Introduced RawPointerPoint for usage with IntermediatePoints (#7581)

Introduced RawPointerPoint for usage with IntermediatePoints

Author: kekekeks

src/Avalonia.Input/MouseDevice.cs

@@ -273,7 +273,7 @@ private bool MouseDown(IMouseDevice device, ulong timestamp, IInputElement root,
         }
 
         private bool MouseMove(IMouseDevice device, ulong timestamp, IInputRoot root, Point p, PointerPointProperties properties,
-            KeyModifiers inputModifiers, IReadOnlyList<Point>? intermediatePoints)
+            KeyModifiers inputModifiers, Lazy<IReadOnlyList<RawPointerPoint>?>? intermediatePoints)
         {
             device = device ?? throw new ArgumentNullException(nameof(device));
             root = root ?? throw new ArgumentNullException(nameof(root));

src/Avalonia.Input/PointerEventArgs.cs

@@ -11,7 +11,7 @@ public class PointerEventArgs : RoutedEventArgs
         private readonly IVisual? _rootVisual;
         private readonly Point _rootVisualPosition;
         private readonly PointerPointProperties _properties;
-        private readonly IReadOnlyList<Point>? _previousPoints;
+        private Lazy<IReadOnlyList<RawPointerPoint>?>? _previousPoints;
 
         public PointerEventArgs(RoutedEvent routedEvent,
             IInteractive? source,
@@ -38,7 +38,7 @@ public PointerEventArgs(RoutedEvent routedEvent,
             ulong timestamp,
             PointerPointProperties properties,
             KeyModifiers modifiers,
-            IReadOnlyList<Point>? previousPoints)
+            Lazy<IReadOnlyList<RawPointerPoint>?>? previousPoints)
             : this(routedEvent, source, pointer, rootVisual, rootVisualPosition, timestamp, properties, modifiers)
         {
             _previousPoints = previousPoints;
@@ -121,13 +121,14 @@ public PointerPoint GetCurrentPoint(IVisual? relativeTo)
         /// <returns></returns>
         public IReadOnlyList<PointerPoint> GetIntermediatePoints(IVisual? relativeTo)
         {
-            if (_previousPoints == null || _previousPoints.Count == 0)
+            var previousPoints = _previousPoints?.Value;            
+            if (previousPoints == null || previousPoints.Count == 0)
                 return new[] { GetCurrentPoint(relativeTo) };
-            var points = new PointerPoint[_previousPoints.Count + 1];
-            for (var c = 0; c < _previousPoints.Count; c++)
+            var points = new PointerPoint[previousPoints.Count + 1];
+            for (var c = 0; c < previousPoints.Count; c++)
             {
-                var pt = _previousPoints[c];
-                points[c] = new PointerPoint(Pointer, GetPosition(pt, relativeTo), _properties);
+                var pt = previousPoints[c];
+                points[c] = new PointerPoint(Pointer, GetPosition(pt.Position, relativeTo), _properties);
             }
 
             points[points.Length - 1] = GetCurrentPoint(relativeTo);

src/Avalonia.Input/Raw/RawPointerEventArgs.cs

@@ -33,6 +33,8 @@ public enum RawPointerEventType
     /// </summary>
     public class RawPointerEventArgs : RawInputEventArgs
     {
+        private RawPointerPoint _point;
+        
         /// <summary>
         /// Initializes a new instance of the <see cref="RawPointerEventArgs"/> class.
         /// </summary>
@@ -58,11 +60,50 @@ public RawPointerEventArgs(
             Type = type;
             InputModifiers = inputModifiers;
         }
+        
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RawPointerEventArgs"/> class.
+        /// </summary>
+        /// <param name="device">The associated device.</param>
+        /// <param name="timestamp">The event timestamp.</param>
+        /// <param name="root">The root from which the event originates.</param>
+        /// <param name="type">The type of the event.</param>
+        /// <param name="point">The point properties and position, in client DIPs.</param>
+        /// <param name="inputModifiers">The input modifiers.</param>
+        public RawPointerEventArgs(
+            IInputDevice device,
+            ulong timestamp,
+            IInputRoot root,
+            RawPointerEventType type,
+            RawPointerPoint point, 
+            RawInputModifiers inputModifiers)
+            : base(device, timestamp, root)
+        {
+            Contract.Requires<ArgumentNullException>(device != null);
+            Contract.Requires<ArgumentNullException>(root != null);
+
+            Point = point;
+            Type = type;
+            InputModifiers = inputModifiers;
+        }
+
+        /// <summary>
+        /// Gets the pointer properties and position, in client DIPs.
+        /// </summary>
+        public RawPointerPoint Point
+        {
+            get => _point;
+            set => _point = value;
+        }
 
         /// <summary>
         /// Gets the mouse position, in client DIPs.
         /// </summary>
-        public Point Position { get; set; }
+        public Point Position
+        {
+            get => _point.Position;
+            set => _point.Position = value;
+        }
 
         /// <summary>
         /// Gets the type of the event.
@@ -78,6 +119,19 @@ public RawPointerEventArgs(
         /// Points that were traversed by a pointer since the previous relevant event,
         /// only valid for Move and TouchUpdate
         /// </summary>
-        public IReadOnlyList<Point>? IntermediatePoints { get; set; }
+        public Lazy<IReadOnlyList<RawPointerPoint>?>? IntermediatePoints { get; set; }
+    }
+
+    public struct RawPointerPoint
+    {
+        /// <summary>
+        /// Pointer position, in client DIPs.
+        /// </summary>
+        public Point Position { get; set; }
+        
+        public RawPointerPoint()
+        {
+            Position = default;
+        }
     }
 }

src/Shared/RawEventGrouping.cs

@@ -53,7 +53,7 @@ private void DispatchFromQueue()
 
             _eventCallback?.Invoke(ev);
 
-            if (ev is RawPointerEventArgs { IntermediatePoints: PooledList<Point> list }) 
+            if (ev is RawPointerEventArgs { IntermediatePoints.Value: PooledList<RawPointerPoint> list }) 
                 list.Dispose();
 
             if (Dispatcher.UIThread.HasJobsWithPriority(DispatcherPriority.Input + 1))
@@ -110,10 +110,14 @@ args is RawPointerEventArgs pointerEvent
         AddToQueue(args);
     }
 
+    private static IReadOnlyList<RawPointerPoint> GetPooledList() => new PooledList<RawPointerPoint>();
+    private static readonly Func<IReadOnlyList<RawPointerPoint>> s_getPooledListDelegate = GetPooledList;
+
     private static void MergeEvents(RawPointerEventArgs last, RawPointerEventArgs current)
     {
-        last.IntermediatePoints ??= new PooledList<Point>();
-        ((PooledList<Point>)last.IntermediatePoints).Add(last.Position);
+        
+        last.IntermediatePoints ??= new Lazy<IReadOnlyList<RawPointerPoint>?>(s_getPooledListDelegate);
+        ((PooledList<RawPointerPoint>)last.IntermediatePoints.Value!).Add(new RawPointerPoint { Position = last.Position });
         last.Position = current.Position;
         last.Timestamp = current.Timestamp;
         last.InputModifiers = current.InputModifiers;