fix(pointers): Fix possible missing pointer exited event with touch u…

…sing wasm on iOS/iPad

src/Uno.UI/Runtime/BrowserPointerInputSource.wasm.cs

@@ -15,6 +15,7 @@
 using _NativeMethods = __Windows.UI.Core.CoreWindow.NativeMethods;
 using System.Runtime.InteropServices;
 using Windows.System;
+using Microsoft.UI.Xaml;
 
 namespace Uno.UI.Runtime;
 
@@ -29,6 +30,7 @@ internal partial class BrowserPointerInputSource : IUnoCorePointerInputSource
 	private static readonly Logger? _logTrace = _log.IsTraceEnabled(LogLevel.Trace) ? _log : null;
 
 	private ulong _bootTime;
+	private bool _isIOs;
 	private bool _isOver;
 	private PointerPoint? _lastPoint;
 	private CoreCursor _pointerCursor = new(CoreCursorType.Arrow, 0);
@@ -55,11 +57,19 @@ public BrowserPointerInputSource()
 	private static partial void Initialize([JSMarshalAs<JSType.Any>] object inputSource);
 
 	[JSExport]
-	private static void OnInitialized([JSMarshalAs<JSType.Any>] object inputSource, double bootTime)
+	private static void OnInitialized([JSMarshalAs<JSType.Any>] object inputSource, double bootTime, string userAgent)
 	{
-		((BrowserPointerInputSource)inputSource)._bootTime = (ulong)bootTime;
+		if (inputSource is BrowserPointerInputSource that)
+		{
+			that._bootTime = (ulong)bootTime;
+			that._isIOs = userAgent.Contains("iPhone") || userAgent.Contains("iPad"); // Note: OperatingSystem.IsIOS() is false
 
-		_logTrace?.Trace("Complete initialization of BrowserPointerInputSource, we are now ready to receive pointer events!");
+			_logTrace?.Trace("Complete initialization of BrowserPointerInputSource, we are now ready to receive pointer events!");
+		}
+		else
+		{
+			_log.Error("Requested init using an invalid source.");
+		}
 	}
 
 	[JSExport]
@@ -121,6 +131,7 @@ private static int OnNativeEvent(
 				case HtmlPointerEvent.pointerleave:
 					that._isOver = false;
 					that.PointerExited?.Invoke(that, args);
+					_PointerIdentifierPool.ReleaseManaged(pointerIdentifier);
 					break;
 
 				case HtmlPointerEvent.pointerdown:
@@ -130,7 +141,13 @@ private static int OnNativeEvent(
 				case HtmlPointerEvent.pointerup:
 					//case HtmlPointerEvent.lostpointercapture: // if pointer is captured, we don't get a up, just a capture lost (with skia for wasm)
 					that.PointerReleased?.Invoke(that, args);
-					_PointerIdentifierPool.ReleaseManaged(pointerIdentifier);
+					if (that._isIOs && args is { CurrentPoint.PointerDeviceType: PointerDeviceType.Touch, DispatchResult: UIElement.PointerEventDispatchResult { VisualTreeAltered: true } })
+					{
+						// On iOS, when the element under the pointer is removed, the browser won't send any pointer leave event.
+
+						args.DispatchResult = null; // To be clean only, the value is not used in the leave case.
+						goto case HtmlPointerEvent.pointerleave;
+					}
 					break;
 
 				case HtmlPointerEvent.pointermove:

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

@@ -239,9 +239,10 @@ private void OnPointerWheelChanged(Windows.UI.Core.PointerEventArgs args, bool i
 #endif
 
 			var routedArgs = new PointerRoutedEventArgs(args, originalSource) { IsInjected = isInjected };
+			var result = default(PointerEventDispatchResult);
 
 			// First raise the event, either on the OriginalSource or on the capture owners if any
-			RaiseUsingCaptures(Wheel, originalSource, routedArgs, setCursor: true);
+			result = RaiseUsingCaptures(Wheel, originalSource, routedArgs, setCursor: true);
 
