pngset.c

一个国人自己实现图像库的程序（有参考价值）

   info_ptr->valid |= PNG_INFO_sCAL;
}
#else
#ifdef PNG_FIXED_POINT_SUPPORTED
void PNGAPI
png_set_sCAL_s(png_structp png_ptr, png_infop info_ptr,
             int unit, png_charp swidth, png_charp sheight)
{
   png_uint_32 length;

   png_debug1(1, "in %s storage function\n", "sCAL");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   info_ptr->scal_unit = (png_byte)unit;

   length = png_strlen(swidth) + 1;
   png_debug1(3, "allocating unit for info (%d bytes)\n", length);
   info_ptr->scal_s_width = (png_charp)png_malloc(png_ptr, length);
   png_memcpy(info_ptr->scal_s_width, swidth, (png_size_t)length);

   length = png_strlen(sheight) + 1;
   png_debug1(3, "allocating unit for info (%d bytes)\n", length);
   info_ptr->scal_s_height = (png_charp)png_malloc(png_ptr, length);
   png_memcpy(info_ptr->scal_s_height, sheight, (png_size_t)length);

   info_ptr->valid |= PNG_INFO_sCAL;
#ifdef PNG_FREE_ME_SUPPORTED
   info_ptr->free_me |= PNG_FREE_SCAL;
#endif
}
#endif
#endif
#endif

#if defined(PNG_pHYs_SUPPORTED)
void PNGAPI
png_set_pHYs(png_structp png_ptr, png_infop info_ptr,
   png_uint_32 res_x, png_uint_32 res_y, int unit_type)
{
   png_debug1(1, "in %s storage function\n", "pHYs");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   info_ptr->x_pixels_per_unit = res_x;
   info_ptr->y_pixels_per_unit = res_y;
   info_ptr->phys_unit_type = (png_byte)unit_type;
   info_ptr->valid |= PNG_INFO_pHYs;
}
#endif

void PNGAPI
png_set_PLTE(png_structp png_ptr, png_infop info_ptr,
   png_colorp palette, int num_palette)
{

   png_debug1(1, "in %s storage function\n", "PLTE");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   /*
    * It may not actually be necessary to set png_ptr->palette here;
    * we do it for backward compatibility with the way the png_handle_tRNS
    * function used to do the allocation.
    */
#ifdef PNG_FREE_ME_SUPPORTED
   png_free_data(png_ptr, info_ptr, PNG_FREE_PLTE, 0);
#endif
   /* Changed in libpng-1.2.1 to allocate 256 instead of num_palette entries,
      in case of an invalid PNG file that has too-large sample values. */
   png_ptr->palette = (png_colorp)png_zalloc(png_ptr, (uInt)256,
      sizeof (png_color));
   png_memcpy(png_ptr->palette, palette, num_palette * sizeof (png_color));
   info_ptr->palette = png_ptr->palette;
   info_ptr->num_palette = png_ptr->num_palette = (png_uint_16)num_palette;

#ifdef PNG_FREE_ME_SUPPORTED
   info_ptr->free_me |= PNG_FREE_PLTE;
#else
   png_ptr->flags |= PNG_FLAG_FREE_PLTE;
#endif

   info_ptr->valid |= PNG_INFO_PLTE;
}

#if defined(PNG_sBIT_SUPPORTED)
void PNGAPI
png_set_sBIT(png_structp png_ptr, png_infop info_ptr,
   png_color_8p sig_bit)
{
   png_debug1(1, "in %s storage function\n", "sBIT");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   png_memcpy(&(info_ptr->sig_bit), sig_bit, sizeof (png_color_8));
   info_ptr->valid |= PNG_INFO_sBIT;
}
#endif

