,
info_ptr->text[i].text,
0);
/* Mark this chunk as written */
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
#else
/* Can't get here */
png_warning(png_ptr, "Unable to write uncompressed text");
#endif
}
}
#endif /* tEXt */
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_PLTE);
#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 PNGAPI
png_write_end(png_structrp png_ptr, png_inforp info_ptr)
{
png_debug(1, "in png_write_end");
if (png_ptr == NULL)
return;
if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
png_error(png_ptr, "No IDATs written into file");
#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
if (png_ptr->num_palette_max > png_ptr->num_palette)
png_benign_error(png_ptr, "Wrote palette index exceeding num_palette");
#endif
/* See if user wants us to write information chunks */
if (info_ptr != NULL)
{
#ifdef PNG_WRITE_TEXT_SUPPORTED
int i; /* local index variable */
#endif
#ifdef PNG_WRITE_tIME_SUPPORTED
/* Check to see if user has supplied a time chunk */
if ((info_ptr->valid & PNG_INFO_tIME) != 0 &&
(png_ptr->mode & PNG_WROTE_tIME) == 0)
png_write_tIME(png_ptr, &(info_ptr->mod_time));
#endif
#ifdef PNG_WRITE_TEXT_SUPPORTED
/* Loop through comment chunks */
for (i = 0; i < info_ptr->num_text; i++)
{
png_debug2(2, "Writing trailer text chunk %d, type %d", i,
info_ptr->text[i].compression);
/* An internationalized chunk? */
if (info_ptr->text[i].compression > 0)
{
#ifdef PNG_WRITE_iTXt_SUPPORTED
/* Write international chunk */
png_write_iTXt(png_ptr,
info_ptr->text[i].compression,
info_ptr->text[i].key,
info_ptr->text[i].lang,
info_ptr->text[i].lang_key,
info_ptr->text[i].text);
/* Mark this chunk as written */
if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
else
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
#else
png_warning(png_ptr, "Unable to write international text");
#endif
}
else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
{
#ifdef 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].compression);
/* Mark this chunk as written */
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
#else
png_warning(png_ptr, "Unable to write compressed text");
#endif
}
else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
{
#ifdef PNG_WRITE_tEXt_SUPPORTED
/* Write uncompressed chunk */
png_write_tEXt(png_ptr, info_ptr->text[i].key,
info_ptr->text[i].text, 0);
/* Mark this chunk as written */
info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
#else
png_warning(png_ptr, "Unable to write uncompressed text");
#endif
}
}
#endif
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
write_unknown_chunks(png_ptr, info_ptr, PNG_AFTER_IDAT);
#endif
}
png_ptr->mode |= PNG_AFTER_IDAT;
/* Write end of PNG file */
png_write_IEND(png_ptr);
/* This flush, added in libpng-1.0.8, removed from libpng-1.0.9beta03,
* and restored again in libpng-1.2.30, may cause some applications that
* do not set png_ptr->output_flush_fn to crash. If your application
* experiences a problem, please try building libpng with
* PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED defined, and report the event to
* png-mng-implement at lists.sf.net .
*/
#ifdef PNG_WRITE_FLUSH_SUPPORTED
# ifdef PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED
png_flush(png_ptr);
# endif
#endif
}
#ifdef PNG_CONVERT_tIME_SUPPORTED
void PNGAPI
png_convert_from_struct_tm(png_timep ptime, PNG_CONST struct tm * ttime)
{
png_debug(1, "in png_convert_from_struct_tm");
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 PNGAPI
png_convert_from_time_t(png_timep ptime, time_t ttime)
{
struct tm *tbuf;
png_debug(1, "in png_convert_from_time_t");
tbuf = gmtime(&ttime);
png_convert_from_struct_tm(ptime, tbuf);
}
#endif
/* Initialize png_ptr structure, and allocate any memory needed */
PNG_FUNCTION(png_structp,PNGAPI
png_create_write_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
{
#ifndef PNG_USER_MEM_SUPPORTED
png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
error_fn, warn_fn, NULL, NULL, NULL);
#else
return png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
warn_fn, NULL, NULL, NULL);
}
/* Alternate initialize png_ptr structure, and allocate any memory needed */
PNG_FUNCTION(png_structp,PNGAPI
png_create_write_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
{
png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
#endif /* USER_MEM */
if (png_ptr != NULL)
{
/* Set the zlib control values to defaults; they can be overridden by the
* application after the struct has been created.
*/
png_ptr->zbuffer_size = PNG_ZBUF_SIZE;
/* The 'zlib_strategy' setting is irrelevant because png_default_claim in
* pngwutil.c defaults it according to whether or not filters will be
* used, and ignores this setting.
*/
png_ptr->zlib_strategy = PNG_Z_DEFAULT_STRATEGY;
png_ptr->zlib_level = PNG_Z_DEFAULT_COMPRESSION;
png_ptr->zlib_mem_level = 8;
png_ptr->zlib_window_bits = 15;
png_ptr->zlib_method = 8;
#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
png_ptr->zlib_text_strategy = PNG_TEXT_Z_DEFAULT_STRATEGY;
png_ptr->zlib_text_level = PNG_TEXT_Z_DEFAULT_COMPRESSION;
png_ptr->zlib_text_mem_level = 8;
png_ptr->zlib_text_window_bits = 15;
png_ptr->zlib_text_method = 8;
#endif /* WRITE_COMPRESSED_TEXT */
/* This is a highly dubious configuration option; by default it is off,
* but it may be appropriate for private builds that are testing
* extensions not conformant to the current specification, or of
* applications that must not fail to write at all costs!
*/
#ifdef PNG_BENIGN_WRITE_ERRORS_SUPPORTED
/* In stable builds only warn if an application error can be completely
* handled.
*/
png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
#endif
/* App warnings are warnings in release (or release candidate) builds but
* are errors during development.