 			// Scrolling can change the element underneath the pointer, so we need to update
 			(originalSource, var staleBranch) = HitTest(args, caller: "OnPointerWheelChanged_post_wheel", isStale: _isOver);
@@ -250,7 +251,9 @@ private void OnPointerWheelChanged(Windows.UI.Core.PointerEventArgs args, bool i
 			// Second raise the PointerExited events on the stale branch
 			if (staleBranch.HasValue)
 			{
-				if (Raise(Leave, staleBranch.Value, routedArgs) is { VisualTreeAltered: true })
+				var leaveResult = Raise(Leave, staleBranch.Value, routedArgs);
+				result += leaveResult;
+				if (leaveResult is { VisualTreeAltered: true })
 				{
 					// The visual tree has been modified in a way that requires performing a new hit test.
 					originalSource = HitTest(args, caller: "OnPointerWheelChanged_post_leave").element ?? _inputManager.ContentRoot.VisualTree.RootElement;
@@ -259,14 +262,16 @@ private void OnPointerWheelChanged(Windows.UI.Core.PointerEventArgs args, bool i
 
 			// Third (try to) raise the PointerEnter on the OriginalSource
 			// Note: This won't do anything if already over.
-			Raise(Enter, originalSource!, routedArgs);
+			result += Raise(Enter, originalSource!, routedArgs);
 
 			if (!PointerCapture.TryGet(routedArgs.Pointer, out var capture) || capture.IsImplicitOnly)
 			{
 				// If pointer is explicitly captured, then we set it in the RaiseUsingCaptures call above.
 				// If not, we make sure to update the cursor based on the new originalSource.
 				SetSourceCursor(originalSource);
 			}
+
+			args.DispatchResult = result;
 		}
 
 		private void OnPointerEntered(Windows.UI.Core.PointerEventArgs args, bool isInjected = false)
@@ -300,7 +305,9 @@ private void OnPointerEntered(Windows.UI.Core.PointerEventArgs args, bool isInje
 
 			var routedArgs = new PointerRoutedEventArgs(args, originalSource) { IsInjected = isInjected };
 
-			Raise(Enter, originalSource, routedArgs);
+			var result = Raise(Enter, originalSource, routedArgs);
+
+			args.DispatchResult = result;
 		}
 
 		private void OnPointerExited(Windows.UI.Core.PointerEventArgs args, bool isInjected = false)
@@ -340,13 +347,16 @@ private void OnPointerExited(Windows.UI.Core.PointerEventArgs args, bool isInjec
 
 			var routedArgs = new PointerRoutedEventArgs(args, originalSource) { IsInjected = isInjected };
 
-			Raise(Leave, overBranchLeaf, routedArgs);
+			var result = Raise(Leave, overBranchLeaf, routedArgs);
+
 			if (!args.CurrentPoint.IsInContact && (PointerDeviceType)args.CurrentPoint.Pointer.Type == PointerDeviceType.Touch)
 			{
 				// We release the captures on exit when pointer if not pressed
 				// Note: for a "Tap" with a finger the sequence is Up / Exited / Lost, so the lost cannot be raised on Up
 				ReleaseCaptures(routedArgs);
 			}
+
+			args.DispatchResult = result;
 		}
 
 		private void OnPointerPressed(Windows.UI.Core.PointerEventArgs args, bool isInjected = false)
@@ -396,7 +406,9 @@ private void OnPointerPressed(Windows.UI.Core.PointerEventArgs args, bool isInje
 			var routedArgs = new PointerRoutedEventArgs(args, originalSource) { IsInjected = isInjected };
 
 			_pressedElements[routedArgs.Pointer] = originalSource;
-			Raise(Pressed, originalSource, routedArgs);
+			var result = Raise(Pressed, originalSource, routedArgs);
+
+			args.DispatchResult = result;
 		}
 
 		private void OnPointerReleased(Windows.UI.Core.PointerEventArgs args, bool isInjected = false)
@@ -439,7 +451,8 @@ private void OnPointerReleased(Windows.UI.Core.PointerEventArgs args, bool isInj
 
 			var routedArgs = new PointerRoutedEventArgs(args, originalSource) { IsInjected = isInjected };
 
