static void from_cairo_format(Uint32 & c)
{
#ifdef _WIN32
    Uint8 r = (c >> 24) & 0xff;
    Uint8 g = (c >> 16) & 0xff;
    Uint8 b = (c >> 8) & 0xff;
    Uint8 a = c & 0xff;
#else
    Uint8 a = (c >> 24) & 0xff;
    Uint8 r = (c >> 16) & 0xff;
    Uint8 g = (c >> 8) & 0xff;
    Uint8 b = c & 0xff;
#endif

    const unsigned div = inverse_table_[a];
    unpremultiply(r, div);
    unpremultiply(g, div);
    unpremultiply(b, div);

    c = (static_cast<Uint32>(a) << 24) | (static_cast<Uint32>(r) << 16) | (static_cast<Uint32>(g) << 8) | static_cast<Uint32>(b);
}