static void handle_alpha(reader& io, uint_32 filler)
{
bool src_alpha = io.get_color_type() & color_mask_alpha;
bool dst_alpha = traits::get_color_type() & color_mask_alpha;
if (src_alpha && !dst_alpha)
{
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
io.set_strip_alpha();
#else
throw error("alpha channel unexpected;"
" recompile with"
" PNG_READ_STRIP_ALPHA_SUPPORTED");
#endif
}
if (!src_alpha && dst_alpha)
{
#if defined(PNG_tRNS_SUPPORTED) && defined(PNG_READ_EXPAND_SUPPORTED)
if ((io.get_color_type() & color_mask_palette)
&& io.has_chunk(chunk_tRNS))
{
io.set_tRNS_to_alpha();
return;
}
#endif
#if defined(PNG_READ_FILLER_SUPPORTED) && !defined(PNG_1_0_X)
io.set_add_alpha(filler, filler_after);
#else
throw error("expected alpha channel but none found;"
" recompile with PNG_READ_FILLER_SUPPORTED"
" and be sure to use libpng > 1.0.x");
#endif
}
}
static void handle_rgb(reader& io)
{
bool src_rgb =
io.get_color_type() & (color_mask_rgb | color_mask_palette);
bool dst_rgb = traits::get_color_type() & color_mask_rgb;
if (src_rgb && !dst_rgb)
{
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
io.set_rgb_to_gray(/*rgb_to_gray_error*/);
#else
throw error("grayscale data expected;"
" recompile with"
" PNG_READ_RGB_TO_GRAY_SUPPORTED");
#endif
}
if (!src_rgb && dst_rgb)
{
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
io.set_gray_to_rgb();
#else
throw error("expected RGB data;"
" recompile with"
" PNG_READ_GRAY_TO_RGB_SUPPORTED");
#endif
}
}
static void handle_gray(reader& io)
{
if ((io.get_color_type() & ~color_mask_alpha)
== color_type_gray)
{
if (io.get_bit_depth() < 8 && traits::get_bit_depth() >= 8)
{
#ifdef PNG_READ_EXPAND_SUPPORTED
io.set_gray_1_2_4_to_8();
#else
throw error("convert_color_space: expected 8-bit data;"
" recompile with"
" PNG_READ_EXPAND_SUPPORTED");
#endif
}
}
}
static void handle_palette(reader& io)
{
if (io.get_color_type() == color_type_palette)
{
#ifdef PNG_READ_EXPAND_SUPPORTED
io.set_palette_to_rgb();
if (traits::get_color_type() != color_type_palette)
{
io.get_info().drop_palette();
}
#else
throw error("indexed colors unexpected;"
" recompile with PNG_READ_EXPAND_SUPPORTED");
#endif
}
}