-			RaiseUsingCaptures(Released, originalSource, routedArgs, setCursor: false);
+			var result = RaiseUsingCaptures(Released, originalSource, routedArgs, setCursor: false);
+
 			if (isOutOfWindow || (PointerDeviceType)args.CurrentPoint.Pointer.Type != PointerDeviceType.Touch)
 			{
 				// We release the captures on up but only after the released event and processed the gesture
@@ -451,6 +464,8 @@ private void OnPointerReleased(Windows.UI.Core.PointerEventArgs args, bool isInj
 				SetSourceCursor(originalSource);
 			}
 			ClearPressedState(routedArgs);
+
+			args.DispatchResult = result;
 		}
 
 		private void OnPointerMoved(Windows.UI.Core.PointerEventArgs args, bool isInjected = false)
@@ -482,11 +497,14 @@ private void OnPointerMoved(Windows.UI.Core.PointerEventArgs args, bool isInject
 			}
 
 			var routedArgs = new PointerRoutedEventArgs(args, originalSource) { IsInjected = isInjected };
+			var result = default(PointerEventDispatchResult);
 
 			// First raise the PointerExited events on the stale branch
 			if (staleBranch.HasValue)
 			{
-				if (Raise(Leave, staleBranch.Value, routedArgs) is { VisualTreeAltered: true })
+				var leaveResult = Raise(Leave, staleBranch.Value, routedArgs);
+				result += leaveResult;
+				if (leaveResult is { VisualTreeAltered: true })
 				{
 					// The visual tree has been modified in a way that requires performing a new hit test.
 					originalSource = HitTest(args, caller: "OnPointerMoved_post_leave").element ?? _inputManager.ContentRoot.VisualTree.RootElement;
@@ -495,14 +513,18 @@ private void OnPointerMoved(Windows.UI.Core.PointerEventArgs args, bool isInject
 
 			// Second (try to) raise the PointerEnter on the OriginalSource
 			// Note: This won't do anything if already over.
-			if (Raise(Enter, originalSource, routedArgs) is { VisualTreeAltered: true })
+			var enterResult = Raise(Enter, originalSource, routedArgs);
+			result += enterResult;
+			if (enterResult is { VisualTreeAltered: true })
 			{
 				// The visual tree has been modified in a way that requires performing a new hit test.
 				originalSource = HitTest(args, caller: "OnPointerMoved_post_enter").element ?? _inputManager.ContentRoot.VisualTree.RootElement;
 			}
 
 			// Finally raise the event, either on the OriginalSource or on the capture owners if any
 			RaiseUsingCaptures(Move, originalSource, routedArgs, setCursor: true);
+
+			args.DispatchResult = result;
 		}
 
 		private void OnPointerCancelled(PointerEventArgs args, bool isInjected = false)
@@ -535,10 +557,12 @@ private void OnPointerCancelled(PointerEventArgs args, bool isInjected = false)
 
 			var routedArgs = new PointerRoutedEventArgs(args, originalSource) { IsInjected = isInjected };
 
-			RaiseUsingCaptures(Cancelled, originalSource, routedArgs, setCursor: false);
+			var result = RaiseUsingCaptures(Cancelled, originalSource, routedArgs, setCursor: false);
 			// Note: No ReleaseCaptures(routedArgs);, the cancel automatically raise it
 			SetSourceCursor(originalSource);
 			ClearPressedState(routedArgs);
+
+			args.DispatchResult = result;
 		}
 
 		#region Captures

src/Uno.UI/ts/Runtime/BrowserPointerInputSource.ts

@@ -54,7 +54,9 @@
 			this._bootTime = Date.now() - performance.now();
 			this._source = manageSource;
 
-			BrowserPointerInputSource._exports.OnInitialized(manageSource, this._bootTime);
+			var userAgent = navigator.userAgent || navigator.vendor || window.opera;
+
+			BrowserPointerInputSource._exports.OnInitialized(manageSource, this._bootTime, userAgent);
 			this.subscribePointerEvents(); // Subscribe only after the managed initialization is done
 		}
 

src/Uno.UWP/UI/Core/PointerEventArgs.cs

@@ -21,6 +21,14 @@ internal PointerEventArgs(PointerPoint currentPoint, VirtualKeyModifiers keyModi
 		public IList<PointerPoint> GetIntermediatePoints()
 			=> new List<PointerPoint> { CurrentPoint };
 
+#nullable enable
+		/// <summary>
+		/// Gets the dispatch result of this event, if any.
+		/// This is defined by the InputManager if the event goes though it.
+		/// </summary>
+		internal object? DispatchResult { get; set; }
+#nullable restore
+
 		/// <inheritdoc />
 		public override string ToString()
 			=> $"{CurrentPoint} | modifiers: {KeyModifiers}";