Fix WASM changing scroll position on focus changing + fix keyboard focus not bringing the new focus target into view

src/Uno.UI.RuntimeTests/Tests/Uno_UI_Xaml_Input/Given_UnoFocusInputHandler.cs

@@ -1,18 +1,18 @@
 #if HAS_UNO // Testing internal UnoFocusInputHandler, not available on Windows
 using System.Threading.Tasks;
-using Private.Infrastructure;
 using Uno.UI.Xaml.Core;
 using Uno.UI.Xaml.Input;
 using Windows.System;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Input;
+using Uno.UI.RuntimeTests.Helpers;
+using static Private.Infrastructure.TestServices;
 
 namespace Uno.UI.RuntimeTests.Tests.Uno_UI_Xaml_Input;
 
 [TestClass]
 [RunsOnUIThread]
-[RequiresFullWindow]
 public class Given_UnoFocusInputHandler
 {
 	private const int CenterButtonIndex = 4;
@@ -26,6 +26,7 @@ public class Given_UnoFocusInputHandler
 	[DataRow(XYFocusKeyboardNavigationMode.Enabled, VirtualKey.Up, true, TopButtonIndex)]
 	[DataRow(XYFocusKeyboardNavigationMode.Enabled, VirtualKey.Down, true, BottomButtonIndex)]
 	[DataRow(XYFocusKeyboardNavigationMode.Disabled, VirtualKey.Down, false, -1)]
+	[RequiresFullWindow]
 	[TestMethod]
 	public async Task When_VerifyEnabledXYKeyboardNavigation(XYFocusKeyboardNavigationMode mode, VirtualKey key, bool shouldSucceed, int targetIndex)
 	{
@@ -36,12 +37,43 @@ await VerifyXYNavigationAsync(
 			targetIndex);
 	}
 
+	[TestMethod]
+	public async Task When_Tab_BringIntoView()
+	{
+		var ts1 = new ToggleSwitch();
+		var ts2 = new ToggleSwitch();
+		var SUT = new ScrollViewer
+		{
+			new StackPanel
+			{
+				Spacing = 1200,
+				Children =
+				{
+					ts1,
+					ts2
+				}
+			}
+		};
+
+		await UITestHelper.Load(SUT);
+
+		Assert.AreEqual(0, SUT.VerticalOffset);
+
+		ts1.Focus(FocusState.Programmatic);
+		await WindowHelper.WaitForIdle();
+		Assert.AreEqual(0, SUT.VerticalOffset);
+
+		KeyboardHelper.Tab();
+		await WindowHelper.WaitForIdle();
+		Assert.AreEqual(SUT.ScrollableHeight, SUT.VerticalOffset);
+	}
+
 	private async Task VerifyXYNavigationAsync(XYFocusKeyboardNavigationMode mode, VirtualKey key, bool shouldSucceed, int targetIndex)
 	{
 		var grid = CreateButtonGrid(mode);
 
-		TestServices.WindowHelper.WindowContent = grid;
-		await TestServices.WindowHelper.WaitForIdle();
+		WindowHelper.WindowContent = grid;
+		await WindowHelper.WaitForIdle();
 
 		var centerButton = (Button)grid.Children[CenterButtonIndex];
 

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_TextBox.cs

@@ -804,5 +804,54 @@ public async Task When_Paste()
 
 			Assert.AreEqual(pasteCount, 1);
 		}
+
+		[TestMethod]
+		[RunsOnUIThread]
+#if __ANDROID__
+		[Ignore("https://github.com/unoplatform/uno/issues/15457")]
+#endif
+		public async Task When_GotFocus_BringIntoView()
+		{
+			var tb = new TextBox();
+			var ts = new ToggleSwitch();
+			var SUT = new ScrollViewer
+			{
+				Content = new StackPanel
+				{
+					Spacing = 1200,
+					Children =
+					{
+						tb,
+						ts
+					}
+				}
+			};
+
+			await UITestHelper.Load(SUT);
+
+			Assert.AreEqual(0, SUT.VerticalOffset);
+
+			ts.Focus(FocusState.Programmatic);
+			await WindowHelper.WaitForIdle();
+#if __WASM__ // wasm needs an additional delay for some reason, probably because of smooth scrolling?
+			await Task.Delay(2000);
+#endif
+
+			Assert.AreEqual(0, SUT.VerticalOffset);
+			SUT.ScrollToVerticalOffset(99999);
+
+			await WindowHelper.WaitForIdle();
+#if __WASM__ // wasm needs an additional delay for some reason, probably because of smooth scrolling?
+			await Task.Delay(2000);
+#endif
+
+			tb.Focus(FocusState.Programmatic);
+			await WindowHelper.WaitForIdle();
+#if __WASM__ // wasm needs an additional delay for some reason, probably because of smooth scrolling?
+			await Task.Delay(2000);
+#endif
+
+			Assert.AreEqual(0, SUT.VerticalOffset);
+		}
 	}
 }