#if defined(PNG_sRGB_SUPPORTED)
void PNGAPI
png_set_sRGB(png_structp png_ptr, png_infop info_ptr, int intent)
{
   png_debug1(1, "in %s storage function\n", "sRGB");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   info_ptr->srgb_intent = (png_byte)intent;
   info_ptr->valid |= PNG_INFO_sRGB;
}

void PNGAPI
png_set_sRGB_gAMA_and_cHRM(png_structp png_ptr, png_infop info_ptr,
   int intent)
{
#if defined(PNG_gAMA_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
   float file_gamma;
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
   png_fixed_point int_file_gamma;
#endif
#endif
#if defined(PNG_cHRM_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
   float white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y;
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
   png_fixed_point int_white_x, int_white_y, int_red_x, int_red_y, int_green_x,
      int_green_y, int_blue_x, int_blue_y;
#endif
#endif
   png_debug1(1, "in %s storage function\n", "sRGB_gAMA_and_cHRM");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   png_set_sRGB(png_ptr, info_ptr, intent);

#if defined(PNG_gAMA_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
   file_gamma = (float).45455;
   png_set_gAMA(png_ptr, info_ptr, file_gamma);
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
   int_file_gamma = 45455L;
   png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
#endif
#endif

#if defined(PNG_cHRM_SUPPORTED)
#ifdef PNG_FIXED_POINT_SUPPORTED
   int_white_x = 31270L;
   int_white_y = 32900L;
   int_red_x   = 64000L;
   int_red_y   = 33000L;
   int_green_x = 30000L;
   int_green_y = 60000L;
   int_blue_x  = 15000L;
   int_blue_y  =  6000L;

   png_set_cHRM_fixed(png_ptr, info_ptr,
      int_white_x, int_white_y, int_red_x, int_red_y, int_green_x, int_green_y,
      int_blue_x, int_blue_y);
#endif
#ifdef PNG_FLOATING_POINT_SUPPORTED
   white_x = (float).3127;
   white_y = (float).3290;
   red_x   = (float).64;
   red_y   = (float).33;
   green_x = (float).30;
   green_y = (float).60;
   blue_x  = (float).15;
   blue_y  = (float).06;

   png_set_cHRM(png_ptr, info_ptr,
      white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y);
#endif
#endif
}
#endif


#if defined(PNG_iCCP_SUPPORTED)
void PNGAPI
png_set_iCCP(png_structp png_ptr, png_infop info_ptr,
             png_charp name, int compression_type,
             png_charp profile, png_uint_32 proflen)
{
   png_charp new_iccp_name;
   png_charp new_iccp_profile;

   png_debug1(1, "in %s storage function\n", "iCCP");
   if (png_ptr == NULL || info_ptr == NULL || name == NULL || profile == NULL)
      return;

   new_iccp_name = (png_charp)png_malloc(png_ptr, png_strlen(name)+1);
   png_strcpy(new_iccp_name, name);
   new_iccp_profile = (png_charp)png_malloc(png_ptr, proflen);
   png_memcpy(new_iccp_profile, profile, (png_size_t)proflen);

   png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, 0);

   info_ptr->iccp_proflen = proflen;
   info_ptr->iccp_name = new_iccp_name;
   info_ptr->iccp_profile = new_iccp_profile;
   /* Compression is always zero but is here so the API and info structure
    * does not have to change if we introduce multiple compression types */
   info_ptr->iccp_compression = (png_byte)compression_type;
#ifdef PNG_FREE_ME_SUPPORTED
   info_ptr->free_me |= PNG_FREE_ICCP;
#endif
   info_ptr->valid |= PNG_INFO_iCCP;
}
#endif

#if defined(PNG_TEXT_SUPPORTED)
void PNGAPI
png_set_text(png_structp png_ptr, png_infop info_ptr, png_textp text_ptr,
   int num_text)
{
   int i;

   png_debug1(1, "in %s storage function\n", (png_ptr->chunk_name[0] == '\0' ?
      "text" : (png_const_charp)png_ptr->chunk_name));

   if (png_ptr == NULL || info_ptr == NULL || num_text == 0)
      return;

