[Android] Restore pinch gestures and fix listview item selection (#1135)

* Repro

* Fail test if tap command is executed more than once.

* Update error message

* Handle context actions and taps without breaking selection

* Fix 58833 test

* Prevent InnerGestureListener from swallowing clicks and preventing selection

* Repro for 57515

* Add gestures category to appropriate tests

* Test notes

* Restore the tap gesture handling

* Better test name

* Simplify InnerGestureListener constructor; handle OnDown only if listening

* OnInterceptTouchEvent for IsEnabled handling

* Fix incorrect class filter in TapGestureHandler

* Restore MotionEventHelper

* Add IsEnabled check on OnTouchEvent

* Reinstate pinch gestures

* Checkpoint (trying to figure out how to handle button elevation)

* Rip out elevation ordering in DefaultRenderer

* Working version of pinch-to-zoom test

* Clean up lazy initializers, remove unnecessary members

* One fewer Java.Lang.Object

* Fix issue number; clean up notes and issue number changes

* Remove conditional

* Restore correct issue number

* Automate all the options for 58833 test

* Remove unnecessary automation ID

* Formatting cleanup; reinstate gesture detector dispose checks

* Updating Xamarin UI test version to avoid iOS crashes; update test to open iOS context actions

* Attempting to get 58833 test running on all iOS versions

1 files changed, 39 insertions, 141 deletions

diff --git a/Xamarin.Forms.Platform.Android/VisualElementRenderer.cs b/Xamarin.Forms.Platform.Android/VisualElementRenderer.cs
index 120cc972..098e85f6 100644
--- a/Xamarin.Forms.Platform.Android/VisualElementRenderer.cs
+++ b/Xamarin.Forms.Platform.Android/VisualElementRenderer.cs
@@ -1,53 +1,66 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
-using System.Collections.Specialized;
 using System.ComponentModel;
 using Android.Support.V4.View;
 using Android.Views;
 using Xamarin.Forms.Internals;
+using Xamarin.Forms.Platform.Android.FastRenderers;
 using AView = Android.Views.View;
 
 namespace Xamarin.Forms.Platform.Android
 {
-	public abstract class VisualElementRenderer<TElement> : FormsViewGroup, IVisualElementRenderer, AView.IOnTouchListener, AView.IOnClickListener, IEffectControlProvider where TElement : VisualElement
+	public abstract class VisualElementRenderer<TElement> : FormsViewGroup, IVisualElementRenderer, 
+		IEffectControlProvider where TElement : VisualElement
 	{
 		readonly List<EventHandler<VisualElementChangedEventArgs>> _elementChangedHandlers = new List<EventHandler<VisualElementChangedEventArgs>>();
 
-		readonly Lazy<GestureDetector> _gestureDetector;
-		readonly PanGestureHandler _panGestureHandler;
-		readonly PinchGestureHandler _pinchGestureHandler;
-		readonly TapGestureHandler _tapGestureHandler;
-
-		NotifyCollectionChangedEventHandler _collectionChangeHandler;
-
 		VisualElementRendererFlags _flags = VisualElementRendererFlags.AutoPackage | VisualElementRendererFlags.AutoTrack;
 
 		string _defaultContentDescription;
 		bool? _defaultFocusable;
 		string _defaultHint;
 		int? _defaultLabelFor;
-		InnerGestureListener _gestureListener;
+		
 		VisualElementPackager _packager;
 		PropertyChangedEventHandler _propertyChangeHandler;
-		Lazy<ScaleGestureDetector> _scaleDetector;
+
+		readonly GestureManager _gestureManager;
 
 		protected VisualElementRenderer() : base(Forms.Context)
 		{
-			_tapGestureHandler = new TapGestureHandler(() => View);
-			_panGestureHandler = new PanGestureHandler(() => View, Context.FromPixels);
-			_pinchGestureHandler = new PinchGestureHandler(() => View);
-
-			_gestureDetector =
-				new Lazy<GestureDetector>(
-					() =>
-					new GestureDetector(
-						_gestureListener =
-						new InnerGestureListener(_tapGestureHandler.OnTap, _tapGestureHandler.TapGestureRecognizers, _panGestureHandler.OnPan, _panGestureHandler.OnPanStarted, _panGestureHandler.OnPanComplete)));
-
-			_scaleDetector = new Lazy<ScaleGestureDetector>(
-					() => new ScaleGestureDetector(Context, new InnerScaleListener(_pinchGestureHandler.OnPinch, _pinchGestureHandler.OnPinchStarted, _pinchGestureHandler.OnPinchEnded))
-					);
+			_gestureManager = new GestureManager(this);
+		}
+
+		public override bool OnTouchEvent(MotionEvent e)
+		{
+			return _gestureManager.OnTouchEvent(e);
+		}
+
+		public override bool OnInterceptTouchEvent(MotionEvent ev)
+		{
+			if (!Enabled)
+			{
+				// If Enabled is false, prevent all the events from being dispatched to child Views
+				// and prevent them from being processed by this View as well
+				return true; // IOW, intercepted
+			}
+
+			return base.OnInterceptTouchEvent(ev);
+		}
+
+		public override bool DispatchTouchEvent(MotionEvent e)
+		{
+			if (InputTransparent)
+			{
+				// If the Element is InputTransparent, this ViewGroup will be marked InputTransparent
+				// If we're InputTransparent we should return false on all touch events without
+				// even bothering to send them to the child Views
+
+				return false; // IOW, not handled
+			}
+
+			return base.DispatchTouchEvent(e);
 		}
 
 		public TElement Element { get; private set; }
@@ -85,54 +98,6 @@ namespace Xamarin.Forms.Platform.Android
 				OnRegisterEffect(platformEffect);
 		}
 