*/
#if PNG_RELEASE_BUILD
png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
#endif
/* TODO: delay this, it can be done in png_init_io() (if the app doesn't
* do it itself) avoiding setting the default function if it is not
* required.
*/
png_set_write_fn(png_ptr, NULL, NULL, NULL);
}
return png_ptr;
}
/* 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 PNGAPI
png_write_rows(png_structrp 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");
if (png_ptr == NULL)
return;
/* 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 PNGAPI
png_write_image(png_structrp png_ptr, png_bytepp image)
{
png_uint_32 i; /* row index */
int pass, num_pass; /* pass variables */
png_bytepp rp; /* points to current row */
if (png_ptr == NULL)
return;
png_debug(1, "in png_write_image");
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Initialize 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);
}
}
}
#ifdef PNG_MNG_FEATURES_SUPPORTED
/* Performs intrapixel differencing */
static void
png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_write_intrapixel");
if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
{
int bytes_per_pixel;
png_uint_32 row_width = row_info->width;
if (row_info->bit_depth == 8)
{
png_bytep rp;
png_uint_32 i;
if (row_info->color_type == PNG_COLOR_TYPE_RGB)
bytes_per_pixel = 3;
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
bytes_per_pixel = 4;
else
return;
for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
{
*(rp) = (png_byte)(*rp - *(rp + 1));
*(rp + 2) = (png_byte)(*(rp + 2) - *(rp + 1));
}
}
#ifdef PNG_WRITE_16BIT_SUPPORTED
else if (row_info->bit_depth == 16)
{
png_bytep rp;
png_uint_32 i;
if (row_info->color_type == PNG_COLOR_TYPE_RGB)
bytes_per_pixel = 6;
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
bytes_per_pixel = 8;
else
return;
for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
{
png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
*(rp ) = (png_byte)(red >> 8);
*(rp + 1) = (png_byte)red;
*(rp + 4) = (png_byte)(blue >> 8);
*(rp + 5) = (png_byte)blue;
}
}
#endif /* WRITE_16BIT */
}
}
#endif /* MNG_FEATURES */
/* Called by user to write a row of image data */
void PNGAPI
png_write_row(png_structrp png_ptr, png_const_bytep row)
{
/* 1.5.6: moved from png_struct to be a local structure: */
png_row_info row_info;
if (png_ptr == NULL)
return;
png_debug2(1, "in png_write_row (row %u, pass %d)",
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)
{
/* Make sure we wrote the header info */
if ((png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE) == 0)
png_error(png_ptr,
"png_write_info was never called before png_write_row");
/* Check for transforms that have been set but were defined out */
#if !defined(PNG_WRITE_INVERT_SUPPORTED) && defined(PNG_READ_INVERT_SUPPORTED)
if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined");
#endif
#if !defined(PNG_WRITE_FILLER_SUPPORTED) && defined(PNG_READ_FILLER_SUPPORTED)
if ((png_ptr->transformations & PNG_FILLER) != 0)
png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined");
#endif
#if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
defined(PNG_READ_PACKSWAP_SUPPORTED)
if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
png_warning(png_ptr,
"PNG_WRITE_PACKSWAP_SUPPORTED is not defined");
#endif
#if !defined(PNG_WRITE_PACK_SUPPORTED) && defined(PNG_READ_PACK_SUPPORTED)
if ((png_ptr->transformations & PNG_PACK) != 0)
png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined");
#endif
#if !defined(PNG_WRITE_SHIFT_SUPPORTED) && defined(PNG_READ_SHIFT_SUPPORTED)
if ((png_ptr->transformations & PNG_SHIFT) != 0)
png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined");
#endif
#if !defined(PNG_WRITE_BGR_SUPPORTED) && defined(PNG_READ_BGR_SUPPORTED)
if ((png_ptr->transformations & PNG_BGR) != 0)
png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined");
#endif
#if !defined(PNG_WRITE_SWAP_SUPPORTED) && defined(PNG_READ_SWAP_SUPPORTED)
if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined");
#endif
png_write_start_row(png_ptr);
}
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* If interlaced and not interested in row, return */
if (png_ptr->interlaced != 0 &&
(png_ptr->transformations & PNG_INTERLACE) != 0)
{
switch (png_ptr->pass)
{
case 0:
if ((png_ptr->row_number & 0x07) != 0)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 1:
if ((png_ptr->row_number & 0x07) != 0 || png_ptr->width < 5)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 2:
if ((png_ptr->row_number & 0x07) != 4)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 3:
if ((png_ptr->row_number & 0x03) != 0 || png_ptr->width < 3)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 4:
if ((png_ptr->row_number & 0x03) != 2)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 5:
if ((png_ptr->row_number & 0x01) != 0 || png_ptr->width < 2)
{
png_write_finish_row(png_ptr);
return;
}
break;
case 6:
if ((png_ptr->row_number & 0x01) == 0)
{
png_write_finish_row(png_ptr);
return;
}
break;
default: /* error: ignore it */
break;
}
}
#endif
/* Set up row info for transformations */
row_info.color_type = png_ptr->color_type;
row_info.width = png_ptr->usr_width;
row_info.channels = png_ptr->usr_channels;
row_info.bit_depth = png_ptr->usr_bit_depth;
row_info.pixel_depth = (png_byte)(row_info.bit_depth * row_info.channels);
row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
png_debug1(3, "row_info->color_type = %d", row_info.color_type);
png_debug1(3, "row_info->width = %u", row_info.width);
png_debug1(3, "row_info->channels = %d", row_info.channels);
png_debug1(3, "row_info->bit_depth = %d", row_info.bit_depth);
png_debug1(3, "row_info->pixel_depth = %d", row_info.pixel_depth);
png_debug1(3, "row_info->rowbytes = %lu", (unsigned long)row_info.rowbytes);
/* Copy user's row into buffer, leaving room for filter byte. */
memcpy(png_ptr->row_buf + 1, row, row_info.rowbytes);
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Handle interlacing */
if (png_ptr->interlaced && png_ptr->pass < 6 &&
(png_ptr->transformations & PNG_INTERLACE) != 0)
{
png_do_write_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass);
/* This should always get caught above, but still ... */
if (row_info.width == 0)
{
png_write_finish_row(png_ptr);
return;
}
}
#endif
#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
/* Handle other transformations */
if (png_ptr->transformations != 0)
png_do_write_transformations(png_ptr, &row_info);
#endif
/* At this point the row_info pixel depth must match the 'transformed' depth,
* which is also the output depth.
