feat: Text input support in Uno Islands

src/SamplesApp/UnoIslands.Shared/MainPage.xaml

@@ -23,6 +23,7 @@
 			<TextBlock Text="{Binding Address}" />
 			<HyperlinkButton Content="{Binding Email}" NavigateUri="{Binding EmailUrl}" Grid.Row="1" />	
 			<TextBlock Text="{Binding Phone}" />
+			<TextBox Text="{Binding Note, Mode=TwoWay}" PlaceholderText="Enter a note..." />
 		</StackPanel>
 	</Grid>
 </Page>

src/SamplesApp/UnoIslands.WPF/PersonViewModel.cs

@@ -22,6 +22,8 @@ public class PersonViewModel
 
 		public string Country { get; set; }
 
+		public string Note { get; set; }
+
 		public string EmailUrl => "mailto:" + Email;
 
 		public string ImageUrl => $"https://www.gravatar.com/avatar/{Name.GetHashCode()}?s=128&d=identicon&r=PG";

src/Uno.UI.Runtime.Skia.Wpf/Extensions/UI/Xaml/Controls/TextBoxViewExtension.cs

@@ -9,6 +9,7 @@
 using Uno.UI.Xaml.Controls.Extensions;
 using Point = Windows.Foundation.Point;
 using WpfCanvas = System.Windows.Controls.Canvas;
+using Uno.UI.Runtime.Skia.Wpf.Hosting;
 
 namespace Uno.UI.Runtime.Skia.WPF.Extensions.UI.Xaml.Controls
 {
@@ -23,7 +24,16 @@ public TextBoxViewExtension(TextBoxView owner)
 			_owner = owner ?? throw new ArgumentNullException(nameof(owner));
 		}
 
-		private WpfCanvas? GetWindowTextInputLayer() => WpfHost.Current?.NativeOverlayLayer;
+		private WpfCanvas? GetWindowTextInputLayer()
+		{
+			if (_owner?.TextBox?.XamlRoot is not { } xamlRoot)
+			{
+				return null;
+			}
+
+			var host = XamlRootMap.GetHostForRoot(xamlRoot);
+			return host?.NativeOverlayLayer;
+		}
 
 		public void StartEntry()
 		{

src/Uno.UI.Runtime.Skia.Wpf/IWpfHost.cs

@@ -2,13 +2,16 @@
 
 using Windows.Devices.Input;
 using Windows.UI.Xaml;
+using WpfCanvas = System.Windows.Controls.Canvas;
 
 namespace Uno.UI.Runtime.Skia.Wpf
 {
 	internal interface IWpfHost
 	{
 		XamlRoot? XamlRoot { get; }
 
+		WpfCanvas? NativeOverlayLayer { get;}
+
 		void ReleasePointerCapture(PointerIdentifier pointer);
 
 		void SetPointerCapture(PointerIdentifier pointer);

src/Uno.UI.Runtime.Skia.Wpf/Islands/UnoXamlHost.cs

@@ -16,6 +16,7 @@ public partial class UnoXamlHost : UnoXamlHostBase
     {
 		public UnoXamlHost()
 		{
+			this.DefaultStyleKey = typeof(UnoXamlHost);
 			this.DataContextChanged += UnoXamlHost_DataContextChanged;
 			this.Loaded += OnLoaded;
 		}

src/Uno.UI.Runtime.Skia.Wpf/Islands/UnoXamlHost.host.cs

@@ -10,19 +10,21 @@
 using Windows.Graphics.Display;
 using WinUI = Windows.UI.Xaml;
 using WpfControl = global::System.Windows.Controls.Control;
+using WpfCanvas = global::System.Windows.Controls.Canvas;
 
 namespace Uno.UI.XamlHost.Skia.Wpf
 {
 	/// <summary>
 	/// UnoXamlHost control hosts UWP XAML content inside the Windows Presentation Foundation
 	/// </summary>
-	abstract partial class UnoXamlHostBase : WpfControl, WinUI.ISkiaHost, IWpfHost
+	partial class UnoXamlHostBase : WpfControl, WinUI.ISkiaHost, IWpfHost
 	{
 		private bool _designMode;
 		private DisplayInformation _displayInformation;
 		private bool _ignorePixelScaling;
 		private WriteableBitmap _bitmap;
 		private HostPointerHandler _hostPointerHandler;
+		private WpfCanvas _nativeOverlayLayer;
 
 		public bool IgnorePixelScaling
 		{
@@ -34,8 +36,6 @@ public bool IgnorePixelScaling
 			}
 		}
 
