feat(focus): Raise Control.GotFocus asynchronously

Bring focus handling closer into line with what UWP does, including ensuring that Control.GotFocus and Control.LostFocus are raised asynchronously, and that calling Focus() on a Control with IsTabStop=false recursively checks children to find one that can take the focus.

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Input/Given_FocusManager.cs

@@ -0,0 +1,159 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Private.Infrastructure;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Input;
+
+namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Input
+{
+	[TestClass]
+	public class Given_FocusManager
+	{
+		[TestMethod]
+		[RunsOnUIThread]
+		public async Task GotLostFocus()
+		{
+			try
+			{
+				var panel = new StackPanel();
+				var wasEventRaised = false;
+
+				var receivedGotFocus = new bool[4];
+				var receivedLostFocus = new bool[4];
+
+				var buttons = new Button[4];
+				for (int i = 0; i < 4; i++)
+				{
+					var button = new Button
+					{
+						Content = $"Button {i}",
+						Name = $"Button{i}"
+					};
+
+					panel.Children.Add(button);
+					buttons[i] = button;
+				}
+
+				TestServices.WindowHelper.WindowContent = panel;
+
+				await TestServices.WindowHelper.WaitForIdle();
+
+				const int tries = 10;
+				var initialSuccess = false;
+				for (int i = 0; i < tries; i++)
+				{
+					initialSuccess = buttons[0].Focus(FocusState.Programmatic);
+					if (initialSuccess)
+					{
+						break;
+					}
+					//await TestServices.WindowHelper.WaitForIdle(); //
+					await Task.Delay(50); //
+				}
+
+				Assert.IsTrue(initialSuccess);
+				AssertHasFocus(buttons[0]);
+				await TestServices.WindowHelper.WaitForIdle();
+
+				AssertHasFocus(buttons[0]);
+
+				for (int i = 0; i < 4; i++)
+				{
+					var inner = i;
+					buttons[i].GotFocus += (o, e) =>
+					{
+						receivedGotFocus[inner] = true;
+						wasEventRaised = true;
+						Assert.IsNotNull(FocusManager.GetFocusedElement());
+					};
+
+					buttons[i].LostFocus += (o, e) =>
+					{
+						receivedLostFocus[inner] = true;
+						wasEventRaised = true;
+						Assert.IsNotNull(FocusManager.GetFocusedElement());
+					};
+				}
+
+				FocusManager.GotFocus += (o, e) =>
+				{
+					Assert.IsNotNull(FocusManager.GetFocusedElement());
+					wasEventRaised = true;
+				};
+				FocusManager.LostFocus += (o, e) =>
+				{
+					Assert.IsNotNull(FocusManager.GetFocusedElement());
+					wasEventRaised = true;
+				};
+
+				buttons[1].Focus(FocusState.Programmatic);
+				buttons[3].Focus(FocusState.Programmatic);
+				buttons[2].Focus(FocusState.Programmatic);
+
+				AssertHasFocus(buttons[2]);
+				Assert.IsFalse(wasEventRaised);
+				await TestServices.WindowHelper.WaitForIdle();
+				AssertHasFocus(buttons[2]);
+				Assert.IsTrue(wasEventRaised);
+
+				Assert.IsFalse(receivedGotFocus[0]);
+				Assert.IsTrue(receivedGotFocus[1]);
+				Assert.IsTrue(receivedGotFocus[2]);
+				Assert.IsTrue(receivedGotFocus[3]);
+
+				Assert.IsTrue(receivedLostFocus[0]);
+				Assert.IsTrue(receivedLostFocus[1]);
+				Assert.IsFalse(receivedLostFocus[2]);
+				Assert.IsTrue(receivedLostFocus[3]);
+				;
+			}
+			finally
+			{
+				TestServices.WindowHelper.WindowContent = null;
+			}
+		}
+
+		[TestMethod]
+		[RunsOnUIThread]
+		public async Task IsTabStop_False_Check_Inner()
+		{
+			var outerControl = new ContentControl() { IsTabStop = false };
+			var innerControl = new Button { Content = "Inner" };
+			var contentRoot = new Border
+			{
+				Child = new Grid
+				{
+					Children =
+					{
+						new TextBlock {Text = "Spinach"},
+						innerControl
+					}
+				}
+			};
+			outerControl.Content = contentRoot;
+
+			TestServices.WindowHelper.WindowContent = outerControl;
+			await TestServices.WindowHelper.WaitForIdle();
+
+			outerControl.Focus(FocusState.Programmatic);
+			AssertHasFocus(innerControl);
+			Assert.AreEqual(FocusState.Unfocused, outerControl.FocusState);
+
+			TestServices.WindowHelper.WindowContent = null;
+		}
+
+		private void AssertHasFocus(Control control)
+		{
+			Assert.IsNotNull(control);
+			var focused = FocusManager.GetFocusedElement();
+			Assert.IsNotNull(focused);
+			Assert.AreEqual(focused, control);
+			Assert.AreNotEqual(FocusState.Unfocused, control.FocusState);
+		}
+	}
+}

