Fix DoubleTapped on touch (#7213)

DoubleTapped now can be triggered by touch
Fixed DoubleTapped triggering logic, previously it could be triggered only when you click twice, didn't work when you click 4 times,6, etc.
Fixed Tapped to be triggered only once when you double-click, now it triggers Tapped once and DoubleTapped once instead of triggering Tapped two times and DoubleTapped once.Matches UWP behaviour.

src/Avalonia.Input/Gestures.cs

@@ -6,6 +6,7 @@ namespace Avalonia.Input
 {
     public static class Gestures
     {
+        private static bool s_isDoubleTapped = false;
         public static readonly RoutedEvent<TappedEventArgs> TappedEvent = RoutedEvent.Register<TappedEventArgs>(
             "Tapped",
             RoutingStrategies.Bubble,
@@ -81,20 +82,23 @@ private static void PointerPressed(RoutedEventArgs ev)
                 var e = (PointerPressedEventArgs)ev;
                 var visual = (IVisual)ev.Source;
 
-#pragma warning disable CS0618 // Type or member is obsolete
-                var clickCount = e.ClickCount;
-#pragma warning restore CS0618 // Type or member is obsolete
-                if (clickCount <= 1)
+                if (e.ClickCount <= 1)
                 {
+                    s_isDoubleTapped = false;
                     s_lastPress.SetTarget(ev.Source);
                 }
-                else if (clickCount == 2 && e.GetCurrentPoint(visual).Properties.IsLeftButtonPressed)
+                else if (e.ClickCount % 2 == 0 && e.GetCurrentPoint(visual).Properties.IsLeftButtonPressed)
                 {
                     if (s_lastPress.TryGetTarget(out var target) && target == e.Source)
                     {
+                        s_isDoubleTapped = true;
                         e.Source.RaiseEvent(new TappedEventArgs(DoubleTappedEvent, e));
                     }
                 }
+                else
+                {
+                    s_isDoubleTapped = false;
+                }
             }
         }
 
@@ -112,7 +116,9 @@ private static void PointerReleased(RoutedEventArgs ev)
                         {
                             e.Source.RaiseEvent(new TappedEventArgs(RightTappedEvent, e));
                         }
-                        else
+                        //s_isDoubleTapped needed here to prevent invoking Tapped event when DoubleTapped is called.
+                        //This behaviour matches UWP behaviour.
+                        else if (s_isDoubleTapped == false)
                         {
                             e.Source.RaiseEvent(new TappedEventArgs(TappedEvent, e));
                         }

src/Avalonia.Input/PointerEventArgs.cs

@@ -114,7 +114,7 @@ public enum MouseButton
 
     public class PointerPressedEventArgs : PointerEventArgs
     {
-        private readonly int _obsoleteClickCount;
+        private readonly int _clickCount;
 
         public PointerPressedEventArgs(
             IInteractive source,
@@ -123,15 +123,14 @@ public PointerPressedEventArgs(
             ulong timestamp,
             PointerPointProperties properties,
             KeyModifiers modifiers,
-            int obsoleteClickCount = 1)
+            int clickCount = 1)
             : base(InputElement.PointerPressedEvent, source, pointer, rootVisual, rootVisualPosition,
                 timestamp, properties, modifiers)
         {
-            _obsoleteClickCount = obsoleteClickCount;
+            _clickCount = clickCount;
         }
 
-        [Obsolete("Use DoubleTapped event or Gestures.DoubleRightTapped attached event")]
-        public int ClickCount => _obsoleteClickCount;
+        public int ClickCount => _clickCount;
 
         [Obsolete("Use PointerPressedEventArgs.GetCurrentPoint(this).Properties")]
         public MouseButton MouseButton => Properties.PointerUpdateKind.GetMouseButton();

src/Avalonia.Input/TouchDevice.cs

@@ -2,7 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using Avalonia.Input.Raw;
-using Avalonia.VisualTree;
+using Avalonia.Platform;
 
 namespace Avalonia.Input
 {
@@ -16,7 +16,9 @@ public class TouchDevice : IInputDevice, IDisposable
     {
         private readonly Dictionary<long, Pointer> _pointers = new Dictionary<long, Pointer>();
         private bool _disposed;
-
+        private int _clickCount;
+        private Rect _lastClickRect;
+        private ulong _lastClickTime;
         KeyModifiers GetKeyModifiers(RawInputModifiers modifiers) =>
             (KeyModifiers)(modifiers & RawInputModifiers.KeyboardMask);
 
@@ -27,10 +29,10 @@ RawInputModifiers GetModifiers(RawInputModifiers modifiers, bool isLeftButtonDow
                 rv |= RawInputModifiers.LeftMouseButton;
             return rv;
         }
-        
+
         public void ProcessRawEvent(RawInputEventArgs ev)
         {
-            if(_disposed)
+            if (_disposed)
                 return;
             var args = (RawTouchEventArgs)ev;
             if (!_pointers.TryGetValue(args.TouchPointId, out var pointer))
@@ -43,16 +45,40 @@ public void ProcessRawEvent(RawInputEventArgs ev)
                     PointerType.Touch, _pointers.Count == 0);
                 pointer.Capture(hit);
             }
-            
+
 
             var target = pointer.Captured ?? args.Root;
             if (args.Type == RawPointerEventType.TouchBegin)
             {
+                if (_pointers.Count > 1)
+                {
+                    _clickCount = 1;
+                    _lastClickTime = 0;
+                    _lastClickRect = new Rect();
+                }
+                else
+                {
+                    var settings = AvaloniaLocator.Current.GetService<IPlatformSettings>();
+                    if (settings == null)
+                    {
+                        throw new Exception("IPlatformSettings can not be null");
+                    }
+                    if (!_lastClickRect.Contains(args.Position)
+                        || ev.Timestamp - _lastClickTime > settings.DoubleClickTime.TotalMilliseconds)
+                    {
+                        _clickCount = 0;
+                    }
+                    ++_clickCount;
+                    _lastClickTime = ev.Timestamp;
+                    _lastClickRect = new Rect(args.Position, new Size())
+                        .Inflate(new Thickness(16, 16));
+                }
+
                 target.RaiseEvent(new PointerPressedEventArgs(target, pointer,
                     args.Root, args.Position, ev.Timestamp,
                     new PointerPointProperties(GetModifiers(args.InputModifiers, true),
                         PointerUpdateKind.LeftButtonPressed),
-                    GetKeyModifiers(args.InputModifiers)));
+                    GetKeyModifiers(args.InputModifiers), _clickCount));
             }
 
             if (args.Type == RawPointerEventType.TouchEnd)
@@ -84,19 +110,19 @@ public void ProcessRawEvent(RawInputEventArgs ev)
                     GetKeyModifiers(args.InputModifiers)));
             }
 
-            
+
         }
 
         public void Dispose()
         {
-            if(_disposed)
+            if (_disposed)
                 return;
             var values = _pointers.Values.ToList();
             _pointers.Clear();
             _disposed = true;
             foreach (var p in values)
                 p.Dispose();
         }
-        
+
     }
 }