reimplement MP audio mode 2 (active instance only)

src/frontend/qt_sdl/EmuInstanceAudio.cpp

@@ -133,6 +133,7 @@ void EmuInstance::micCallback(void* data, Uint8* stream, int len)
 void EmuInstance::audioMute()
 {
     audioMuted = false;
+    if (numEmuInstances() < 2) return;
 
     switch (mpAudioMode)
     {
@@ -141,10 +142,16 @@ void EmuInstance::audioMute()
             break;
 
         case 2: // only currently focused instance
-            //if (mainWindow != nullptr)
-            //    audioMuted = !mainWindow->isActiveWindow();
-            // TODO!!
-            printf("TODO!! audioMute mode 2\n");
+            audioMuted = true;
+            for (int i = 0; i < kMaxWindows; i++)
+            {
+                if (!windowList[i]) continue;
+                if (windowList[i]->isFocused())
+                {
+                    audioMuted = false;
+                    break;
+                }
+            }
             break;
     }
 }

src/frontend/qt_sdl/Screen.cpp

@@ -385,6 +385,10 @@ bool ScreenPanel::event(QEvent* event)
         touchEvent((QTouchEvent*)event);
         return true;
     }
+    else if (event->type() == QEvent::FocusIn)
+        mainWindow->onFocusIn();
+    else if (event->type() == QEvent::FocusOut)
+        mainWindow->onFocusOut();
 
     return QWidget::event(event);
 }

src/frontend/qt_sdl/Window.cpp

@@ -235,7 +235,8 @@ MainWindow::MainWindow(int id, EmuInstance* inst, QWidget* parent) :
     localCfg(inst->localCfg),
     windowCfg(localCfg.GetTable("Window"+std::to_string(id), "Window0")),
     emuThread(inst->getEmuThread()),
-    enabledSaved(false)
+    enabledSaved(false),
+    focused(true)
 {
 #ifndef _WIN32
     if (!parent)
@@ -1015,13 +1016,26 @@ void MainWindow::dropEvent(QDropEvent* event)
 
 void MainWindow::focusInEvent(QFocusEvent* event)
 {
-    emuInstance->audioMute();
+    onFocusIn();
 }
 
 void MainWindow::focusOutEvent(QFocusEvent* event)
+{
+    onFocusOut();
+}
+
+void MainWindow::onFocusIn()
+{
+    focused = true;
+    if (emuInstance)
+        emuInstance->audioMute();
+}
+
+void MainWindow::onFocusOut()
 {
     // focusOutEvent is called through the window close event handler
     // prevent use after free
+    focused = false;
     if (emuInstance)
         emuInstance->audioMute();
 }

src/frontend/qt_sdl/Window.h

@@ -131,6 +131,10 @@ public:
 
     void onAppStateChanged(Qt::ApplicationState state);
 
+    void onFocusIn();
+    void onFocusOut();
+    bool isFocused() { return focused; }
+
     void osdAddMessage(unsigned int color, const char* msg);
 
     // called when the MP interface is changed
@@ -264,6 +268,8 @@ private:
     int windowID;
     bool enabledSaved;
 
+    bool focused;
+
     EmuInstance* emuInstance;
     EmuThread* emuThread;