replace IGestureRecognizer with abstrac GestureRecognizer. remove related obsolete interfaces.

src/Avalonia.Base/Input/GestureRecognizers/GestureRecognizer.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Avalonia.Input.GestureRecognizers
+{
+    public abstract class GestureRecognizer : StyledElement
+    {
+        public abstract IInputElement? Target { get; }
+        public abstract void Initialize(IInputElement target);
+        public abstract void PointerPressed(PointerPressedEventArgs e);
+        public abstract void PointerReleased(PointerReleasedEventArgs e);
+        public abstract void PointerMoved(PointerEventArgs e);
+        public abstract void PointerCaptureLost(IPointer pointer);
+
+        protected void Capture(IPointer pointer)
+        {
+            (pointer as Pointer)?.CaptureGestureRecognizer(this);
+        }
+    }
+}

src/Avalonia.Base/Input/GestureRecognizers/GestureRecognizerCollection.cs

@@ -6,26 +6,26 @@ using Avalonia.Reactive;
 
 namespace Avalonia.Input.GestureRecognizers
 {
-    public class GestureRecognizerCollection : IReadOnlyCollection<IGestureRecognizer>, IGestureRecognizerActionsDispatcher
+    public class GestureRecognizerCollection : IReadOnlyCollection<GestureRecognizer>
     {
         private readonly IInputElement _inputElement;
-        private List<IGestureRecognizer>? _recognizers;
+        private List<GestureRecognizer>? _recognizers;
 
         public GestureRecognizerCollection(IInputElement inputElement)
         {
             _inputElement = inputElement;
         }
 
-        public void Add(IGestureRecognizer recognizer)
+        public void Add(GestureRecognizer recognizer)
         {
             if (_recognizers == null)
             {
                 // We initialize the collection when the first recognizer is added
-                _recognizers = new List<IGestureRecognizer>();
+                _recognizers = new List<GestureRecognizer>();
             }
 
             _recognizers.Add(recognizer);
-            recognizer.Initialize(_inputElement, this);
+            recognizer.Initialize(_inputElement);
 
             // Hacks to make bindings work
 
@@ -38,16 +38,15 @@ namespace Avalonia.Input.GestureRecognizers
             }
         }
 
-        static readonly List<IGestureRecognizer> s_Empty = new List<IGestureRecognizer>();
+        static readonly List<GestureRecognizer> s_Empty = new List<GestureRecognizer>();
 
-        public IEnumerator<IGestureRecognizer> GetEnumerator()
+        public IEnumerator<GestureRecognizer> GetEnumerator()
             => _recognizers?.GetEnumerator() ?? s_Empty.GetEnumerator();
 
         IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
 
         public int Count => _recognizers?.Count ?? 0;
 
-
         internal bool HandlePointerPressed(PointerPressedEventArgs e)
         {
             if (_recognizers == null)
@@ -91,19 +90,5 @@ namespace Avalonia.Input.GestureRecognizers
             }
             return e.Handled;
         }
-
-        void IGestureRecognizerActionsDispatcher.Capture(IPointer pointer, IGestureRecognizer recognizer)
-        {
-            var p = pointer as Pointer;
-
-            p?.CaptureGestureRecognizer(recognizer);
-
-            foreach (var r in _recognizers!)
-            {
-                if (r != recognizer)
-                    r.PointerCaptureLost(pointer);
-            }
-        }
-
     }
 }

src/Avalonia.Base/Input/GestureRecognizers/IGestureRecognizer.cs

@@ -1,24 +0,0 @@
-namespace Avalonia.Input.GestureRecognizers
-{
-    public interface IGestureRecognizer
-    {
-        IInputElement? Target { get; }
-        void Initialize(IInputElement target, IGestureRecognizerActionsDispatcher actions);
-        void PointerPressed(PointerPressedEventArgs e);
-        void PointerReleased(PointerReleasedEventArgs e);
-        void PointerMoved(PointerEventArgs e);
-        void PointerCaptureLost(IPointer pointer);
-    }
-    
-    public interface IGestureRecognizerActionsDispatcher
-    {
-        void Capture(IPointer pointer, IGestureRecognizer recognizer);
-    }
-    
-    public enum GestureRecognizerResult
-    {
-        None,
-        Capture,
-        ReleaseCapture
-    }
-}

src/Avalonia.Base/Input/GestureRecognizers/PinchGestureRecognizer.cs

@@ -2,10 +2,9 @@
 
 namespace Avalonia.Input
 {
-    public class PinchGestureRecognizer : AvaloniaObject, IGestureRecognizer
+    public class PinchGestureRecognizer : GestureRecognizer
     {
         private IInputElement? _target;
-        private IGestureRecognizerActionsDispatcher? _actions;
         private float _initialDistance;
         private IPointer? _firstContact;
         private Point _firstPoint;
@@ -13,12 +12,11 @@ namespace Avalonia.Input
         private Point _secondPoint;
         private Point _origin;
 
