fixed zooming surfaces to keep alpha channel

[rocksndiamonds.git] / src / libgame / sdl.c

diff --git a/src/libgame/sdl.c b/src/libgame/sdl.c
index 30ca17949a8ad2f9192eed9fb0bd697a75207fd7..60b40b3a29568bdebf76b1fb6ea592803031432c 100644 (file)
--- a/src/libgame/sdl.c
+++ b/src/libgame/sdl.c
@@ -2124,7 +2124,8 @@ SDL_Surface *zoomSurface(SDL_Surface *src, int dst_width, int dst_height)
   {
     /* new source surface is 32 bit with a defined RGB ordering */
     zoom_src = SDL_CreateRGBSurface(SURFACE_FLAGS, src->w, src->h, 32,
-                                   0x000000ff, 0x0000ff00, 0x00ff0000, 0);
+                                   0x000000ff, 0x0000ff00, 0x00ff0000,
+                                   (src->format->Amask ? 0xff000000 : 0));
     SDL_BlitSurface(src, NULL, zoom_src, NULL);
     is_32bit = TRUE;
     is_converted = TRUE;
@@ -2137,7 +2138,8 @@ SDL_Surface *zoomSurface(SDL_Surface *src, int dst_width, int dst_height)
     zoom_dst = SDL_CreateRGBSurface(SURFACE_FLAGS, dst_width, dst_height, 32,
                                    zoom_src->format->Rmask,
                                    zoom_src->format->Gmask,
-                                   zoom_src->format->Bmask, 0);
+                                   zoom_src->format->Bmask,
+                                   zoom_src->format->Amask);
   }
   else
   {
@@ -2178,10 +2180,28 @@ SDL_Surface *zoomSurface(SDL_Surface *src, int dst_width, int dst_height)
   return zoom_dst;
 }
 
+static void SetOpaqueBitmapSurface(Bitmap *bitmap)
+{
+  if (bitmap == NULL)
+    return;
+
+  if (bitmap->surface)
+    SDL_FreeSurface(bitmap->surface);
+
+  if ((bitmap->surface = SDLGetNativeSurface(bitmap->surface_masked)) == NULL)
+    Error(ERR_EXIT, "SDL_DisplayFormat() failed");
+
+  /* remove alpha channel from native non-transparent surface, if defined */
+  SDLSetAlpha(bitmap->surface, FALSE, 0);
+
+  /* remove transparent color from native non-transparent surface, if defined */
+  SDL_SetColorKey(bitmap->surface, UNSET_TRANSPARENT_PIXEL, 0);
+}
+
 Bitmap *SDLZoomBitmap(Bitmap *src_bitmap, int dst_width, int dst_height)
 {
   Bitmap *dst_bitmap = CreateBitmapStruct();
-  SDL_Surface **dst_surface = &dst_bitmap->surface;
+  SDL_Surface **dst_surface = &dst_bitmap->surface_masked;
 
   dst_width  = MAX(1, dst_width);      /* prevent zero bitmap width */
   dst_height = MAX(1, dst_height);     /* prevent zero bitmap height */
@@ -2190,11 +2210,19 @@ Bitmap *SDLZoomBitmap(Bitmap *src_bitmap, int dst_width, int dst_height)
   dst_bitmap->height = dst_height;
 
   /* create zoomed temporary surface from source surface */
-  *dst_surface = zoomSurface(src_bitmap->surface, dst_width, dst_height);
+  *dst_surface = zoomSurface(src_bitmap->surface_masked, dst_width, dst_height);
 
   /* create native format destination surface from zoomed temporary surface */
   SDLSetNativeSurface(dst_surface);
 
+  /* set color key for zoomed surface from source surface, if defined */
+  if (SDLHasColorKey(src_bitmap->surface_masked))
+    SDL_SetColorKey(*dst_surface, SET_TRANSPARENT_PIXEL,
+                   SDLGetColorKey(src_bitmap->surface_masked));
+
+  /* create native non-transparent surface for opaque blitting */
+  SetOpaqueBitmapSurface(dst_bitmap);
+
   return dst_bitmap;
 }