Fix capturing mouse motion outside the window on sdl2-compat

app/main.cpp

@@ -718,10 +718,6 @@ int main(int argc, char *argv[])
     SDL_SetHint(SDL_HINT_AUDIO_DEVICE_APP_NAME, "Moonlight");
     SDL_SetHint(SDL_HINT_APP_NAME, "Moonlight");
 
-    // We handle capturing the mouse ourselves when it leaves the window, so we don't need
-    // SDL doing it for us behind our backs.
-    SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "0");
-
     // SDL will try to lock the mouse cursor on Wayland if it's not visible in order to
     // support applications that assume they can warp the cursor (which isn't possible
     // on Wayland). We don't want this behavior because it interferes with seamless mouse

app/streaming/input/input.cpp

@@ -40,6 +40,19 @@ SdlInputHandler::SdlInputHandler(StreamingPreferences& prefs, int streamWidth, i
         m_CaptureSystemKeysMode = StreamingPreferences::CSK_ALWAYS;
     }
 
+    // SDL3 breaks our auto-capture-on-leave logic because the mouse focus has already
+    // been lost by the time we attempt to call SDL_CaptureMouse(). Fortunately, SDL3's
+    // own auto-capture logic seems to be stable now (unlike SDL2), so we can rely on
+    // that instead of our own hack when running on sdl2-compat.
+    // https://github.com/libsdl-org/SDL/commit/e54001b02809dcebbb822bd0297919c8c76976a1
+    SDL_version ver;
+    SDL_GetVersion(&ver);
+    m_NeedsManualCaptureOnLeave = !(ver.major == 2 && ver.minor >= 30 && ver.patch >= 50) && !SDL_GetHint("SDL3_VERSION");
+    if (m_NeedsManualCaptureOnLeave) {
+        // Disable the buggy auto-capture on earlier SDL2 builds
+        SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "0");
+    }
+
     // Allow gamepad input when the app doesn't have focus if requested
     SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, prefs.backgroundGamepad ? "1" : "0");
 
@@ -276,6 +289,7 @@ void SdlInputHandler::raiseAllKeys()
 
 void SdlInputHandler::notifyMouseLeave()
 {
+    if (m_NeedsManualCaptureOnLeave) {
         // SDL on Windows doesn't send the mouse button up until the mouse re-enters the window
         // after leaving it. This breaks some of the Aero snap gestures, so we'll capture it to
         // allow us to receive the mouse button up events later.
@@ -292,6 +306,7 @@ void SdlInputHandler::notifyMouseLeave()
                 }
             }
         }
+    }
 }
 
 void SdlInputHandler::notifyFocusLost()

app/streaming/input/input.h

@@ -210,6 +210,7 @@ private:
     bool m_ReverseScrollDirection;
     bool m_SwapFaceButtons;
 
+    bool m_NeedsManualCaptureOnLeave;
     bool m_MouseWasInVideoRegion;
     bool m_PendingMouseButtonsAllUpOnVideoRegionLeave;
     bool m_PointerRegionLockActive;

app/streaming/input/mouse.cpp

@@ -128,8 +128,10 @@ void SdlInputHandler::handleMouseMotionEvent(SDL_MouseMotionEvent* event)
         Uint32 buttonState = SDL_GetMouseState(nullptr, nullptr);
         if (buttonState == 0) {
             if (m_PendingMouseButtonsAllUpOnVideoRegionLeave) {
+                if (m_NeedsManualCaptureOnLeave) {
                     // Stop capturing the mouse now
                     SDL_CaptureMouse(SDL_FALSE);
+                }
                 m_PendingMouseButtonsAllUpOnVideoRegionLeave = false;
             }
         }