Initial attempt at platform based processing from the CameraView

samples/CommunityToolkit.Maui.Sample/AppShell.xaml.cs

@@ -118,6 +118,7 @@ public partial class AppShell : Shell
 		CreateViewModelMapping<AvatarViewShadowsPage, AvatarViewShadowsViewModel, ViewsGalleryPage, ViewsGalleryViewModel>(),
 		CreateViewModelMapping<AvatarViewShapesPage, AvatarViewShapesViewModel, ViewsGalleryPage, ViewsGalleryViewModel>(),
 		CreateViewModelMapping<AvatarViewSizesPage, AvatarViewSizesViewModel, ViewsGalleryPage, ViewsGalleryViewModel>(),
+		CreateViewModelMapping<BarcodeScanningPage, BarcodeScanningViewModel, ViewsGalleryPage, ViewsGalleryViewModel>(),
 		CreateViewModelMapping<BasicMapsPage, BasicMapsViewModel, ViewsGalleryPage, ViewsGalleryViewModel>(),
 		CreateViewModelMapping<CameraViewPage, CameraViewViewModel, ViewsGalleryPage, ViewsGalleryViewModel>(),
 		CreateViewModelMapping<DrawingViewPage, DrawingViewViewModel, ViewsGalleryPage, ViewsGalleryViewModel>(),

samples/CommunityToolkit.Maui.Sample/CommunityToolkit.Maui.Sample.csproj

@@ -89,6 +89,11 @@
     <ProjectReference Include="..\..\src\CommunityToolkit.Maui.Maps\CommunityToolkit.Maui.Maps.csproj" />
   </ItemGroup>
 
+  <ItemGroup Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'android'">
+    <!-- Required NuGet Packages -->
+    <PackageReference Include="Xamarin.Google.MLKit.BarcodeScanning" Version="117.3.0.3" />
+  </ItemGroup>
+
   <PropertyGroup Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)'))=='windows' and $(Configuration) == 'Release'">
     <RuntimeIdentifier>win-x64</RuntimeIdentifier>
   </PropertyGroup>

samples/CommunityToolkit.Maui.Sample/MauiProgram.cs

@@ -247,6 +247,7 @@ static void RegisterViewsAndViewModels(in IServiceCollection services)
 		services.AddTransientWithShellRoute<NavigationBarPage, NavigationBarAndroidViewModel>();
 
 		// Add Views Pages + ViewModels
+		services.AddTransientWithShellRoute<BarcodeScanningPage, BarcodeScanningViewModel>();
 		services.AddTransientWithShellRoute<BasicMapsPage, BasicMapsViewModel>();
 		services.AddTransientWithShellRoute<CameraViewPage, CameraViewViewModel>();
 		services.AddTransientWithShellRoute<DrawingViewPage, DrawingViewViewModel>();

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

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<pages:BasePage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+                xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+                xmlns:pages="clr-namespace:CommunityToolkit.Maui.Sample.Pages"
+                xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"
+                xmlns:viewModels="clr-namespace:CommunityToolkit.Maui.Sample.ViewModels.Views"
+                xmlns:sample="clr-namespace:CommunityToolkit.Maui.Sample"
+                Title="Barcode Scanning"
+                x:Class="CommunityToolkit.Maui.Sample.Pages.Views.BarcodeScanningPage"
+                x:TypeArguments="viewModels:BarcodeScanningViewModel"
+                x:DataType="viewModels:BarcodeScanningViewModel">
+
+    <Grid RowDefinitions="200,*,Auto,Auto" ColumnDefinitions="3*,*">
+        <toolkit:CameraView
+            x:Name="Camera"
+            Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="2" Grid.RowSpan="3">
+            <toolkit:CameraView.Scenarios>
+                <sample:PlatformBarcodeScanningScenario Command="{Binding CodeDetectedCommand}" />
+            </toolkit:CameraView.Scenarios>
+        </toolkit:CameraView>
+    </Grid>
+</pages:BasePage>

samples/CommunityToolkit.Maui.Sample/Pages/Views/CameraView/BarcodeScanningPage.xaml.cs

