a bits per pixel value; usually 15, 16, or 32.
the red mask for the format.
the green mask for the format.
the blue mask for the format.
the alpha mask for the format.
the SDL_PixelFormat value corresponding to the format masks, or SDL_PIXELFORMAT_UNKNOWN if there isn't a match.
Threadsafety: It is safe to call this function from any thread.
Convert a bpp value and RGBA masks to an enumerated pixel format.
This will return SDL_PIXELFORMAT_UNKNOWN if the conversion wasn't possible.