The Tor Browser: media/libpng/pngwrite.c@97036ab72558 (annotated)

media/libpng/pngwrite.c@97036ab72558 (annotated)

media/libpng/pngwrite.c

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* pngwrite.c - general routines to write a PNG file
  *
  * Last changed in libpng 1.6.10 [March 6, 2014]
  * Copyright (c) 1998-2014 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)
    {
       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)
       {
          /* 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 /* PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED */
 /* 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))
    {
    /* Write PNG signature */
    png_write_sig(png_ptr);
 #ifdef PNG_MNG_FEATURES_SUPPORTED
    if ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) && \
        (png_ptr->mng_features_permitted))
    {
       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
 
 #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 and
     * 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_WRITE_APNG_SUPPORTED
    if (info_ptr->valid & PNG_INFO_acTL)
       png_write_acTL(png_ptr, info_ptr->num_frames, info_ptr->num_plays);
 #endif
 #ifdef PNG_GAMMA_SUPPORTED
 #  ifdef PNG_WRITE_gAMA_SUPPORTED
       if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
          (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_gAMA) &&
          (info_ptr->valid & PNG_INFO_gAMA))
          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) &&
          (info_ptr->valid & PNG_INFO_iCCP))
       {
 #        ifdef PNG_WRITE_sRGB_SUPPORTED
             if (info_ptr->valid & PNG_INFO_sRGB)
                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) &&
          (info_ptr->valid & PNG_INFO_sRGB))
          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)
       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) &&
          (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) &&
          (info_ptr->valid & PNG_INFO_cHRM))
          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)
       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)
    {
 #ifdef 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_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)
       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)
       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)
       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)
       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)
       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)
       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)
    {
       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)
       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);
 #else
           png_warning(png_ptr, "Unable to write international text");
 #endif
           /* Mark this chunk as written */
           info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
       }
       /* 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, 0,
              info_ptr->text[i].compression);
 #else
          png_warning(png_ptr, "Unable to write compressed text");
 #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)
       {
 #ifdef PNG_WRITE_tEXt_SUPPORTED
          /* Write uncompressed chunk */
          png_write_tEXt(png_ptr, info_ptr->text[i].key,
              info_ptr->text[i].text,
 );
          /* 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))
       png_error(png_ptr, "No IDATs written into file");
 #ifdef PNG_WRITE_APNG_SUPPORTED
    if (png_ptr->num_frames_written != png_ptr->num_frames_to_write)
       png_error(png_ptr, "Not enough frames written");
 #endif
 #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) &&
           !(png_ptr->mode & PNG_WROTE_tIME))
          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);
 #else
             png_warning(png_ptr, "Unable to write international text");
 #endif
             /* Mark this chunk as written */
             info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
          }
          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, 0,
                 info_ptr->text[i].compression);
 #else
             png_warning(png_ptr, "Unable to write compressed text");
 #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)
          {
 #ifdef PNG_WRITE_tEXt_SUPPORTED
             /* Write uncompressed chunk */
             png_write_tEXt(png_ptr, info_ptr->text[i].key,
                 info_ptr->text[i].text, 0);
 #else
             png_warning(png_ptr, "Unable to write uncompressed text");
 #endif
             /* Mark this chunk as written */
             info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
          }
       }
 #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 /* PNG_USER_MEM_SUPPORTED */
    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 /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
       /* 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
       png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
       /* In stable builds only warn if an application error can be completely
        * handled.
        */
 #endif
       /* App warnings are warnings in release (or release candidate) builds but
        * are errors during development.
        */
 #if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
       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))
    {
       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)) & 0xff);
             *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
          }
       }
 #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) & 0xff);
             *(rp + 1) = (png_byte)(red & 0xff);
             *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
             *(rp + 5) = (png_byte)(blue & 0xff);
          }
       }
 #endif /* PNG_WRITE_16BIT_SUPPORTED */
    }
 }
 #endif /* PNG_MNG_FEATURES_SUPPORTED */
 /* 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))
          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)
          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)
          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)
          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)
          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)
          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)
          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)
          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 && (png_ptr->transformations & PNG_INTERLACE))