*/
if (row_info.pixel_depth != png_ptr->pixel_depth ||
row_info.pixel_depth != png_ptr->transformed_pixel_depth)
png_error(png_ptr, "internal write transform logic error");
#ifdef PNG_MNG_FEATURES_SUPPORTED
/* 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 ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
(png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
{
/* Intrapixel differencing */
png_do_write_intrapixel(&row_info, png_ptr->row_buf + 1);
}
#endif
/* Added at libpng-1.5.10 */
#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
/* Check for out-of-range palette index */
if (row_info.color_type == PNG_COLOR_TYPE_PALETTE &&
png_ptr->num_palette_max >= 0)
png_do_check_palette_indexes(png_ptr, &row_info);
#endif
/* Find a filter if necessary, filter the row and write it out. */
png_write_find_filter(png_ptr, &row_info);
if (png_ptr->write_row_fn != NULL)
(*(png_ptr->write_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
}
#ifdef PNG_WRITE_FLUSH_SUPPORTED
/* Set the automatic flush interval or 0 to turn flushing off */
void PNGAPI
png_set_flush(png_structrp png_ptr, int nrows)
{
png_debug(1, "in png_set_flush");
if (png_ptr == NULL)
return;
png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
}
/* Flush the current output buffers now */
void PNGAPI
png_write_flush(png_structrp png_ptr)
{
png_debug(1, "in png_write_flush");
if (png_ptr == NULL)
return;
/* We have already written out all of the data */
if (png_ptr->row_number >= png_ptr->num_rows)
return;
png_compress_IDAT(png_ptr, NULL, 0, Z_SYNC_FLUSH);
png_ptr->flush_rows = 0;
png_flush(png_ptr);
}
#endif /* WRITE_FLUSH */
/* Free any memory used in png_ptr struct without freeing the struct itself. */
static void
png_write_destroy(png_structrp png_ptr)
{
png_debug(1, "in png_write_destroy");
/* Free any memory zlib uses */
if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
deflateEnd(&png_ptr->zstream);
/* Free our memory. png_free checks NULL for us. */
png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
png_free(png_ptr, png_ptr->row_buf);
png_ptr->row_buf = NULL;
#ifdef PNG_WRITE_FILTER_SUPPORTED
png_free(png_ptr, png_ptr->prev_row);
png_free(png_ptr, png_ptr->try_row);
png_free(png_ptr, png_ptr->tst_row);
png_ptr->prev_row = NULL;
png_ptr->try_row = NULL;
png_ptr->tst_row = NULL;
#endif
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
png_free(png_ptr, png_ptr->chunk_list);
png_ptr->chunk_list = NULL;
#endif
/* The error handling and memory handling information is left intact at this
* point: the jmp_buf may still have to be freed. See png_destroy_png_struct
* for how this happens.
*/
}
/* Free all memory used by the write.
* In libpng 1.6.0 this API changed quietly to no longer accept a NULL value for
* *png_ptr_ptr. Prior to 1.6.0 it would accept such a value and it would free
* the passed in info_structs but it would quietly fail to free any of the data
* inside them. In 1.6.0 it quietly does nothing (it has to be quiet because it
* has no png_ptr.)
*/
void PNGAPI
png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
{
png_debug(1, "in png_destroy_write_struct");
if (png_ptr_ptr != NULL)
{
png_structrp png_ptr = *png_ptr_ptr;
if (png_ptr != NULL) /* added in libpng 1.6.0 */
{
png_destroy_info_struct(png_ptr, info_ptr_ptr);
*png_ptr_ptr = NULL;
png_write_destroy(png_ptr);
png_destroy_png_struct(png_ptr);
}
}
}
/* Allow the application to select one or more row filters to use. */
void PNGAPI
png_set_filter(png_structrp png_ptr, int method, int filters)
{
png_debug(1, "in png_set_filter");
if (png_ptr == NULL)
return;
#ifdef PNG_MNG_FEATURES_SUPPORTED
if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
(method == PNG_INTRAPIXEL_DIFFERENCING))
method = PNG_FILTER_TYPE_BASE;
#endif
if (method == PNG_FILTER_TYPE_BASE)
{
switch (filters & (PNG_ALL_FILTERS | 0x07))
{
#ifdef PNG_WRITE_FILTER_SUPPORTED
case 5:
case 6:
case 7: png_app_error(png_ptr, "Unknown row filter for method 0");
/* FALL THROUGH */
#endif /* WRITE_FILTER */
case PNG_FILTER_VALUE_NONE:
png_ptr->do_filter = PNG_FILTER_NONE; break;
#ifdef PNG_WRITE_FILTER_SUPPORTED
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;
#else
default:
png_app_error(png_ptr, "Unknown row filter for method 0");
#endif /* WRITE_FILTER */
}
#ifdef PNG_WRITE_FILTER_SUPPORTED
/* 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 remove them
* or add them back after the start of compression.
*
* NOTE: this is a nasty constraint on the code, because it means that the
* prev_row buffer must be maintained even if there are currently no
* 'prev_row' requiring filters active.
*/
if (png_ptr->row_buf != NULL)
{
int num_filters;
png_alloc_size_t buf_size;
/* Repeat the checks in png_write_start_row; 1 pixel high or wide
* images cannot benefit from certain filters. If this isn't done here
* the check below will fire on 1 pixel high images.