@@ -0,0 +1,19 @@
+using CommunityToolkit.Maui.Sample.ViewModels.Views;
+
+namespace CommunityToolkit.Maui.Sample.Pages.Views;
+
+public partial class BarcodeScanningPage : BasePage<BarcodeScanningViewModel>
+{
+	public BarcodeScanningPage(BarcodeScanningViewModel viewModel) : base(viewModel)
+	{
+		InitializeComponent();
+	}
+
+	protected override async void OnAppearing()
+	{
+		base.OnAppearing();
+
+		var cancellationTokenSource = new CancellationTokenSource(TimeSpan.FromSeconds(3));
+		await BindingContext.RefreshCamerasCommand.ExecuteAsync(cancellationTokenSource.Token);
+	}
+}

samples/CommunityToolkit.Maui.Sample/PlatformBarcodeScanningScenario.cs

@@ -0,0 +1,25 @@
+using System.Windows.Input;
+using CommunityToolkit.Maui.Core;
+
+namespace CommunityToolkit.Maui.Sample;
+
+/// <summary>
+/// 
+/// </summary>
+public partial class PlatformBarcodeScanningScenario : PlatformCameraScenario
+{
+	/// <summary>
+	/// Backing BindableProperty for the <see cref="Command"/> property.
+	/// </summary>
+	public static readonly BindableProperty CommandProperty =
+		BindableProperty.Create(nameof(Command), typeof(ICommand), typeof(PlatformBarcodeScanningScenario));
+
+	/// <summary>
+	/// The Command that should be executed when a barcode is detected.
+	/// </summary>
+	public ICommand? Command
+	{
+		get => (ICommand?)GetValue(CommandProperty);
+		set => SetValue(CommandProperty, value);
+	}
+}

samples/CommunityToolkit.Maui.Sample/Platforms/Android/BarcodeAnalyzer.cs

@@ -0,0 +1,93 @@
+using System.Diagnostics;
+using System.Windows.Input;
+using Android.Gms.Tasks;
+using Android.Runtime;
+using AndroidX.Camera.Core;
+using Xamarin.Google.MLKit.Vision.Barcode.Common;
+using Xamarin.Google.MLKit.Vision.BarCode;
+using Xamarin.Google.MLKit.Vision.Common;
+
+using Scanner = Xamarin.Google.MLKit.Vision.BarCode.BarcodeScanning;
+
+namespace CommunityToolkit.Maui.Sample;
+
+public class BarcodeAnalyzer : Java.Lang.Object, ImageAnalysis.IAnalyzer
+{
+	readonly ICommand command;
+	IBarcodeScanner? barcodeScanner;
+	readonly Lock resultsLock = new();
+
+	public BarcodeAnalyzer(ICommand command)
+	{
+		this.command = command;
+	}
+
+	internal void UpdateSymbologies()
+	{
+		barcodeScanner?.Dispose();
+		barcodeScanner = Scanner.GetClient(new BarcodeScannerOptions.Builder()
+			.SetBarcodeFormats(Barcode.FormatAllFormats)
+			.Build());
+	}
+
+	public void Analyze(IImageProxy proxy)
+	{
+		try
+		{
+			ArgumentNullException.ThrowIfNull(proxy?.Image);
+			ArgumentNullException.ThrowIfNull(barcodeScanner);
+
+			using var inputImage = InputImage.FromMediaImage(proxy.Image, 0);
+			using var task  = barcodeScanner.Process(inputImage);
+			var result = TasksClass.Await(task);
+
+			lock (resultsLock)
+			{
+				ProcessResults(result);
+			}
+
+			result?.Dispose();
+		}
+		catch (Exception ex)
+		{
+			Debug.WriteLine(ex);
+		}
+		finally
+		{
+			try
+			{
+				proxy?.Close();
+			}
+			catch (Exception ex)
+			{
+				Debug.WriteLine(ex);
+			}
+		}
+	}
+
+	void ProcessResults(Java.Lang.Object? result)
+	{
+		if (result is not JavaList javaList)
+		{
+			return;
+		}
+
+		foreach (Barcode barcode in javaList)
+		{
+			if (barcode is null)
+			{
+				continue;
+			}
+
+			if (string.IsNullOrEmpty(barcode.DisplayValue) && string.IsNullOrEmpty(barcode.RawValue))
+			{
+				continue;
+			}
+
+			if (this.command?.CanExecute(barcode.RawValue) is true)
+			{
+				this.command.Execute(barcode.RawValue);
+			}
+		}
+	}
+}

samples/CommunityToolkit.Maui.Sample/Platforms/Android/PlatformBarcodeScanningScenario.cs

