- png_struct *png = 0;
- png_info *info = 0;
- priv.data = 0;
-
- try
- {
- png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
- info = png_create_info_struct(png);
-
- if(setjmp(png_jmpbuf(png)))
- throw bad_image_data("PNG error");
-
- png_set_read_fn(png, &in, read);
- png_read_info(png, info);
- png_uint_32 width;
- png_uint_32 height;
- int depth;
- int color;
- png_get_IHDR(png, info, &width, &height, &depth, &color, 0, 0, 0);
- priv.width = width;
- priv.height = height;
- if(depth!=8)
- throw unsupported_image_format("depth!=8");
- switch(color)
- {
- case PNG_COLOR_TYPE_PALETTE: priv.fmt = COLOR_INDEX; break;
- case PNG_COLOR_TYPE_GRAY: priv.fmt = LUMINANCE; break;
- case PNG_COLOR_TYPE_GRAY_ALPHA: priv.fmt = LUMINANCE_ALPHA; break;
- case PNG_COLOR_TYPE_RGB: priv.fmt = RGB; break;
- case PNG_COLOR_TYPE_RGB_ALPHA: priv.fmt = RGBA; break;
- default: throw unsupported_image_format("unknown color type");
- }