Add SKGLElement to SkiaSharp.Views.WPF

source/SkiaSharp.Views/SkiaSharp.Views.WPF/SKGLElement.cs

@@ -0,0 +1,221 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using OpenTK.Graphics;
+using System.Windows.Media.Media3D;
+using SkiaSharp.Views.Desktop;
+using OpenTK.Wpf;
+using SkiaSharp;
+using OpenTK.Graphics.OpenGL;
+using OpenTK.Platform.Windows;
+using OpenTK;
+using System.Windows.Interop;
+using OpenTK.Platform;
+#if NETCOREAPP || NET
+using OpenTK.Mathematics;
+#endif
+
+namespace SkiaSharp.Views.WPF
+{
+	[DefaultEvent("PaintSurface")]
+	[DefaultProperty("Name")]
+	public class SKGLElement : GLWpfControl, IDisposable
+	{
+		private const SKColorType colorType = SKColorType.Rgba8888;
+		private const GRSurfaceOrigin surfaceOrigin = GRSurfaceOrigin.BottomLeft;
+
+		private bool designMode;
+
+		private GRContext grContext;
+		private GRGlFramebufferInfo glInfo;
+		private GRBackendRenderTarget renderTarget;
+		private SKSurface surface;
+		private SKCanvas canvas;
+
+		private SKSizeI lastSize;
+
+		public SKGLElement()
+			: base()
+		{
+			Initialize();
+		}
+
+		private void Initialize()
+		{
+			designMode = DesignerProperties.GetIsInDesignMode(this);
+			var settings = new GLWpfControlSettings() { MajorVersion = 2, MinorVersion = 1, RenderContinuously = false };
+
+			this.Render += OnPaint;
+
+			this.Loaded += SKGLElement_Loaded;
+			this.Unloaded += SKGLElement_Unloaded;
+
+#if NETCOREAPP
+			this.RegisterToEventsDirectly = false;
+#endif
+
+			Start(settings);
+		}
+
+		private void SKGLElement_Unloaded(object sender, RoutedEventArgs e)
+		{
+			Release();
+		}
+		private void SKGLElement_Loaded(object sender, RoutedEventArgs e)
+		{
+			InvalidateVisual();
+		}
+
+		public SKSize CanvasSize => lastSize;
+
+		public GRContext GRContext => grContext;
+
+		[Category("Appearance")]
+		public event EventHandler<SKPaintGLSurfaceEventArgs> PaintSurface;
+
+		private SKSizeI GetSize()
+		{
+			var currentWidth = ActualWidth;
+			var currentHeight = ActualHeight;
+
+			if (currentWidth < 0 ||
+				currentHeight < 0)
+			{
+				currentWidth = 0;
+				currentHeight = 0;
+			}
+
+			PresentationSource source = PresentationSource.FromVisual(this);
+
+			double dpiX = 1.0;
+			double dpiY = 1.0;
+			if (source != null)
+			{
+				dpiX = source.CompositionTarget.TransformToDevice.M11;
+				dpiY = source.CompositionTarget.TransformToDevice.M22;
+			}
+
+			return new SKSizeI((int)(currentWidth * dpiX), (int)(currentHeight * dpiY));
+		}
+
+		protected override void OnRender(DrawingContext drawingContext)
+		{
+			if (grContext != null)
+			{
+				grContext.ResetContext();
+			}
+			base.OnRender(drawingContext);
+		}
+
+		protected virtual void OnPaint(TimeSpan e)
+		{
+			if (disposed)
+			{
+				return;
+			}
+			if (designMode)
+			{
+				return;
+			}
+
+			// create the contexts if not done already
+			if (grContext == null)
+			{
+				var glInterface = GRGlInterface.Create();
+				grContext = GRContext.CreateGl(glInterface);
+			}
+
+			// get the new surface size
+			var newSize = GetSize();
+
+			GL.ClearColor(Color4.Transparent);
+			GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit | ClearBufferMask.StencilBufferBit);
+
+			// manage the drawing surface
+			if (renderTarget == null || lastSize != newSize || !renderTarget.IsValid)
+			{
+
+				// create or update the dimensions
+				lastSize = newSize;
+
+				GL.GetInteger(GetPName.FramebufferBinding, out var framebuffer);
+				GL.GetInteger(GetPName.StencilBits, out var stencil);
+				GL.GetInteger(GetPName.Samples, out var samples);
+				var maxSamples = grContext.GetMaxSurfaceSampleCount(colorType);
+				if (samples > maxSamples)
+					samples = maxSamples;
+				glInfo = new GRGlFramebufferInfo((uint)framebuffer, colorType.ToGlSizedFormat());
+
+				// destroy the old surface
+				surface?.Dispose();
+				surface = null;
+				canvas = null;
+
+				// re-create the render target
+				renderTarget?.Dispose();
+				renderTarget = new GRBackendRenderTarget(newSize.Width, newSize.Height, samples, stencil, glInfo);
+			}
+
+			// create the surface
+			if (surface == null)
+			{
+				surface = SKSurface.Create(grContext, renderTarget, surfaceOrigin, colorType);
+				canvas = surface.Canvas;
+			}
+
+			using (new SKAutoCanvasRestore(canvas, true))
+			{
+				// start drawing
+				OnPaintSurface(new SKPaintGLSurfaceEventArgs(surface, renderTarget, surfaceOrigin, colorType));
+			}
+
+			// update the control
+			canvas.Flush();
+		}
+
+		protected virtual void OnPaintSurface(SKPaintGLSurfaceEventArgs e)
+		{
+			// invoke the event
+			PaintSurface?.Invoke(this, e);
+		}
+
+		private bool disposed = false;
+
+
+		protected virtual void Dispose(bool disposing)
+		{
+			if (disposed)
+			{
+				return;
+			}
+
+			Release();
+
+			disposed = true;
+		}
+
+		private void Release()
+		{
+			canvas = null;
+			surface?.Dispose();
+			surface = null;
+			renderTarget?.Dispose();
+			renderTarget = null;
+			grContext?.Dispose();
+			grContext = null;
+		}
+
+		public void Dispose()
+        {
+            Dispose(true);
+		}
+	}
+
+}

source/SkiaSharp.Views/SkiaSharp.Views.WPF/SkiaSharp.Views.WPF.csproj

@@ -7,8 +7,17 @@
     <PackagingGroup>SkiaSharp.Views.WPF</PackagingGroup>
     <DefineConstants>$(DefineConstants);__DESKTOP__;__WPF__</DefineConstants>
     <Title>SkiaSharp Views &amp; Layers for Windows Presentation Foundation (WPF)</Title>
+    <SignAssembly Condition="'$(TargetFramework)' != 'net462'">false</SignAssembly>
     <PackageTags>wpf</PackageTags>
   </PropertyGroup>
+  <ItemGroup Condition="'$(TargetFramework)' == 'net462'">
+    <PackageReference Include="OpenTK" Version="3.3.1" NoWarn="NU1701" />
+    <PackageReference Include="OpenTK.GLWpfControl" Version="3.3.0" NoWarn="NU1701" />
+  </ItemGroup>
+  <ItemGroup Condition="'$(TargetFramework)' != 'net462'">
+    <PackageReference Include="OpenTK" Version="4.3.0" NoWarn="NU1701" />
+    <PackageReference Include="OpenTK.GLWpfControl" Version="4.2.3" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\..\binding\SkiaSharp\SkiaSharp.csproj" />
     <ProjectReference Include="..\SkiaSharp.Views.Desktop.Common\SkiaSharp.Views.Desktop.Common.csproj" />