*/
if (png_ptr->height == 1)
filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
if (png_ptr->width == 1)
filters &= ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH);
if ((filters & (PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH)) != 0
&& png_ptr->prev_row == NULL)
{
/* This is the error case, however it is benign - the previous row
* is not available so the filter can't be used. Just warn here.
*/
png_app_warning(png_ptr,
"png_set_filter: UP/AVG/PAETH cannot be added after start");
filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
}
num_filters = 0;
if (filters & PNG_FILTER_SUB)
num_filters++;
if (filters & PNG_FILTER_UP)
num_filters++;
if (filters & PNG_FILTER_AVG)
num_filters++;
if (filters & PNG_FILTER_PAETH)
num_filters++;
/* Allocate needed row buffers if they have not already been
* allocated.
*/
buf_size = PNG_ROWBYTES(png_ptr->usr_channels * png_ptr->usr_bit_depth,
png_ptr->width) + 1;
if (png_ptr->try_row == NULL)
png_ptr->try_row = png_voidcast(png_bytep,
png_malloc(png_ptr, buf_size));
if (num_filters > 1)
{
if (png_ptr->tst_row == NULL)
png_ptr->tst_row = png_voidcast(png_bytep,
png_malloc(png_ptr, buf_size));
}
}
png_ptr->do_filter = (png_byte)filters;
#endif
}
else
png_error(png_ptr, "Unknown custom filter method");
}
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* DEPRECATED */
/* Provide floating and fixed point APIs */
#ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_filter_heuristics(png_structrp png_ptr, int heuristic_method,
int num_weights, png_const_doublep filter_weights,
png_const_doublep filter_costs)
{
PNG_UNUSED(png_ptr)
PNG_UNUSED(heuristic_method)
PNG_UNUSED(num_weights)
PNG_UNUSED(filter_weights)
PNG_UNUSED(filter_costs)
}
#endif /* FLOATING_POINT */
#ifdef PNG_FIXED_POINT_SUPPORTED
void PNGAPI
png_set_filter_heuristics_fixed(png_structrp png_ptr, int heuristic_method,
int num_weights, png_const_fixed_point_p filter_weights,
png_const_fixed_point_p filter_costs)
{
PNG_UNUSED(png_ptr)
PNG_UNUSED(heuristic_method)
PNG_UNUSED(num_weights)
PNG_UNUSED(filter_weights)
PNG_UNUSED(filter_costs)
}
#endif /* FIXED_POINT */
#endif /* WRITE_WEIGHTED_FILTER */
#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
void PNGAPI
png_set_compression_level(png_structrp png_ptr, int level)
{
png_debug(1, "in png_set_compression_level");
if (png_ptr == NULL)
return;
png_ptr->zlib_level = level;
}
void PNGAPI
png_set_compression_mem_level(png_structrp png_ptr, int mem_level)
{
png_debug(1, "in png_set_compression_mem_level");
if (png_ptr == NULL)
return;
png_ptr->zlib_mem_level = mem_level;
}
void PNGAPI
png_set_compression_strategy(png_structrp png_ptr, int strategy)
{
png_debug(1, "in png_set_compression_strategy");
if (png_ptr == NULL)
return;
/* The flag setting here prevents the libpng dynamic selection of strategy.
*/
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
png_ptr->zlib_strategy = strategy;
}
/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
* smaller value of window_bits if it can do so safely.
*/
void PNGAPI
png_set_compression_window_bits(png_structrp png_ptr, int window_bits)
{
if (png_ptr == NULL)
return;
/* Prior to 1.6.0 this would warn but then set the window_bits value. This
* meant that negative window bits values could be selected that would cause
* libpng to write a non-standard PNG file with raw deflate or gzip
* compressed IDAT or ancillary chunks. Such files can be read and there is
* no warning on read, so this seems like a very bad idea.
*/
if (window_bits > 15)
{
png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
window_bits = 15;
}
else if (window_bits < 8)
{
png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
window_bits = 8;
}
png_ptr->zlib_window_bits = window_bits;
}
void PNGAPI
png_set_compression_method(png_structrp png_ptr, int method)
{
png_debug(1, "in png_set_compression_method");
if (png_ptr == NULL)
return;
/* This would produce an invalid PNG file if it worked, but it doesn't and
* deflate will fault it, so it is harmless to just warn here.
*/
if (method != 8)
png_warning(png_ptr, "Only compression method 8 is supported by PNG");
png_ptr->zlib_method = method;
}
#endif /* WRITE_CUSTOMIZE_COMPRESSION */
/* The following were added to libpng-1.5.4 */
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
void PNGAPI
png_set_text_compression_level(png_structrp png_ptr, int level)
{
png_debug(1, "in png_set_text_compression_level");
if (png_ptr == NULL)
return;
png_ptr->zlib_text_level = level;
}
void PNGAPI
png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level)
{
png_debug(1, "in png_set_text_compression_mem_level");
if (png_ptr == NULL)
return;
png_ptr->zlib_text_mem_level = mem_level;
}
void PNGAPI
png_set_text_compression_strategy(png_structrp png_ptr, int strategy)
{
png_debug(1, "in png_set_text_compression_strategy");
if (png_ptr == NULL)
return;
png_ptr->zlib_text_strategy = strategy;
}
/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
* smaller value of window_bits if it can do so safely.