src/Uno.UI/UI/Xaml/Controls/Control/Control.Android.cs

@@ -50,21 +50,5 @@ public IFrameworkElement GetTemplateRoot()
 		{
 			return this.GetChildren()?.FirstOrDefault() as IFrameworkElement;
 		}
-
-		partial void OnFocusStateChangedPartial(FocusState oldValue, FocusState newValue)
-		{
-			if (newValue == FocusState.Pointer && Focusable)
-			{
-				//Set native focus to this view
-				RequestFocus();
-			}
-		}
-
-		protected virtual bool RequestFocus(FocusState state)
-		{
-			FocusState = state;
-
-			return true;
-		}
 	}
 }

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

@@ -146,7 +146,7 @@ internal View TemplatedRoot
 
 				if (value != null)
 				{
-					if(_templatedRoot is IDependencyObjectStoreProvider provider)
+					if (_templatedRoot is IDependencyObjectStoreProvider provider)
 					{
 						provider.Store.SetValue(provider.Store.TemplatedParentProperty, this, DependencyPropertyValuePrecedences.Local);
 					}
@@ -310,7 +310,7 @@ private static object FindNameInScope(IFrameworkElement root, string name)
 				&& NameScope.GetNameScope(root) is INameScope nameScope
 				&& nameScope.FindName(name) is DependencyObject element
 				// Doesn't currently support ElementStub (fallbacks to other FindName implementation)
-				&& !(element is ElementStub) 
+				&& !(element is ElementStub)
 					? element
 					: null;
 		}
@@ -363,7 +363,7 @@ private void UpdateTemplate()
 			}
 
 			if (
-				!FeatureConfiguration.FrameworkElement.UseLegacyApplyStylePhase && 
+				!FeatureConfiguration.FrameworkElement.UseLegacyApplyStylePhase &&
 				FeatureConfiguration.FrameworkElement.ClearPreviousOnStyleChange
 			)
 			{
@@ -610,8 +610,7 @@ public FocusState FocusState
 				typeof(FocusState),
 				typeof(Control),
 				new PropertyMetadata(
-					(FocusState)FocusState.Unfocused,
-					(s, e) => ((Control)s)?.OnFocusStateChanged((FocusState)e.OldValue, (FocusState)e.NewValue)
+					(FocusState)FocusState.Unfocused
 				)
 			);
 
@@ -668,11 +667,13 @@ public bool Focus(FocusState value)
 				throw new ArgumentException("Value does not fall within the expected range.", nameof(value));
 			}
 
-#if __WASM__
-			return Visibility == Visibility.Visible && IsEnabled && RequestFocus(value);
-#else
-			return IsFocusable && RequestFocus(value);
-#endif
+			return RequestFocus(value);
+		}
+
+
+		protected virtual bool RequestFocus(FocusState state)
+		{
+			return FocusManager.SetFocusedElement(this, FocusNavigationDirection.None, state);
 		}
 
 		internal void Unfocus()
@@ -736,29 +737,12 @@ protected virtual void OnBorderBrushChanged(Brush oldValue, Brush newValue)
 
 		partial void OnBorderBrushChangedPartial(Brush oldValue, Brush newValue);
 
-		protected virtual void OnFocusStateChanged(FocusState oldValue, FocusState newValue)
+		internal virtual void UpdateFocusState(FocusState focusState)
 		{
-			if (newValue == FocusState.Unfocused && oldValue == newValue)
-			{
-				return;
-			}
-
-			OnFocusStateChangedPartial(oldValue, newValue);
-#if XAMARIN || __WASM__
-			FocusManager.OnFocusChanged(this, newValue);
-#endif
-
-			if (newValue == FocusState.Unfocused)
-			{
-				RaiseEvent(LostFocusEvent, new RoutedEventArgs(this));
-			}
-			else
-			{
-				RaiseEvent(GotFocusEvent, new RoutedEventArgs(this));
-			}
+			FocusState = focusState;
 		}
 
