Added initial touch support to the Forms views:

- iOS
 - Android
 - macOS

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Android/SKTouchHandler.cs

@@ -0,0 +1,91 @@
+using System;
+using Android.Views;
+
+namespace SkiaSharp.Views.Forms
+{
+	internal class SKTouchHandler
+	{
+		private Action<SKTouchActionEventArgs> onTouchAction;
+		private Func<float, float> scalePixels;
+
+		public SKTouchHandler(Action<SKTouchActionEventArgs> onTouchAction, Func<float, float> scalePixels)
+		{
+			this.onTouchAction = onTouchAction;
+			this.scalePixels = scalePixels;
+		}
+
+		public void Attach(View view)
+		{
+			view.Touch += OnTouch;
+		}
+
+		public void Detach(View view)
+		{
+			// clean the view
+			if (view != null)
+			{
+				view.Touch -= OnTouch;
+			}
+
+			// remove references
+			onTouchAction = null;
+			scalePixels = null;
+		}
+
+		private void OnTouch(object sender, View.TouchEventArgs e)
+		{
+			if (onTouchAction == null || scalePixels == null)
+				return;
+
+			var evt = e.Event;
+			var pointer = evt.ActionIndex;
+
+			var id = evt.GetPointerId(pointer);
+			var coords = new SKPoint(scalePixels(evt.GetX(pointer)), scalePixels(evt.GetY(pointer)));
+
+			switch (evt.ActionMasked)
+			{
+				case MotionEventActions.Down:
+				case MotionEventActions.PointerDown:
+					{
+						var args = new SKTouchActionEventArgs(id, SKTouchActionType.Pressed, coords);
+						onTouchAction(args);
+						e.Handled = args.Handled;
+						break;
+					}
+
+				case MotionEventActions.Move:
+					{
+						var count = evt.PointerCount;
+						for (pointer = 0; pointer < count; pointer++)
+						{
+							id = evt.GetPointerId(pointer);
+							coords = new SKPoint(scalePixels(evt.GetX(pointer)), scalePixels(evt.GetY(pointer)));
+
+							var args = new SKTouchActionEventArgs(id, SKTouchActionType.Moved, coords);
+							onTouchAction(args);
+							e.Handled = e.Handled || args.Handled;
+						}
+						break;
+					}
+
+				case MotionEventActions.Up:
+				case MotionEventActions.PointerUp:
+					{
+						var args = new SKTouchActionEventArgs(id, SKTouchActionType.Released, coords);
+						onTouchAction(args);
+						e.Handled = args.Handled;
+						break;
+					}
+
+				case MotionEventActions.Cancel:
+					{
+						var args = new SKTouchActionEventArgs(id, SKTouchActionType.Cancelled, coords);
+						onTouchAction(args);
+						e.Handled = args.Handled;
+						break;
+					}
+			}
+		}
+	}
+}

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Android/SkiaSharp.Views.Forms.Android.csproj

@@ -85,6 +85,7 @@
     <Compile Include="SKCanvasViewRenderer.cs" />
     <Compile Include="SKGLViewRenderer.cs" />
     <Compile Include="SKImageSourceHandler.cs" />
+    <Compile Include="SKTouchHandler.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="packages.config" />

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Mac/SKTouchHandler.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Linq;
+using Foundation;
+using AppKit;
+
+namespace SkiaSharp.Views.Forms
+{
+	internal class SKTouchHandler : NSGestureRecognizer
+	{
+		private Action<SKTouchActionEventArgs> onTouchAction;
+		private Func<nfloat, nfloat> scalePixels;
+
+		public SKTouchHandler(Action<SKTouchActionEventArgs> onTouchAction, Func<nfloat, nfloat> scalePixels)
+		{
+			this.onTouchAction = onTouchAction;
+			this.scalePixels = scalePixels;
+		}
+
+		public void Attach(NSView view)
+		{
+			view.AddGestureRecognizer(this);
+		}
+
+		public void Detach(NSView view)
+		{
+			// clean the view
+			if (view != null)
+			{
+				view.RemoveGestureRecognizer(this);
+			}
+
+			// remove references
+			onTouchAction = null;
+			scalePixels = null;
+		}
+
+		public override void MouseDown(NSEvent mouseEvent)
+		{
+			base.MouseDown(mouseEvent);
+
+			FireEvent(SKTouchActionType.Pressed, mouseEvent);
+		}
+
+		public override void MouseUp(NSEvent mouseEvent)
+		{
+			base.MouseUp(mouseEvent);
+
+			FireEvent(SKTouchActionType.Released, mouseEvent);
+		}
+
+		public override void MouseDragged(NSEvent mouseEvent)
+		{
+			base.MouseDragged(mouseEvent);
+
+			FireEvent(SKTouchActionType.Moved, mouseEvent);
+		}
+
+		private bool FireEvent(SKTouchActionType actionType, NSEvent mouseEvent)
+		{
+			if (onTouchAction == null || scalePixels == null)
+				return false;
+
+			var id = mouseEvent.ButtonNumber;
+
+			var cgPoint = LocationInView(View);
+			// flip the Y coordinate for macOS
+			cgPoint.Y = View.Bounds.Height - cgPoint.Y;
+
+			var point = new SKPoint((float)scalePixels(cgPoint.X), (float)scalePixels(cgPoint.Y));
+
+			var args = new SKTouchActionEventArgs(id, actionType, point);
+			onTouchAction(args);
+			return args.Handled;
+		}
+	}
+}