    {
       switch (png_ptr->pass)
       {
          case 0:
             if (png_ptr->row_number & 0x07)
             {
                png_write_finish_row(png_ptr);
                return;
             }
             break;
          case 1:
             if ((png_ptr->row_number & 0x07) || 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) || 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) || png_ptr->width < 2)
             {
                png_write_finish_row(png_ptr);
                return;
             }
             break;
          case 6:
             if (!(png_ptr->row_number & 0x01))
             {
                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))
    {
       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))
       {
          png_write_finish_row(png_ptr);
          return;
       }
    }
 #endif
 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
    /* Handle other transformations */
    if (png_ptr->transformations)
       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) &&
        (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 /* PNG_WRITE_FLUSH_SUPPORTED */
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
 static void png_reset_filter_heuristics(png_structrp png_ptr);/* forward decl */
 #endif
 /* 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)
       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);
 #ifdef PNG_WRITE_FILTER_SUPPORTED
    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);
 #endif
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    /* Use this to save a little code space, it doesn't free the filter_costs */
    png_reset_filter_heuristics(png_ptr);
    png_free(png_ptr, png_ptr->filter_costs);
    png_free(png_ptr, png_ptr->inv_filter_costs);
 #endif
 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
    png_free(png_ptr, png_ptr->chunk_list);
 #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) &&
        (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 /* PNG_WRITE_FILTER_SUPPORTED */
          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 /* 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 add and
        * remove them after the start of compression.
        */
       if (png_ptr->row_buf != NULL)
       {
 #ifdef PNG_WRITE_FILTER_SUPPORTED
          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_byte)(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_byte)(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_byte)(~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)
 #endif /* PNG_WRITE_FILTER_SUPPORTED */
             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.
  */
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED      /* GRR 970116 */
 /* Convenience reset API. */
 static void
 png_reset_filter_heuristics(png_structrp png_ptr)
 {
    /* Clear out any old values in the 'weights' - this must be done because if
     * the app calls set_filter_heuristics multiple times with different
     * 'num_weights' values we would otherwise potentially have wrong sized
     * arrays.
     */
    png_ptr->num_prev_filters = 0;
    png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
    if (png_ptr->prev_filters != NULL)
    {
       png_bytep old = png_ptr->prev_filters;
       png_ptr->prev_filters = NULL;
       png_free(png_ptr, old);
    }
    if (png_ptr->filter_weights != NULL)
    {
       png_uint_16p old = png_ptr->filter_weights;
       png_ptr->filter_weights = NULL;
       png_free(png_ptr, old);
    }
    if (png_ptr->inv_filter_weights != NULL)
    {
       png_uint_16p old = png_ptr->inv_filter_weights;
       png_ptr->inv_filter_weights = NULL;
       png_free(png_ptr, old);
    }
    /* Leave the filter_costs - this array is fixed size. */
 }
 static int
 png_init_filter_heuristics(png_structrp png_ptr, int heuristic_method,
    int num_weights)
 {
    if (png_ptr == NULL)
       return 0;
    /* Clear out the arrays */
    png_reset_filter_heuristics(png_ptr);
    /* Check arguments; the 'reset' function makes the correct settings for the
     * unweighted case, but we must handle the weight case by initializing the
     * arrays for the caller.
     */
    if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
    {
       int i;
       if (num_weights > 0)
       {
          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;
          }
          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;
          }
          /* Safe to set this now */
          png_ptr->num_prev_filters = (png_byte)num_weights;
       }
       /* 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;
       }
       /* All the arrays are inited, safe to set this: */
       png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_WEIGHTED;
       /* Return the 'ok' code. */
       return 1;
    }
    else if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT ||
       heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
    {
       return 1;
    }
    else
    {
       png_warning(png_ptr, "Unknown filter heuristic method");
       return 0;
    }
 }
 /* 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_debug(1, "in png_set_filter_heuristics");
    /* The internal API allocates all the arrays and ensures that the elements of
     * those arrays are set to the default value.
     */
    if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
       return;
    /* If using the weighted method copy in the weights. */
    if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
    {
       int i;
       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)(PNG_WEIGHT_FACTOR*filter_weights[i]+.5);
             png_ptr->filter_weights[i] =
                 (png_uint_16)(PNG_WEIGHT_FACTOR/filter_weights[i]+.5);
          }
       }
       /* 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[i] >= 1.0)
       {
          png_ptr->inv_filter_costs[i] =
              (png_uint_16)(PNG_COST_FACTOR / filter_costs[i] + .5);
          png_ptr->filter_costs[i] =
              (png_uint_16)(PNG_COST_FACTOR * filter_costs[i] + .5);
       }
    }
 }
 #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_debug(1, "in png_set_filter_heuristics_fixed");
    /* The internal API allocates all the arrays and ensures that the elements of
     * those arrays are set to the default value.
     */
    if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
       return;
    /* If using the weighted method copy in the weights. */
