SDL: Restore the original video mode when unloading the Surface graphics manager

We set a custom video mode that might have a different BPP from the default. To ensure that other graphics managers will get the proper results when listing available video modes, we need to restore the initial BPP when unloading.

This fixes an issue when switching to OpenGL on Windows 8 and later. On those OSes, fullscreen OpenGL only has a 32bpp mode. It is correctly listed in the options but we call SLD_SetVideoMode later in the surface graphics manager. When we list the mode again after a switch, the internally selected BPP is still 16 and we fail to find any available fullscreen modes.

2 files changed, 15 insertions, 0 deletions

diff --git a/backends/graphics/surfacesdl/surfacesdl-graphics.cpp b/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
index d08925349a..d74a6082e3 100644
--- a/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
+++ b/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
@@ -144,6 +144,7 @@ SurfaceSdlGraphicsManager::SurfaceSdlGraphicsManager(SdlEventSource *sdlEventSou
 #ifdef USE_SDL_DEBUG_FOCUSRECT
 	_enableFocusRectDebugCode(false), _enableFocusRect(false), _focusRect(),
 #endif
+	_originalBitsPerPixel(0),
 	_transactionMode(kTransactionNone) {
 
 	// allocate palette storage
@@ -797,6 +798,12 @@ bool SurfaceSdlGraphicsManager::loadGFXMode() {
 	} else
 #endif
 		{
+		// Save the original bpp to be able to restore the video mode on unload
+		if (_originalBitsPerPixel == 0) {
+			const SDL_VideoInfo *videoInfo = SDL_GetVideoInfo();
+			_originalBitsPerPixel = videoInfo->vfmt->BitsPerPixel;
+		}
+
 		_hwscreen = SDL_SetVideoMode(_videoMode.hardwareWidth, _videoMode.hardwareHeight, 16,
 			_videoMode.fullscreen ? (SDL_FULLSCREEN|SDL_SWSURFACE) : SDL_SWSURFACE
 			);
@@ -929,6 +936,11 @@ void SurfaceSdlGraphicsManager::unloadGFXMode() {
 	}
 #endif
 	DestroyScalers();
+
+	// Reset video mode to original
+	// This will ensure that any new graphic manager will use the initial BPP when listing available modes
+	if (_originalBitsPerPixel != 0)
+		SDL_SetVideoMode(_videoMode.screenWidth, _videoMode.screenHeight, _originalBitsPerPixel, _videoMode.fullscreen ? (SDL_FULLSCREEN | SDL_SWSURFACE) : SDL_SWSURFACE);
 }
 
 bool SurfaceSdlGraphicsManager::hotswapGFXMode() {
diff --git a/backends/graphics/surfacesdl/surfacesdl-graphics.h b/backends/graphics/surfacesdl/surfacesdl-graphics.h
index 4ba15a304b..2431ce8664 100644
--- a/backends/graphics/surfacesdl/surfacesdl-graphics.h
+++ b/backends/graphics/surfacesdl/surfacesdl-graphics.h
@@ -236,6 +236,9 @@ protected:
 	};
 	VideoState _videoMode, _oldVideoMode;
 
+	// Original BPP to restore the video mode on unload
+	uint8 _originalBitsPerPixel;
+
 	/** Force full redraw on next updateScreen */
 	bool _forceFull;