Additional orthogonalization and defensive coding around colorkeys and alpha mods

sc2/src/libs/graphics/sdl/sdl1_common.c

@@ -400,6 +400,16 @@ TFB_SetGamma (float gamma)
 	}
 }
 
+int
+TFB_HasSurfaceAlphaMod (SDL_Surface *surface)
+{
+	if (!surface)
+	{
+		return 0;
+	}
+	return (surface->flags & SDL_SRCALPHA) ? 1 : 0;
+}
+
 int
 TFB_GetSurfaceAlphaMod (SDL_Surface *surface, Uint8 *alpha)
 {
@@ -421,12 +431,20 @@ TFB_GetSurfaceAlphaMod (SDL_Surface *surface, Uint8 *alpha)
 int
 TFB_SetSurfaceAlphaMod (SDL_Surface *surface, Uint8 alpha)
 {
+	if (!surface)
+	{
+		return -1;
+	}
 	return SDL_SetAlpha (surface, SDL_SRCALPHA, alpha);
 }
 
 int
 TFB_DisableSurfaceAlphaMod (SDL_Surface *surface)
 {
+	if (!surface)
+	{
+		return -1;
+	}
 	return SDL_SetAlpha (surface, 0, 255);
 }
 
@@ -445,12 +463,20 @@ TFB_GetColorKey (SDL_Surface *surface, Uint32 *key)
 int
 TFB_SetColorKey (SDL_Surface *surface, Uint32 key)
 {
+	if (!surface)
+	{
+		return -1;
+	}
 	return SDL_SetColorKey (surface, SDL_SRCCOLORKEY, key);
 }
 
 int
 TFB_DisableColorKey (SDL_Surface *surface)
 {
+	if (!surface)
+	{
+		return -1;
+	}
 	return SDL_SetColorKey (surface, 0, 0);
 }
 #endif

sc2/src/libs/graphics/sdl/sdl2_common.c

@@ -366,6 +366,21 @@ TFB_SetGamma (float gamma)
 	log_add (log_Warning, "Custom gamma correction is not available in the SDL2 engine.");
 }
 
+int
+TFB_HasSurfaceAlphaMod (SDL_Surface *surface)
+{
+	SDL_BlendMode blend_mode;
+	if (!surface)
+	{
+		return 0;
+	}
+	if (SDL_GetSurfaceBlendMode (surface, &blend_mode) != 0)
+	{
+		return 0;
+	}
+	return blend_mode == SDL_BLENDMODE_BLEND;
+}
+
 int
 TFB_GetSurfaceAlphaMod (SDL_Surface *surface, Uint8 *alpha)
 {
@@ -376,7 +391,10 @@ TFB_GetSurfaceAlphaMod (SDL_Surface *surface, Uint8 *alpha)
 	}
 	if (SDL_GetSurfaceBlendMode (surface, &blend_mode) == 0)
 	{
-		return SDL_GetSurfaceAlphaMod (surface, alpha);
+		if (blend_mode == SDL_BLENDMODE_BLEND)
+		{
+			return SDL_GetSurfaceAlphaMod (surface, alpha);
+		}
 	}
 	*alpha = 255;
 	return 0;
@@ -385,7 +403,12 @@ TFB_GetSurfaceAlphaMod (SDL_Surface *surface, Uint8 *alpha)
 int
 TFB_SetSurfaceAlphaMod (SDL_Surface *surface, Uint8 alpha)
 {
-	int result = SDL_SetSurfaceBlendMode (surface, SDL_BLENDMODE_BLEND);
+	int result;
+	if (!surface)
+	{
+		return -1;
+	}
+	result = SDL_SetSurfaceBlendMode (surface, SDL_BLENDMODE_BLEND);
 	if (result == 0)
 	{
 		result = SDL_SetSurfaceAlphaMod (surface, alpha);
@@ -396,6 +419,10 @@ TFB_SetSurfaceAlphaMod (SDL_Surface *surface, Uint8 alpha)
 int
 TFB_DisableSurfaceAlphaMod (SDL_Surface *surface)
 {
+	if (!surface)
+	{
+		return -1;
+	}
 	SDL_SetSurfaceAlphaMod (surface, 255);
 	return SDL_SetSurfaceBlendMode (surface, SDL_BLENDMODE_NONE);
 }
@@ -403,18 +430,30 @@ TFB_DisableSurfaceAlphaMod (SDL_Surface *surface)
 int
 TFB_GetColorKey (SDL_Surface *surface, Uint32 *key)
 {
+	if (!surface || !key)
+	{
+		return -1;
+	}
 	return SDL_GetColorKey (surface, key);
 }
 
 int
 TFB_SetColorKey (SDL_Surface *surface, Uint32 key)
 {
+	if (!surface)
+	{
+		return -1;
+	}
 	return SDL_SetColorKey (surface, SDL_TRUE, key);
 }
 
 int
 TFB_DisableColorKey (SDL_Surface *surface)
 {
+	if (!surface)
+	{
+		return -1;
+	}
 	return SDL_SetColorKey (surface, SDL_FALSE, 0);
 }
 

sc2/src/libs/graphics/sdl/sdl_common.c

@@ -243,3 +243,10 @@ TFB_UploadTransitionScreen (void)
 {
 	graphics_backend->uploadTransitionScreen ();
 }
+
+int
+TFB_HasColorKey (SDL_Surface *surface)
+{
+	Uint32 key;
+	return TFB_GetColorKey (surface, &key) != 0;
+}

sc2/src/libs/graphics/sdl/sdl_common.h

@@ -45,9 +45,11 @@ extern SDL_Surface *SDL_Screens[TFB_GFX_NUMSCREENS];
 extern SDL_Surface *format_conv_surf;
 
 SDL_Surface* TFB_DisplayFormatAlpha (SDL_Surface *surface);
+int TFB_HasSurfaceAlphaMod (SDL_Surface *surface);
 int TFB_GetSurfaceAlphaMod (SDL_Surface *surface, Uint8 *alpha);
 int TFB_SetSurfaceAlphaMod (SDL_Surface *surface, Uint8 alpha);
 int TFB_DisableSurfaceAlphaMod (SDL_Surface *surface);
+int TFB_HasColorKey (SDL_Surface *surface);
 int TFB_GetColorKey (SDL_Surface *surface, Uint32 *key);
 int TFB_SetColorKey (SDL_Surface *surface, Uint32 key);
 int TFB_DisableColorKey (SDL_Surface *surface);