[A] Fix Bugzilla 40173 (#62)

* [A]Fix issue where Frame would block all tap gestures under it even if it didn't have one

* [A]Make BoxView non-blocking inside a ListView only

* Add UITest for bz40173

* Fix code review issues

4 files changed, 190 insertions, 6 deletions

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla40173.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla40173.cs
new file mode 100644
index 00000000..422e363d
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla40173.cs
@@ -0,0 +1,110 @@
+using Xamarin.Forms.CustomAttributes;
+#if UITEST
+using NUnit.Framework;
+#endif
+
+namespace Xamarin.Forms.Controls
+{
+    [Preserve(AllMembers = true)]
+    [Issue(IssueTracker.Bugzilla, 40173, "Android BoxView/Frame not clickthrough in ListView")]
+    public class Bugzilla40173 : TestContentPage // or TestMasterDetailPage, etc ...
+    {
+        const string CantTouchButtonId = "CantTouchButtonId";
+        const string CanTouchButtonId = "CanTouchButtonId";
+        const string ListTapTarget = "ListTapTarget";
+        const string CantTouchFailText = "Failed";
+        const string CanTouchSuccessText = "ButtonTapped";
+        const string ListTapSuccessText = "ItemTapped";
+
+#if UITEST
+        [Test]
+        public void ButtonBlocked()
+        {
+            RunningApp.Tap(q => q.Marked(CantTouchButtonId));
+            RunningApp.WaitForNoElement(q => q.Text(CantTouchFailText));
+
+            RunningApp.Tap(q => q.Marked(CanTouchButtonId));
+            RunningApp.WaitForElement(q => q.Text(CanTouchSuccessText));
+
+            RunningApp.Tap(q => q.Marked(ListTapTarget));
+            RunningApp.WaitForElement(q => q.Text(ListTapSuccessText));
+        }
+#endif
+
+        protected override void Init()
+        {
+            var outputLabel = new Label();
+            var testButton = new Button
+            {
+                Text = "Can't Touch This",
+                AutomationId = CantTouchButtonId
+            };
+
+            testButton.Clicked += (sender, args) => outputLabel.Text = CantTouchFailText;
+
+            var testGrid = new Grid
+            {
+                Children =
+                {
+                    testButton,
+                    new BoxView
+                    {
+                        Color = Color.Pink.MultiplyAlpha(0.5)
+                    }
+                }
+            };
+
+            // BoxView over Button prevents Button click
+            var testButtonOk = new Button
+            {
+                Text = "Can Touch This",
+                AutomationId = CanTouchButtonId
+            };
+
+            testButtonOk.Clicked += (sender, args) => outputLabel.Text = CanTouchSuccessText;
+
+            var testGridOk = new Grid
+            {
+                Children =
+                {
+                    testButtonOk,
+                    new BoxView
+                    {
+                        Color = Color.Pink.MultiplyAlpha(0.5),
+                        InputTransparent = true
+                    }
+                }
+            };
+
+            var testListView = new ListView();
+            var items = new[] { "Foo" };
+            testListView.ItemsSource = items;
+            testListView.ItemTemplate = new DataTemplate(() =>
+            {
+                var result = new ViewCell
+                {
+                    View = new Grid
+                    {
+                        Children =
+                        {
+                            new BoxView
+                            {
+                                AutomationId = ListTapTarget,
+                                Color = Color.Pink.MultiplyAlpha(0.5)
+                            }
+                        }
+                    }
+                };
+
+                return result;
+            });
+
+            testListView.ItemSelected += (sender, args) => outputLabel.Text = ListTapSuccessText;
+
+            Content = new StackLayout
+            {
+                Children = { outputLabel, testGrid, testGridOk, testListView }
+            };
+        }
+    }
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index e13847bf..e7afb089 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -95,6 +95,7 @@
       <SubType>Code</SubType>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla39702.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla40173.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CarouselAsync.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla34561.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla34727.cs" />
diff --git a/Xamarin.Forms.Platform.Android/AppCompat/FrameRenderer.cs b/Xamarin.Forms.Platform.Android/AppCompat/FrameRenderer.cs
index 7b544b25..232b6a6f 100644
--- a/Xamarin.Forms.Platform.Android/AppCompat/FrameRenderer.cs
+++ b/Xamarin.Forms.Platform.Android/AppCompat/FrameRenderer.cs
@@ -1,4 +1,6 @@
 using System;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
 using System.ComponentModel;
 using Android.Content;
 using Android.Support.V4.View;
@@ -19,11 +21,13 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 
 		float _defaultElevation = -1f;
 