-        public IInputElement? Target => _target;
+        public override IInputElement? Target => _target;
 
-        public void Initialize(IInputElement target, IGestureRecognizerActionsDispatcher actions)
+        public override void Initialize(IInputElement target)
         {
             _target = target;
-            _actions = actions;
         }
 
         private void OnPointerPressed(object? sender, PointerPressedEventArgs e)
@@ -31,12 +29,12 @@ namespace Avalonia.Input
             PointerReleased(e);
         }
 
-        public void PointerCaptureLost(IPointer pointer)
+        public override void PointerCaptureLost(IPointer pointer)
         {
             RemoveContact(pointer);
         }
 
-        public void PointerMoved(PointerEventArgs e)
+        public override void PointerMoved(PointerEventArgs e)
         {
             if (_target != null && _target is Visual visual)
             {
@@ -67,7 +65,7 @@ namespace Avalonia.Input
             }
         }
 
-        public void PointerPressed(PointerPressedEventArgs e)
+        public override void PointerPressed(PointerPressedEventArgs e)
         {
             if (_target != null && _target is Visual visual && (e.Pointer.Type == PointerType.Touch || e.Pointer.Type == PointerType.Pen))
             {
@@ -94,13 +92,13 @@ namespace Avalonia.Input
 
                     _origin = new Point((_firstPoint.X + _secondPoint.X) / 2.0f, (_firstPoint.Y + _secondPoint.Y) / 2.0f);
 
-                    _actions!.Capture(_firstContact, this);
-                    _actions!.Capture(_secondContact, this);
+                    Capture(_firstContact);
+                    Capture(_secondContact);
                 }
             }
         }
 
-        public void PointerReleased(PointerReleasedEventArgs e)
+        public override void PointerReleased(PointerReleasedEventArgs e)
         {
             RemoveContact(e.Pointer);
         }

src/Avalonia.Base/Input/GestureRecognizers/PullGestureRecognizer.cs

@@ -3,12 +3,11 @@ using Avalonia.Input.GestureRecognizers;
 
 namespace Avalonia.Input
 {
-    public class PullGestureRecognizer : AvaloniaObject, IGestureRecognizer
+    public class PullGestureRecognizer : GestureRecognizer
     {
         internal static int MinPullDetectionSize = 50;
 
         private IInputElement? _target;
-        private IGestureRecognizerActionsDispatcher? _actions;
         private Point _initialPosition;
         private int _gestureId;
         private IPointer? _tracking;
@@ -26,7 +25,7 @@ namespace Avalonia.Input
             set => SetValue(PullDirectionProperty, value);
         }
 
-        public IInputElement? Target => _target;
+        public override IInputElement? Target => _target;
 
         public PullGestureRecognizer(PullDirection pullDirection)
         {
@@ -35,13 +34,12 @@ namespace Avalonia.Input
 
         public PullGestureRecognizer() { }
 
-        public void Initialize(IInputElement target, IGestureRecognizerActionsDispatcher actions)
+        public override void Initialize(IInputElement target)
         {
             _target = target;
-            _actions = actions;
         }
 
-        public void PointerCaptureLost(IPointer pointer)
+        public override void PointerCaptureLost(IPointer pointer)
         {
             if (_tracking == pointer)
             {
@@ -49,12 +47,12 @@ namespace Avalonia.Input
             }
         }
 
-        public void PointerMoved(PointerEventArgs e)
+        public override void PointerMoved(PointerEventArgs e)
         {
             if (_tracking == e.Pointer && _target is Visual visual)
             {
                 var currentPosition = e.GetPosition(visual);
-                _actions!.Capture(e.Pointer, this);
+                Capture(e.Pointer);
                 e.PreventGestureRecognition();
 
                 Vector delta = default;
@@ -94,7 +92,7 @@ namespace Avalonia.Input
             }
         }
 
-        public void PointerPressed(PointerPressedEventArgs e)
+        public override void PointerPressed(PointerPressedEventArgs e)
         {
             if (_target != null && _target is Visual visual && (e.Pointer.Type == PointerType.Touch || e.Pointer.Type == PointerType.Pen))
             {
@@ -129,7 +127,7 @@ namespace Avalonia.Input
             }
         }
 