-		partial void OnFocusStateChangedPartial(FocusState oldValue, FocusState newValue);
+		partial void UpdateFocusStatePartial(FocusState focusState);
 
 		protected virtual void OnPointerPressed(PointerRoutedEventArgs args) { }
 		protected virtual void OnPointerReleased(PointerRoutedEventArgs args) { }

src/Uno.UI/UI/Xaml/Controls/Control/Control.iOSmacOS.cs

@@ -60,13 +60,6 @@ partial void RegisterSubView(View child)
 
 			AddSubview(child);
 		}
-
-		protected virtual bool RequestFocus(FocusState state)
-		{
-			FocusState = state;
-
-			return true;
-		}
 	}
 }
 

src/Uno.UI/UI/Xaml/Controls/Control/Control.wasm.cs

@@ -18,7 +18,7 @@ public partial class Control
 	{
 		/// This binary compatibility workaround that can be removed
 		public new static DependencyProperty IsEnabledProperty => FrameworkElement.IsEnabledProperty;
-		
+
 		public Control(string htmlTag = "div") : base(htmlTag)
 		{
 			InitializeControl();
@@ -46,15 +46,6 @@ public IFrameworkElement GetTemplateRoot()
 			return this.GetChildren()?.FirstOrDefault() as IFrameworkElement;
 		}
 
-		partial void OnFocusStateChangedPartial(FocusState oldValue, FocusState newValue)
-		{
-			//if (newValue == FocusState.Pointer && Focusable)
-			//{
-			//	//Set native focus to this view
-			//	RequestFocus();
-			//}
-		}
-
 		partial void OnIsFocusableChanged()
 		{
 			var isFocusable = IsFocusable && !IsDelegatingFocusToTemplateChild();
@@ -63,40 +54,5 @@ partial void OnIsFocusableChanged()
 		}
 
 		protected virtual bool IsDelegatingFocusToTemplateChild() => false;
-
-		private FocusState? _pendingFocusRequestState;
-		protected virtual bool RequestFocus(FocusState state)
-		{
-			try
-			{
-				_pendingFocusRequestState = state;
-				return FocusManager.Focus(this);
-			}
-			finally
-			{
-				_pendingFocusRequestState = null;
-			}
-		}
-
-		internal bool SetFocused(bool isFocused)
-		{
-			if (isFocused)
-			{
-				if (IsFocusable)
-				{
-					FocusState = _pendingFocusRequestState ?? FocusState.Pointer;
-					return true;
-				}
-				else
-				{
-					return false;
-				}
-			}
-			else
-			{
-				Unfocus();
-				return true;
-			}
-		}
 	}
 }

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

@@ -19,6 +19,7 @@
 using Windows.UI.Xaml.Media;
 using Windows.Foundation;
 using Windows.UI.Core;
+using Microsoft.Extensions.Logging;
 
 namespace Windows.UI.Xaml.Controls
 {
@@ -153,7 +154,8 @@ protected override void OnApplyTemplate()
 		public string Text
 		{
 			get => (string)this.GetValue(TextProperty);
-			set {
+			set
+			{
 				if (value == null)
 				{
 					throw new ArgumentNullException();
@@ -581,12 +583,15 @@ public TextAlignment TextAlignment
 
 		#endregion
 
-		protected override void OnFocusStateChanged(FocusState oldValue, FocusState newValue)
-			=> OnFocusStateChanged(oldValue, newValue, initial: false);
+		internal override void UpdateFocusState(FocusState focusState)
+		{
+			var oldValue = FocusState;
+			base.UpdateFocusState(focusState);
+			OnFocusStateChanged(oldValue, focusState, initial: false);
+		}
 
 		private void OnFocusStateChanged(FocusState oldValue, FocusState newValue, bool initial)
 		{
-			base.OnFocusStateChanged(oldValue, newValue);
 			OnFocusStateChangedPartial(newValue);
 
 			if (!initial && newValue == FocusState.Unfocused && _hasTextChangedThisFocusSession)
@@ -646,6 +651,11 @@ protected override void OnKeyDown(KeyRoutedEventArgs args)
 
 		private void UpdateButtonStates()
 		{
+			if (this.Log().IsEnabled(LogLevel.Debug))
+			{
+				this.Log().LogDebug(nameof(UpdateButtonStates));
+			}
+
 			if (Text.HasValue()
 				&& FocusState != FocusState.Unfocused
 				&& !IsReadOnly