Workaround to File-New-Project/EarTrumpet#1305 (part of)

EarTrumpet/App.xaml.cs

@@ -118,6 +118,21 @@ private void ContinueStartup()
         // Initialize the FlyoutWindow last because its Show/Hide cycle will pump messages, causing UI frames
         // to be executed, breaking the assumption that startup is complete.
         FlyoutWindow.Initialize();
+
+        // listen for user session change
+        // When user come back after user switch, do some workaround for issue of losing audio sessions
+        SystemEvents.SessionSwitch += SystemEvents_SessionSwitch;
+        Exit += (_, __) => SystemEvents.SessionSwitch -= SystemEvents_SessionSwitch;
+    }
+
+    private void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)
+    {
+        Trace.WriteLine($"Detected User Session Switch: {e.Reason}");
+        if (e.Reason == SessionSwitchReason.ConsoleConnect)
+        {
+            var devManager = WindowsAudioFactory.Create(AudioDeviceKind.Playback);
+            devManager.RefreshAllDevices();
+        }
     }
 
     private void CompleteStartup()

EarTrumpet/DataModel/Audio/IAudioDeviceManager.cs

@@ -12,4 +12,5 @@ public interface IAudioDeviceManager
     string Kind { get; }
     void UpdatePeakValues();
     void AddFilter(Func<ObservableCollection<IAudioDevice>, ObservableCollection<IAudioDevice>> filter);
+    void RefreshAllDevices();
 }

EarTrumpet/DataModel/WindowsAudio/Internal/AudioDeviceManager.cs

@@ -335,4 +335,33 @@ private void TraceLine(string message)
     {
         System.Diagnostics.Trace.WriteLine($"AudioDeviceManager-({_kind}) {message}");
     }
+
+    public void RefreshAllDevices()
+    {
+        foreach (var dev in Devices.ToArray())
+        {
+            ((IMMNotificationClient)this).OnDeviceRemoved(dev.Id);
+        }
+        _default = null;
+
+        _enumerator = (IMMDeviceEnumerator)new MMDeviceEnumerator();
+        _enumerator.RegisterEndpointNotificationCallback(this);
+
+        _enumerator.EnumAudioEndpoints(Flow, DEVICE_STATE.DEVICE_STATE_ACTIVE, out var devices);
+        devices.GetCount(out var deviceCount);
+        for (uint i = 0; i < deviceCount; i++)
+        {
+            devices.Item(i, out var device);
+            device.GetId(out var deviceId);
+            ((IMMNotificationClient)this).OnDeviceAdded(deviceId);
+        }
+        this.OnDefaultDeviceChanged(EDataFlow.eRender, ERole.eMultimedia, null);
+        this.OnDefaultDeviceChanged(EDataFlow.eRender, ERole.eConsole, null);
+
+        _dispatcher.Invoke((Action)(() =>
+        {
+            QueryDefaultDevice();
+        }));
+
+    }
 }