Use Metal as a backend on Mac Catalyst

source/SkiaSharp.Views.Maui/SkiaSharp.Views.Maui.Core/Handlers/SKGLView/SKGLViewHandler.MacCatalyst.cs

@@ -1,19 +1,127 @@
 using System;
 using Microsoft.Maui.Handlers;
+using SkiaSharp.Views.iOS;
+using SkiaSharp.Views.Maui.Platform;
 using UIKit;
 
 namespace SkiaSharp.Views.Maui.Handlers
 {
-	public partial class SKGLViewHandler : ViewHandler<ISKGLView, UIView>
+	public partial class SKGLViewHandler : ViewHandler<ISKGLView, SKMetalView>
 	{
-		protected override UIView CreatePlatformView() => throw new PlatformNotSupportedException("OpenGL-based views (such as SKGLView) are not supported on Mac Catalyst. Instead, use Metal-based views.");
+		private SKSizeI lastCanvasSize;
+		private GRContext? lastGRContext;
+		private SKTouchHandler? touchHandler;
 
-		public static void MapIgnorePixelScaling(SKGLViewHandler handler, ISKGLView view) { }
+		protected override SKMetalView CreatePlatformView() =>
+			new MauiSKMetalView
+			{
+				BackgroundColor = UIColor.Clear,
+				Opaque = false,
+			};
 
-		public static void MapHasRenderLoop(SKGLViewHandler handler, ISKGLView view) { }
+		protected override void ConnectHandler(SKMetalView platformView)
+		{
+			platformView.PaintSurface += OnPaintSurface;
 
-		public static void MapEnableTouchEvents(SKGLViewHandler handler, ISKGLView view) { }
+			base.ConnectHandler(platformView);
+		}
 
-		public static void OnInvalidateSurface(SKGLViewHandler handler, ISKGLView view, object? args) { }
+		protected override void DisconnectHandler(SKMetalView platformView)
+		{
+			touchHandler?.Detach(platformView);
+			touchHandler = null;
+
+			platformView.PaintSurface -= OnPaintSurface;
+
+			base.DisconnectHandler(platformView);
+		}
+
+		// Mapper actions / properties
+
+		public static void OnInvalidateSurface(SKGLViewHandler handler, ISKGLView view, object? args)
+		{
+			if (handler.PlatformView.Paused && handler.PlatformView.EnableSetNeedsDisplay)
+				handler.PlatformView.SetNeedsDisplay();
+		}
+
+		public static void MapIgnorePixelScaling(SKGLViewHandler handler, ISKGLView view)
+		{
+			if (handler.PlatformView is MauiSKMetalView pv)
+			{
+				pv.IgnorePixelScaling = view.IgnorePixelScaling;
+				handler.PlatformView.SetNeedsDisplay();
+			}
+		}
+
+		public static void MapHasRenderLoop(SKGLViewHandler handler, ISKGLView view)
+		{
+			handler.PlatformView.Paused = !view.HasRenderLoop;
+			handler.PlatformView.EnableSetNeedsDisplay = !view.HasRenderLoop;
+		}
+
+		public static void MapEnableTouchEvents(SKGLViewHandler handler, ISKGLView view)
+		{
+			handler.touchHandler ??= new SKTouchHandler(
+				args => view.OnTouch(args),
+				(x, y) => handler.OnGetScaledCoord(x, y));
+
+			handler.touchHandler?.SetEnabled(handler.PlatformView, view.EnableTouchEvents);
+		}
+
+		// helper methods
+
+		private void OnPaintSurface(object? sender, iOS.SKPaintMetalSurfaceEventArgs e)
+		{
+			var newCanvasSize = e.Info.Size;
+			if (lastCanvasSize != newCanvasSize)
+			{
+				lastCanvasSize = newCanvasSize;
+				VirtualView?.OnCanvasSizeChanged(newCanvasSize);
+			}
+			if (sender is SKMetalView platformView)
+			{
+				var newGRContext = platformView.GRContext;
+				if (lastGRContext != newGRContext)
+				{
+					lastGRContext = newGRContext;
+					VirtualView?.OnGRContextChanged(newGRContext);
+				}
+			}
+
+			VirtualView?.OnPaintSurface(new SKPaintGLSurfaceEventArgs(e.Surface, e.BackendRenderTarget, e.Origin, e.Info, e.RawInfo));
+		}
+
+		private SKPoint OnGetScaledCoord(double x, double y)
+		{
+			if (VirtualView?.IgnorePixelScaling == false && PlatformView != null)
+			{
+				var scale = PlatformView.ContentScaleFactor;
+
+				x *= scale;
+				y *= scale;
+			}
+
+			return new SKPoint((float)x, (float)y);
+		}
+
+		private class MauiSKMetalView : SKMetalView
+		{
+			public bool IgnorePixelScaling { get; set; }
+
+			protected override void OnPaintSurface(iOS.SKPaintMetalSurfaceEventArgs e)
+			{
+				if (IgnorePixelScaling)
+				{
+					var userVisibleSize = new SKSizeI((int)Bounds.Width, (int)Bounds.Height);
+					var canvas = e.Surface.Canvas;
+					canvas.Scale((float)ContentScaleFactor);
+					canvas.Save();
+
+					e = new iOS.SKPaintMetalSurfaceEventArgs(e.Surface, e.BackendRenderTarget, e.Origin, e.Info.WithSize(userVisibleSize), e.Info);
+				}
+
+				base.OnPaintSurface(e);
+			}
+		}
 	}
 }

