+static Pixel SDLGetColorKey(SDL_Surface *surface)
+{
+ Pixel color_key;
+
+ if (SDL_GetColorKey(surface, &color_key) != 0)
+ return -1;
+
+ return color_key;
+}
+
+static boolean SDLHasColorKey(SDL_Surface *surface)
+{
+ return (SDLGetColorKey(surface) != -1);
+}
+
+static boolean SDLHasAlpha(SDL_Surface *surface)
+{
+ SDL_BlendMode blend_mode;
+
+ if (SDL_GetSurfaceBlendMode(surface, &blend_mode) != 0)
+ return FALSE;
+
+ return (blend_mode == SDL_BLENDMODE_BLEND);
+}
+
+static void SDLSetAlpha(SDL_Surface *surface, boolean set, int alpha)
+{
+ SDL_BlendMode blend_mode = (set ? SDL_BLENDMODE_BLEND : SDL_BLENDMODE_NONE);
+
+ SDL_SetSurfaceBlendMode(surface, blend_mode);
+ SDL_SetSurfaceAlphaMod(surface, alpha);
+}
+