NAME
SDL_SetColorKey - Sets the color key (transparent pixel) in a blittable
surface and RLE acceleration.
SYNOPSIS
#include "SDL.h"
int SDL_SetColorKey(SDL_Surface *surface, Uint32 flag, Uint32 key);
DESCRIPTION
Sets the color key (transparent pixel) in a blittable surface and
enables or disables RLE blit acceleration.
RLE acceleration can substantially speed up blitting of images with
large horizontal runs of transparent pixels (i.e., pixels that match
the key value). The key must be of the same pixel format as the
surface, SDL_MapRGB is often useful for obtaining an acceptable value.
If flag is SDL_SRCCOLORKEY then key is the transparent pixel value in
the source image of a blit.
If flag is OR’d with SDL_RLEACCEL then the surface will be draw using
RLE acceleration when drawn with SDL_BlitSurface. The surface will
actually be encoded for RLE acceleration the first time SDL_BlitSurface
or SDL_DisplayFormat is called on the surface.
If flag is 0, this function clears any current color key.
RETURN VALUE
This function returns 0, or -1 if there was an error.
SEE ALSO
SDL_BlitSurface, SDL_DisplayFormat, SDL_MapRGB, SDL_SetAlpha