-		void AView.IOnClickListener.OnClick(AView v)
-		{
-			_tapGestureHandler.OnSingleClick();
-		}
-
-		public override bool OnInterceptTouchEvent(MotionEvent ev)
-		{
-			if (!Element.IsEnabled || (Element.InputTransparent && Element.IsEnabled))
-			{
-				return true;
-			}
-
-			return base.OnInterceptTouchEvent(ev);
-		}
-
-		bool AView.IOnTouchListener.OnTouch(AView v, MotionEvent e)
-		{
-			if (!Element.IsEnabled)
-				return true;
-
-			if (Element.InputTransparent)
-				return false;
-
-			var handled = false;
-			if (_pinchGestureHandler.IsPinchSupported)
-			{
-				if (!_scaleDetector.IsValueCreated)
-					ScaleGestureDetectorCompat.SetQuickScaleEnabled(_scaleDetector.Value, true);
-				handled = _scaleDetector.Value.OnTouchEvent(e);
-			}
-
-			_gestureListener?.OnTouchEvent(e);
-
-			if (_gestureDetector.IsValueCreated && _gestureDetector.Value.Handle == IntPtr.Zero)
-			{
-				// This gesture detector has already been disposed, probably because it's on a cell which is going away
-				return handled;
-			}
-
-			// It's very important that the gesture detection happen first here
-			// if we check handled first, we might short-circuit and never check for tap/pan
-			handled = _gestureDetector.Value.OnTouchEvent(e) || handled;
-
-			v.EnsureLongClickCancellation(e, handled, Element);
-
-			return handled;
-		}
-
 		VisualElement IVisualElementRenderer.Element => Element;
 
 		event EventHandler<VisualElementChangedEventArgs> IVisualElementRenderer.ElementChanged
@@ -183,7 +148,6 @@ namespace Xamarin.Forms.Platform.Android
 			if (oldElement != null)
 			{
 				oldElement.PropertyChanged -= _propertyChangeHandler;
-				UnsubscribeGestureRecognizers(oldElement);
 			}
 
 			// element may be allowed to be passed as null in the future
@@ -198,19 +162,12 @@ namespace Xamarin.Forms.Platform.Android
 				_propertyChangeHandler = OnElementPropertyChanged;
 
 			element.PropertyChanged += _propertyChangeHandler;
-			SubscribeGestureRecognizers(element);
 
 			if (oldElement == null)
 			{
-				SetOnClickListener(this);
-				SetOnTouchListener(this);
 				SoundEffectsEnabled = false;
 			}
 
-			// must be updated AFTER SetOnClickListener is called
-			// SetOnClickListener implicitly calls Clickable = true
-			UpdateGestureRecognizers(true);
-
 			OnElementChanged(new ElementChangedEventArgs<TElement>(oldElement, element));
 
 			if (AutoPackage && _packager == null)
@@ -263,18 +220,6 @@ namespace Xamarin.Forms.Platform.Android
 					_packager = null;
 				}
 
-				if (_scaleDetector != null && _scaleDetector.IsValueCreated)
-				{
-					_scaleDetector.Value.Dispose();
-					_scaleDetector = null;
-				}
-
-				if (_gestureListener != null)
-				{
-					_gestureListener.Dispose();
-					_gestureListener = null;
-				}
-
 				if (ManageNativeControlLifetime)
 				{
 					int count = ChildCount;
@@ -290,7 +235,6 @@ namespace Xamarin.Forms.Platform.Android
 				if (Element != null)
 				{
 					Element.PropertyChanged -= _propertyChangeHandler;
-					UnsubscribeGestureRecognizers(Element);
 
 					if (Platform.GetRenderer(Element) == this)
 						Platform.SetRenderer(Element, null);
@@ -328,6 +272,7 @@ namespace Xamarin.Forms.Platform.Android
 				SetFocusable();
 			else if (e.PropertyName == VisualElement.InputTransparentProperty.PropertyName)
 				UpdateInputTransparent();
+			
 
 			ElementPropertyChanged?.Invoke(this, e);
 		}
@@ -441,11 +386,6 @@ namespace Xamarin.Forms.Platform.Android
 			element.SendViewInitialized(nativeView);
 		}
 
-		void HandleGestureRecognizerCollectionChanged(object sender, NotifyCollectionChangedEventArgs notifyCollectionChangedEventArgs)
-		{
-			UpdateGestureRecognizers();
-		}
-
 		void IVisualElementRenderer.SetLabelFor(int? id)
 		{
 			if (_defaultLabelFor == null)
@@ -453,47 +393,5 @@ namespace Xamarin.Forms.Platform.Android
 
 			LabelFor = (int)(id ?? _defaultLabelFor);
 		}
-
-		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 UpdateClickable(bool force = false)
-		{
-			var view = Element as View;
-			if (view == null)
-				return;
-
-			bool newValue = view.ShouldBeMadeClickable();
-			if (force || newValue)
-				Clickable = newValue;
-		}
-
-		void UpdateGestureRecognizers(bool forceClick = false)
-		{
-			if (View == null)
-				return;
-
-			UpdateClickable(forceClick);
-		}
 	}
 }
\ No newline at end of file