Refactoring GestureHandler for extension

 - Design : http://suprem.sec.samsung.net/confluence/display/SPTDTLC/Refactoring+GestureHandler

Change-Id: I1cbcf830b4b1076c227b0ea641508198c7cb2102
Signed-off-by: SungHyun Min <shyun.min@samsung.com>

1 files changed, 22 insertions, 271 deletions

diff --git a/Xamarin.Forms.Platform.Tizen/GestureHandler.cs b/Xamarin.Forms.Platform.Tizen/GestureHandler.cs
index 209da3e3..0d1bb93d 100644
--- a/Xamarin.Forms.Platform.Tizen/GestureHandler.cs
+++ b/Xamarin.Forms.Platform.Tizen/GestureHandler.cs
@@ -1,299 +1,50 @@
-using System.Linq;
-using System.Collections.ObjectModel;
-using System.Collections.Specialized;
-using System.Collections.Generic;
+using System;
+using System.ComponentModel;
 using ElmSharp;
-using EColor = ElmSharp.Color;
 
 namespace Xamarin.Forms.Platform.Tizen
 {
-	internal class GestureHandler
+	public abstract class GestureHandler : IGestureController, INotifyPropertyChanged, IRegisterable
 	{
-		internal readonly IVisualElementRenderer _renderer;
-		internal GestureLayer _gestureLayer;
-		View _view => _renderer.Element as View;
-		IPanGestureController _currentPanGestureController;
-		int _currentPanGestureId;
-		IPinchGestureController _currentPinchGestureController;
-		Point _currentScalePoint;
-		int _previousPinchRadius;
-		double _originalPinchScale;
-		Polygon _hitBox;
+		public IGestureRecognizer Recognizer { get; private set; }
 