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Mac/SkiaSharp.Views.Forms.Mac.csproj

@@ -61,6 +61,7 @@
     <Compile Include="SKCanvasViewRenderer.cs" />
     <Compile Include="SKGLViewRenderer.cs" />
     <Compile Include="SKImageSourceHandler.cs" />
+    <Compile Include="SKTouchHandler.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\SkiaSharp.Views\SkiaSharp.Views.Mac\SkiaSharp.Views.Mac.csproj">

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Native.Shared/SKCanvasViewRendererBase.cs

@@ -27,6 +27,25 @@ namespace SkiaSharp.Views.Forms
 		where TFormsView : SKFormsView
 		where TNativeView : SKNativeView
 	{
+		private readonly SKTouchHandler touchHandler;
+
+		public SKCanvasViewRendererBase()
+		{
+#if __ANDROID__
+			touchHandler = new SKTouchHandler(
+				args => ((ISKCanvasViewController)Element).OnTouchAction(args),
+				coord => Element.IgnorePixelScaling ? (float)Context.FromPixels(coord) : coord);
+#elif __IOS__
+			touchHandler = new SKTouchHandler(
+				args => ((ISKCanvasViewController)Element).OnTouchAction(args),
+				coord => Element.IgnorePixelScaling ? coord : coord * Control.ContentScaleFactor);
+#elif __MACOS__
+			touchHandler = new SKTouchHandler(
+				args => ((ISKCanvasViewController)Element).OnTouchAction(args),
+				coord => Element.IgnorePixelScaling ? coord : coord * Control.Window.BackingScaleFactor);
+#endif
+		}
+
 		protected override void OnElementChanged(ElementChangedEventArgs<TFormsView> e)
 		{
 			if (e.OldElement != null)
@@ -47,6 +66,7 @@ namespace SkiaSharp.Views.Forms
 				{
 					var view = CreateNativeControl();
 					view.PaintSurface += OnPaintSurface;
+					touchHandler.Attach(view);
 					SetNativeControl(view);
 				}
 
@@ -102,6 +122,9 @@ namespace SkiaSharp.Views.Forms
 				control.PaintSurface -= OnPaintSurface;
 			}
 
+			// detach, regardless of state
+			touchHandler.Detach(control);
+
 			base.Dispose(disposing);
 		}
 

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Native.Shared/SKGLViewRendererBase.cs

@@ -28,6 +28,15 @@ namespace SkiaSharp.Views.Forms
 		where TFormsView : SKFormsView
 		where TNativeView : SKNativeView
 	{
+		private readonly SKTouchHandler touchHandler;
+
+		public SKGLViewRendererBase()
+		{
+			touchHandler = new SKTouchHandler(
+				args => ((ISKGLViewController)Element).OnTouchAction(args),
+				coord => coord);
+		}
+
 		protected override void OnElementChanged(ElementChangedEventArgs<TFormsView> e)
 		{
 			if (e.OldElement != null)
@@ -52,6 +61,7 @@ namespace SkiaSharp.Views.Forms
 #else
 					view.PaintSurface += OnPaintSurface;
 #endif
+					touchHandler.Attach(view);
 					SetNativeControl(view);
 				}
 
@@ -108,6 +118,9 @@ namespace SkiaSharp.Views.Forms
 #endif
 			}
 
+			// detach, regardless of state
+			touchHandler.Detach(control);
+
 			base.Dispose(disposing);
 		}
 

