feat(textbox): start skia-based TextBox implementation

src/Uno.UI/FeatureConfiguration.cs

@@ -503,6 +503,12 @@ public static class TextBox
 			/// <remarks>This feature is used to avoid screenshot comparisons false positives</remarks>
 			public static bool HideCaret { get; set; }
 
+			/// <summary>
+			/// Determines if a native (Gtk/Wpf) TextBox overlay should be used on the skia targets instead of the
+			/// Uno skia-based TextBox implementation.
+			/// </summary>
+			public static bool UseOverlayOnSkia { get; set; } = false;
+
 #if __ANDROID__
 			/// <summary>
 			/// The legacy <see cref="Windows.UI.Xaml.Controls.TextBox.InputScope"/> prevents invalid input on hardware keyboard.

src/Uno.UI/UI/Xaml/Controls/TextBlock/TextBlock.skia.cs

@@ -104,7 +104,7 @@ internal override void OnPropertyChanged2(DependencyPropertyChangedEventArgs arg
 		private Hyperlink? FindHyperlinkAt(Point point)
 		{
 			var padding = Padding;
-			var span = Inlines.GetRenderSegmentSpanAt(point - new Point(padding.Left, padding.Top), false);
+			var span = Inlines.GetRenderSegmentSpanAt(point - new Point(padding.Left, padding.Top), false)?.span;
 
 			if (span == null)
 			{

src/Uno.UI/UI/Xaml/Controls/TextBox/TextBox.cs

@@ -22,6 +22,7 @@
 using Uno.UI.Helpers;
 using Uno.UI.Xaml.Media;
 using Windows.ApplicationModel.DataTransfer;
+using Uno.UI;
 
 #if HAS_UNO_WINUI
 using Microsoft.UI.Input;
@@ -116,6 +117,10 @@ public TextBox()
 
 			DefaultStyleKey = typeof(TextBox);
 			SizeChanged += OnSizeChanged;
+
+#if __SKIA__
+			_timer.Tick += TimerOnTick;
+#endif
 		}
 
 		private protected override void OnLoaded()
@@ -150,10 +155,15 @@ private protected override void OnLoaded()
 				// When support for TemplateBinding for attached DPs was added, TextBox broke (test: TextBox_AutoGrow_Vertically_Wrapping_Test) because of
 				// change in the values of these properties. The following code serves as a workaround to set the values to what they used to be
 				// before the support for TemplateBinding for attached DPs.
-				scrollViewer.HorizontalScrollMode = ScrollMode.Enabled; // The template sets this to Auto
-				scrollViewer.VerticalScrollMode = ScrollMode.Enabled; // The template sets this to Auto
-				scrollViewer.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled; // The template sets this to Hidden
-				scrollViewer.VerticalScrollBarVisibility = ScrollBarVisibility.Auto; // The template sets this to Hidden
+#if __SKIA__
+				if (FeatureConfiguration.TextBox.UseOverlayOnSkia)
+#endif
+				{
+					scrollViewer.HorizontalScrollMode = ScrollMode.Enabled; // The template sets this to Auto
+					scrollViewer.VerticalScrollMode = ScrollMode.Enabled; // The template sets this to Auto
+					scrollViewer.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled; // The template sets this to Hidden
+					scrollViewer.VerticalScrollBarVisibility = ScrollBarVisibility.Auto; // The template sets this to Hidden
+				}
 #endif
 			}
 		}
@@ -896,6 +906,14 @@ private void OnFocusStateChanged(FocusState oldValue, FocusState newValue, bool
 			}
 
 			UpdateVisualState();
+#if __SKIA__
+			if (!FeatureConfiguration.TextBox.UseOverlayOnSkia)
+			{
+				// this is needed so that we UpdateScrolling after the button appears.
+				UpdateLayout();
+				UpdateScrolling();
+			}
+#endif
 		}
 
 		partial void OnFocusStateChangedPartial(FocusState focusState);
@@ -946,8 +964,12 @@ protected override void OnPointerPressed(PointerRoutedEventArgs args)
 			}
 
 			args.Handled = true;
+
+			OnPointerPressedNative(args);
 		}
 
+		partial void OnPointerPressedNative(PointerRoutedEventArgs e);
+
 		/// <inheritdoc />
 		protected override void OnPointerReleased(PointerRoutedEventArgs args)
 		{
@@ -971,7 +993,16 @@ protected override void OnTapped(TappedRoutedEventArgs e)
 		partial void OnTappedPartial();
 
 		/// <inheritdoc />
-		protected override void OnKeyDown(KeyRoutedEventArgs args)
+		protected override void OnKeyDown(KeyRoutedEventArgs args) => OnKeyDownPartial(args);
+
+		private partial void OnKeyDownPartial(KeyRoutedEventArgs args);
+
+#if !__SKIA__
+		private partial void OnKeyDownPartial(KeyRoutedEventArgs args) => OnKeyDownInternal(args);
+
+#endif
+
+		private void OnKeyDownInternal(KeyRoutedEventArgs args)
 		{
 			base.OnKeyDown(args);