*/
void PNGAPI
png_set_text_compression_window_bits(png_structrp png_ptr, int window_bits)
{
if (png_ptr == NULL)
return;
if (window_bits > 15)
{
png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
window_bits = 15;
}
else if (window_bits < 8)
{
png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
window_bits = 8;
}
png_ptr->zlib_text_window_bits = window_bits;
}
void PNGAPI
png_set_text_compression_method(png_structrp png_ptr, int method)
{
png_debug(1, "in png_set_text_compression_method");
if (png_ptr == NULL)
return;
if (method != 8)
png_warning(png_ptr, "Only compression method 8 is supported by PNG");
png_ptr->zlib_text_method = method;
}
#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
/* end of API added to libpng-1.5.4 */
void PNGAPI
png_set_write_status_fn(png_structrp png_ptr, png_write_status_ptr write_row_fn)
{
if (png_ptr == NULL)
return;
png_ptr->write_row_fn = write_row_fn;
}
#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
void PNGAPI
png_set_write_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
write_user_transform_fn)
{
png_debug(1, "in png_set_write_user_transform_fn");
if (png_ptr == NULL)
return;
png_ptr->transformations |= PNG_USER_TRANSFORM;
png_ptr->write_user_transform_fn = write_user_transform_fn;
}
#endif
#ifdef PNG_INFO_IMAGE_SUPPORTED
void PNGAPI
png_write_png(png_structrp png_ptr, png_inforp info_ptr,
int transforms, voidp params)
{
if (png_ptr == NULL || info_ptr == NULL)
return;
if ((info_ptr->valid & PNG_INFO_IDAT) == 0)
{
png_app_error(png_ptr, "no rows for png_write_image to write");
return;
}
/* Write the file header information. */
png_write_info(png_ptr, info_ptr);
/* ------ these transformations don't touch the info structure ------- */
/* Invert monochrome pixels */
if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
#ifdef PNG_WRITE_INVERT_SUPPORTED
png_set_invert_mono(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
#endif
/* Shift the pixels up to a legal bit depth and fill in
* as appropriate to correctly scale the image.
*/
if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
#ifdef PNG_WRITE_SHIFT_SUPPORTED
if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
png_set_shift(png_ptr, &info_ptr->sig_bit);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
#endif
/* Pack pixels into bytes */
if ((transforms & PNG_TRANSFORM_PACKING) != 0)
#ifdef PNG_WRITE_PACK_SUPPORTED
png_set_packing(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
#endif
/* Swap location of alpha bytes from ARGB to RGBA */
if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
png_set_swap_alpha(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
#endif
/* Remove a filler (X) from XRGB/RGBX/AG/GA into to convert it into
* RGB, note that the code expects the input color type to be G or RGB; no
* alpha channel.
*/
if ((transforms & (PNG_TRANSFORM_STRIP_FILLER_AFTER|
PNG_TRANSFORM_STRIP_FILLER_BEFORE)) != 0)
{
#ifdef PNG_WRITE_FILLER_SUPPORTED
if ((transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER) != 0)
{
if ((transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE) != 0)
png_app_error(png_ptr,
"PNG_TRANSFORM_STRIP_FILLER: BEFORE+AFTER not supported");
/* Continue if ignored - this is the pre-1.6.10 behavior */
png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
}
else if ((transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE) != 0)
png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_FILLER not supported");
#endif
}
/* Flip BGR pixels to RGB */
if ((transforms & PNG_TRANSFORM_BGR) != 0)
#ifdef PNG_WRITE_BGR_SUPPORTED
png_set_bgr(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
#endif
/* Swap bytes of 16-bit files to most significant byte first */
if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
#ifdef PNG_WRITE_SWAP_SUPPORTED
png_set_swap(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
#endif
/* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */
if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
png_set_packswap(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
#endif
/* Invert the alpha channel from opacity to transparency */
if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
png_set_invert_alpha(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
#endif
/* ----------------------- end of transformations ------------------- */
/* Write the bits */
png_write_image(png_ptr, info_ptr->row_pointers);
/* It is REQUIRED to call this to finish writing the rest of the file */
png_write_end(png_ptr, info_ptr);
PNG_UNUSED(params)
}
#endif
#ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
# ifdef PNG_STDIO_SUPPORTED /* currently required for png_image_write_* */
/* Initialize the write structure - general purpose utility. */
static int
png_image_write_init(png_imagep image)
{
png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, image,
png_safe_error, png_safe_warning);
if (png_ptr != NULL)
{
png_infop info_ptr = png_create_info_struct(png_ptr);
if (info_ptr != NULL)
{
png_controlp control = png_voidcast(png_controlp,
png_malloc_warn(png_ptr, (sizeof *control)));
if (control != NULL)
{
memset(control, 0, (sizeof *control));
control->png_ptr = png_ptr;
control->info_ptr = info_ptr;
control->for_write = 1;
image->opaque = control;
return 1;
}
/* Error clean up */
png_destroy_info_struct(png_ptr, &info_ptr);
}
png_destroy_write_struct(&png_ptr, NULL);
}
return png_image_error(image, "png_image_write_: out of memory");
}
/* Arguments to png_image_write_main: */
typedef struct
{
/* Arguments: */
png_imagep image;
png_const_voidp buffer;
png_int_32 row_stride;
png_const_voidp colormap;
int convert_to_8bit;
/* Local variables: */
png_const_voidp first_row;
ptrdiff_t row_bytes;
png_voidp local_row;
} png_image_write_control;
/* Write png_uint_16 input to a 16-bit PNG; the png_ptr has already been set to
* do any necessary byte swapping. The component order is defined by the
* png_image format value.
*/
static int
png_write_image_16bit(png_voidp argument)
{
png_image_write_control *display = png_voidcast(png_image_write_control*,
argument);
png_imagep image = display->image;
png_structrp png_ptr = image->opaque->png_ptr;
png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
display->first_row);
png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
png_uint_16p row_end;
const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
int aindex = 0;
png_uint_32 y = image->height;
if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
{
# ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
if ((image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
{
aindex = -1;
++input_row; /* To point to the first component */
++output_row;
}
else
aindex = channels;
# else
aindex = channels;
# endif
}
else
png_error(png_ptr, "png_write_image: internal call error");
/* Work out the output row end and count over this, note that the increment
* above to 'row' means that row_end can actually be beyond the end of the
* row; this is correct.