-		WinUI.XamlRoot? IWpfHost.XamlRoot => ChildInternal?.XamlRoot;
-
 		private void InitializeHost()
 		{
 			_designMode = DesignerProperties.GetIsInDesignMode(this);
@@ -123,5 +123,9 @@ protected override void OnRender(DrawingContext drawingContext)
 		void IWpfHost.ReleasePointerCapture(PointerIdentifier pointer) => CaptureMouse(); //TODO:MZ:This should capture the correct type of pointer (stylus/mouse/touch)
 
 		void IWpfHost.SetPointerCapture(PointerIdentifier pointer) => ReleaseMouseCapture();
+
+		WinUI.XamlRoot? IWpfHost.XamlRoot => ChildInternal?.XamlRoot;
+
+		System.Windows.Controls.Canvas? IWpfHost.NativeOverlayLayer => _nativeOverlayLayer;
 	}
 }

src/Uno.UI.Runtime.Skia.Wpf/Islands/UnoXamlHostBase.Focus.cs

@@ -8,12 +8,16 @@
 using WF = Windows.Foundation;
 using WUX = Windows.UI.Xaml;
 
+//TODO:MZ: We need to make sure that when the UnoXamlHost loses focus, focus is changed in the XamlRoot as well,
+//so that for active input fields the native overlay is closed and changes are committed to underlying TextBox text
+//before potential data binding changes.
+
 namespace Uno.UI.XamlHost.Skia.Wpf
 {
     /// <summary>
     /// Focus and Keyboard handling for Focus integration with UWP XAML
     /// </summary>
-    public partial class UnoXamlHostBase
+    partial class UnoXamlHostBase
     {
         /// <summary>
         /// Dictionary that maps WPF (host framework) FocusNavigationDirection to UWP XAML XxamlSourceFocusNavigationReason

src/Uno.UI.Runtime.Skia.Wpf/Islands/UnoXamlHostBase.cs

@@ -5,15 +5,15 @@
 using System;
 using Uno.UI.Runtime.Skia.Wpf.Hosting;
 using Uno.UI.Skia.Platform;
-using Uno.UI.XamlHost;
+using Windows.UI.Xaml;
 using WUX = Windows.UI.Xaml;
 
 namespace Uno.UI.XamlHost.Skia.Wpf
 {
 	/// <summary>
 	/// UnoXamlHost control hosts UWP XAML content inside the Windows Presentation Foundation
 	/// </summary>
-	abstract partial class UnoXamlHostBase
+	public abstract partial class UnoXamlHostBase
 	{
 		/// <summary>
 		/// An instance of <seealso cref="IXamlMetadataContainer"/>. Required to
@@ -102,6 +102,14 @@ public UnoXamlHostBase(string typeName)
 			ChildInternal.SetWrapper(this);
 		}
 
+		// Uno specific: We need native overlay layer to show input for TextBoxes.
+		public override void OnApplyTemplate()
+		{
+			base.OnApplyTemplate();
+
+			_nativeOverlayLayer = GetTemplateChild("NativeOverlayLayer") as System.Windows.Controls.Canvas;
+		}
+
 		/// <summary>
 		/// Gets the current instance of <seealso cref="XamlApplication"/>
 		/// </summary>
@@ -184,6 +192,16 @@ protected WUX.UIElement ChildInternal
 				}
 
