Commit 5669743a435f8fe9ea43e5f6b49601ba9dabe2ae
2022-05-19T09:45:57
Make sure SDL_CaptureMouse() is only called on the main thread Windows handles mouse capture on a per-thread basis, and capture must be done on the thread used to create a window. Fixes https://github.com/libsdl-org/SDL/issues/5577
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diff --git a/src/events/SDL_mouse.c b/src/events/SDL_mouse.c
index e6bb096..dfa9a6c 100644
--- a/src/events/SDL_mouse.c
+++ b/src/events/SDL_mouse.c
@@ -1069,6 +1069,17 @@ SDL_CaptureMouse(SDL_bool enabled)
return SDL_Unsupported();
}
+#ifdef __WIN32__
+ /* Windows mouse capture is tied to the current thread, and must be called
+ * from the thread that created the window being captured. Since we update
+ * the mouse capture state from the event processing, any application state
+ * changes must be processed on that thread as well.
+ */
+ if (!SDL_OnVideoThread()) {
+ return SDL_SetError("SDL_CaptureMouse() must be called on the main thread");
+ }
+#endif /* __WIN32__ */
+
if (enabled && SDL_GetKeyboardFocus() == NULL) {
return SDL_SetError("No window has focus");
}
diff --git a/src/video/SDL_sysvideo.h b/src/video/SDL_sysvideo.h
index 70a4991..b1876b2 100644
--- a/src/video/SDL_sysvideo.h
+++ b/src/video/SDL_sysvideo.h
@@ -333,6 +333,7 @@ struct SDL_VideoDevice
/* * * */
/* Data common to all drivers */
+ SDL_threadID thread;
SDL_bool checked_texture_framebuffer;
SDL_bool is_dummy;
SDL_bool suspend_screensaver;
@@ -461,6 +462,8 @@ extern VideoBootStrap NGAGE_bootstrap;
extern VideoBootStrap OS2DIVE_bootstrap;
extern VideoBootStrap OS2VMAN_bootstrap;
+/* Use SDL_OnVideoThread() sparingly, to avoid regressions in use cases that currently happen to work */
+extern SDL_bool SDL_OnVideoThread(void);
extern SDL_VideoDevice *SDL_GetVideoDevice(void);
extern int SDL_AddBasicVideoDisplay(const SDL_DisplayMode * desktop_mode);
extern int SDL_AddVideoDisplay(const SDL_VideoDisplay * display, SDL_bool send_event);
diff --git a/src/video/SDL_video.c b/src/video/SDL_video.c
index 305ed7a..58f9d74 100644
--- a/src/video/SDL_video.c
+++ b/src/video/SDL_video.c
@@ -470,6 +470,7 @@ SDL_VideoInit(const char *driver_name)
_this = video;
_this->name = bootstrap[i]->name;
_this->next_object_id = 1;
+ _this->thread = SDL_ThreadID();
/* Set some very sane GL defaults */
@@ -549,6 +550,12 @@ SDL_GetVideoDevice(void)
return _this;
}
+SDL_bool
+SDL_OnVideoThread()
+{
+ return (_this && SDL_ThreadID() == _this->thread) ? SDL_TRUE : SDL_FALSE;
+}
+
int
SDL_AddBasicVideoDisplay(const SDL_DisplayMode * desktop_mode)
{