*/
row_end = output_row + image->width * (channels+1);
while (y-- > 0)
{
png_const_uint_16p in_ptr = input_row;
png_uint_16p out_ptr = output_row;
while (out_ptr < row_end)
{
const png_uint_16 alpha = in_ptr[aindex];
png_uint_32 reciprocal = 0;
int c;
out_ptr[aindex] = alpha;
/* Calculate a reciprocal. The correct calculation is simply
* component/alpha*65535 << 15. (I.e. 15 bits of precision); this
* allows correct rounding by adding .5 before the shift. 'reciprocal'
* is only initialized when required.
*/
if (alpha > 0 && alpha < 65535)
reciprocal = ((0xffff<<15)+(alpha>>1))/alpha;
c = channels;
do /* always at least one channel */
{
png_uint_16 component = *in_ptr++;
/* The following gives 65535 for an alpha of 0, which is fine,
* otherwise if 0/0 is represented as some other value there is more
* likely to be a discontinuity which will probably damage
* compression when moving from a fully transparent area to a
* nearly transparent one. (The assumption here is that opaque
* areas tend not to be 0 intensity.)
*/
if (component >= alpha)
component = 65535;
/* component<alpha, so component/alpha is less than one and
* component*reciprocal is less than 2^31.
*/
else if (component > 0 && alpha < 65535)
{
png_uint_32 calc = component * reciprocal;
calc += 16384; /* round to nearest */
component = (png_uint_16)(calc >> 15);
}
*out_ptr++ = component;
}
while (--c > 0);
/* Skip to next component (skip the intervening alpha channel) */
++in_ptr;
++out_ptr;
}
png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
input_row += display->row_bytes/(sizeof (png_uint_16));
}
return 1;
}
/* Given 16-bit input (1 to 4 channels) write 8-bit output. If an alpha channel
* is present it must be removed from the components, the components are then
* written in sRGB encoding. No components are added or removed.
*
* Calculate an alpha reciprocal to reverse pre-multiplication. As above the
* calculation can be done to 15 bits of accuracy; however, the output needs to
* be scaled in the range 0..255*65535, so include that scaling here.
*/
# define UNP_RECIPROCAL(alpha) ((((0xffff*0xff)<<7)+(alpha>>1))/alpha)
static png_byte
png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
png_uint_32 reciprocal/*from the above macro*/)
{
/* The following gives 1.0 for an alpha of 0, which is fine, otherwise if 0/0
* is represented as some other value there is more likely to be a
* discontinuity which will probably damage compression when moving from a
* fully transparent area to a nearly transparent one. (The assumption here
* is that opaque areas tend not to be 0 intensity.)
*
* There is a rounding problem here; if alpha is less than 128 it will end up
* as 0 when scaled to 8 bits. To avoid introducing spurious colors into the
* output change for this too.
*/
if (component >= alpha || alpha < 128)
return 255;
/* component<alpha, so component/alpha is less than one and
* component*reciprocal is less than 2^31.
*/
else if (component > 0)
{
/* The test is that alpha/257 (rounded) is less than 255, the first value
* that becomes 255 is 65407.
* NOTE: this must agree with the PNG_DIV257 macro (which must, therefore,
* be exact!) [Could also test reciprocal != 0]
*/
if (alpha < 65407)
{
component *= reciprocal;
component += 64; /* round to nearest */
component >>= 7;
}
else
component *= 255;
/* Convert the component to sRGB. */
return (png_byte)PNG_sRGB_FROM_LINEAR(component);
}
else
return 0;
}
static int
png_write_image_8bit(png_voidp argument)
{
png_image_write_control *display = png_voidcast(png_image_write_control*,
argument);
png_imagep image = display->image;
png_structrp png_ptr = image->opaque->png_ptr;
png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
display->first_row);
png_bytep output_row = png_voidcast(png_bytep, display->local_row);
png_uint_32 y = image->height;
const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
{
png_bytep row_end;
int aindex;
# ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
if ((image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
{
aindex = -1;
++input_row; /* To point to the first component */
++output_row;
}
else
# endif
aindex = channels;
/* Use row_end in place of a loop counter: */
row_end = output_row + image->width * (channels+1);
while (y-- > 0)
{
png_const_uint_16p in_ptr = input_row;
png_bytep out_ptr = output_row;
while (out_ptr < row_end)
{
png_uint_16 alpha = in_ptr[aindex];
png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
png_uint_32 reciprocal = 0;
int c;
/* Scale and write the alpha channel. */
out_ptr[aindex] = alphabyte;
if (alphabyte > 0 && alphabyte < 255)
reciprocal = UNP_RECIPROCAL(alpha);
c = channels;
do /* always at least one channel */
*out_ptr++ = png_unpremultiply(*in_ptr++, alpha, reciprocal);
while (--c > 0);
/* Skip to next component (skip the intervening alpha channel) */
++in_ptr;
++out_ptr;
} /* while out_ptr < row_end */
png_write_row(png_ptr, png_voidcast(png_const_bytep,
display->local_row));
input_row += display->row_bytes/(sizeof (png_uint_16));
} /* while y */
}
else
{
/* No alpha channel, so the row_end really is the end of the row and it
* is sufficient to loop over the components one by one.
*/
png_bytep row_end = output_row + image->width * channels;
while (y-- > 0)
{
png_const_uint_16p in_ptr = input_row;
png_bytep out_ptr = output_row;
while (out_ptr < row_end)
{
png_uint_32 component = *in_ptr++;
component *= 255;
*out_ptr++ = (png_byte)PNG_sRGB_FROM_LINEAR(component);
}
png_write_row(png_ptr, output_row);
input_row += display->row_bytes/(sizeof (png_uint_16));
}
}
return 1;
}
static void
png_image_set_PLTE(png_image_write_control *display)
{
const png_imagep image = display->image;
const void *cmap = display->colormap;
const int entries = image->colormap_entries > 256 ? 256 :
(int)image->colormap_entries;
/* NOTE: the caller must check for cmap != NULL and entries != 0 */
const png_uint_32 format = image->format;
const int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
# if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
const int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
(format & PNG_FORMAT_FLAG_ALPHA) != 0;
# else
# define afirst 0
# endif
# ifdef PNG_FORMAT_BGR_SUPPORTED
const int bgr = (format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
# else
# define bgr 0
# endif
int i, num_trans;
png_color palette[256];
png_byte tRNS[256];
memset(tRNS, 255, (sizeof tRNS));
memset(palette, 0, (sizeof palette));
for (i=num_trans=0; i<entries; ++i)
{
/* This gets automatically converted to sRGB with reversal of the
* pre-multiplication if the color-map has an alpha channel.