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Shared/SKCanvasView.cs

@@ -12,6 +12,9 @@ namespace SkiaSharp.Views.Forms
 		// the user can subscribe to repaint
 		public event EventHandler<SKPaintSurfaceEventArgs> PaintSurface;
 
+		// the user can subscribe to touch events
+		public event EventHandler<SKTouchActionEventArgs> TouchAction;
+
 		// the native listens to this event
 		private event EventHandler SurfaceInvalidated;
 		private event EventHandler<GetCanvasSizeEventArgs> GetCanvasSize;
@@ -47,6 +50,12 @@ namespace SkiaSharp.Views.Forms
 			PaintSurface?.Invoke(this, e);
 		}
 
+		// the native view responds to a touch
+		protected virtual void OnTouchAction(SKTouchActionEventArgs e)
+		{
+			TouchAction?.Invoke(this, e);
+		}
+
 		// ISKViewController implementation
 
 		event EventHandler ISKCanvasViewController.SurfaceInvalidated
@@ -66,6 +75,11 @@ namespace SkiaSharp.Views.Forms
 			OnPaintSurface(e);
 		}
 
+		void ISKCanvasViewController.OnTouchAction(SKTouchActionEventArgs e)
+		{
+			OnTouchAction(e);
+		}
+
 		protected override SizeRequest OnMeasure(double widthConstraint, double heightConstraint)
 		{
 			return new SizeRequest(new Size(40.0, 40.0));
@@ -80,5 +94,8 @@ namespace SkiaSharp.Views.Forms
 
 		// the native view tells the user to repaint
 		void OnPaintSurface(SKPaintSurfaceEventArgs e);
+
+		// the native view responds to a touch
+		void OnTouchAction(SKTouchActionEventArgs e);
 	}
 }

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Shared/SKGLView.cs

@@ -17,6 +17,9 @@ namespace SkiaSharp.Views.Forms
 
 		// the user can subscribe to repaint
 		public event EventHandler<SKPaintGLSurfaceEventArgs> PaintSurface;
+	
+		// the user can subscribe to touch events
+		public event EventHandler<SKTouchActionEventArgs> TouchAction;
 
 		// the native listens to this event
 		private event EventHandler SurfaceInvalidated;
@@ -46,6 +49,12 @@ namespace SkiaSharp.Views.Forms
 		{
 			PaintSurface?.Invoke(this, e);
 		}
+	
+		// the native view responds to a touch
+		protected virtual void OnTouchAction(SKTouchActionEventArgs e)
+		{
+			TouchAction?.Invoke(this, e);
+		}
 
 		// ISKViewController implementation
 
@@ -66,6 +75,11 @@ namespace SkiaSharp.Views.Forms
 			OnPaintSurface(e);
 		}
 
+		void ISKGLViewController.OnTouchAction(SKTouchActionEventArgs e)
+		{
+			OnTouchAction(e);
+		}
+
 		protected override SizeRequest OnMeasure(double widthConstraint, double heightConstraint)
 		{
 			return new SizeRequest(new Size(40.0, 40.0));
@@ -80,5 +94,8 @@ namespace SkiaSharp.Views.Forms
 
 		// the native view tells the user to repaint
 		void OnPaintSurface(SKPaintGLSurfaceEventArgs e);
+
+		// the native view responds to a touch
+		void OnTouchAction(SKTouchActionEventArgs e);
 	}
 }

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Shared/SKTouchActionEventArgs.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Linq;
+
+namespace SkiaSharp.Views.Forms
+{
+	public class SKTouchActionEventArgs : EventArgs
+	{
+		public SKTouchActionEventArgs(long id, SKTouchActionType type, SKPoint[] locations)
+		{
+			Id = id;
+			Type = type;
+			Locations = locations ?? new SKPoint[0];
+			Handled = true;
+		}
+
+		public SKTouchActionEventArgs(long id, SKTouchActionType type, SKPoint location)
+		{
+			Id = id;
+			Type = type;
+			Locations = new[] { location };
+			Handled = true;
+		}
+
+		// this may be removed, but for now keep it
+		internal bool Handled { get; set; }
+
+		public long Id { get; private set; }
+
+		public SKTouchActionType Type { get; private set; }
+
+		public SKPoint[] Locations { get; private set; }
+
+		public SKPoint Location => Locations.FirstOrDefault();
+
+		public bool InContact => Type == SKTouchActionType.Pressed || Type == SKTouchActionType.Moved;
+	}
+
+	public enum SKTouchActionType
+	{
+		Pressed,
+		Moved,
+		Released,
+		Cancelled
+	}
+}

