Implemented the OSystem framebuffer API, as discussed on scummvm-devel. All changes are just fine, and won't cause any compile problems or regressions, despite the fact that I can't test most of the non-SDL backend changes, at an improbability level of two to the power of two hundred and seventy-six thousand to one against - possibly much higher. Anything you still can't cope with is therefore your own problem. Please relax.

svn-id: r27548

3 files changed, 35 insertions, 28 deletions

diff --git a/backends/platform/sdl/graphics.cpp b/backends/platform/sdl/graphics.cpp
index e0b7de28ab..f93c806aa8 100644
--- a/backends/platform/sdl/graphics.cpp
+++ b/backends/platform/sdl/graphics.cpp
@@ -761,22 +761,6 @@ void OSystem_SDL::setAspectRatioCorrection(bool enable) {
 	}
 }
 
-void OSystem_SDL::clearScreen() {
-	assert (_transactionMode == kTransactionNone);
-
-	// Try to lock the screen surface
-	if (SDL_LockSurface(_screen) == -1)
-		error("SDL_LockSurface failed: %s", SDL_GetError());
-
-	byte *dst = (byte *)_screen->pixels;
-
-	// Clear the screen
-	memset(dst, 0, _screenWidth * _screenHeight);
-
-	// Unlock the screen surface
-	SDL_UnlockSurface(_screen);
-}
-
 void OSystem_SDL::copyRectToScreen(const byte *src, int pitch, int x, int y, int w, int h) {
 	assert (_transactionMode == kTransactionNone);
 	assert(src);
@@ -848,24 +832,44 @@ void OSystem_SDL::copyRectToScreen(const byte *src, int pitch, int x, int y, int
 	SDL_UnlockSurface(_screen);
 }
 
-bool OSystem_SDL::grabRawScreen(Graphics::Surface *surf) {
-	assert(_screen);
-	assert(surf);
+Graphics::Surface *OSystem_SDL::lockScreen() {
+	assert (_transactionMode == kTransactionNone);
 
-	Common::StackLock lock(_graphicsMutex);	// Lock the mutex until this function ends
+	// Lock the graphics mutex
+	lockMutex(_graphicsMutex);
 
-	surf->create(_screenWidth, _screenHeight, _screen->format->BytesPerPixel);
+	// paranoia check
+	assert(!_screenIsLocked);
+	_screenIsLocked = true;
 
 	// Try to lock the screen surface
 	if (SDL_LockSurface(_screen) == -1)
 		error("SDL_LockSurface failed: %s", SDL_GetError());
 
-	memcpy(surf->pixels, _screen->pixels, _screenWidth * _screenHeight * _screen->format->BytesPerPixel);
+	_framebuffer.pixels = _screen->pixels;
+	_framebuffer.w = _screen->w;
+	_framebuffer.h = _screen->h;
+	_framebuffer.pitch = _screen->pitch;
+	_framebuffer.bytesPerPixel = 1;
+
+	return &_framebuffer;
+}
+
+void OSystem_SDL::unlockScreen() {
+	assert (_transactionMode == kTransactionNone);
+
+	// paranoia check
+	assert(_screenIsLocked);
+	_screenIsLocked = false;
 
 	// Unlock the screen surface
 	SDL_UnlockSurface(_screen);
 
-	return true;
+	// Trigger a full screen update
+	_forceFull = true;
+
+	// Finally unlock the graphics mutex
+	unlockMutex(_graphicsMutex);
 }
 
 void OSystem_SDL::addDirtyRect(int x, int y, int w, int h, bool realCoordinates) {
diff --git a/backends/platform/sdl/sdl-common.h b/backends/platform/sdl/sdl-common.h
index e66ca71e7f..4795b22a53 100644
--- a/backends/platform/sdl/sdl-common.h
+++ b/backends/platform/sdl/sdl-common.h
@@ -92,11 +92,8 @@ public:
 	// The screen will not be updated to reflect the new bitmap
 	virtual void copyRectToScreen(const byte *src, int pitch, int x, int y, int w, int h); // overloaded by CE backend (FIXME)
 
-	// Copies the screen to a buffer
-	bool grabRawScreen(Graphics::Surface *surf);
-
-	// Clear the screen
-	void clearScreen();
+	virtual Graphics::Surface *lockScreen();
+	virtual void unlockScreen();
 
 	// Update the dirty areas of the screen
 	void updateScreen();
@@ -218,6 +215,8 @@ protected:
 
 	// unseen game screen
 	SDL_Surface *_screen;
+	
+	// TODO: We could get rid of the following two vars and just use _screen instead
 	int _screenWidth, _screenHeight;
 
 	// temporary screen (for scalers)
@@ -274,6 +273,9 @@ protected:
 	int _mode;
 	int _transactionMode;
 	bool _fullscreen;
+	
+	bool _screenIsLocked;
+	Graphics::Surface _framebuffer;
 
 	/** Current video mode flags (see DF_* constants) */
 	uint32 _modeFlags;
diff --git a/backends/platform/sdl/sdl.cpp b/backends/platform/sdl/sdl.cpp
index 0fe16e0520..fe78bd4236 100644
--- a/backends/platform/sdl/sdl.cpp
+++ b/backends/platform/sdl/sdl.cpp
@@ -243,6 +243,7 @@ OSystem_SDL::OSystem_SDL()
 	_savefile(0),
 	_mixer(0),
 	_timer(0),
+	_screenIsLocked(false),
 	_graphicsMutex(0), _transactionMode(kTransactionNone) {
 
 	// allocate palette storage