@@ -0,0 +1,30 @@
+using AndroidX.Camera.Core;
+
+namespace CommunityToolkit.Maui.Sample;
+
+public partial class PlatformBarcodeScanningScenario
+{
+	readonly Lazy<UseCase>? lazyUseCase = null;
+
+	public PlatformBarcodeScanningScenario()
+	{
+		lazyUseCase = new Lazy<UseCase>(() =>
+		{
+			var imageAnalysis =
+				new ImageAnalysis.Builder()
+					.SetBackpressureStrategy(ImageAnalysis.StrategyKeepOnlyLatest)
+					.Build();
+
+			if (imageAnalysis.BackgroundExecutor is null)
+			{
+				throw new InvalidOperationException("Background executor must be set before use case.");
+			}
+
+			imageAnalysis.SetAnalyzer(imageAnalysis.BackgroundExecutor, new BarcodeAnalyzer(Command!));
+
+			return imageAnalysis;
+		});
+	}
+
+	public override UseCase UseCase => lazyUseCase?.Value!;
+}

samples/CommunityToolkit.Maui.Sample/Platforms/MacCatalyst/PlatformBarcodeScanningScenario.cs

@@ -0,0 +1,60 @@
+using System.Windows.Input;
+using AVFoundation;
+using CoreFoundation;
+
+namespace CommunityToolkit.Maui.Sample;
+
+/// <summary>
+/// Apple based implementation
+/// </summary>
+public partial class PlatformBarcodeScanningScenario
+{
+	readonly Lazy<AVCaptureMetadataOutput> lazyOutput;
+
+	public PlatformBarcodeScanningScenario()
+	{
+		lazyOutput = new Lazy<AVCaptureMetadataOutput>(() =>
+		{
+			var output = new AVCaptureMetadataOutput();
+
+			output.SetDelegate(new BarcodeDetectionDelegate(Command), DispatchQueue.MainQueue);
+			output.MetadataObjectTypes =
+				AVMetadataObjectType.QRCode | AVMetadataObjectType.EAN13Code;
+
+			return output;
+		});
+	}
+
+	public override AVCaptureOutput Output => lazyOutput.Value;
+}
+
+sealed class BarcodeDetectionDelegate : AVCaptureMetadataOutputObjectsDelegate
+{
+	readonly ICommand? command;
+
+	public BarcodeDetectionDelegate(ICommand? command)
+	{
+		this.command = command;
+	}
+
+	public override void DidOutputMetadataObjects(
+		AVCaptureMetadataOutput captureOutput,
+		AVMetadataObject[] metadataObjects,
+		AVCaptureConnection connection)
+	{
+		foreach (var metadataObject in metadataObjects)
+		{
+			if (metadataObject is AVMetadataMachineReadableCodeObject readableObject)
+			{
+				var code = readableObject.StringValue;
+
+				Console.WriteLine($"Metadata object {code} at {string.Join(",", readableObject.Corners?? [])}");
+
+				if (this.command?.CanExecute(readableObject.StringValue) is true)
+				{
+					this.command.Execute(readableObject.StringValue);
+				}
+			}
+		}
+	}
+}

samples/CommunityToolkit.Maui.Sample/Platforms/PlatformBarcodeScanningScenario.cs

@@ -0,0 +1,12 @@
+using System.Windows.Input;
+using CommunityToolkit.Maui.Core;
+
+namespace CommunityToolkit.Maui.Sample;
+
+/// <summary>
+/// 
+/// </summary>
+public partial class PlatformBarcodeScanningScenario : PlatformCameraScenario
+{
+	public ICommand? Command { get; set; }
+}

samples/CommunityToolkit.Maui.Sample/Platforms/iOS/PlatformBarcodeScanningScenario.cs