-		public GestureHandler(IVisualElementRenderer renderer)
-		{
-			_renderer = renderer;
-			// Whenever a GestureRecognizer is added to the View, it will be connected to GestureLayer
-			(_view.GestureRecognizers as ObservableCollection<IGestureRecognizer>).CollectionChanged += OnGestureRecognizersChanged;
-			// handle GestureRecognizers which were already set by the time we got here
-			if (_view.GestureRecognizers.Count > 0)
-			{
-				CreateGestureLayer();
-				foreach (var item in _view.GestureRecognizers)
-					ToggleRecognizer(item, true);
-			}
-		}
-
-		public void Clear()
-		{
-			// this will clear all callbacks in ElmSharp GestureLayer
-			_gestureLayer.Unrealize();
-			(_view.GestureRecognizers as ObservableCollection<IGestureRecognizer>).CollectionChanged -= OnGestureRecognizersChanged;
-			if (_hitBox != null)
-			{
-				_hitBox.Unrealize();
-				_hitBox = null;
-			}
-		}
-
-		public void UpdateHitBox()
-		{
-			if (_hitBox == null)
-				return;
-			// _hitBox has to be used because gestures do not work well with transformations (EvasMap)
-			// so we create additional object which has the same shape as tranformed target, but does not have EvasMap on it
-			EvasObject target = _renderer.NativeView;
-			_hitBox.ClearPoints();
-			if (target.IsMapEnabled)
-			{
-				var map = target.EvasMap;
-				Point3D point;
-				for (var i = 0; i < 4; i++)
-				{
-					point = map.GetPointCoordinate(i);
-					_hitBox.AddPoint(point.X, point.Y);
-				}
-			}
-			else
-			{
-				var geometry = target.Geometry;
-				if (geometry.Width == 0 || geometry.Height == 0)
-					return;
-				_hitBox.AddPoint(geometry.Left, geometry.Top);
-				_hitBox.AddPoint(geometry.Right, geometry.Top);
-				_hitBox.AddPoint(geometry.Right, geometry.Bottom);
-				_hitBox.AddPoint(geometry.Left, geometry.Bottom);
-			}
-		}
-
-		protected void ToggleRecognizer(IGestureRecognizer recognizer, bool enable)
-		{
-			TapGestureRecognizer tapRecognizer;
-			PanGestureRecognizer panRecognizer;
-			PinchGestureRecognizer pinchRecognizer;
-
-			if ((tapRecognizer = recognizer as TapGestureRecognizer) != null)
-			{
-				ToggleTapRecognizer(tapRecognizer, enable);
-			}
-			else if ((panRecognizer = recognizer as PanGestureRecognizer) != null)
-			{
-				if (enable)
-					AddPanRecognizer(panRecognizer);
-				else
-					RemovePanRecognizer(panRecognizer);
-			}
-			else if ((pinchRecognizer = recognizer as PinchGestureRecognizer) != null)
-			{
-				if (enable)
-					AddPinchRecognizer(pinchRecognizer);
-				else
-					RemovePinchRecognizer(pinchRecognizer);
-			}
-			else
-			{
-				Log.Error("Unknown GestureRecognizer will be ignored: {0}", recognizer);
-			}
-		}
-
-		void ToggleTapRecognizer(TapGestureRecognizer recognizer, bool enable)
-		{
-			GestureLayer.GestureType type;
-			switch (recognizer.NumberOfTapsRequired)
-			{
-				case 1:
-					type = GestureLayer.GestureType.Tap;
-					break;
-				case 2:
-					type = GestureLayer.GestureType.DoubleTap;
-					break;
-				default:
-					type = GestureLayer.GestureType.TripleTap;
-					break;
-			}
-			if (enable)
-				_gestureLayer.SetTapCallback(type, GestureLayer.GestureState.End, (data) => recognizer.SendTapped(_view));
-			else
-				_gestureLayer.SetTapCallback(type, GestureLayer.GestureState.End, null);
-		}
-
-		void AddPanRecognizer(PanGestureRecognizer recognizer)
-		{
-			if (_currentPanGestureController != null)
-				Log.Warn("More than one PanGestureRecognizer on {0}. Only the last one will work.", _view);
-			EnsureHitBoxExists();
-			_currentPanGestureController = recognizer;
-			_gestureLayer.SetLineCallback(GestureLayer.GestureState.Start, OnPanStarted);
-			_gestureLayer.SetLineCallback(GestureLayer.GestureState.Move, OnPanMoved);
-			_gestureLayer.SetLineCallback(GestureLayer.GestureState.End, OnPanCompleted);
-			_gestureLayer.SetLineCallback(GestureLayer.GestureState.Abort, OnPanCancelled);
-		}
-
-		void RemovePanRecognizer(PanGestureRecognizer recognizer)
-		{
-			_gestureLayer.SetLineCallback(GestureLayer.GestureState.Start, null);
-			_gestureLayer.SetLineCallback(GestureLayer.GestureState.Move, null);
-			_gestureLayer.SetLineCallback(GestureLayer.GestureState.End, null);
-			_gestureLayer.SetLineCallback(GestureLayer.GestureState.Abort, null);
-			_currentPanGestureController = null;
-		}
-
-		void AddPinchRecognizer(PinchGestureRecognizer recognizer)
-		{
-			if (_currentPinchGestureController != null)
-				Log.Warn("More than one PinchGestureRecognizer on {0}. Only the last one will work.", _view);
-			EnsureHitBoxExists();
-			_currentPinchGestureController = recognizer;
-			_gestureLayer.SetZoomCallback(GestureLayer.GestureState.Start, OnPinchStarted);
-			_gestureLayer.SetZoomCallback(GestureLayer.GestureState.Move, OnPinchMoved);
-			_gestureLayer.SetZoomCallback(GestureLayer.GestureState.End, OnPinchCompleted);
-			_gestureLayer.SetZoomCallback(GestureLayer.GestureState.Abort, OnPinchCancelled);
-		}
-
-		void RemovePinchRecognizer(PinchGestureRecognizer recognizer)
-		{
-			_gestureLayer.SetZoomCallback(GestureLayer.GestureState.Start, null);
-			_gestureLayer.SetZoomCallback(GestureLayer.GestureState.Move, null);
-			_gestureLayer.SetZoomCallback(GestureLayer.GestureState.End, null);
-			_gestureLayer.SetZoomCallback(GestureLayer.GestureState.Abort, null);
-			_currentPinchGestureController = null;
-		}
-
-		void CreateGestureLayer()
-		{
-			_gestureLayer = new GestureLayer(_renderer.NativeView);
-			_gestureLayer.Attach(_renderer.NativeView);
-		}
+		public abstract GestureLayer.GestureType Type { get; }
 
-		void EnsureHitBoxExists()
-		{
-			if (_hitBox == null)
-			{
-				Box parent = (Platform.GetRenderer(_renderer.Element.RealParent) as LayoutRenderer).Control;
-				_hitBox = new Polygon(parent)
-				{
-					Color = EColor.Transparent
-				};
-				_hitBox.Show();
-				UpdateHitBox();
-				parent.PackAfter(_hitBox, _renderer.NativeView);
-				_gestureLayer.Attach(_hitBox);
-			}
-		}
+		public virtual double Timeout { get; }
 
