SDL: Do not reset window size when engines update rendering surface

This change allows:

* Engines to update their target rendering surface/size and pixel
  format with the backend multiple times during gameplay;
* Users to resize the ScummVM window without having it reset
  size/position every time an engine updates its target surface
  format;
* Conversions/scaling to continue to run efficiently in hardware,
  instead of requiring engines to pick their maximum possible
  output format once and upscale inefficiently in software;
* The window to reset size once when an engine calls to set its
  initial output size, and to reset again once ScummVM returns to
  the launcher.

This is relevant for at least SCI32 and DreamWeb engines, which
perform graphics mode switches during games.

1 files changed, 7 insertions, 2 deletions

diff --git a/backends/graphics/surfacesdl/surfacesdl-graphics.cpp b/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
index 983b71ab28..cd7e11b32d 100644
--- a/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
+++ b/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
@@ -784,9 +784,14 @@ void SurfaceSdlGraphicsManager::initSize(uint w, uint h, const Graphics::PixelFo
 	}
 #endif
 
-	// Avoid redundant res changes
+#if !SDL_VERSION_ATLEAST(2, 0, 0)
+	// Avoid redundant res changes, only in SDL1. In SDL2, redundancies may not
+	// actually be redundant if ScummVM is switching between game engines and
+	// the screen dimensions are being reinitialized, since window resizing is
+	// supposed to reset when this happens
 	if ((int)w == _videoMode.screenWidth && (int)h == _videoMode.screenHeight)
 		return;
+#endif
 
 	_videoMode.screenWidth = w;
 	_videoMode.screenHeight = h;
@@ -2797,7 +2802,7 @@ SDL_Surface *SurfaceSdlGraphicsManager::SDL_SetVideoMode(int width, int height,
 		createWindowFlags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
 	}
 
-	if (!_window->createOrUpdateWindow(width, height, createWindowFlags)) {
+	if (!createOrUpdateWindow(width, height, createWindowFlags)) {
 		return nullptr;
 	}