-        public void PointerReleased(PointerReleasedEventArgs e)
+        public override void PointerReleased(PointerReleasedEventArgs e)
         {
             if (_tracking == e.Pointer && _pullInProgress)
             {

src/Avalonia.Base/Input/GestureRecognizers/ScrollGestureRecognizer.cs

@@ -4,7 +4,7 @@ using Avalonia.Threading;
 
 namespace Avalonia.Input.GestureRecognizers
 {
-    public class ScrollGestureRecognizer : AvaloniaObject, IGestureRecognizer
+    public class ScrollGestureRecognizer : GestureRecognizer
     {
         // Pixels per second speed that is considered to be the stop of inertial scroll
         internal const double InertialScrollSpeedEnd = 5;
@@ -19,7 +19,6 @@ namespace Avalonia.Input.GestureRecognizers
         private Point _trackedRootPoint;
         private IPointer? _tracking;
         private IInputElement? _target;
-        private IGestureRecognizerActionsDispatcher? _actions;
         private int _gestureId;
         private Point _pointerPressedPoint;
         private VelocityTracker? _velocityTracker;
@@ -93,15 +92,14 @@ namespace Avalonia.Input.GestureRecognizers
             set => SetAndRaise(ScrollStartDistanceProperty, ref _scrollStartDistance, value);
         }
 
-        public IInputElement? Target => _target;
+        public override IInputElement? Target => _target;
 
-        public void Initialize(IInputElement target, IGestureRecognizerActionsDispatcher actions)
+        public override void Initialize(IInputElement target)
         {
             _target = target;
-            _actions = actions;
         }
         
-        public void PointerPressed(PointerPressedEventArgs e)
+        public override void PointerPressed(PointerPressedEventArgs e)
         {
             if (e.Pointer.IsPrimary && 
                 (e.Pointer.Type == PointerType.Touch || e.Pointer.Type == PointerType.Pen))
@@ -112,8 +110,8 @@ namespace Avalonia.Input.GestureRecognizers
                 _trackedRootPoint = _pointerPressedPoint = e.GetPosition((Visual?)_target);
             }
         }
-        
-        public void PointerMoved(PointerEventArgs e)
+
+        public override void PointerMoved(PointerEventArgs e)
         {
             if (e.Pointer == _tracking)
             {
@@ -133,7 +131,7 @@ namespace Avalonia.Input.GestureRecognizers
                             _trackedRootPoint.X - (_trackedRootPoint.X >= rootPoint.X ? ScrollStartDistance : -ScrollStartDistance),
                             _trackedRootPoint.Y - (_trackedRootPoint.Y >= rootPoint.Y ? ScrollStartDistance : -ScrollStartDistance));
 
-                        _actions!.Capture(e.Pointer, this);
+                        Capture(e.Pointer);
 
                         e.PreventGestureRecognition();
                     }
@@ -153,7 +151,7 @@ namespace Avalonia.Input.GestureRecognizers
             }
         }
 
-        public void PointerCaptureLost(IPointer pointer)
+        public override void PointerCaptureLost(IPointer pointer)
         {
             if (pointer == _tracking) EndGesture();
         }
@@ -173,7 +171,7 @@ namespace Avalonia.Input.GestureRecognizers
         }
 
 
-        public void PointerReleased(PointerReleasedEventArgs e)
+        public override void PointerReleased(PointerReleasedEventArgs e)
         {
             if (e.Pointer == _tracking && _scrolling)
             {

src/Avalonia.Base/Input/MouseDevice.cs

@@ -163,14 +163,11 @@ namespace Avalonia.Input
             device = device ?? throw new ArgumentNullException(nameof(device));
             root = root ?? throw new ArgumentNullException(nameof(root));
 
-            IInputElement? source;
-            if (_pointer.CapturedGestureRecognizer is IGestureRecognizer gestureRecognizer)
+            if (_pointer.CapturedGestureRecognizer is GestureRecognizer gestureRecognizer)
             {
-                source = gestureRecognizer.Target ?? hitTest;
-
-                if(source != null)
+                if(gestureRecognizer.Target != null)
                 {
-                    var e = new PointerEventArgs(InputElement.PointerMovedEvent, source, _pointer, (Visual)root,
+                    var e = new PointerEventArgs(InputElement.PointerMovedEvent, gestureRecognizer.Target, _pointer, (Visual)root,
                         p, timestamp, properties, inputModifiers, intermediatePoints);
                     gestureRecognizer.PointerMoved(e);
 