-		void AddAndRemoveRecognizers(IEnumerable<IGestureRecognizer> removed, IEnumerable<IGestureRecognizer> added)
+		protected GestureHandler(IGestureRecognizer recognizer)
 		{
-			if (_hitBox == null &&
-				added != null &&
-				added.Any(item => (item is IPanGestureController || item is IPinchGestureController)))
-			{
-				// at least one of the added recognizers requires _hitBot, which is not ready
-				_gestureLayer.ClearCallbacks();
-				EnsureHitBoxExists();
-				// as _gestureLayer was reattached, register all callbacks, not only new ones
-				removed = null;
-				added = _view.GestureRecognizers;
-			}
-
-			if (removed != null)
-			{
-				foreach (var item in removed)
-					ToggleRecognizer(item, false);
-			}
-			if (added != null)
-			{
-				foreach (var item in added)
-					ToggleRecognizer(item, true);
-			}
+			Recognizer = recognizer;
 		}
 
-		void OnGestureRecognizersChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
-		{
-			// Gestures will be registered/unregistered according to changes in the GestureRecognizers list
-			switch (e.Action)
-			{
-				case NotifyCollectionChangedAction.Add:
-					if (_gestureLayer == null)
-						CreateGestureLayer();
-					AddAndRemoveRecognizers(null, e.NewItems.OfType<IGestureRecognizer>());
-					break;
+		public virtual event PropertyChangedEventHandler PropertyChanged;
 
-				case NotifyCollectionChangedAction.Replace:
-					AddAndRemoveRecognizers(e.OldItems.OfType<IGestureRecognizer>(), e.NewItems.OfType<IGestureRecognizer>());
-					break;
+		protected abstract void OnStarted(View sender, object data);
 
-				case NotifyCollectionChangedAction.Remove:
-					AddAndRemoveRecognizers(e.OldItems.OfType<IGestureRecognizer>(), null);
-					break;
+		protected abstract void OnMoved(View sender, object data);
 
-				case NotifyCollectionChangedAction.Reset:
-					AddAndRemoveRecognizers(_view.GestureRecognizers, null);
-					break;
-			}
-		}
+		protected abstract void OnCompleted(View sender, object data);
 
-		void OnPanStarted(GestureLayer.LineData data)
-		{
-			_currentPanGestureId++;
-			_currentPanGestureController.SendPanStarted(_view, _currentPanGestureId);
-		}
-
-		void OnPanMoved(GestureLayer.LineData data)
-		{
-			_currentPanGestureController.SendPan(_view, data.X2 - data.X1, data.Y2 - data.Y1, _currentPanGestureId);
-		}
-
-		void OnPanCompleted(GestureLayer.LineData data)
-		{
-			_currentPanGestureController.SendPanCompleted(_view, _currentPanGestureId);
-		}
-
-		void OnPanCancelled(GestureLayer.LineData data)
-		{
-			// don't trust ElmSharp that the gesture has been aborted, report that it is completed
-			_currentPanGestureController.SendPanCompleted(_view, _currentPanGestureId);
-		}
+		protected abstract void OnCanceled(View sender, object data);
 
-		void OnPinchStarted(GestureLayer.ZoomData data)
+		void IGestureController.SendStarted(View sender, object data)
 		{
-			var geometry = _renderer.NativeView.Geometry;
-			_currentScalePoint = new Point((data.X - geometry.X) / (double)geometry.Width, (data.Y - geometry.Y) / (double)geometry.Height);
-			_originalPinchScale = _view.Scale;
-			_previousPinchRadius = data.Radius;
-			_currentPinchGestureController.SendPinchStarted(_view, _currentScalePoint);
+			OnStarted(sender, data);
 		}
 
-		void OnPinchMoved(GestureLayer.ZoomData data)
+		void IGestureController.SendCompleted(View sender, object data)
 		{
-			if (_previousPinchRadius <= 0)
-				_previousPinchRadius = 1;
-			// functionality limitation: _currentScalePoint is not updated
-			_currentPinchGestureController.SendPinch(_view,
-				1 + _originalPinchScale * (data.Radius - _previousPinchRadius) / _previousPinchRadius,
-				_currentScalePoint
-			);
-			_previousPinchRadius = data.Radius;
+			OnCompleted(sender, data);
 		}
 
-		void OnPinchCompleted(GestureLayer.ZoomData data)
+		void IGestureController.SendMoved(View sender, object data)
 		{
-			_currentPinchGestureController.SendPinchEnded(_view);
+			OnMoved(sender, data);
 		}
 
-		void OnPinchCancelled(GestureLayer.ZoomData data)
+		void IGestureController.SendCanceled(View sender, object data)
 		{
-			// ElmSharp says the gesture has been aborted really too often, report completion instead
-			_currentPinchGestureController.SendPinchEnded(_view);
+			OnCanceled(sender, data);
 		}
 	}
-}
+}
\ No newline at end of file