Add support for MAUI embedding

src/Controls/samples/Controls.Sample.Embedding/Platforms/Android/FirstFragment.cs

@@ -11,6 +11,10 @@ namespace Maui.Controls.Sample.Droid;
 [Register("com.microsoft.maui.sample.emdedding." + nameof(FirstFragment))]
 public class FirstFragment : Fragment
 {
+	EmbeddingScenarios.IScenario? _scenario;
+	MyMauiContent? _mauiView;
+	Android.Views.View? _nativeView;
+
 	public override View? OnCreateView(LayoutInflater inflater, ViewGroup? container, Bundle? savedInstanceState) =>
 		inflater.Inflate(Resource.Layout.fragment_first, container, false);
 
@@ -26,14 +30,43 @@ public override void OnViewCreated(View view, Bundle? savedInstanceState)
 
 		var button3 = view.FindViewById<Button>(Resource.Id.button3)!;
 		button3.Click += OnMagicClicked;
+
+		// Uncomment the scenario to test:
+		//_scenario = new EmbeddingScenarios.Scenario1_Basic();
+		//_scenario = new EmbeddingScenarios.Scenario2_Scoped();
+		_scenario = new EmbeddingScenarios.Scenario3_Correct();
+
+		// Create the view and (maybe) the window
+		(_mauiView, _nativeView) = _scenario!.Embed(Activity!);
+
+		// Add the new view to the UI
+		var rootLayout = view.FindViewById<LinearLayout>(Resource.Id.layout_first)!;
+		rootLayout.AddView(_nativeView, 1, new LinearLayout.LayoutParams(MatchParent, WrapContent));
 	}
 
 	public override void OnDestroyView()
 	{
 		base.OnDestroyView();
+
+		// Remove the view from the UI
+		var rootLayout = View!.FindViewById<LinearLayout>(Resource.Id.layout_first)!;
+		rootLayout.RemoveView(_nativeView);
+
+		// If we used a window, then clean that up
+		if (_mauiView?.Window is IWindow window)
+			window.Destroying();
+
+		base.OnStop();
 	}
 
-	private void OnMagicClicked(object? sender, EventArgs e)
+	private async void OnMagicClicked(object? sender, EventArgs e)
 	{
+		if (_mauiView?.DotNetBot is not Image bot)
+			return;
+
+		await bot.RotateTo(360, 1000);
+		bot.Rotation = 0;
+
+		bot.HeightRequest = 90;
 	}
 }

src/Controls/samples/Controls.Sample.Embedding/Platforms/Android/SettingsFragment.cs

@@ -11,6 +11,10 @@ namespace Maui.Controls.Sample.Droid;
 [Register("com.microsoft.maui.sample.emdedding." + nameof(SettingsFragment))]
 public class SettingsFragment : Fragment
 {
+	EmbeddingScenarios.IScenario? _scenario;
+	MyMauiContent? _mauiView;
+	Android.Views.View? _nativeView;
+
 	public override View? OnCreateView(LayoutInflater inflater, ViewGroup? container, Bundle? savedInstanceState) =>
 		inflater.Inflate(Resource.Layout.fragment_settings, container, false);
 
@@ -26,14 +30,43 @@ public override void OnViewCreated(View view, Bundle? savedInstanceState)
 
 		var button3 = view.FindViewById<Button>(Resource.Id.button3)!;
 		button3.Click += OnMagicClicked;
+
+		// Uncomment the scenario to test:
+		//_scenario = new EmbeddingScenarios.Scenario1_Basic();
+		//_scenario = new EmbeddingScenarios.Scenario2_Scoped();
+		_scenario = new EmbeddingScenarios.Scenario3_Correct();
+
+		// Create the view and (maybe) the window
+		(_mauiView, _nativeView) = _scenario!.Embed(Activity!);
+
+		// Add the new view to the UI
+		var rootLayout = view.FindViewById<LinearLayout>(Resource.Id.layout_settings)!;
+		rootLayout.AddView(_nativeView, 1, new LinearLayout.LayoutParams(MatchParent, WrapContent));
 	}
 
 	public override void OnDestroyView()
 	{
 		base.OnDestroyView();
+
+		// Remove the view from the UI
+		var rootLayout = View!.FindViewById<LinearLayout>(Resource.Id.layout_settings)!;
+		rootLayout.RemoveView(_nativeView);
+
+		// If we used a window, then clean that up
+		if (_mauiView?.Window is IWindow window)
+			window.Destroying();
+
+		base.OnStop();
 	}
 