*/
if ((format & PNG_FORMAT_FLAG_LINEAR) != 0)
{
png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
entry += i * channels;
if ((channels & 1) != 0) /* no alpha */
{
if (channels >= 3) /* RGB */
{
palette[i].blue = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
entry[(2 ^ bgr)]);
palette[i].green = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
entry[1]);
palette[i].red = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
entry[bgr]);
}
else /* Gray */
palette[i].blue = palette[i].red = palette[i].green =
(png_byte)PNG_sRGB_FROM_LINEAR(255 * *entry);
}
else /* alpha */
{
png_uint_16 alpha = entry[afirst ? 0 : channels-1];
png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
png_uint_32 reciprocal = 0;
/* Calculate a reciprocal, as in the png_write_image_8bit code above
* this is designed to produce a value scaled to 255*65535 when
* divided by 128 (i.e. asr 7).
*/
if (alphabyte > 0 && alphabyte < 255)
reciprocal = (((0xffff*0xff)<<7)+(alpha>>1))/alpha;
tRNS[i] = alphabyte;
if (alphabyte < 255)
num_trans = i+1;
if (channels >= 3) /* RGB */
{
palette[i].blue = png_unpremultiply(entry[afirst + (2 ^ bgr)],
alpha, reciprocal);
palette[i].green = png_unpremultiply(entry[afirst + 1], alpha,
reciprocal);
palette[i].red = png_unpremultiply(entry[afirst + bgr], alpha,
reciprocal);
}
else /* gray */
palette[i].blue = palette[i].red = palette[i].green =
png_unpremultiply(entry[afirst], alpha, reciprocal);
}
}
else /* Color-map has sRGB values */
{
png_const_bytep entry = png_voidcast(png_const_bytep, cmap);
entry += i * channels;
switch (channels)
{
case 4:
tRNS[i] = entry[afirst ? 0 : 3];
if (tRNS[i] < 255)
num_trans = i+1;
/* FALL THROUGH */
case 3:
palette[i].blue = entry[afirst + (2 ^ bgr)];
palette[i].green = entry[afirst + 1];
palette[i].red = entry[afirst + bgr];
break;
case 2:
tRNS[i] = entry[1 ^ afirst];
if (tRNS[i] < 255)
num_trans = i+1;
/* FALL THROUGH */
case 1:
palette[i].blue = palette[i].red = palette[i].green =
entry[afirst];
break;
default:
break;
}
}
}
# ifdef afirst
# undef afirst
# endif
# ifdef bgr
# undef bgr
# endif
png_set_PLTE(image->opaque->png_ptr, image->opaque->info_ptr, palette,
entries);
if (num_trans > 0)
png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
num_trans, NULL);
image->colormap_entries = entries;
}
static int
png_image_write_main(png_voidp argument)
{
png_image_write_control *display = png_voidcast(png_image_write_control*,
argument);
png_imagep image = display->image;
png_structrp png_ptr = image->opaque->png_ptr;
png_inforp info_ptr = image->opaque->info_ptr;
png_uint_32 format = image->format;
/* The following four ints are actually booleans */
int colormap = (format & PNG_FORMAT_FLAG_COLORMAP);
int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR); /* input */
int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA);
int write_16bit = linear && !colormap && (display->convert_to_8bit == 0);
# ifdef PNG_BENIGN_ERRORS_SUPPORTED
/* Make sure we error out on any bad situation */
png_set_benign_errors(png_ptr, 0/*error*/);
# endif
/* Default the 'row_stride' parameter if required. */
if (display->row_stride == 0)
display->row_stride = PNG_IMAGE_ROW_STRIDE(*image);
/* Set the required transforms then write the rows in the correct order. */
if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0)
{
if (display->colormap != NULL && image->colormap_entries > 0)
{
png_uint_32 entries = image->colormap_entries;
png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
entries > 16 ? 8 : (entries > 4 ? 4 : (entries > 2 ? 2 : 1)),
PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
png_image_set_PLTE(display);
}
else
png_error(image->opaque->png_ptr,
"no color-map for color-mapped image");
}
else
png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
write_16bit ? 16 : 8,
((format & PNG_FORMAT_FLAG_COLOR) ? PNG_COLOR_MASK_COLOR : 0) +
((format & PNG_FORMAT_FLAG_ALPHA) ? PNG_COLOR_MASK_ALPHA : 0),
PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
/* Counter-intuitively the data transformations must be called *after*
* png_write_info, not before as in the read code, but the 'set' functions
* must still be called before. Just set the color space information, never
* write an interlaced image.
*/
if (write_16bit != 0)
{
/* The gamma here is 1.0 (linear) and the cHRM chunk matches sRGB. */
png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_LINEAR);
if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
png_set_cHRM_fixed(png_ptr, info_ptr,
/* color x y */
/* white */ 31270, 32900,
/* red */ 64000, 33000,
/* green */ 30000, 60000,
/* blue */ 15000, 6000
);
}
else if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_PERCEPTUAL);
/* Else writing an 8-bit file and the *colors* aren't sRGB, but the 8-bit
* space must still be gamma encoded.
*/
else
png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_sRGB_INVERSE);
/* Write the file header. */
png_write_info(png_ptr, info_ptr);
/* Now set up the data transformations (*after* the header is written),
* remove the handled transformations from the 'format' flags for checking.
