pngrutil.c

游戏编程精华01－含有几十个游戏编程例子

      /* Should be an error, but we can cope with it */
      png_warning(png_ptr, "Out of place sBIT chunk");
   }
   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_sBIT)
   {
      png_warning(png_ptr, "Duplicate sBIT chunk");
      png_crc_finish(png_ptr, length);
      return;
   }

   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      truelen = 3;
   else
      truelen = (png_size_t)png_ptr->channels;

   if (length != truelen)
   {
      png_warning(png_ptr, "Incorrect sBIT chunk length");
      png_crc_finish(png_ptr, length);
      return;
   }

   png_crc_read(png_ptr, buf, truelen);
   if (png_crc_finish(png_ptr, 0))
      return;

   if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
   {
      png_ptr->sig_bit.red = buf[0];
      png_ptr->sig_bit.green = buf[1];
      png_ptr->sig_bit.blue = buf[2];
      png_ptr->sig_bit.alpha = buf[3];
   }
   else
   {
      png_ptr->sig_bit.gray = buf[0];
      png_ptr->sig_bit.alpha = buf[1];
   }
   png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
}
#endif

#if defined(PNG_READ_cHRM_SUPPORTED)
void
png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
   png_byte buf[4];
   png_uint_32 val;
   float white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y;

   png_debug(1, "in png_handle_cHRM\n");

   if (!(png_ptr->mode & PNG_HAVE_IHDR))
      png_error(png_ptr, "Missing IHDR before sBIT");
   else if (png_ptr->mode & PNG_HAVE_IDAT)
   {
      png_warning(png_ptr, "Invalid cHRM after IDAT");
      png_crc_finish(png_ptr, length);
      return;
   }
   else if (png_ptr->mode & PNG_HAVE_PLTE)
      /* Should be an error, but we can cope with it */
      png_warning(png_ptr, "Missing PLTE before cHRM");

   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_cHRM
#if defined(PNG_READ_sRGB_SUPPORTED)
      && !(info_ptr->valid & PNG_INFO_sRGB)
#endif
      )
   {
      png_warning(png_ptr, "Duplicate cHRM chunk");
      png_crc_finish(png_ptr, length);
      return;
   }

   if (length != 32)
   {
      png_warning(png_ptr, "Incorrect cHRM chunk length");
      png_crc_finish(png_ptr, length);
      return;
   }

   png_crc_read(png_ptr, buf, 4);
   val = png_get_uint_32(buf);
   white_x = (float)val / (float)100000.0;

   png_crc_read(png_ptr, buf, 4);
   val = png_get_uint_32(buf);
   white_y = (float)val / (float)100000.0;

   if (white_x < 0 || white_x > 0.8 || white_y < 0 || white_y > 0.8 ||
       white_x + white_y > 1.0)
   {
      png_warning(png_ptr, "Invalid cHRM white point");
      png_crc_finish(png_ptr, 24);
      return;
   }

   png_crc_read(png_ptr, buf, 4);
   val = png_get_uint_32(buf);
   red_x = (float)val / (float)100000.0;

   png_crc_read(png_ptr, buf, 4);
   val = png_get_uint_32(buf);
   red_y = (float)val / (float)100000.0;

   if (red_x < 0 || red_x > 0.8 || red_y < 0 || red_y > 0.8 ||
       red_x + red_y > 1.0)
   {
      png_warning(png_ptr, "Invalid cHRM red point");
      png_crc_finish(png_ptr, 16);
      return;
   }

   png_crc_read(png_ptr, buf, 4);
   val = png_get_uint_32(buf);
   green_x = (float)val / (float)100000.0;

   png_crc_read(png_ptr, buf, 4);
   val = png_get_uint_32(buf);
   green_y = (float)val / (float)100000.0;

   if (green_x < 0 || green_x > 0.8 || green_y < 0 || green_y > 0.8 ||
       green_x + green_y > 1.0)
   {
      png_warning(png_ptr, "Invalid cHRM green point");
      png_crc_finish(png_ptr, 8);
      return;
   }

   png_crc_read(png_ptr, buf, 4);
   val = png_get_uint_32(buf);
   blue_x = (float)val / (float)100000.0;

   png_crc_read(png_ptr, buf, 4);
   val = png_get_uint_32(buf);
   blue_y = (float)val / (float)100000.0;

   if (blue_x < (float)0 || blue_x > (float)0.8 || blue_y < (float)0 ||
       blue_y > (float)0.8 || blue_x + blue_y > (float)1.0)
   {
      png_warning(png_ptr, "Invalid cHRM blue point");
      png_crc_finish(png_ptr, 0);
      return;
   }

   if (png_crc_finish(png_ptr, 0))
      return;

