Merge pull request #2371 from AvaloniaUI/expose-skcanvas

Custom draw operations, exposed SkCanvas and reduced Skia api visibility

samples/RenderDemo/MainWindow.xaml

@@ -33,6 +33,9 @@
       <TabItem Header="Drawing">
         <pages:DrawingPage/>
       </TabItem>
+      <TabItem Header="SkCanvas">
+        <pages:CustomSkiaPage/>
+      </TabItem>
     </TabControl>
   </DockPanel>
 </Window>

samples/RenderDemo/Pages/CustomSkiaPage.cs

@@ -0,0 +1,119 @@
+using System;
+using System.Diagnostics;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Media;
+using Avalonia.Platform;
+using Avalonia.Rendering.SceneGraph;
+using Avalonia.Skia;
+using Avalonia.Threading;
+using SkiaSharp;
+
+namespace RenderDemo.Pages
+{
+    public class CustomSkiaPage : Control
+    {
+        public CustomSkiaPage()
+        {
+            ClipToBounds = true;
+        }
+        
+        class CustomDrawOp : ICustomDrawOperation
+        {
+            private readonly FormattedText _noSkia;
+
+            public CustomDrawOp(Rect bounds, FormattedText noSkia)
+            {
+                _noSkia = noSkia;
+                Bounds = bounds;
+            }
+            
+            public void Dispose()
+            {
+                // No-op
+            }
+
+            public Rect Bounds { get; }
+            public bool HitTest(Point p) => false;
+            public bool Equals(ICustomDrawOperation other) => false;
+            static Stopwatch St = Stopwatch.StartNew();
+            public void Render(IDrawingContextImpl context)
+            {
+                var canvas = (context as ISkiaDrawingContextImpl)?.SkCanvas;
+                if (canvas == null)
+                    context.DrawText(Brushes.Black, new Point(), _noSkia.PlatformImpl);
+                else
+                {
+                    canvas.Save();
+                    // create the first shader
+                    var colors = new SKColor[] {
+                        new SKColor(0, 255, 255),
+                        new SKColor(255, 0, 255),
+                        new SKColor(255, 255, 0),
+                        new SKColor(0, 255, 255)
+                    };
+
+                    var sx = Animate(100, 2, 10);
+                    var sy = Animate(1000, 5, 15);
+                    var lightPosition = new SKPoint(
+                        (float)(Bounds.Width / 2 + Math.Cos(St.Elapsed.TotalSeconds) * Bounds.Width / 4),
+                        (float)(Bounds.Height / 2 + Math.Sin(St.Elapsed.TotalSeconds) * Bounds.Height / 4));
+                    using (var sweep =
+                        SKShader.CreateSweepGradient(new SKPoint((int)Bounds.Width / 2, (int)Bounds.Height / 2), colors,
+                            null)) 
+                    using(var turbulence = SKShader.CreatePerlinNoiseFractalNoise(0.05f, 0.05f, 4, 0))
+                    using(var shader = SKShader.CreateCompose(sweep, turbulence, SKBlendMode.SrcATop))
+                    using(var blur = SKImageFilter.CreateBlur(Animate(100, 2, 10), Animate(100, 5, 15)))
+                    using (var paint = new SKPaint
+                    {
+                        Shader = shader,
+                        ImageFilter = blur
+                    })
+                        canvas.DrawPaint(paint);
+                    
+                    using (var pseudoLight = SKShader.CreateRadialGradient(
+                        lightPosition,
+                        (float) (Bounds.Width/3),
+                        new [] { 
+                            new SKColor(255, 200, 200, 100), 
+                            SKColors.Transparent,
+                            new SKColor(40,40,40, 220), 
+                            new SKColor(20,20,20, (byte)Animate(100, 200,220)) },
+                        new float[] { 0.3f, 0.3f, 0.8f, 1 },
+                        SKShaderTileMode.Clamp))
+                    using (var paint = new SKPaint
+                    {
+                        Shader = pseudoLight
+                    })
+                        canvas.DrawPaint(paint);
+                    canvas.Restore();
+                }
+            }    
+            static int Animate(int d, int from, int to)
+            {
+                var ms = (int)(St.ElapsedMilliseconds / d);
+                var diff = to - from;
+                var range = diff * 2;
+                var v = ms % range;
+                if (v > diff)
+                    v = range - v;
+                var rv = v + from;
+                if (rv < from || rv > to)
+                    throw new Exception("WTF");
+                return rv;
+            }
+        }
+
+
+        
+        public override void Render(DrawingContext context)
+        {
+            var noSkia = new FormattedText()
+            {
+                Text = "Current rendering API is not Skia"
+            };
+            context.Custom(new CustomDrawOp(new Rect(0, 0, Bounds.Width, Bounds.Height), noSkia));
+            Dispatcher.UIThread.InvokeAsync(InvalidateVisual, DispatcherPriority.Background);
+        }
+    }
+}

src/Avalonia.Visuals/Media/DrawingContext.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using Avalonia.Media.Imaging;
 using Avalonia.Platform;
+using Avalonia.Rendering.SceneGraph;
 using Avalonia.Threading;
 using Avalonia.Visuals.Media.Imaging;
 