-	private void OnMagicClicked(object? sender, EventArgs e)
+	private async void OnMagicClicked(object? sender, EventArgs e)
 	{
+		if (_mauiView?.DotNetBot is not Image bot)
+			return;
+
+		await bot.RotateTo(360, 1000);
+		bot.Rotation = 0;
+
+		bot.HeightRequest = 90;
 	}
 }

src/Controls/samples/Controls.Sample.Embedding/Platforms/MacCatalyst/MainViewController.cs

@@ -2,6 +2,10 @@
 
 public class MainViewController : UIViewController
 {
+	EmbeddingScenarios.IScenario? _scenario;
+	MyMauiContent? _mauiView;
+	UIView? _nativeView;
+
 	public override void ViewDidLoad()
 	{
 		base.ViewDidLoad();
@@ -34,7 +38,16 @@ public override void ViewDidLoad()
 		firstButton.SetTitle("UIKit Button Above MAUI", UIControlState.Normal);
 		stackView.AddArrangedSubview(firstButton);
 
-		// TODO: The MAUI content will go here.
+		// Uncomment the scenario to test:
+		//_scenario = new EmbeddingScenarios.Scenario1_Basic();
+		//_scenario = new EmbeddingScenarios.Scenario2_Scoped();
+		_scenario = new EmbeddingScenarios.Scenario3_Correct();
+
+		// create the view and (maybe) the window
+		(_mauiView, _nativeView) = _scenario.Embed(ParentViewController!.View!.Window);
+
+		// add the new view to the UI
+		stackView.AddArrangedSubview(new ContainerView(_nativeView));
 
 		// Create UIKit button
 		var secondButton = new UIButton(UIButtonType.System);
@@ -44,11 +57,23 @@ public override void ViewDidLoad()
 		// Create UIKit button
 		var thirdButton = new UIButton(UIButtonType.System);
 		thirdButton.SetTitle("UIKit Button Magic", UIControlState.Normal);
+		thirdButton.TouchUpInside += OnMagicClicked;
 		stackView.AddArrangedSubview(thirdButton);
 
 		AddNavBarButtons();
 	}
 
+	private async void OnMagicClicked(object? sender, EventArgs e)
+	{
+		if (_mauiView?.DotNetBot is not Image bot)
+			return;
+
+		await bot.RotateTo(360, 1000);
+		bot.Rotation = 0;
+
+		bot.HeightRequest = 90;
+	}
+
 	private void AddNavBarButtons()
 	{
 		var addNewWindowButton = new UIBarButtonItem(
@@ -87,4 +112,33 @@ private void RequestSession(string? activityType = null)
 			});
 		}
 	}
+
+	// UIStackView uses IntrinsicContentSize instead of SizeThatFits
+	// so we need to create a container view to wrap the Maui view and
+	// redirect the IntrinsicContentSize to the Maui view's SizeThatFits.
+	class ContainerView : UIView
+	{
+		public ContainerView(UIView view)
+		{
+			AddSubview(view);
+		}
+
+		public override CGSize IntrinsicContentSize =>
+			SizeThatFits(new CGSize(nfloat.MaxValue, nfloat.MaxValue));
+
+		public override void LayoutSubviews()
+		{
+			if (Subviews?.FirstOrDefault() is {} view)
+				view.Frame = Bounds;
+		}
+
+		public override void SetNeedsLayout()
+		{
+			base.SetNeedsLayout();
+			InvalidateIntrinsicContentSize();
+		}
+
+		public override CGSize SizeThatFits(CGSize size) =>
+			Subviews?.FirstOrDefault()?.SizeThatFits(size) ?? CGSize.Empty;
+	}
 }

src/Controls/samples/Controls.Sample.Embedding/Platforms/Windows/MainWindow.xaml.cs

@@ -4,21 +4,54 @@ namespace Maui.Controls.Sample.WinUI;
 
 public sealed partial class MainWindow : Microsoft.UI.Xaml.Window
 {
+	EmbeddingScenarios.IScenario? _scenario;
+	MyMauiContent? _mauiView;
+	FrameworkElement? _nativeView;
+
 	public MainWindow()
 	{
 		InitializeComponent();
 	}
 
