Implement basic mouse support for macOS

Source/OxyPlot.Maui.Skia/AppHostBuilderExtensions.cs

@@ -14,7 +14,7 @@ public static MauiAppBuilder UseOxyPlotSkia(this MauiAppBuilder builder)
 #elif WINDOWS
             effects.Add<MyTouchEffect, Windows.Effects.PlatformTouchEffect>();
 #elif MACCATALYST
-            // not implemented
+            effects.Add<MyTouchEffect, macOS.Effects.PlatformTouchEffect>();
 #elif __IOS__
             effects.Add<MyTouchEffect, ios.Effects.PlatformTouchEffect>();
 #endif

Source/OxyPlot.Maui.Skia/Platforms/MacCatalyst/Effects/PlatformTouchEffect.cs

@@ -0,0 +1,129 @@
+using CoreGraphics;
+using Foundation;
+using Microsoft.Maui.Controls.Platform;
+using OxyPlot.Maui.Skia.Effects;
+using UIKit;
+
+namespace OxyPlot.Maui.Skia.macOS.Effects;
+
+public class PlatformTouchEffect : PlatformEffect
+{
+    private UIView _view;
+    private TouchRecognizer _touchRecognizer;
+    private MyTouchEffect _touchEffect;
+    protected override void OnAttached()
+    {
+        _view = Control ?? Container;
+        _touchEffect = Element.Effects.OfType<MyTouchEffect>().FirstOrDefault();
+
+        if (_touchEffect == null || _view == null) return;
+
+        _touchRecognizer = new TouchRecognizer(Element, _touchEffect);
+        _view.AddGestureRecognizer(_touchRecognizer);
+        _view.AddGestureRecognizer(GetMouseWheelRecognizer(_view));
+    }
+
+    protected override void OnDetached()
+    {
+        if (_touchRecognizer != null)
+        {
+            _touchRecognizer.Detach();
+            _view.RemoveGestureRecognizer(_touchRecognizer);
+        }
+    }
+
+    // https://github.com/dotnet/maui/issues/16130
+    private UIPanGestureRecognizer GetMouseWheelRecognizer(UIView v)
+    {
+        return new UIPanGestureRecognizer((e) =>
+        {
+            if (e.State == UIGestureRecognizerState.Ended)
+                return;
+
+            var isZoom = e.NumberOfTouches == 0;
+            if (!isZoom) return;
+
+            var l = e.LocationInView(v);
+            var t = e.TranslationInView(v);
+            var deltaX = t.X / 2;
+            var deltaY = t.Y / 2;
+            var delta = deltaY != 0 ? deltaY : deltaX;
+
+            var tolerance = 5;
+            if (Math.Abs(delta) < tolerance) return;
+
+            var pointerX = l.X - t.X;
+            var pointerY = l.Y - t.Y;
+            var locations = new[] { new Point(pointerX, pointerY) };
+
+            var eventArgs = new TouchActionEventArgs(0, TouchActionType.MouseWheel, locations, false)
+            {
+                MouseWheelDelta = (int)delta
+            };
+
+            _touchEffect.OnTouchAction(Element, eventArgs);
+        })
+        {
+            AllowedScrollTypesMask = UIScrollTypeMask.Discrete | UIScrollTypeMask.Continuous,
+            MinimumNumberOfTouches = 0,
+            ShouldRecognizeSimultaneously = (_, _) => true
+        };
+    }
+}
+
+internal class TouchRecognizer : UIGestureRecognizer
+{
+    private readonly Microsoft.Maui.Controls.Element _element;
+    private readonly MyTouchEffect _touchEffect;
+    private uint _activeTouchesCount = 0;
+
+    public TouchRecognizer(Microsoft.Maui.Controls.Element element, MyTouchEffect touchEffect)
+    {
+        this._element = element;
+        this._touchEffect = touchEffect;
+        ShouldRecognizeSimultaneously = (_, _) => true;
+    }
+
+    public void Detach()
+    {
+        ShouldRecognizeSimultaneously = null;
+    }
+
+    public override void TouchesBegan(NSSet touches, UIEvent evt)
+    {
+        base.TouchesBegan(touches, evt);
+        _activeTouchesCount += touches.Count.ToUInt32();
+        FireEvent(touches, TouchActionType.Pressed, true);
+    }
+
+    public override void TouchesMoved(NSSet touches, UIEvent evt)
+    {
+        base.TouchesMoved(touches, evt);
+
+        if (_activeTouchesCount == touches.Count.ToUInt32())
+        {
+            FireEvent(touches, TouchActionType.Moved, true);
+        }
+    }
+
+    public override void TouchesEnded(NSSet touches, UIEvent evt)
+    {
+        base.TouchesEnded(touches, evt);
+        _activeTouchesCount -= touches.Count.ToUInt32();
+        FireEvent(touches, TouchActionType.Released, false);
+    }
+
+    private void FireEvent(NSSet touches, TouchActionType actionType, bool isInContact)
+    {
+        UITouch[] uiTouches = touches.Cast<UITouch>().ToArray();
+        long id = ((IntPtr)uiTouches.First().Handle).ToInt64();
+        Point[] points = new Point[uiTouches.Length];
+
+        for (int i = 0; i < uiTouches.Length; i++)
+        {
+            CGPoint cgPoint = uiTouches[i].LocationInView(View);
+            points[i] = new(cgPoint.X, cgPoint.Y);
+        }
+        _touchEffect.OnTouchAction(_element, new(id, actionType, points, isInContact));
+    }
+}

Source/OxyPlot.Maui.Skia/PlotController.cs

@@ -17,8 +17,11 @@ public PlotController()
         this.BindTouchDown(cmd);
 
 #if WINDOWS
-            this.BindMouseWheel(OxyPlot.PlotCommands.ZoomWheel);
-            this.BindMouseWheel(OxyModifierKeys.Control, OxyPlot.PlotCommands.ZoomWheelFine);
+        this.BindMouseWheel(OxyPlot.PlotCommands.ZoomWheel);
+        this.BindMouseWheel(OxyModifierKeys.Control, OxyPlot.PlotCommands.ZoomWheelFine);
+#endif
+#if MACCATALYST
+        this.BindMouseWheel(OxyPlot.PlotCommands.ZoomWheel);
 #endif
     }
 }