Detect when USB is (dis)connected, update displayed devices

src/Baballonia/App.axaml.cs

@@ -153,6 +153,7 @@ public override void OnFrameworkInitializationCompleted()
                 services.AddTransient<FirmwareView>();
                 services.AddTransient<OnboardingViewModel>();
                 services.AddTransient<OnboardingView>();
+                services.AddTransient<IUsbService, UsbService>();
             }
 
             ConfigurePlatformServices.Invoke(services);

src/Baballonia/Baballonia.csproj

@@ -65,6 +65,7 @@
         <PackageReference Include="SoundFlow" Version="1.2.1" />
         <PackageReference Include="System.IO.Ports" Version="9.0.8" />
         <PackageReference Include="System.Management" Version="9.0.8" />
+        <PackageReference Include="Usb.Events" Version="11.1.1.1" />
         <PackageReference Include="VRChat.OSCQuery" Version="0.0.7" />
     </ItemGroup>
 

src/Baballonia/Contracts/IUsbService.cs

@@ -0,0 +1,9 @@
+using System;
+
+namespace Baballonia.Contracts;
+
+public interface IUsbService
+{
+    public event Action<string> OnUsbConnected;
+    public event Action<string> OnUsbDisconnected;
+}

src/Baballonia/Services/USBService.cs

@@ -0,0 +1,68 @@
+using System;
+using Baballonia.Contracts;
+using Usb.Events;
+
+namespace Baballonia.Services;
+
+public sealed class UsbService : IUsbService
+{
+    public event Action<string>? OnUsbConnected;
+    public event Action<string>? OnUsbDisconnected;
+
+    private static readonly IUsbEventWatcher UsbEventWatcher = new UsbEventWatcher(
+        startImmediately: true,
+        addAlreadyPresentDevicesToList: true,
+        usePnPEntity: false,
+        includeTTY: true);
+
+    private readonly TimeSpan _eventThrottleInterval = TimeSpan.FromSeconds(1);
+    private DateTime _lastEventTime = DateTime.MinValue;
+    private readonly object _eventLock = new();
+
+    public UsbService()
+    {
+        UsbEventWatcher.UsbDeviceAdded += UsbDeviceAdded;
+        UsbEventWatcher.UsbDeviceRemoved += UsbDeviceRemoved;
+    }
+
+    private void UsbDeviceAdded(object? sender, UsbDevice? device)
+    {
+        if (device == null)
+            return;
+
+        RateLimitedAction(device.DeviceName, OnUsbConnected);
+    }
+
+    private void UsbDeviceRemoved(object? sender, UsbDevice? device)
+    {
+        if (device == null)
+            return;
+
+        RateLimitedAction(device.DeviceName, OnUsbDisconnected);
+    }
+
+    private void RateLimitedAction(string deviceName, Action<string>? action)
+    {
+        lock (_eventLock)
+        {
+            var now = DateTime.UtcNow;
+            var timeSinceLastEvent = now - _lastEventTime;
+
+            if (timeSinceLastEvent < _eventThrottleInterval)
+            {
+                return;
+            }
+
+            _lastEventTime = now;
+        }
+
+        action?.Invoke(deviceName);
+    }
+
+    ~UsbService()
+    {
+        UsbEventWatcher.UsbDeviceAdded -= UsbDeviceAdded;
+        UsbEventWatcher.UsbDeviceRemoved -= UsbDeviceRemoved;
+        UsbEventWatcher.Dispose();
+    }
+}

src/Baballonia/Views/HomePageView.axaml.cs

@@ -6,11 +6,14 @@
 using Avalonia.Interactivity;
 using Avalonia.Media;
 using Avalonia.Platform.Storage;
+using Avalonia.Threading;
 using Avalonia.VisualTree;
 using Baballonia.Assets;
 using Baballonia.Contracts;
 using Baballonia.Helpers;
+using Baballonia.Services;
 using Baballonia.ViewModels.SplitViewPane;
+using CommunityToolkit.Mvvm.DependencyInjection;
 
 namespace Baballonia.Views;
 
@@ -26,6 +29,7 @@ public partial class HomePageView : UserControl
 
     private readonly IDeviceEnumerator _deviceEnumerator;
     private readonly ILocalSettingsService _localSettings;
+    private IUsbService _usbService;
 
     public HomePageView(IDeviceEnumerator deviceEnumerator, ILocalSettingsService localSettings)
     {
@@ -116,6 +120,17 @@ public HomePageView(IDeviceEnumerator deviceEnumerator, ILocalSettingsService lo
 
             vm.SelectedCalibrationTextBlock = this.Find<TextBlock>("SelectedCalibrationTextBlockColor")!;
             vm.SelectedCalibrationTextBlock.Text = Assets.Resources.Home_Eye_Calibration;
+
+            if (!Utils.IsSupportedDesktopOS) return;
+            _usbService = Ioc.Default.GetService<IUsbService>()!;
+            _usbService.OnUsbConnected += RefreshDevices;
+            _usbService.OnUsbDisconnected += RefreshDevices;
+        };
+        Unloaded += (_, _) =>
+        {
+            if (_usbService != null) return;
+            _usbService!.OnUsbConnected -= RefreshDevices;
+            _usbService!.OnUsbDisconnected -= RefreshDevices;
         };
     }
 
@@ -199,6 +214,12 @@ private void RefreshConnectedFaceDevices(object? sender, CancelEventArgs e)
         //vm.FaceCamera.UpdateCameraDropDown();
     }
 
+    private async void RefreshDevices(string deviceName)
+    {
+        await Dispatcher.UIThread.InvokeAsync(
+            () => RefreshDevices(null, null!));
+    }
+
     private async void RefreshDevices(object? sender, RoutedEventArgs e)
     {
         if (DataContext is not HomePageViewModel vm) return;