moved screen mutex from smush into SDL backend (other backends have to make sure they are thread safe by themselves)

svn-id: r7230

1 files changed, 4 insertions, 2 deletions

diff --git a/backends/sdl/sdl.cpp b/backends/sdl/sdl.cpp
index 6c6dd255e1..3c977e20b9 100644
--- a/backends/sdl/sdl.cpp
+++ b/backends/sdl/sdl.cpp
@@ -230,6 +230,8 @@ void OSystem_SDL::hotswap_gfx_mode() {
 void OSystem_SDL::update_screen() {
 	assert(_hwscreen != NULL);
 
+	StackLock lock(_mutex);	// Lock the mutex until this function ends
+
 	// If the shake position changed, fill the dirty area with blackness
 	if (_currentShakePos != _newShakePos) {
 		SDL_Rect blackrect = {0, 0, _screenWidth * _scaleFactor, _newShakePos * _scaleFactor};
@@ -277,12 +279,12 @@ void OSystem_SDL::update_screen() {
 		if (!_overlayVisible) {
 			for(r = _dirty_rect_list; r != last_rect; ++r) {
 				dst = *r;
+				dst.x++;	// Shift rect by one since 2xSai needs to acces the data around
+				dst.y++;	// any pixel to scale it, and we want to avoid mem access crashes.
 				if (_scaler_proc == Normal1x) {
 					if (SDL_BlitSurface(_screen, r, _hwscreen, &dst) != 0)
 						error("SDL_BlitSurface failed: %s", SDL_GetError());
 				} else {
-					dst.x++;	// Shift rect by one since 2xSai needs to acces the data around
-					dst.y++;	// any pixel to scale it, and we want to avoid mem access crashes.
 					if (SDL_BlitSurface(_screen, r, _tmpscreen, &dst) != 0)
 						error("SDL_BlitSurface failed: %s", SDL_GetError());
 				}