libpng-alpha.patch

   1 recent change from libpng 1.2.7 broke alpha stripping
   2 png_set_strip_alpha() does info_ptr->color_type &= ~PNG_COLOR_MASK_ALPHA,
   3 but png_do_strip_filler checks png_ptr->row_info.color_type not
   4 info_ptr->color_type
   5
   6 --- libpng-1.2.7/pngread.c.orig 2004-09-12 04:19:31.000000000 +0200
   7 +++ libpng-1.2.7/pngread.c      2004-10-13 16:22:29.000000000 +0200
   8 @@ -726,6 +726,10 @@
   9     png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
  10     png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
  11         png_ptr->row_info.width);
  12 +#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
  13 +   if (png_ptr->transformations & PNG_STRIP_ALPHA)
  14 +          png_ptr->row_info.color_type &= ~PNG_COLOR_MASK_ALPHA;
  15 +#endif
  16
  17     if(png_ptr->row_buf[0])
  18     png_read_filter_row(png_ptr, &(png_ptr->row_info),