*
* First check for a little endian system if writing 16-bit files.
*/
if (write_16bit != 0)
{
PNG_CONST png_uint_16 le = 0x0001;
if ((*(png_const_bytep) & le) != 0)
png_set_swap(png_ptr);
}
# ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
if ((format & PNG_FORMAT_FLAG_BGR) != 0)
{
if (colormap == 0 && (format & PNG_FORMAT_FLAG_COLOR) != 0)
png_set_bgr(png_ptr);
format &= ~PNG_FORMAT_FLAG_BGR;
}
# endif
# ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
{
if (colormap == 0 && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
png_set_swap_alpha(png_ptr);
format &= ~PNG_FORMAT_FLAG_AFIRST;
}
# endif
/* If there are 16 or fewer color-map entries we wrote a lower bit depth
* above, but the application data is still byte packed.
*/
if (colormap != 0 && image->colormap_entries <= 16)
png_set_packing(png_ptr);
/* That should have handled all (both) the transforms. */
if ((format & ~(png_uint_32)(PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_LINEAR |
PNG_FORMAT_FLAG_ALPHA | PNG_FORMAT_FLAG_COLORMAP)) != 0)
png_error(png_ptr, "png_write_image: unsupported transformation");
{
png_const_bytep row = png_voidcast(png_const_bytep, display->buffer);
ptrdiff_t row_bytes = display->row_stride;
if (linear != 0)
row_bytes *= (sizeof (png_uint_16));
if (row_bytes < 0)
row += (image->height-1) * (-row_bytes);
display->first_row = row;
display->row_bytes = row_bytes;
}
/* Apply 'fast' options if the flag is set. */
if ((image->flags & PNG_IMAGE_FLAG_FAST) != 0)
{
png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_NO_FILTERS);
/* NOTE: determined by experiment using pngstest, this reflects some
* balance between the time to write the image once and the time to read
* it about 50 times. The speed-up in pngstest was about 10-20% of the
* total (user) time on a heavily loaded system.
*/
# ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
png_set_compression_level(png_ptr, 3);
# endif
}
/* Check for the cases that currently require a pre-transform on the row
* before it is written. This only applies when the input is 16-bit and
* either there is an alpha channel or it is converted to 8-bit.
*/
if ((linear != 0 && alpha != 0 ) ||
(colormap == 0 && display->convert_to_8bit != 0))
{
png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr,
png_get_rowbytes(png_ptr, info_ptr)));
int result;
display->local_row = row;
if (write_16bit != 0)
result = png_safe_execute(image, png_write_image_16bit, display);
else
result = png_safe_execute(image, png_write_image_8bit, display);
display->local_row = NULL;
png_free(png_ptr, row);
/* Skip the 'write_end' on error: */
if (result == 0)
return 0;
}
/* Otherwise this is the case where the input is in a format currently
* supported by the rest of the libpng write code; call it directly.
*/
else
{
png_const_bytep row = png_voidcast(png_const_bytep, display->first_row);
ptrdiff_t row_bytes = display->row_bytes;
png_uint_32 y = image->height;
while (y-- > 0)
{
png_write_row(png_ptr, row);
row += row_bytes;
}
}
png_write_end(png_ptr, info_ptr);
return 1;
}
int PNGAPI
png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
const void *buffer, png_int_32 row_stride, const void *colormap)
{
/* Write the image to the given (FILE*). */
if (image != NULL && image->version == PNG_IMAGE_VERSION)
{
if (file != NULL)
{
if (png_image_write_init(image) != 0)
{
png_image_write_control display;
int result;
/* This is slightly evil, but png_init_io doesn't do anything other
* than this and we haven't changed the standard IO functions so
* this saves a 'safe' function.
*/
image->opaque->png_ptr->io_ptr = file;
memset(&display, 0, (sizeof display));
display.image = image;
display.buffer = buffer;
display.row_stride = row_stride;
display.colormap = colormap;
display.convert_to_8bit = convert_to_8bit;
result = png_safe_execute(image, png_image_write_main, &display);
png_image_free(image);
return result;
}
else
return 0;
}
else
return png_image_error(image,
"png_image_write_to_stdio: invalid argument");
}
else if (image != NULL)
return png_image_error(image,
"png_image_write_to_stdio: incorrect PNG_IMAGE_VERSION");
else
return 0;
}
int PNGAPI
png_image_write_to_file(png_imagep image, const char *file_name,
int convert_to_8bit, const void *buffer, png_int_32 row_stride,
const void *colormap)
{
/* Write the image to the named file. */
if (image != NULL && image->version == PNG_IMAGE_VERSION)
{
if (file_name != NULL)
{
FILE *fp = fopen(file_name, "wb");
if (fp != NULL)
{
if (png_image_write_to_stdio(image, fp, convert_to_8bit, buffer,
row_stride, colormap) != 0)
{
int error; /* from fflush/fclose */
/* Make sure the file is flushed correctly. */
if (fflush(fp) == 0 && ferror(fp) == 0)
{
if (fclose(fp) == 0)
return 1;
error = errno; /* from fclose */
}
else
{
error = errno; /* from fflush or ferror */
(void)fclose(fp);
}
(void)remove(file_name);
/* The image has already been cleaned up; this is just used to
* set the error (because the original write succeeded).
*/
return png_image_error(image, strerror(error));
}
else
{
/* Clean up: just the opened file. */
(void)fclose(fp);
(void)remove(file_name);
return 0;
}
}
else
return png_image_error(image, strerror(errno));
}
else
return png_image_error(image,
"png_image_write_to_file: invalid argument");
}
else if (image != NULL)
return png_image_error(image,
"png_image_write_to_file: incorrect PNG_IMAGE_VERSION");
else
return 0;
}
# endif /* STDIO */
#endif /* SIMPLIFIED_WRITE */
#endif /* WRITE */