/* pngwrite.c - general routines to write a PNG file

*

* Last changed in libpng 1.6.35 [July 15, 2018]

* Copyright (c) 1998-2002,2004,2006-2018 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_SIMPLIFIED_WRITE_STDIO_SUPPORTED

# include <errno.h>

#endif /* SIMPLIFIED_WRITE_STDIO */

#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_eXIf_SUPPORTED

if ((info_ptr->valid & PNG_INFO_eXIf) != 0)

png_write_eXIf(png_ptr, info_ptr->exif, info_ptr->num_exif);

#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_eXIf_SUPPORTED

if ((info_ptr->valid & PNG_INFO_eXIf) != 0)

png_write_eXIf(png_ptr, info_ptr->exif, info_ptr->num_exif);

#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 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);

png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);

png_uint_32 s2 = (png_uint_32)(*(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 : (png_uint_32)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)