Fix camera view app crashes when switching camera on windows (#2907)

* Update Sample App + Fix Bug

* Add `ICameraProvider.AvailableCamerasChanged`

* Update MockCameraProvider

* Add Unit Tests

* Add Unit Tests

Author: TheCodeTraveler

samples/CommunityToolkit.Maui.Sample/Pages/Views/CameraView/CameraViewPage.xaml

@@ -61,6 +61,12 @@
 
             <FlexLayout Margin="5" JustifyContent="SpaceBetween" Wrap="Wrap">
 
+                <Picker 
+                    Title="Cameras" 
+                    ItemsSource="{Binding Cameras}"
+                    ItemDisplayBinding="{Binding Name}" 
+                    SelectedItem="{Binding SelectedCamera}" />
+
                 <Picker 
                     Title="Flash"
                     IsVisible="{Binding Path=SelectedCamera.IsFlashSupported, FallbackValue=false}"

samples/CommunityToolkit.Maui.Sample/ViewModels/Views/CameraView/CameraViewViewModel.cs

@@ -66,13 +66,36 @@ partial void OnSelectedResolutionChanged(Size value)
 		UpdateResolutionText();
 	}
 
+	partial void OnSelectedCameraChanged(CameraInfo? oldValue, CameraInfo? newValue)
+	{
+		UpdateCameraInfoText();
+	}
+
+	void UpdateCameraInfoText()
+	{
+		if (SelectedCamera is null)
+		{
+			CameraNameText = string.Empty;
+			ZoomRangeText = string.Empty;
+		}
+		else
+		{
+			CameraNameText = $"{SelectedCamera.Name}";
+			ZoomRangeText = $"Min Zoom: {SelectedCamera.MinimumZoomFactor}, Max Zoom: {SelectedCamera.MaximumZoomFactor}";
+			UpdateFlashModeText();
+		}
+	}
+
 	void UpdateFlashModeText()
 	{
 		if (SelectedCamera is null)
 		{
-			return;
+			FlashModeText = string.Empty;
+		}
+		else
+		{
+			FlashModeText = $"{(SelectedCamera.IsFlashSupported ? $"Flash mode: {FlashMode}" : "Flash not supported")}";
 		}
-		FlashModeText = $"{(SelectedCamera.IsFlashSupported ? $"Flash mode: {FlashMode}" : "Flash not supported")}";
 	}
 
 	void UpdateCurrentZoomText()

src/CommunityToolkit.Maui.Camera/Providers/CameraProvider.windows.cs

@@ -14,12 +14,12 @@ public async partial ValueTask RefreshAvailableCameras(CancellationToken token)
 		var deviceInfoCollection = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture).AsTask(token);
 		var mediaFrameSourceGroup = await MediaFrameSourceGroup.FindAllAsync().AsTask(token);
 		var videoCaptureSourceGroup = mediaFrameSourceGroup.Where(sourceGroup => deviceInfoCollection.Any(deviceInfo => deviceInfo.Id == sourceGroup.Id)).ToList();
-		var mediaCapture = new MediaCapture();
 
 		var availableCameras = new List<CameraInfo>();
 
 		foreach (var sourceGroup in videoCaptureSourceGroup)
 		{
+			using var mediaCapture = new MediaCapture();
 			await mediaCapture.InitializeCameraForCameraView(sourceGroup.Id, token);
 
 			CameraPosition position = CameraPosition.Unknown;