#if defined(PNG_READ_sRGB_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_sRGB)
      {
      if (fabs(white_x - (float).3127) > (float).001 ||
          fabs(white_y - (float).3290) > (float).001 ||
          fabs(  red_x - (float).6400) > (float).001 ||
          fabs(  red_y - (float).3300) > (float).001 ||
          fabs(green_x - (float).3000) > (float).001 ||
          fabs(green_y - (float).6000) > (float).001 ||
          fabs( blue_x - (float).1500) > (float).001 ||
          fabs( blue_y - (float).0600) > (float).001)
         {

            png_warning(png_ptr,
              "Ignoring incorrect cHRM value when sRGB is also present");
#ifndef PNG_NO_STDIO
            fprintf(stderr,"wx=%f, wy=%f, rx=%f, ry=%f\n",
               white_x, white_y, red_x, red_y);
            fprintf(stderr,"gx=%f, gy=%f, bx=%f, by=%f\n",
               green_x, green_y, blue_x, blue_y);
#endif
         }
         return;
      }
#endif /* PNG_READ_sRGB_SUPPORTED */

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

#if defined(PNG_READ_sRGB_SUPPORTED)
void
png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
   int intent;
   png_byte buf[1];

   png_debug(1, "in png_handle_sRGB\n");

   if (!(png_ptr->mode & PNG_HAVE_IHDR))
      png_error(png_ptr, "Missing IHDR before sRGB");
   else if (png_ptr->mode & PNG_HAVE_IDAT)
   {
      png_warning(png_ptr, "Invalid sRGB after IDAT");
      png_crc_finish(png_ptr, length);
      return;
   }
   else if (png_ptr->mode & PNG_HAVE_PLTE)
      /* Should be an error, but we can cope with it */
      png_warning(png_ptr, "Out of place sRGB chunk");

   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_sRGB)
   {
      png_warning(png_ptr, "Duplicate sRGB chunk");
      png_crc_finish(png_ptr, length);
      return;
   }

   if (length != 1)
   {
      png_warning(png_ptr, "Incorrect sRGB chunk length");
      png_crc_finish(png_ptr, length);
      return;
   }

   png_crc_read(png_ptr, buf, 1);
   if (png_crc_finish(png_ptr, 0))
      return;

   intent = buf[0];
   /* check for bad intent */
   if (intent >= PNG_sRGB_INTENT_LAST)
   {
      png_warning(png_ptr, "Unknown sRGB intent");
      return;
   }

#if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
   if ((info_ptr->valid & PNG_INFO_gAMA))
      if((png_uint_32)(png_ptr->gamma*(float)100000.+.5) != (png_uint_32)45000L)
      {
         png_warning(png_ptr,
           "Ignoring incorrect gAMA value when sRGB is also present");
#ifndef PNG_NO_STDIO
           fprintf(stderr,"gamma=%f\n",png_ptr->gamma);
#endif
      }
#endif /* PNG_READ_gAMA_SUPPORTED */

#ifdef PNG_READ_cHRM_SUPPORTED
   if (info_ptr->valid & PNG_INFO_cHRM)
      if (fabs(info_ptr->x_white - (float).3127) > (float).001 ||
          fabs(info_ptr->y_white - (float).3290) > (float).001 ||
          fabs(  info_ptr->x_red - (float).6400) > (float).001 ||
          fabs(  info_ptr->y_red - (float).3300) > (float).001 ||
          fabs(info_ptr->x_green - (float).3000) > (float).001 ||
          fabs(info_ptr->y_green - (float).6000) > (float).001 ||
          fabs( info_ptr->x_blue - (float).1500) > (float).001 ||
          fabs( info_ptr->y_blue - (float).0600) > (float).001)
         {
            png_warning(png_ptr,
              "Ignoring incorrect cHRM value when sRGB is also present");
         }
#endif /* PNG_READ_cHRM_SUPPORTED */

   png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);
}
#endif /* PNG_READ_sRGB_SUPPORTED */

#if defined(PNG_READ_tRNS_SUPPORTED)
void
png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
   png_debug(1, "in png_handle_tRNS\n");

   if (!(png_ptr->mode & PNG_HAVE_IHDR))
      png_error(png_ptr, "Missing IHDR before tRNS");
   else if (png_ptr->mode & PNG_HAVE_IDAT)
   {
      png_warning(png_ptr, "Invalid tRNS after IDAT");
      png_crc_finish(png_ptr, length);
      return;
   }
   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_tRNS)
   {
      png_warning(png_ptr, "Duplicate tRNS chunk");
      png_crc_finish(png_ptr, length);
      return;
   }