    if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
    {
       int i;
       for (i = 0; i < num_weights; i++)
       {
          if (filter_weights[i] <= 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)
                ((PNG_WEIGHT_FACTOR*filter_weights[i]+PNG_FP_HALF)/PNG_FP_1);
             png_ptr->filter_weights[i] = (png_uint_16)((PNG_WEIGHT_FACTOR*
                PNG_FP_1+(filter_weights[i]/2))/filter_weights[i]);
          }
       }
       /* 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[i] >= PNG_FP_1)
       {
          png_uint_32 tmp;
          /* Use a 32 bit unsigned temporary here because otherwise the
           * intermediate value will be a 32 bit *signed* integer (ANSI rules)
           * and this will get the wrong answer on division.
           */
          tmp = PNG_COST_FACTOR*PNG_FP_1 + (filter_costs[i]/2);
          tmp /= filter_costs[i];
          png_ptr->inv_filter_costs[i] = (png_uint_16)tmp;
          tmp = PNG_COST_FACTOR * filter_costs[i] + PNG_FP_HALF;
          tmp /= PNG_FP_1;
          png_ptr->filter_costs[i] = (png_uint_16)tmp;
       }
    }
 }
 #endif /* FIXED_POINT */
 #endif /* PNG_WRITE_WEIGHTED_FILTER_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 which 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;
 }
 /* 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 /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
 /* 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)
 #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)
 #ifdef PNG_WRITE_SHIFT_SUPPORTED
       if (info_ptr->valid & PNG_INFO_sBIT)
          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)
 #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)
 #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))
    {
 #ifdef PNG_WRITE_FILLER_SUPPORTED
       if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
       {
          if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
             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)
          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)
 #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)
 #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, 2, 4 bit packed pixel formats */
    if (transforms & PNG_TRANSFORM_PACKSWAP)
 #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)
 #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) ? 3 : 1;
    int aindex = 0;
    png_uint_32 y = image->height;
    if (image->format & PNG_FORMAT_FLAG_ALPHA)
    {
 #     ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
          if (image->format & PNG_FORMAT_FLAG_AFIRST)
          {
             aindex = -1;
             ++input_row; /* To point to the first component */
             ++output_row;
          }
          else
 #     endif
          aindex = channels;
    }
    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) ? 3 : 1;
    if (image->format & PNG_FORMAT_FLAG_ALPHA)
    {
       png_bytep row_end;
       int aindex;
 #     ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
          if (image->format & PNG_FORMAT_FLAG_AFIRST)
          {
             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) ? 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)
       {
          png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
          entry += i * channels;
          if (channels & 1) /* 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;
    int colormap = (format & PNG_FORMAT_FLAG_COLORMAP) != 0;
    int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR) != 0; /* input */
    int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0;
    int write_16bit = linear && !colormap && !display->convert_to_8bit;
 #  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)
    {
       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)
    {
       /* 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))
          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))
       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)
    {
       PNG_CONST png_uint_16 le = 0x0001;
       if (*(png_const_bytep)&le)
          png_set_swap(png_ptr);
    }
 #  ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
       if (format & PNG_FORMAT_FLAG_BGR)
       {
          if (!colormap && (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)
       {
          if (!colormap && (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 && 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)
          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.
        */
       png_set_compression_level(png_ptr, 3);
    }
    /* 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 && alpha) || (!colormap && display->convert_to_8bit))
    {
       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)
          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)
          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))
          {
             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))
             {
                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 /* PNG_STDIO_SUPPORTED */
 #endif /* SIMPLIFIED_WRITE */
 #ifdef PNG_WRITE_APNG_SUPPORTED
 void PNGAPI
 png_write_frame_head(png_structp png_ptr, png_infop info_ptr,
     png_bytepp row_pointers, png_uint_32 width, png_uint_32 height,
     png_uint_32 x_offset, png_uint_32 y_offset,
     png_uint_16 delay_num, png_uint_16 delay_den, png_byte dispose_op,
     png_byte blend_op)
 {
     png_debug(1, "in png_write_frame_head");
     /* there is a chance this has been set after png_write_info was called,
     * so it would be set but not written. is there a way to be sure? */
     if (!(info_ptr->valid & PNG_INFO_acTL))
         png_error(png_ptr, "png_write_frame_head(): acTL not set");
     png_write_reset(png_ptr);
     png_write_reinit(png_ptr, info_ptr, width, height);
     if ( !(png_ptr->num_frames_written == 0 &&
            (png_ptr->apng_flags & PNG_FIRST_FRAME_HIDDEN) ) )
         png_write_fcTL(png_ptr, width, height, x_offset, y_offset,
                        delay_num, delay_den, dispose_op, blend_op);
     PNG_UNUSED(row_pointers)
 }
 void PNGAPI
 png_write_frame_tail(png_structp png_ptr, png_infop info_ptr)
 {
     png_debug(1, "in png_write_frame_tail");
     png_ptr->num_frames_written++;
     PNG_UNUSED(info_ptr)
 }
 #endif /* PNG_WRITE_APNG_SUPPORTED */
 #endif /* PNG_WRITE_SUPPORTED */

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media/libpng/pngwrite.c@97036ab72558 (annotated)

media/libpng/pngwrite.c