Fix keys being stuck after Moonlight loses focus or is quit via OS shortcut (Alt+Tab/Alt+F4)

app/streaming/input.cpp

@@ -121,25 +121,11 @@ void SdlInputHandler::handleKeyEvent(SDL_KeyboardEvent* event)
             (event->keysym.mod & KMOD_CTRL) &&
             (event->keysym.mod & KMOD_ALT) &&
             (event->keysym.mod & KMOD_SHIFT)) {
-
-        // Force raise all keys in the combo to avoid
-        // leaving them down after disconnecting
-        LiSendKeyboardEvent(0xA0, KEY_ACTION_UP, 0);
-        LiSendKeyboardEvent(0xA1, KEY_ACTION_UP, 0);
-        LiSendKeyboardEvent(0xA2, KEY_ACTION_UP, 0);
-        LiSendKeyboardEvent(0xA3, KEY_ACTION_UP, 0);
-        LiSendKeyboardEvent(0xA4, KEY_ACTION_UP, 0);
-        LiSendKeyboardEvent(0xA5, KEY_ACTION_UP, 0);
-
         // Check for quit combo (Ctrl+Alt+Shift+Q)
         if (event->keysym.sym == SDLK_q) {
             SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
                         "Detected quit key combo");
 
-            // Uncapture the mouse to avoid processing any
-            // further keyboard input
-            SDL_SetRelativeMouseMode(SDL_FALSE);
-
             // Push a quit event to the main loop
             SDL_Event event;
             event.type = SDL_QUIT;
@@ -151,7 +137,13 @@ void SdlInputHandler::handleKeyEvent(SDL_KeyboardEvent* event)
         else if (event->keysym.sym == SDLK_z) {
             SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
                         "Detected mouse capture toggle combo");
+
+            // Stop handling future input
             SDL_SetRelativeMouseMode((SDL_bool)!SDL_GetRelativeMouseMode());
+
+            // Force raise all keys to ensure they aren't stuck,
+            // since we won't get their key up events.
+            raiseAllKeys();
             return;
         }
         // Check for the full-screen combo (Ctrl+Alt+Shift+X)
@@ -159,6 +151,10 @@ void SdlInputHandler::handleKeyEvent(SDL_KeyboardEvent* event)
             SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
                         "Detected full-screen toggle combo");
             Session::s_ActiveSession->toggleFullscreen();
+
+            // Force raise all keys just be safe across this full-screen/windowed
+            // transition just in case key events get lost.
+            raiseAllKeys();
             return;
         }
     }
@@ -384,6 +380,14 @@ void SdlInputHandler::handleKeyEvent(SDL_KeyboardEvent* event)
         }
     }
 
+    // Track the key state so we always know which keys are down
+    if (event->state == SDL_PRESSED) {
+        m_KeysDown.insert(keyCode);
+    }
+    else {
+        m_KeysDown.remove(keyCode);
+    }
+
     LiSendKeyboardEvent(keyCode,
                         event->state == SDL_PRESSED ?
                             KEY_ACTION_DOWN : KEY_ACTION_UP,
@@ -914,6 +918,23 @@ int SdlInputHandler::getAttachedGamepadMask()
     return mask;
 }
 
+void SdlInputHandler::raiseAllKeys()
+{
+    if (m_KeysDown.isEmpty()) {
+        return;
+    }
+
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                "Raising %d keys",
+                m_KeysDown.count());
+
+    for (auto keyDown : m_KeysDown) {
+        LiSendKeyboardEvent(keyDown, KEY_ACTION_UP, 0);
+    }
+
+    m_KeysDown.clear();
+}
+
 QString SdlInputHandler::getUnmappedGamepads()
 {
     QString ret;

app/streaming/input.h

@@ -47,6 +47,8 @@ public:
 
     int getAttachedGamepadMask();
 
+    void raiseAllKeys();
+
     static
     QString getUnmappedGamepads();
 
@@ -70,6 +72,7 @@ private:
     bool m_NeedsInputDelay;
     int m_GamepadMask;
     GamepadState m_GamepadState[MAX_GAMEPADS];
+    QSet<short> m_KeysDown;
 
     SDL_TouchFingerEvent m_TouchDownEvent[MAX_FINGERS];
     float m_CumulativeDelta[MAX_FINGERS];

app/streaming/session.cpp

@@ -992,13 +992,19 @@ void Session::exec(int displayOriginX, int displayOriginY)
             }
 #endif
 
-            // Release mouse cursor when another window is activated (e.g. by using ALT+TAB).
-            // This lets user to interact with our window's title bar and with the buttons in it.
-            // Doing this while the window is full-screen breaks the transition out of FS
-            // (desktop and exclusive), so we must check for that before releasing mouse capture.
-            if (event.window.event == SDL_WINDOWEVENT_FOCUS_LOST &&
-                    !(SDL_GetWindowFlags(m_Window) & SDL_WINDOW_FULLSCREEN)) {
-                SDL_SetRelativeMouseMode(SDL_FALSE);
+
+            if (event.window.event == SDL_WINDOWEVENT_FOCUS_LOST) {
+                // Release mouse cursor when another window is activated (e.g. by using ALT+TAB).
+                // This lets user to interact with our window's title bar and with the buttons in it.
+                // Doing this while the window is full-screen breaks the transition out of FS
+                // (desktop and exclusive), so we must check for that before releasing mouse capture.
+                if (!(SDL_GetWindowFlags(m_Window) & SDL_WINDOW_FULLSCREEN)) {
+                    SDL_SetRelativeMouseMode(SDL_FALSE);
+                }
+
+                // Raise all keys that are currently pressed. If we don't do this, certain keys
+                // used in shortcuts that cause focus loss (such as Alt+Tab) may get stuck down.
+                inputHandler.raiseAllKeys();
             }
 
             // We want to recreate the decoder for resizes (full-screen toggles) and the initial shown event.
@@ -1139,6 +1145,9 @@ DispatchDeferredCleanup:
     SDL_EnableScreenSaver();
     SDL_SetHint(SDL_HINT_TIMER_RESOLUTION, "0");
 
+    // Raise any keys that are still down
+    inputHandler.raiseAllKeys();
+
     // Destroy the decoder, since this must be done on the main thread
     SDL_AtomicLock(&m_DecoderLock);
     delete m_VideoDecoder;