@@ -178,7 +175,7 @@ namespace Avalonia.Input
                 }
             }
 
-            source = _pointer.Captured ?? hitTest;
+            var source = _pointer.Captured ?? hitTest;
 
             if (source is object)
             {
@@ -198,15 +195,12 @@ namespace Avalonia.Input
         {
             device = device ?? throw new ArgumentNullException(nameof(device));
             root = root ?? throw new ArgumentNullException(nameof(root));
-
-            IInputElement? source;
-            if (_pointer.CapturedGestureRecognizer is IGestureRecognizer gestureRecognizer)
+            
+            if (_pointer.CapturedGestureRecognizer is GestureRecognizer gestureRecognizer)
             {
-                source = gestureRecognizer.Target ?? hitTest;
-
-                if (source != null)
+                if (gestureRecognizer.Target != null)
                 {
-                    var e = new PointerReleasedEventArgs(source, _pointer, (Visual)root, p, timestamp, props, inputModifiers,
+                    var e = new PointerReleasedEventArgs(gestureRecognizer.Target, _pointer, (Visual)root, p, timestamp, props, inputModifiers,
                     _lastMouseDownButton);
                     gestureRecognizer.PointerReleased(e);
 
@@ -214,7 +208,7 @@ namespace Avalonia.Input
                 }
             }
 
-            source = _pointer.Captured ?? hitTest;
+            var source = _pointer.Captured ?? hitTest;
 
             if (source is not null)
             {

src/Avalonia.Base/Input/PenDevice.cs

@@ -115,14 +115,11 @@ namespace Avalonia.Input
             KeyModifiers inputModifiers, IInputElement? hitTest,
             Lazy<IReadOnlyList<RawPointerPoint>?>? intermediatePoints)
         {
-            IInputElement? source;
-            if (pointer.CapturedGestureRecognizer is IGestureRecognizer gestureRecognizer)
+            if (pointer.CapturedGestureRecognizer is GestureRecognizer gestureRecognizer)
             {
-                source = gestureRecognizer.Target ?? hitTest;
-
-                if (source != null)
+                if (gestureRecognizer.Target != null)
                 {
-                    var e = new PointerEventArgs(InputElement.PointerMovedEvent, source, pointer, (Visual)root,
+                    var e = new PointerEventArgs(InputElement.PointerMovedEvent, gestureRecognizer.Target, pointer, (Visual)root,
                         p, timestamp, properties, inputModifiers, intermediatePoints);
                     gestureRecognizer.PointerMoved(e);
 
@@ -130,7 +127,7 @@ namespace Avalonia.Input
                 }
             }
 
-            source = pointer.Captured ?? hitTest;
+            var source = pointer.Captured ?? hitTest;
 
             if (source is not null)
             {
@@ -148,14 +145,11 @@ namespace Avalonia.Input
             IInputElement root, Point p, PointerPointProperties properties,
             KeyModifiers inputModifiers, IInputElement? hitTest)
         {
-            IInputElement? source;
-            if (pointer.CapturedGestureRecognizer is IGestureRecognizer gestureRecognizer)
+            if (pointer.CapturedGestureRecognizer is GestureRecognizer gestureRecognizer)
             {
-                source = gestureRecognizer.Target ?? hitTest;
-
-                if (source != null)
+                if (gestureRecognizer.Target != null)
                 {
-                    var e = new PointerReleasedEventArgs(source, pointer, (Visual)root, p, timestamp, properties, inputModifiers,
+                    var e = new PointerReleasedEventArgs(gestureRecognizer.Target, pointer, (Visual)root, p, timestamp, properties, inputModifiers,
                     _lastMouseDownButton);
                     gestureRecognizer.PointerReleased(e);
 
@@ -163,7 +157,7 @@ namespace Avalonia.Input
                 }
             }
 
-            source = pointer.Captured ?? hitTest;
+            var source = pointer.Captured ?? hitTest;
 
             if (source is not null)
             {

src/Avalonia.Base/Input/Pointer.cs

@@ -77,7 +77,7 @@ namespace Avalonia.Input
         /// <summary>
         /// Gets the gesture recognizer that is currently capturing by the pointer, if any.
         /// </summary>
-        internal IGestureRecognizer? CapturedGestureRecognizer { get; private set; }
+        internal GestureRecognizer? CapturedGestureRecognizer { get; private set; }
 
         public void Dispose()
         {
@@ -89,7 +89,7 @@ namespace Avalonia.Input
         /// </summary>
         /// <param name="gestureRecognizer">The gesture recognizer.</param>
         /// </remarks>
-        internal void CaptureGestureRecognizer(IGestureRecognizer? gestureRecognizer)
+        internal void CaptureGestureRecognizer(GestureRecognizer? gestureRecognizer)
         {
             if (CapturedGestureRecognizer != gestureRecognizer)
                 CapturedGestureRecognizer?.PointerCaptureLost(this);