 				_childInternal = value;
+
+				if (_childInternal.XamlRoot is not null)
+				{
+					XamlRootMap.Register(_childInternal.XamlRoot, this);
+				}
+				else if (_childInternal is FrameworkElement element)
+				{
+					element.Loading += OnChildLoading;
+				}
+
 				SetContent();
 
 				var frameworkElement = ChildInternal as WUX.FrameworkElement;
@@ -205,6 +223,12 @@ protected WUX.UIElement ChildInternal
 			}
 		}
 
+		private void OnChildLoading(FrameworkElement sender, object args)
+		{
+			// Ensure the XamlRoot is registered early.
+			XamlRootMap.Register(sender.XamlRoot, this);
+		}
+
 		private void XamlRoot_InvalidateRender()
 		{
 			//InvalidateOverlays();

src/Uno.UI.Runtime.Skia.Wpf/Islands/WpfIslandsHost.cs

@@ -42,6 +42,7 @@
 
 namespace Uno.UI.Skia.Platform
 {
+	// TODO:MZ: Get rid of this class and use the one UnoXamlHost directly.
 	[TemplatePart(Name = NativeOverlayLayerPart, Type = typeof(WpfCanvas))]
 	public class WpfIslandsHost : WpfControl, WinUI.ISkiaHost, IWpfHost
 	{
@@ -191,6 +192,8 @@ public bool IgnorePixelScaling
 
 		WinUI.XamlRoot? IWpfHost.XamlRoot => throw new NotImplementedException();
 
+		WpfCanvas? IWpfHost.NativeOverlayLayer => NativeOverlayLayer;
+
 		protected override void OnRender(DrawingContext drawingContext)
 		{
 			base.OnRender(drawingContext);

src/Uno.UI.Runtime.Skia.Wpf/Themes/Generic.xaml

@@ -2,6 +2,7 @@
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:platform="clr-namespace:Uno.UI.Skia.Platform"
+	xmlns:xamlHostWpf="clr-namespace:Uno.UI.XamlHost.Skia.Wpf"
     xmlns:controls="clr-namespace:Uno.UI.Runtime.Skia.WPF.Controls">
 
     <Style TargetType="{x:Type platform:WpfHost}">
@@ -18,6 +19,20 @@
         </Setter>
     </Style>
 
+	<Style TargetType="{x:Type xamlHostWpf:UnoXamlHost}">
+		<Setter Property="Template">
+			<Setter.Value>
+				<ControlTemplate TargetType="{x:Type xamlHostWpf:UnoXamlHost}">
+					<Border Background="{TemplateBinding Background}"
+                            BorderBrush="{TemplateBinding BorderBrush}"
+                            BorderThickness="{TemplateBinding BorderThickness}">
+						<Canvas x:Name="NativeOverlayLayer" />
+					</Border>
+				</ControlTemplate>
+			</Setter.Value>
+		</Setter>
+	</Style>
+
 	<Style TargetType="{x:Type controls:WpfTextViewTextBox}">
 		<Setter Property="SnapsToDevicePixels" Value="True" />
 		<Setter Property="KeyboardNavigation.TabNavigation" Value="None" />

src/Uno.UI.Runtime.Skia.Wpf/WpfHost.cs

@@ -257,8 +257,6 @@ public bool IgnorePixelScaling
 			}
 		}
 
-		WinUI.XamlRoot? IWpfHost.XamlRoot => WinUI.Window.Current?.RootElement?.XamlRoot;
-
 		protected override void OnRender(DrawingContext drawingContext)
 		{
 			base.OnRender(drawingContext);
@@ -340,5 +338,10 @@ private void InvalidateOverlays()
 		void IWpfHost.ReleasePointerCapture(PointerIdentifier pointer) => CaptureMouse(); //TODO:MZ:This should capture the correct type of pointer (stylus/mouse/touch)
 
 		void IWpfHost.SetPointerCapture(PointerIdentifier pointer) => ReleaseMouseCapture();
+
+		//TODO:MZ: This will need to be adjusted when multi-window support is added.
+		WinUI.XamlRoot? IWpfHost.XamlRoot => WinUI.Window.Current?.RootElement?.XamlRoot;
+
+		WpfCanvas? IWpfHost.NativeOverlayLayer => NativeOverlayLayer;
 	}
 }