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

@@ -10,6 +10,7 @@
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Controls.Primitives;
 using Microsoft.UI.Xaml.Input;
+using Uno.UI.RuntimeTests.Helpers;
 
 namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Input
 {
@@ -463,6 +464,49 @@ public async Task When_ScrollViewer_TryMoveFocus()
 			Assert.AreEqual(button, focused);
 		}
 
+		[TestMethod]
+		[RunsOnUIThread]
+#if __ANDROID__
+		[Ignore("https://github.com/unoplatform/uno/issues/15457")]
+#endif
+		public async Task When_FocusChanged_PreventScroll()
+		{
+			var ts1 = new ToggleSwitch();
+			var ts2 = new ToggleSwitch();
+			var SUT = new ScrollViewer
+			{
+				Content = new StackPanel
+				{
+					Spacing = 1200,
+					Children =
+					{
+						ts1, ts2
+					}
+				}
+			};
+
+			await UITestHelper.Load(SUT);
+
+			Assert.AreEqual(0, SUT.VerticalOffset);
+
+			ts2.Focus(FocusState.Programmatic);
+			await TestServices.WindowHelper.WaitForIdle();
+#if __WASM__ // wasm needs an additional delay for some reason, probably because of smooth scrolling?
+			await Task.Delay(2000);
+#endif
+
+			Assert.AreEqual(0, SUT.VerticalOffset);
+			SUT.ScrollToVerticalOffset(99999);
+
+			ts1.Focus(FocusState.Programmatic);
+			await TestServices.WindowHelper.WaitForIdle();
+#if __WASM__ // wasm needs an additional delay for some reason, probably because of smooth scrolling?
+			await Task.Delay(2000);
+#endif
+
+			Assert.AreEqual(SUT.ScrollableHeight, SUT.VerticalOffset);
+		}
+
 		private async Task WaitForLoadedEvent(FocusNavigationPage page)
 		{
 			await TestServices.WindowHelper.WaitFor(() => page.LoadedEventFinished);

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

@@ -209,6 +209,11 @@ private void InitializeProperties()
 			InitializePropertiesPartial();
 		}
 
+		protected override void OnGotFocus(RoutedEventArgs e) => StartBringIntoView(new BringIntoViewOptions
+		{
+			AnimationDesired = false
+		});
+
 		protected override void OnApplyTemplate()
 		{
 			base.OnApplyTemplate();

src/Uno.UI/UI/Xaml/Input/Internal/UnoFocusInputHandler.cs

@@ -78,6 +78,7 @@ internal bool TryHandleTabFocus(bool isShiftDown)
 		var focusMovement = new FocusMovement(XYFocusOptions.Default, direction, null);
 		focusMovement.IsShiftPressed = _isShiftDown;
 		focusMovement.IsProcessingTab = true;
+		focusMovement.ForceBringIntoView = true;
 		var result = focusManager?.FindAndSetNextFocus(focusMovement);
 		return result?.WasMoved == true;
 	}

src/Uno.UI/UI/Xaml/Internal/InputManager.cs

@@ -56,9 +56,16 @@ internal bool ShouldRequestFocusSound()
 		return false;
 	}
 
-	internal void NotifyFocusChanged(DependencyObject? focusedElement, bool bringIntoView, bool animateIfBringIntoView)
+	internal void NotifyFocusChanged(DependencyObject focusedElement, bool bringIntoView, bool animateIfBringIntoView)
 	{
-		//TODO Uno: Implement
+		//TODO Uno: match WinUI
+		if (bringIntoView)
+		{
+			((UIElement)focusedElement).StartBringIntoView(new BringIntoViewOptions
+			{
+				AnimationDesired = animateIfBringIntoView
+			});
+		}
 	}
 
 	internal bool LastInputWasNonFocusNavigationKeyFromSIP()

src/Uno.UI/ts/WindowManager.ts

@@ -1512,7 +1512,7 @@ namespace Uno.UI {
 				throw `Element id ${elementId} is not focusable.`;
 			}
 
-			element.focus();
+			element.focus({ preventScroll: true });
 		}
 
 		/**