   /* Make sure we have enough space in the "text" array in info_struct
    * to hold all of the incoming text_ptr objects.
    */
   if (info_ptr->num_text + num_text > info_ptr->max_text)
   {
      if (info_ptr->text != NULL)
      {
         png_textp old_text;
         int old_max;

         old_max = info_ptr->max_text;
         info_ptr->max_text = info_ptr->num_text + num_text + 8;
         old_text = info_ptr->text;
         info_ptr->text = (png_textp)png_malloc(png_ptr,
            (png_uint_32)(info_ptr->max_text * sizeof (png_text)));
         png_memcpy(info_ptr->text, old_text, (png_size_t)(old_max *
            sizeof(png_text)));
         png_free(png_ptr, old_text);
      }
      else
      {
         info_ptr->max_text = num_text + 8;
         info_ptr->num_text = 0;
         info_ptr->text = (png_textp)png_malloc(png_ptr,
            (png_uint_32)(info_ptr->max_text * sizeof (png_text)));
#ifdef PNG_FREE_ME_SUPPORTED
         info_ptr->free_me |= PNG_FREE_TEXT;
#endif
      }
      png_debug1(3, "allocated %d entries for info_ptr->text\n",
         info_ptr->max_text);
   }
   for (i = 0; i < num_text; i++)
   {
      png_size_t text_length,key_len;
      png_size_t lang_len,lang_key_len;
      png_textp textp = &(info_ptr->text[info_ptr->num_text]);

      if (text_ptr[i].key == NULL)
          continue;

      key_len = png_strlen(text_ptr[i].key);

      if(text_ptr[i].compression <= 0)
      {
        lang_len = 0;
        lang_key_len = 0;
      }
      else
#ifdef PNG_iTXt_SUPPORTED
      {
        /* set iTXt data */
        if (text_ptr[i].key != NULL)
          lang_len = png_strlen(text_ptr[i].lang);
        else
          lang_len = 0;
        if (text_ptr[i].lang_key != NULL)
          lang_key_len = png_strlen(text_ptr[i].lang_key);
        else
          lang_key_len = 0;
      }
#else
      {
        png_warning(png_ptr, "iTXt chunk not supported.");
        continue;
      }
#endif

      if (text_ptr[i].text == NULL || text_ptr[i].text[0] == '\0')
      {
         text_length = 0;
#ifdef PNG_iTXt_SUPPORTED
         if(text_ptr[i].compression > 0)
            textp->compression = PNG_ITXT_COMPRESSION_NONE;
         else
#endif
            textp->compression = PNG_TEXT_COMPRESSION_NONE;
      }
      else
      {
         text_length = png_strlen(text_ptr[i].text);
         textp->compression = text_ptr[i].compression;
      }

      textp->key = (png_charp)png_malloc(png_ptr,
         (png_uint_32)(key_len + text_length + lang_len + lang_key_len + 4));
      png_debug2(2, "Allocated %lu bytes at %x in png_set_text\n",
         (png_uint_32)(key_len + lang_len + lang_key_len + text_length + 4),
         (int)textp->key);

      png_memcpy(textp->key, text_ptr[i].key,
         (png_size_t)(key_len));
      *(textp->key+key_len) = '\0';
#ifdef PNG_iTXt_SUPPORTED
      if (text_ptr[i].compression > 0)
      {
         textp->lang=textp->key + key_len + 1;
         png_memcpy(textp->lang, text_ptr[i].lang, lang_len);
         *(textp->lang+lang_len) = '\0';
         textp->lang_key=textp->lang + lang_len + 1;
         png_memcpy(textp->lang_key, text_ptr[i].lang_key, lang_key_len);
         *(textp->lang_key+lang_key_len) = '\0';
         textp->text=textp->lang_key + lang_key_len + 1;
      }
      else
#endif
      {
#ifdef PNG_iTXt_SUPPORTED
         textp->lang=NULL;
         textp->lang_key=NULL;
#endif
         textp->text=textp->key + key_len + 1;
      }
      if(text_length)
         png_memcpy(textp->text, text_ptr[i].text,
            (png_size_t)(text_length));
      *(textp->text+text_length) = '\0';