   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
   {
      if (!(png_ptr->mode & PNG_HAVE_PLTE))
      {
         /* Should be an error, but we can cope with it */
         png_warning(png_ptr, "Missing PLTE before tRNS");
      }
      else if (length > png_ptr->num_palette)
      {
         png_warning(png_ptr, "Incorrect tRNS chunk length");
         png_crc_finish(png_ptr, length);
         return;
      }
      if (length == 0)
      {
         png_warning(png_ptr, "Zero length tRNS chunk");
         png_crc_finish(png_ptr, length);
         return;
      }

      png_ptr->trans = (png_bytep)png_malloc(png_ptr, length);
      png_ptr->flags |= PNG_FLAG_FREE_TRANS;
      png_crc_read(png_ptr, png_ptr->trans, (png_size_t)length);
      png_ptr->num_trans = (png_uint_16)length;
   }
   else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
   {
      png_byte buf[6];

      if (length != 6)
      {
         png_warning(png_ptr, "Incorrect tRNS chunk length");
         png_crc_finish(png_ptr, length);
         return;
      }

      png_crc_read(png_ptr, buf, (png_size_t)length);
      png_ptr->num_trans = 1;
      png_ptr->trans_values.red = png_get_uint_16(buf);
      png_ptr->trans_values.green = png_get_uint_16(buf + 2);
      png_ptr->trans_values.blue = png_get_uint_16(buf + 4);
   }
   else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
   {
      png_byte buf[6];

      if (length != 2)
      {
         png_warning(png_ptr, "Incorrect tRNS chunk length");
         png_crc_finish(png_ptr, length);
         return;
      }

      png_crc_read(png_ptr, buf, 2);
      png_ptr->num_trans = 1;
      png_ptr->trans_values.gray = png_get_uint_16(buf);
   }
   else
   {
      png_warning(png_ptr, "tRNS chunk not allowed with alpha channel");
      png_crc_finish(png_ptr, length);
      return;
   }

   if (png_crc_finish(png_ptr, 0))
      return;

   png_set_tRNS(png_ptr, info_ptr, png_ptr->trans, png_ptr->num_trans,
      &(png_ptr->trans_values));
}
#endif

#if defined(PNG_READ_bKGD_SUPPORTED)
void
png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
   png_size_t truelen;
   png_byte buf[6];

   png_debug(1, "in png_handle_bKGD\n");

   if (!(png_ptr->mode & PNG_HAVE_IHDR))
      png_error(png_ptr, "Missing IHDR before bKGD");
   else if (png_ptr->mode & PNG_HAVE_IDAT)
   {
      png_warning(png_ptr, "Invalid bKGD after IDAT");
      png_crc_finish(png_ptr, length);
      return;
   }
   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
            !(png_ptr->mode & PNG_HAVE_PLTE))
   {
      png_warning(png_ptr, "Missing PLTE before bKGD");
      png_crc_finish(png_ptr, length);
      return;
   }
   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_bKGD)
   {
      png_warning(png_ptr, "Duplicate bKGD chunk");
      png_crc_finish(png_ptr, length);
      return;
   }

   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      truelen = 1;
   else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
      truelen = 6;
   else
      truelen = 2;

   if (length != truelen)
   {
      png_warning(png_ptr, "Incorrect bKGD chunk length");
      png_crc_finish(png_ptr, length);
      return;
   }

   png_crc_read(png_ptr, buf, truelen);
   if (png_crc_finish(png_ptr, 0))
      return;

   /* We convert the index value into RGB components so that we can allow
    * arbitrary RGB values for background when we have transparency, and
    * so it is easy to determine the RGB values of the background color
    * from the info_ptr struct. */
   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
   {
      png_ptr->background.index = buf[0];
      png_ptr->background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
      png_ptr->background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
      png_ptr->background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
   }
   else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
   {
      png_ptr->background.red =
      png_ptr->background.green =
      png_ptr->background.blue =
      png_ptr->background.gray = png_get_uint_16(buf);
   }
   else
   {
      png_ptr->background.red = png_get_uint_16(buf);
      png_ptr->background.green = png_get_uint_16(buf + 2);
      png_ptr->background.blue = png_get_uint_16(buf + 4);
   }

   png_set_bKGD(png_ptr, info_ptr, &(png_ptr->background));
}
#endif

#if defined(PNG_READ_hIST_SUPPORTED)
void
png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{
   int num, i;

   png_debug(1, "in png_handle_hIST\n");

   if (!(png_ptr->mode & PNG_HAVE_IHDR))
      png_error(png_ptr, "Missing IHDR before hIST");
   else if (png_ptr->mode & PNG_HAVE_IDAT)
   {
      png_warning(png_ptr, "Invalid hIST after IDAT");
      png_crc_finish(png_ptr, length);
      return;
   }
   else if (!(png_ptr->mode & PNG_HAVE_PLTE))
   {
      png_warning(png_ptr, "Missing PLTE before hIST");
      png_crc_finish(png_ptr, length);
      return;
   }
   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_hIST)
   {
      png_warning(png_ptr, "Duplicate hIST chunk");
      png_crc_finish(png_ptr, length);
      return;
   }

   if (length != (png_uint_32)(2 * png_ptr->num_palette))
   {
      png_warning(png_ptr, "Incorrect hIST chunk length");