-	private void OnRootLayoutLoaded(object? sender, RoutedEventArgs e)
+	private async void OnRootLayoutLoaded(object? sender, RoutedEventArgs e)
 	{
+		// Sometimes Loaded fires twice...
+		if (_nativeView is not null)
+			return;
+
+		await Task.Yield();
+
+		// Uncomment the scenario to test:
+		//_scenario = new EmbeddingScenarios.Scenario1_Basic();
+		//_scenario = new EmbeddingScenarios.Scenario2_Scoped();
+		_scenario = new EmbeddingScenarios.Scenario3_Correct();
+
+		// create the view and (maybe) the window
+		(_mauiView, _nativeView) = _scenario.Embed(this);
+
+		// add the new view to the UI
+		RootLayout.Children.Insert(1, _nativeView);
 	}
 
 	private void OnWindowClosed(object? sender, WindowEventArgs args)
 	{
+		// Remove the view from the UI
+		RootLayout.Children.Remove(_nativeView);
+
+		// If we used a window, then clean that up
+		if (_mauiView?.Window is IWindow window)
+			window.Destroying();
 	}
 
-	private void OnMagicClicked(object? sender, RoutedEventArgs e)
+	private async void OnMagicClicked(object? sender, RoutedEventArgs e)
 	{
+		if (_mauiView?.DotNetBot is not Image bot)
+			return;
+
+		await bot.RotateTo(360, 1000);
+		bot.Rotation = 0;
+
+		bot.HeightRequest = 90;
 	}
 
 	private void OnNewWindowClicked(object? sender, RoutedEventArgs e)

src/Controls/samples/Controls.Sample.Embedding/Shared/EmbeddingScenarios.cs

@@ -0,0 +1,76 @@
+using Microsoft.Maui.Platform;
+using Microsoft.Maui.Controls.Embedding;
+
+#if ANDROID
+using PlatformView = Android.Views.View;
+using PlatformWindow = Android.App.Activity;
+#elif IOS || MACCATALYST
+using PlatformView = UIKit.UIView;
+using PlatformWindow = UIKit.UIWindow;
+#elif WINDOWS
+using PlatformView = Microsoft.UI.Xaml.FrameworkElement;
+using PlatformWindow = Microsoft.UI.Xaml.Window;
+#endif
+
+namespace Maui.Controls.Sample;
+
+class EmbeddingScenarios
+{
+	public interface IScenario
+	{
+		(MyMauiContent, PlatformView) Embed(PlatformWindow window);
+	}
+
+	public class Scenario1_Basic : IScenario
+	{
+		public (MyMauiContent, PlatformView) Embed(PlatformWindow window)
+		{
+			var mauiApp = MauiProgram.CreateMauiApp();
+#if ANDROID
+			var mauiContext = new MauiContext(mauiApp.Services, window);
+#else
+			var mauiContext = new MauiContext(mauiApp.Services);
+#endif
+			var mauiView = new MyMauiContent();
+			var nativeView = mauiView.ToPlatform(mauiContext);
+			return (mauiView, nativeView);
+		}
+	}
+
+	public class Scenario2_Scoped : IScenario
+	{
+		public (MyMauiContent, PlatformView) Embed(PlatformWindow window)
+		{
+			var mauiApp = MauiProgram.CreateMauiApp();
+			var mauiView = new MyMauiContent();
+			var nativeView = mauiView.ToPlatformEmbedded(mauiApp, window);
+			return (mauiView, nativeView);
+		}
+	}
+
+	public class Scenario3_Correct : IScenario
+	{
+		public static class MyEmbeddedMauiApp
+		{
+			static MauiApp? _shared;
+
+			public static MauiApp Shared => _shared ??= MauiProgram.CreateMauiApp();
+		}
+
+		PlatformWindow? _window;
+		IMauiContext? _windowContext;
+
+		public IMauiContext WindowContext =>
+			_windowContext ??= MyEmbeddedMauiApp.Shared.CreateEmbeddedWindowContext(_window ?? throw new InvalidOperationException());
+
+		public (MyMauiContent, PlatformView) Embed(PlatformWindow window)
+		{
+			_window ??= window;
+
+			var context = WindowContext;
+			var mauiView = new MyMauiContent();
+			var nativeView = mauiView.ToPlatformEmbedded(context);
+			return (mauiView, nativeView);
+		}
+	}
+}

src/Controls/samples/Controls.Sample.Embedding/Shared/MauiProgram.cs

@@ -1,4 +1,5 @@
 using Microsoft.Extensions.Logging;
+using Microsoft.Maui.Controls.Embedding;
 
 namespace Maui.Controls.Sample;
 
@@ -10,6 +11,7 @@ public static MauiApp CreateMauiApp()
 
 		builder
 			.UseMauiApp<App>()
+			.UseMauiEmbedding()
 			.ConfigureFonts(fonts =>
 			{
 				fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");