@@ -0,0 +1,60 @@
+using System.Windows.Input;
+using AVFoundation;
+using CoreFoundation;
+
+namespace CommunityToolkit.Maui.Sample;
+
+/// <summary>
+/// Apple based implementation
+/// </summary>
+public partial class PlatformBarcodeScanningScenario
+{
+	readonly Lazy<AVCaptureMetadataOutput> lazyOutput;
+
+	public PlatformBarcodeScanningScenario()
+	{
+		lazyOutput = new Lazy<AVCaptureMetadataOutput>(() =>
+		{
+			var output = new AVCaptureMetadataOutput();
+
+			output.SetDelegate(new BarcodeDetectionDelegate(Command), DispatchQueue.MainQueue);
+			output.MetadataObjectTypes =
+				AVMetadataObjectType.QRCode | AVMetadataObjectType.EAN13Code;
+
+			return output;
+		});
+	}
+
+	public override AVCaptureOutput Output => lazyOutput.Value;
+}
+
+sealed class BarcodeDetectionDelegate : AVCaptureMetadataOutputObjectsDelegate
+{
+	readonly ICommand? command;
+
+	public BarcodeDetectionDelegate(ICommand? command)
+	{
+		this.command = command;
+	}
+
+	public override void DidOutputMetadataObjects(
+		AVCaptureMetadataOutput captureOutput,
+		AVMetadataObject[] metadataObjects,
+		AVCaptureConnection connection)
+	{
+		foreach (var metadataObject in metadataObjects)
+		{
+			if (metadataObject is AVMetadataMachineReadableCodeObject readableObject)
+			{
+				var code = readableObject.StringValue;
+
+				Console.WriteLine($"Metadata object {code} at {string.Join(",", readableObject.Corners?? [])}");
+
+				if (this.command?.CanExecute(readableObject.StringValue) is true)
+				{
+					this.command.Execute(readableObject.StringValue);
+				}
+			}
+		}
+	}
+}

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

@@ -0,0 +1,22 @@
+using CommunityToolkit.Maui.Core;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+
+namespace CommunityToolkit.Maui.Sample.ViewModels.Views;
+
+public partial class BarcodeScanningViewModel(ICameraProvider cameraProvider) : BaseViewModel
+{
+	readonly ICameraProvider cameraProvider = cameraProvider;
+
+	[ObservableProperty]
+	public partial string DetectedCode { get; set; }
+
+	[RelayCommand]
+	void OnCodeDetected(string code)
+	{
+		DetectedCode = code;
+	}
+
+	[RelayCommand]
+	async Task RefreshCameras(CancellationToken token) => await cameraProvider.RefreshAvailableCameras(token);
+}

samples/CommunityToolkit.Maui.Sample/ViewModels/Views/ViewsGalleryViewModel.cs

@@ -15,6 +15,7 @@ public sealed partial class ViewsGalleryViewModel() : BaseGalleryViewModel(
 	SectionModel.Create<AvatarViewShadowsViewModel>("AvatarView Shadows Page", Colors.Red, "A page demonstrating AvatarViews with various shadow options."),
 	SectionModel.Create<AvatarViewShapesViewModel>("AvatarView Shapes Page", Colors.Red, "A page demonstrating AvatarViews with various shape options."),
 	SectionModel.Create<AvatarViewSizesViewModel>("AvatarView Sizes Page", Colors.Red, "A page demonstrating AvatarViews with various size options."),
+	SectionModel.Create<BarcodeScanningViewModel>("Barcode Page", Colors.Red, "Barcode scanning support using the CameraView."),
 	SectionModel.Create<CameraViewViewModel>("CameraView Page", Colors.Red, "CameraView is a view for displaying camera output."),
 	SectionModel.Create<DrawingViewViewModel>("DrawingView", Colors.Red, "DrawingView provides a canvas for users to \"paint\" on the screen. The drawing can also be captured and displayed as an Image."),
 	SectionModel.Create<ExpanderViewModel>("Expander Page", Colors.Red, "Expander allows collapse and expand content."),