SDL: Automatically grab mouse upon entering fullscreen

Folks are confused about the new behaviour where the mouse is not
restricted to the game area in fullscreen, which is understandable.

This changes mouseIsGrabbed to use SDL directly in order to avoid
making changes to the user preference in the _inputGrabState.
Otherwise we'd either clobber the user's previous windowed mouse
grab preference, or require maintaining a second variable just to
track the original state, when we can have SDL do that for us.

2 files changed, 11 insertions, 3 deletions

diff --git a/backends/platform/sdl/sdl-window.cpp b/backends/platform/sdl/sdl-window.cpp
index fe27d84de2..b38a97c5ef 100644
--- a/backends/platform/sdl/sdl-window.cpp
+++ b/backends/platform/sdl/sdl-window.cpp
@@ -129,7 +129,7 @@ void SdlWindow::setWindowCaption(const Common::String &caption) {
 void SdlWindow::toggleMouseGrab() {
 #if SDL_VERSION_ATLEAST(2, 0, 0)
 	if (_window) {
-		_inputGrabState = !(SDL_GetWindowGrab(_window) == SDL_TRUE);
+		_inputGrabState = SDL_GetWindowGrab(_window) == SDL_FALSE;
 		SDL_SetWindowGrab(_window, _inputGrabState ? SDL_TRUE : SDL_FALSE);
 	}
 #else
@@ -279,7 +279,8 @@ bool SdlWindow::createOrUpdateWindow(int width, int height, uint32 flags) {
 		}
 
 		SDL_SetWindowFullscreen(_window, fullscreenFlags);
-		SDL_SetWindowGrab(_window, (flags & SDL_WINDOW_INPUT_GRABBED) ? SDL_TRUE : SDL_FALSE);
+		const bool shouldGrab = (flags & SDL_WINDOW_INPUT_GRABBED) | fullscreenFlags;
+		SDL_SetWindowGrab(_window, shouldGrab ? SDL_TRUE : SDL_FALSE);
 	}
 
 	if (!_window) {
diff --git a/backends/platform/sdl/sdl-window.h b/backends/platform/sdl/sdl-window.h
index e1a3499d19..05893c47d3 100644
--- a/backends/platform/sdl/sdl-window.h
+++ b/backends/platform/sdl/sdl-window.h
@@ -76,7 +76,14 @@ public:
 	 */
 	bool getSDLWMInformation(SDL_SysWMinfo *info) const;
 
-	bool mouseIsGrabbed() const { return _inputGrabState; }
+	bool mouseIsGrabbed() const {
+#if SDL_VERSION_ATLEAST(2, 0, 0)
+		if (_window) {
+			return SDL_GetWindowGrab(_window) == SDL_TRUE;
+		}
+#endif
+		return _inputGrabState;
+	}
 
 private:
 	bool _inputGrabState;