Allow LayoutView to pass touches to child controls when CascadeInputT…

…ransparent is false (#7236)

* Allow LayoutView to pass touches to child controls when CascadeInputTransparent is false
Fixes #6574

* Remove tests that don't make sense anymore

src/Controls/src/Core/Platform/GestureManager/GestureManager.iOS.cs

@@ -373,40 +373,6 @@ static bool ShouldRecognizeTapsTogether(NativeGestureRecognizer gesture, NativeG
 			return true;
 		}
 
-		// This logic should all be replaced once we implement the "InputTransparent" property
-		// https://github.com/dotnet/maui/issues/1190		
-		bool? _previousUserInteractionEnabled;
-		void CalculateUserInteractionEnabled()
-		{
-			if (ElementGestureRecognizers == null || _platformView == null || _handler?.VirtualView == null)
-				return;
-
-			bool hasGestureRecognizers = ElementGestureRecognizers.Count > 0;
-
-			// If no gestures have ever been added then don't do anything
-			if (!hasGestureRecognizers && _previousUserInteractionEnabled == null)
-				return;
-
-			_previousUserInteractionEnabled ??= _platformView.UserInteractionEnabled;
-
-			if (hasGestureRecognizers)
-			{
-				_platformView.UserInteractionEnabled = true;
-			}
-			else
-			{
-				_platformView.UserInteractionEnabled = _previousUserInteractionEnabled.Value;
-
-				// These are the known places where UserInteractionEnabled is modified inside Maui.Core
-				// Once we implement "InputTransparent" all of this should just get managed the "InputTransparent" mapper property
-				if (_handler.VirtualView is ITextInput)
-					_handler.UpdateValue(nameof(ITextInput.IsReadOnly));
-
-				_handler.UpdateValue(nameof(IView.IsEnabled));
-				_previousUserInteractionEnabled = null;
-			}
-		}
-
 		void LoadRecognizers()
 		{
 			if (ElementGestureRecognizers == null)
@@ -418,7 +384,6 @@ void LoadRecognizers()
 				_shouldReceiveTouch = ShouldReceiveTouch;
 			}
 
-			CalculateUserInteractionEnabled();
 			UIDragInteraction? uIDragInteraction = null;
 			UIDropInteraction? uIDropInteraction = null;
 
@@ -526,21 +491,30 @@ void LoadRecognizers()
 
 		bool ShouldReceiveTouch(UIGestureRecognizer recognizer, UITouch touch)
 		{
-			if (touch.View == _handler.PlatformView)
+			var platformView = _handler?.PlatformView;
+			var virtualView = _handler?.VirtualView;
+
+			if (virtualView == null || platformView == null)
+			{
+				return false;
+			}
+
+			if (virtualView.InputTransparent)
+			{
+				return false;
+			}
+
+			if (touch.View == platformView)
 			{
 				return true;
 			}
 
 			// If the touch is coming from the UIView our handler is wrapping (e.g., if it's  
 			// wrapping a UIView which already has a gesture recognizer), then we should let it through
 			// (This goes for children of that control as well)
-			if (_handler?.PlatformView == null)
-			{
-				return false;
-			}
 
-			if (touch.View.IsDescendantOfView(_handler.PlatformView) &&
-				(touch.View.GestureRecognizers?.Length > 0 || _handler.PlatformView.GestureRecognizers?.Length > 0))
+			if (touch.View.IsDescendantOfView(platformView) &&
+				(touch.View.GestureRecognizers?.Length > 0 || platformView.GestureRecognizers?.Length > 0))
 			{
 				return true;
 			}

src/Controls/tests/DeviceTests/GestureTests.iOS.cs

@@ -27,33 +27,5 @@ public async Task UserInteractionEnabledTrueWhenInitializedWithGestureRecognizer
 				Assert.True(handler.PlatformView.UserInteractionEnabled);
 			});
 		}
-
-		[Fact]
-		public async Task UserInteractionEnabledSetAfterAddingGestureRecognizer()
-		{
-			var label = new Label();
-
-			await InvokeOnMainThreadAsync(() =>
-			{
-				var handler = CreateHandler<LabelHandler>(label);
-				label.GestureRecognizers.Add(new TapGestureRecognizer() { NumberOfTapsRequired = 1 });
-				Assert.True(handler.PlatformView.UserInteractionEnabled);
-			});
-		}
-
-		[Fact]
-		public async Task UserInteractionEnabledUnsetAfterRemovingGestureRecognizer()
-		{
-			var label = new Label();
-			label.GestureRecognizers.Add(new TapGestureRecognizer() { NumberOfTapsRequired = 1 });
-
-			await InvokeOnMainThreadAsync(() =>
-			{
-				var handler = CreateHandler<LabelHandler>(label);
-				Assert.True(handler.PlatformView.UserInteractionEnabled);
-				label.GestureRecognizers.Clear();
-				Assert.False(handler.PlatformView.UserInteractionEnabled);
-			});
-		}
 	}
 }

src/Core/src/Platform/iOS/LayoutView.cs

@@ -7,6 +7,8 @@ namespace Microsoft.Maui.Platform
 {
 	public class LayoutView : MauiView
 	{
+		bool _userInteractionEnabled;
+
 		// TODO: Possibly reconcile this code with ViewHandlerExtensions.MeasureVirtualView
 		// If you make changes here please review if those changes should also
 		// apply to ViewHandlerExtensions.MeasureVirtualView
@@ -52,5 +54,35 @@ public override void WillRemoveSubview(UIView uiview)
 
 		internal Func<double, double, Size>? CrossPlatformMeasure { get; set; }
 		internal Func<Rect, Size>? CrossPlatformArrange { get; set; }
+
+		public override UIView HitTest(CGPoint point, UIEvent? uievent)
+		{
+			var result = base.HitTest(point, uievent);
+
+			if (!_userInteractionEnabled && this.Equals(result))
+			{
+				// If user interaction is disabled (IOW, if the corresponding Layout is InputTransparent),
+				// then we exclude the LayoutView itself from hit testing. But it's children are valid
+				// hit testing targets.
+
+				return null!;
+			}
+
+			return result;
+		}
+
+		public override bool UserInteractionEnabled
+		{
+			get => base.UserInteractionEnabled;
+			set
+			{
+				// We leave the base UIE value true no matter what, so that hit testing will find children
+				// of the LayoutView. But we track the intended value so we can use it during hit testing
+				// to ignore the LayoutView itself, if necessary.
+
+				base.UserInteractionEnabled = true;
+				_userInteractionEnabled = value;
+			}
+		}
 	}
 }

src/Core/tests/DeviceTests/Handlers/HandlerTestBaseOfT.iOS.cs

@@ -112,6 +112,13 @@ public async Task RotationInitializeCorrectly(float rotation)
 		[InlineData(false)]
 		public async Task InputTransparencyInitializesCorrectly(bool inputTransparent)
 		{
+			if (typeof(TStub) == typeof(LayoutStub))
+			{
+				// The platform type for Layouts (LayoutView) always has UserInteractionEnabled
+				// to allow for its children to be interacted with
+				return;
+			}
+
 			var view = new TStub()
 			{
 				InputTransparent = inputTransparent