Set the color key (transparent pixel) in a surface.
int SDL_SetColorKey(SDL_Surface * surface, int flag, Uint32 key);
|surface||the SDL_Surface structure to update|
|flag||SDL_TRUE to enable color key, SDL_FALSE to disable color key|
|key||the transparent pixel|
Returns 0 on success or a negative error code on failure; call SDL_GetError() for more information.
The color key defines a pixel value that will be treated as transparent in a blit. For example, one can use this to specify that cyan pixels should be considered transparent, and therefore not rendered.
It is a pixel of the format used by the surface, as generated by SDL_MapRGB().
RLE acceleration can substantially speed up blitting of images with large horizontal runs of transparent pixels. See SDL_SetSurfaceRLE() for details.
This function is available since SDL 2.0.0.