+		bool _clickable;
 		bool _disposed;
 		Frame _element;
 		InnerGestureListener _gestureListener;
 		VisualElementPackager _visualElementPackager;
 		VisualElementTracker _visualElementTracker;
+		NotifyCollectionChangedEventHandler _collectionChangeHandler;
 
 		public FrameRenderer() : base(Forms.Context)
 		{
@@ -147,17 +151,20 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 			ElementChanged?.Invoke(this, new VisualElementChangedEventArgs(e.OldElement, e.NewElement));
 
 			if (e.OldElement != null)
-				e.OldElement.PropertyChanged -= OnElementPropertyChanged;
-			else
 			{
-				SetOnClickListener(this);
-				SetOnTouchListener(this);
+				e.OldElement.PropertyChanged -= OnElementPropertyChanged;
+				UnsubscribeGestureRecognizers(e.OldElement);
 			}
 
 			if (e.NewElement != null)
 			{
 				if (_visualElementTracker == null)
 				{
+					SetOnClickListener(this);
+					SetOnTouchListener(this);
+
+					UpdateGestureRecognizers(true);
+
 					_visualElementTracker = new VisualElementTracker(this);
 					_visualElementPackager = new VisualElementPackager(this);
 					_visualElementPackager.Load();
@@ -166,6 +173,7 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 				e.NewElement.PropertyChanged += OnElementPropertyChanged;
 				UpdateShadow();
 				UpdateBackgroundColor();
+				SubscribeGestureRecognizers(e.NewElement);
 			}
 		}
 
@@ -185,6 +193,11 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 			}
 		}
 
+		void HandleGestureRecognizerCollectionChanged(object sender, NotifyCollectionChangedEventArgs notifyCollectionChangedEventArgs)
+		{
+			UpdateGestureRecognizers();
+		}
+
 		void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
 		{
 			if (e.PropertyName == Frame.HasShadowProperty.PropertyName)
@@ -193,12 +206,54 @@ namespace Xamarin.Forms.Platform.Android.AppCompat
 				UpdateBackgroundColor();
 		}
 
+		void SubscribeGestureRecognizers(VisualElement element)
+		{
+			var view = element as View;
+			if (view == null)
+				return;
+
+			if (_collectionChangeHandler == null)
+				_collectionChangeHandler = HandleGestureRecognizerCollectionChanged;
+
+			var observableCollection = (ObservableCollection<IGestureRecognizer>)view.GestureRecognizers;
+			observableCollection.CollectionChanged += _collectionChangeHandler;
+		}
+
+		void UnsubscribeGestureRecognizers(VisualElement element)
+		{
+			var view = element as View;
+			if (view == null || _collectionChangeHandler == null)
+				return;
+
+			var observableCollection = (ObservableCollection<IGestureRecognizer>)view.GestureRecognizers;
+			observableCollection.CollectionChanged -= _collectionChangeHandler;
+		}
+
 		void UpdateBackgroundColor()
 		{
 			Color bgColor = Element.BackgroundColor;
 			SetCardBackgroundColor(bgColor.IsDefault ? AColor.White : bgColor.ToAndroid());
 		}
 
+		void UpdateClickable(bool force = false)
+		{
+			var view = Element as View;
+			if (view == null)
+				return;
+
+			bool newValue = view.ShouldBeMadeClickable();
+			if (force || _clickable != newValue)
+				Clickable = newValue;
+		}
+
+		void UpdateGestureRecognizers(bool forceClick = false)
+		{
+			if (Element == null)
+				return;
+
+			UpdateClickable(forceClick);
+		}
+
 		void UpdateShadow()
 		{
 			float elevation = _defaultElevation;
diff --git a/Xamarin.Forms.Platform.Android/Renderers/BoxRenderer.cs b/Xamarin.Forms.Platform.Android/Renderers/BoxRenderer.cs
index 725829f4..b29dd760 100644
--- a/Xamarin.Forms.Platform.Android/Renderers/BoxRenderer.cs
+++ b/Xamarin.Forms.Platform.Android/Renderers/BoxRenderer.cs
@@ -5,6 +5,8 @@ namespace Xamarin.Forms.Platform.Android
 {
 	public class BoxRenderer : VisualElementRenderer<BoxView>
 	{
+		bool _isInViewCell;
+
 		public BoxRenderer()
 		{
 			AutoPackage = false;
@@ -12,13 +14,29 @@ namespace Xamarin.Forms.Platform.Android
 
 		public override bool OnTouchEvent(MotionEvent e)
 		{
-			base.OnTouchEvent(e);
-			return !Element.InputTransparent;
+			if (base.OnTouchEvent(e))
+				return true;
+			return !Element.InputTransparent && !_isInViewCell;
 		}
 
 		protected override void OnElementChanged(ElementChangedEventArgs<BoxView> e)
 		{
 			base.OnElementChanged(e);
+
+			if (e.NewElement != null)
+			{
+				var parent = e.NewElement.Parent;
+				while (parent != null)
+				{
+					if (parent is ViewCell)
+					{
+						_isInViewCell = true;
+						break;
+					}
+					parent = parent.Parent;
+				}
+			}
+
 			UpdateBackgroundColor();
 		}