Fixed bug 3158 - SDL display window scrambled over VNC

Witek Jachimczyk

I'm using SDL to develop a video viewer for MATLAB.  The window is scrambled while using thightVNC with its default mode of RGB656.

SDL does not correctly recognize the pixel mode.


I found a solution for this problem.  The solution involves modifying
SDL/src/video/SDL_pixels.c

Adding the following "if statement" under case 16: of SDL_MasksToPixelFormatEnum resolves the issue:

        if (Rmask == 0x003F &&
            Gmask == 0x07C0 &&
            Bmask == 0xF800 &&
            Amask == 0x0000) {
            return SDL_PIXELFORMAT_RGB565;
        }

I hope that this helps someone.  I took me a while to figure it out.

src/video/SDL_pixels.c

@@ -403,6 +403,13 @@ SDL_MasksToPixelFormatEnum(int bpp, Uint32 Rmask, Uint32 Gmask, Uint32 Bmask,
             Amask == 0x0000) {
             return SDL_PIXELFORMAT_BGR565;
         }
+        if (Rmask == 0x003F &&
+            Gmask == 0x07C0 &&
+            Bmask == 0xF800 &&
+            Amask == 0x0000) {
+            /* Technically this would be BGR556, but Witek says this works in bug 3158 */
+            return SDL_PIXELFORMAT_RGB565;
+        }
         break;
     case 24:
         switch (Rmask) {