@@ -131,6 +132,12 @@ namespace Avalonia.Media
             }
         }
 
+        /// <summary>
+        /// Draws a custom drawing operation
+        /// </summary>
+        /// <param name="custom">custom operation</param>
+        public void Custom(ICustomDrawOperation custom) => PlatformImpl.Custom(custom);
+
         /// <summary>
         /// Draws text.
         /// </summary>

src/Avalonia.Visuals/Platform/IDrawingContextImpl.cs

@@ -3,6 +3,7 @@
 
 using System;
 using Avalonia.Media;
+using Avalonia.Rendering.SceneGraph;
 using Avalonia.Utilities;
 using Avalonia.Visuals.Media.Imaging;
 
@@ -139,5 +140,11 @@ namespace Avalonia.Platform
         /// Pops the latest pushed geometry clip.
         /// </summary>
         void PopGeometryClip();
+
+        /// <summary>
+        /// Adds a custom draw operation
+        /// </summary>
+        /// <param name="custom">Custom draw operation</param>
+        void Custom(ICustomDrawOperation custom);
     }
 }

src/Avalonia.Visuals/Rendering/SceneGraph/CustomDrawOperation.cs

@@ -0,0 +1,39 @@
+using System;
+using Avalonia.Media;
+using Avalonia.Platform;
+
+namespace Avalonia.Rendering.SceneGraph
+{
+    internal sealed class CustomDrawOperation : DrawOperation
+    {
+        public Matrix Transform { get; }
+        public ICustomDrawOperation Custom { get; }
+        public CustomDrawOperation(ICustomDrawOperation custom, Matrix transform) 
+            : base(custom.Bounds, transform, null)
+        {
+            Transform = transform;
+            Custom = custom;
+        }
+
+        public override bool HitTest(Point p)
+        {
+            return Custom.HitTest(p * Transform);
+        }
+
+        public override void Render(IDrawingContextImpl context)
+        {
+            context.Transform = Transform;
+            Custom.Render(context);
+        }
+
+        public override void Dispose() => Custom.Dispose();
+
+        public bool Equals(Matrix transform, ICustomDrawOperation custom) =>
+            Transform == transform && Custom?.Equals(custom) == true;
+    }
+
+    public interface ICustomDrawOperation : IDrawOperation, IEquatable<ICustomDrawOperation>
+    {
+        
+    }
+}

src/Avalonia.Visuals/Rendering/SceneGraph/DeferredDrawingContextImpl.cs

@@ -165,6 +165,15 @@ namespace Avalonia.Rendering.SceneGraph
                 ++_drawOperationindex;
             }
         }
+        
+        public void Custom(ICustomDrawOperation custom)
+        {
+            var next = NextDrawAs<CustomDrawOperation>();
+            if (next == null || !next.Item.Equals(Transform, custom))
+                Add(new CustomDrawOperation(custom, Transform));
+            else
+                ++_drawOperationindex;
+        }
 
         /// <inheritdoc/>
         public void DrawText(IBrush foreground, Point origin, IFormattedTextImpl text)

src/Skia/Avalonia.Skia/DrawingContextImpl.cs

@@ -9,6 +9,7 @@ using System.Threading;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.Rendering;
+using Avalonia.Rendering.SceneGraph;
 using Avalonia.Rendering.Utilities;
 using Avalonia.Utilities;
 using Avalonia.Visuals.Media.Imaging;
@@ -19,7 +20,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Skia based drawing context.
     /// </summary>
-    public class DrawingContextImpl : IDrawingContextImpl
+    internal class DrawingContextImpl : IDrawingContextImpl, ISkiaDrawingContextImpl
     {
         private IDisposable[] _disposables;
         private readonly Vector _dpi;
@@ -99,6 +100,8 @@ namespace Avalonia.Skia
         /// </summary>
         public SKCanvas Canvas { get; }
 
+        SKCanvas ISkiaDrawingContextImpl.SkCanvas => Canvas;
+
         /// <inheritdoc />
         public void Clear(Color color)
         {
@@ -296,6 +299,8 @@ namespace Avalonia.Skia
             Canvas.Restore();
         }
 