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Shared/SkiaSharp.Views.Forms.Shared.projitems

@@ -17,5 +17,6 @@
     <Compile Include="$(MSBuildThisFileDirectory)SKCanvasView.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)RendererTypes.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)SKImageSource.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)SKTouchActionEventArgs.cs" />
   </ItemGroup>
 </Project>

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.iOS/SKCanvasViewRenderer.cs

@@ -13,7 +13,6 @@ namespace SkiaSharp.Views.Forms
 		{
 			var view = base.CreateNativeControl();
 
-			view.UserInteractionEnabled = false;
 			// Force the opacity to false for consistency with the other platforms
 			view.Opaque = false;
 

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.iOS/SKGLViewRenderer.cs

@@ -17,7 +17,6 @@ namespace SkiaSharp.Views.Forms
 		{
 			var view = base.CreateNativeControl();
 
-			view.UserInteractionEnabled = false;
 			// Force the opacity to false for consistency with the other platforms
 			view.Opaque = false;
 

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.iOS/SKTouchHandler.cs

@@ -0,0 +1,92 @@
+using System;
+using System.Linq;
+using Foundation;
+using UIKit;
+
+namespace SkiaSharp.Views.Forms
+{
+	internal class SKTouchHandler : UIGestureRecognizer
+	{
+		private Action<SKTouchActionEventArgs> onTouchAction;
+		private Func<nfloat, nfloat> scalePixels;
+
+		public SKTouchHandler(Action<SKTouchActionEventArgs> onTouchAction, Func<nfloat, nfloat> scalePixels)
+		{
+			this.onTouchAction = onTouchAction;
+			this.scalePixels = scalePixels;
+		}
+
+		public void Attach(UIView view)
+		{
+			view.AddGestureRecognizer(this);
+		}
+
+		public void Detach(UIView view)
+		{
+			// clean the view
+			if (view != null)
+			{
+				view.RemoveGestureRecognizer(this);
+			}
+
+			// remove references
+			onTouchAction = null;
+			scalePixels = null;
+		}
+
+		public override void TouchesBegan(NSSet touches, UIEvent evt)
+		{
+			base.TouchesBegan(touches, evt);
+
+			foreach (UITouch touch in touches.Cast<UITouch>())
+			{
+				FireEvent(SKTouchActionType.Pressed, touch);
+			}
+		}
+
+		public override void TouchesMoved(NSSet touches, UIEvent evt)
+		{
+			base.TouchesMoved(touches, evt);
+
+			foreach (UITouch touch in touches.Cast<UITouch>())
+			{
+				FireEvent(SKTouchActionType.Moved, touch);
+			}
+		}
+
+		public override void TouchesEnded(NSSet touches, UIEvent evt)
+		{
+			base.TouchesEnded(touches, evt);
+
+			foreach (UITouch touch in touches.Cast<UITouch>())
+			{
+				FireEvent(SKTouchActionType.Released, touch);
+			}
+		}
+
+		public override void TouchesCancelled(NSSet touches, UIEvent evt)
+		{
+			base.TouchesCancelled(touches, evt);
+
+			foreach (UITouch touch in touches.Cast<UITouch>())
+			{
+				FireEvent(SKTouchActionType.Cancelled, touch);
+			}
+		}
+
+		private bool FireEvent(SKTouchActionType actionType, UITouch touch)
+		{
+			if (onTouchAction == null || scalePixels == null)
+				return false;
+
+			var id = touch.Handle.ToInt64();
+
+			var cgPoint = touch.LocationInView(View);
+			var point = new SKPoint((float)scalePixels(cgPoint.X), (float)scalePixels(cgPoint.Y));
+
+			var args = new SKTouchActionEventArgs(id, actionType, point);
+			onTouchAction(args);
+			return args.Handled;
+		}
+	}
+}

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.iOS/SkiaSharp.Views.Forms.iOS.csproj

@@ -69,6 +69,7 @@
     <Compile Include="SKGLViewRenderer.cs" />
     <Compile Include="SKCanvasViewRenderer.cs" />
     <Compile Include="SKImageSourceHandler.cs" />
+    <Compile Include="SKTouchHandler.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\..\Binding\SkiaSharp.iOS\SkiaSharp.iOS.csproj">