Use tap size as default size for scrolling start. reset IsGestureRecognitionSkipped when pointer is released (#15524)

* use tap size as default size for scrolling start. reset IsGestureRecognitionSkipped when pointer is released

* use static default constant for scroll distance

* fix typo

Author: emmauss

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

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using Avalonia.Platform;
 using Avalonia.Threading;
 
 namespace Avalonia.Input.GestureRecognizers
@@ -13,7 +14,8 @@ public class ScrollGestureRecognizer : GestureRecognizer
         private bool _canHorizontallyScroll;
         private bool _canVerticallyScroll;
         private bool _isScrollInertiaEnabled;
-        private int _scrollStartDistance = 30;
+        private readonly static int s_defaultScrollStartDistance = (int)((AvaloniaLocator.Current?.GetService<IPlatformSettings>()?.GetTapSize(PointerType.Touch).Height ?? 10) / 2);
+        private int _scrollStartDistance = s_defaultScrollStartDistance;
 
         private bool _scrolling;
         private Point _trackedRootPoint;
@@ -54,7 +56,7 @@ public class ScrollGestureRecognizer : GestureRecognizer
         public static readonly DirectProperty<ScrollGestureRecognizer, int> ScrollStartDistanceProperty =
             AvaloniaProperty.RegisterDirect<ScrollGestureRecognizer, int>(nameof(ScrollStartDistance),
                 o => o.ScrollStartDistance, (o, v) => o.ScrollStartDistance = v,
-                unsetValue: 30);
+                unsetValue: s_defaultScrollStartDistance);
 
         /// <summary>
         /// Gets or sets a value indicating whether the content can be scrolled horizontally.

src/Avalonia.Base/Input/MouseDevice.cs

@@ -205,6 +205,7 @@ private bool MouseUp(IMouseDevice device, ulong timestamp, IInputRoot root, Poin
                 {
                     _pointer.Capture(null);
                     _pointer.CaptureGestureRecognizer(null);
+                    _pointer.IsGestureRecognitionSkipped = false;
                     _lastMouseDownButton = default;
                 }
                 return e.Handled;

src/Avalonia.Base/Input/PenDevice.cs

@@ -167,6 +167,7 @@ private bool PenUp(Pointer pointer, ulong timestamp,
                 {
                     pointer.Capture(null);
                     pointer.CaptureGestureRecognizer(null);
+                    pointer.IsGestureRecognitionSkipped = false;
                     _lastMouseDownButton = default;
                 }
 

src/Avalonia.Base/Input/TouchDevice.cs

@@ -119,6 +119,8 @@ public void ProcessRawEvent(RawInputEventArgs ev)
                 {
                     pointer?.Capture(null);
                     pointer?.CaptureGestureRecognizer(null);
+                    if (pointer != null)
+                        pointer.IsGestureRecognitionSkipped = false;
                 }
             }
 

tests/Avalonia.UnitTests/TouchTestHelper.cs

@@ -49,8 +49,7 @@ public void Up(Interactive target, Interactive source, Point position = default,
             else
                 source.RaiseEvent(e);
 
-            _pointer.Capture(null);
-            _pointer.CaptureGestureRecognizer(null);
+           Cancel();
         }
 
         public void Tap(Interactive target, Point position = default,  KeyModifiers modifiers = default)
@@ -66,6 +65,7 @@ public void Cancel()
         {
             _pointer.Capture(null);
             _pointer.CaptureGestureRecognizer(null);
+            _pointer.IsGestureRecognitionSkipped = false;
         }
     }
 }