+        public void Custom(ICustomDrawOperation custom) => custom.Render(this);
+
         /// <inheritdoc />
         public void PushOpacityMask(IBrush mask, Rect bounds)
         {

src/Skia/Avalonia.Skia/FormattedTextImpl.cs

@@ -13,7 +13,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Skia formatted text implementation.
     /// </summary>
-    public class FormattedTextImpl : IFormattedTextImpl
+    internal class FormattedTextImpl : IFormattedTextImpl
     {
         public FormattedTextImpl(
             string text,

src/Skia/Avalonia.Skia/FramebufferRenderTarget.cs

@@ -13,7 +13,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Skia render target that renders to a framebuffer surface. No gpu acceleration available.
     /// </summary>
-    public class FramebufferRenderTarget : IRenderTarget
+    internal class FramebufferRenderTarget : IRenderTarget
     {
         private readonly IFramebufferPlatformSurface _platformSurface;
         private SKImageInfo _currentImageInfo;

src/Skia/Avalonia.Skia/GeometryImpl.cs

@@ -11,7 +11,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// A Skia implementation of <see cref="IGeometryImpl"/>.
     /// </summary>
-    public abstract class GeometryImpl : IGeometryImpl
+    internal abstract class GeometryImpl : IGeometryImpl
     {
         private PathCache _pathCache;
         

src/Skia/Avalonia.Skia/GlRenderTarget.cs

@@ -8,7 +8,7 @@ using static Avalonia.OpenGL.GlConsts;
 
 namespace Avalonia.Skia
 {
-    public class GlRenderTarget : IRenderTarget
+    internal class GlRenderTarget : IRenderTarget
     {
         private readonly GRContext _grContext;
         private IGlPlatformSurfaceRenderTarget _surface;

src/Skia/Avalonia.Skia/ISkiaDrawingContextImpl.cs

@@ -0,0 +1,10 @@
+using Avalonia.Platform;
+using SkiaSharp;
+
+namespace Avalonia.Skia
+{
+    public interface ISkiaDrawingContextImpl : IDrawingContextImpl
+    {
+        SKCanvas SkCanvas { get; }
+    }
+}

src/Skia/Avalonia.Skia/ImmutableBitmap.cs

@@ -12,7 +12,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Immutable Skia bitmap.
     /// </summary>
-    public class ImmutableBitmap : IDrawableBitmapImpl
+    internal class ImmutableBitmap : IDrawableBitmapImpl
     {
         private readonly SKImage _image;
 

src/Skia/Avalonia.Skia/PlatformRenderInterface.cs

@@ -15,7 +15,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Skia platform render interface.
     /// </summary>
-    public class PlatformRenderInterface : IPlatformRenderInterface
+    internal class PlatformRenderInterface : IPlatformRenderInterface
     {
         private GRContext GrContext { get; }
 

src/Skia/Avalonia.Skia/StreamGeometryImpl.cs

@@ -10,7 +10,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// A Skia implementation of a <see cref="IStreamGeometryImpl"/>.
     /// </summary>
-    public class StreamGeometryImpl : GeometryImpl, IStreamGeometryImpl
+    internal class StreamGeometryImpl : GeometryImpl, IStreamGeometryImpl
     {
         private Rect _bounds;
         private readonly SKPath _effectivePath;

src/Skia/Avalonia.Skia/SurfaceRenderTarget.cs

@@ -14,7 +14,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Skia render target that writes to a surface.
     /// </summary>
-    public class SurfaceRenderTarget : IRenderTargetBitmapImpl, IDrawableBitmapImpl
+    internal class SurfaceRenderTarget : IRenderTargetBitmapImpl, IDrawableBitmapImpl
     {
         private readonly SKSurface _surface;
         private readonly SKCanvas _canvas;

src/Skia/Avalonia.Skia/TransformedGeometryImpl.cs

@@ -9,7 +9,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// A Skia implementation of a <see cref="ITransformedGeometryImpl"/>.
     /// </summary>
-    public class TransformedGeometryImpl : GeometryImpl, ITransformedGeometryImpl
+    internal class TransformedGeometryImpl : GeometryImpl, ITransformedGeometryImpl
     {
         /// <summary>
         ///  Initializes a new instance of the <see cref="TransformedGeometryImpl"/> class.

src/Skia/Avalonia.Skia/WriteableBitmapImpl.cs

@@ -13,7 +13,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Skia based writeable bitmap.
     /// </summary>
-    public class WriteableBitmapImpl : IWriteableBitmapImpl, IDrawableBitmapImpl
+    internal class WriteableBitmapImpl : IWriteableBitmapImpl, IDrawableBitmapImpl
     {
         private static readonly SKBitmapReleaseDelegate s_releaseDelegate = ReleaseProc;
         private readonly SKBitmap _bitmap;

src/Windows/Avalonia.Direct2D1/Media/DrawingContextImpl.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.Rendering;
+using Avalonia.Rendering.SceneGraph;
 using Avalonia.Utilities;
 using SharpDX;
 using SharpDX.Direct2D1;
@@ -508,5 +509,7 @@ namespace Avalonia.Direct2D1.Media
         {
             PopLayer();
         }
+        
+        public void Custom(ICustomDrawOperation custom) => custom.Render(this);
     }
 }

src/Windows/Avalonia.Direct2D1/Media/FormattedTextImpl.cs

@@ -9,7 +9,7 @@ using DWrite = SharpDX.DirectWrite;
 
 namespace Avalonia.Direct2D1.Media
 {
-    public class FormattedTextImpl : IFormattedTextImpl
+    internal class FormattedTextImpl : IFormattedTextImpl
     {
         public FormattedTextImpl(
             string text,