source/SkiaSharp.Views.Uno/SkiaSharp.Views.Uno.WinUI/SkiaSharp.Views.Uno.WinUI.csproj

@@ -65,7 +65,7 @@
     <Compile Remove="**\*.iOS.cs" />
     <None Include="**\*.iOS.cs" />
   </ItemGroup>
-  <!-- macOS -->
+  <!-- Mac Catalyst -->
   <ItemGroup Condition="!$(TargetFramework.Contains('-maccatalyst'))">
     <Compile Remove="**\MacCatalyst\**\*.cs" />
     <None Include="**\MacCatalyst\**\*.cs" />

source/SkiaSharp.Views/SkiaSharp.Views.Shared/GlesInterop/Gles.cs

@@ -1,4 +1,4 @@
-#if !__WASM__ && (!UNO_REFERENCE_API || (NET6_0_OR_GREATER && (__IOS__ || __MACOS__)))
+#if !__WASM__ && (!UNO_REFERENCE_API || (NET6_0_OR_GREATER && (__IOS__ || __MACOS__))) && !MACCATALYST
 // Note that `(!UNO_REFERENCE_API || (NET6_0_OR_GREATER && (__IOS__ || __MACOS__)))` is required
 // because of https://github.com/unoplatform/uno/issues/8814, where !UNO_REFERENCE_API should be enough.
 

source/SkiaSharp.Views/SkiaSharp.Views.Shared/SKPaintGLSurfaceEventArgs.cs

@@ -1,4 +1,5 @@
-using System;
+#if !MACCATALYST || HAS_UNO_WINUI
+using System;
 using System.ComponentModel;
 
 #if HAS_UNO_WINUI
@@ -68,3 +69,4 @@ public SKPaintGLSurfaceEventArgs(SKSurface surface, GRBackendRenderTarget render
 		public SKImageInfo RawInfo { get; private set; }
 	}
 }
+#endif

source/SkiaSharp.Views/SkiaSharp.Views/Platform/Apple/SKPaintMetalSurfaceEventArgs.cs

@@ -20,6 +20,23 @@ public SKPaintMetalSurfaceEventArgs(SKSurface surface, GRBackendRenderTarget ren
 			BackendRenderTarget = renderTarget;
 			ColorType = colorType;
 			Origin = origin;
+			Info = new SKImageInfo(renderTarget.Width, renderTarget.Height, ColorType);
+			RawInfo = Info;
+		}
+
+		public SKPaintMetalSurfaceEventArgs(SKSurface surface, GRBackendRenderTarget renderTarget, GRSurfaceOrigin origin, SKImageInfo info)
+			: this(surface, renderTarget, origin, info, info)
+		{
+		}
+
+		public SKPaintMetalSurfaceEventArgs(SKSurface surface, GRBackendRenderTarget renderTarget, GRSurfaceOrigin origin, SKImageInfo info, SKImageInfo rawInfo)
+		{
+			Surface = surface;
+			BackendRenderTarget = renderTarget;
+			ColorType = info.ColorType;
+			Origin = origin;
+			Info = info;
+			RawInfo = rawInfo;
 		}
 
 		public SKSurface Surface { get; private set; }
@@ -29,6 +46,10 @@ public SKPaintMetalSurfaceEventArgs(SKSurface surface, GRBackendRenderTarget ren
 		public SKColorType ColorType { get; private set; }
 
 		public GRSurfaceOrigin Origin { get; private set; }
+
+		public SKImageInfo Info { get; private set; }
+
+		public SKImageInfo RawInfo { get; private set; }
 	}
 }
 #endif