view release on metacpan or  search on metacpan

src/Source/LibPNG/png.c  view on Meta::CPAN

         break;
# endif
         }
      }
   }

   return 0; /* no match */
}
#endif

#ifdef PNG_sRGB_SUPPORTED
void /* PRIVATE */
png_icc_set_sRGB(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
{
   /* Is this profile one of the known ICC sRGB profiles?  If it is, just set
    * the sRGB information.
    */
#if PNG_sRGB_PROFILE_CHECKS >= 0
   if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
#endif
      (void)png_colorspace_set_sRGB(png_ptr, colorspace,
         (int)/*already checked*/png_get_uint_32(profile+64));
}
#endif /* READ_sRGB */

int /* PRIVATE */
png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
   png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
   int color_type)
{
   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
      return 0;

   if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
       png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
          color_type) != 0 &&
       png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
          profile) != 0)
   {
#     ifdef PNG_sRGB_SUPPORTED
         /* If no sRGB support, don't try storing sRGB information */
         png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
#     endif
      return 1;
   }

   /* Failure case */
   return 0;
}
#endif /* iCCP */

#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
void /* PRIVATE */
png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
{
   /* Set the rgb_to_gray coefficients from the colorspace. */
   if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
      (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
   {
      /* png_set_background has not been called, get the coefficients from the Y
       * values of the colorspace colorants.
       */
      png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
      png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
      png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
      png_fixed_point total = r+g+b;

      if (total > 0 &&
         r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
         g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
         b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
         r+g+b <= 32769)
      {
         /* We allow 0 coefficients here.  r+g+b may be 32769 if two or
          * all of the coefficients were rounded up.  Handle this by
          * reducing the *largest* coefficient by 1; this matches the
          * approach used for the default coefficients in pngrtran.c
          */
         int add = 0;

         if (r+g+b > 32768)
            add = -1;
         else if (r+g+b < 32768)
            add = 1;

         if (add != 0)
         {
            if (g >= r && g >= b)
               g += add;
            else if (r >= g && r >= b)
               r += add;
            else
               b += add;
         }

         /* Check for an internal error. */
         if (r+g+b != 32768)
            png_error(png_ptr,
               "internal error handling cHRM coefficients");

         else
         {
            png_ptr->rgb_to_gray_red_coeff   = (png_uint_16)r;
            png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
         }
      }

      /* This is a png_error at present even though it could be ignored -
       * it should never happen, but it is important that if it does, the
       * bug is fixed.
       */
      else
         png_error(png_ptr, "internal error handling cHRM->XYZ");
   }
}
#endif

#endif /* COLORSPACE */

#ifdef __GNUC__

src/Source/LibPNG/png.c  view on Meta::CPAN

#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
  }
#ifdef PNG_16BIT_SUPPORTED
  else
  {
     png_byte shift, sig_bit;

     if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
     {
        sig_bit = png_ptr->sig_bit.red;

        if (png_ptr->sig_bit.green > sig_bit)
           sig_bit = png_ptr->sig_bit.green;

        if (png_ptr->sig_bit.blue > sig_bit)
           sig_bit = png_ptr->sig_bit.blue;
     }
     else
        sig_bit = png_ptr->sig_bit.gray;

     /* 16-bit gamma code uses this equation:
      *
      *   ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
      *
      * Where 'iv' is the input color value and 'ov' is the output value -
      * pow(iv, gamma).
      *
      * Thus the gamma table consists of up to 256 256-entry tables.  The table
      * is selected by the (8-gamma_shift) most significant of the low 8 bits of
      * the color value then indexed by the upper 8 bits:
      *
      *   table[low bits][high 8 bits]
      *
      * So the table 'n' corresponds to all those 'iv' of:
      *
      *   <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
      *
      */
     if (sig_bit > 0 && sig_bit < 16U)
        shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */

     else
        shift = 0; /* keep all 16 bits */

     if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
     {
        /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
         * the significant bits in the *input* when the output will
         * eventually be 8 bits.  By default it is 11.
         */
        if (shift < (16U - PNG_MAX_GAMMA_8))
           shift = (16U - PNG_MAX_GAMMA_8);
     }

     if (shift > 8U)
        shift = 8U; /* Guarantees at least one table! */

     png_ptr->gamma_shift = shift;

     /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
      * PNG_COMPOSE).  This effectively smashed the background calculation for
      * 16-bit output because the 8-bit table assumes the result will be reduced
      * to 8 bits.
      */
     if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
         png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
         png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
         png_ptr->screen_gamma) : PNG_FP_1);

     else
         png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
         png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
         png_ptr->screen_gamma) : PNG_FP_1);

#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
   defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
     if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
     {
        png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
            png_reciprocal(png_ptr->colorspace.gamma));

        /* Notice that the '16 from 1' table should be full precision, however
         * the lookup on this table still uses gamma_shift, so it can't be.
         * TODO: fix this.
         */
        png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
            png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
            png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
     }
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
  }
#endif /* 16BIT */
}
#endif /* READ_GAMMA */

/* HARDWARE OR SOFTWARE OPTION SUPPORT */
#ifdef PNG_SET_OPTION_SUPPORTED
int PNGAPI
png_set_option(png_structrp png_ptr, int option, int onoff)
{
   if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
      (option & 1) == 0)
   {
      int mask = 3 << option;
      int setting = (2 + (onoff != 0)) << option;
      int current = png_ptr->options;

      png_ptr->options = (png_byte)((current & ~mask) | setting);

      return (current & mask) >> option;
   }

   return PNG_OPTION_INVALID;
}
#endif

/* sRGB support */
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
/* sRGB conversion tables; these are machine generated with the code in