Added optimized Blit method for render layers

src/Avalonia.Headless/HeadlessPlatformRenderInterface.cs

@@ -238,7 +238,7 @@ namespace Avalonia.Headless
             }
         }
 
-        class HeadlessBitmapStub : IBitmapImpl, IRenderTargetBitmapImpl, IWriteableBitmapImpl
+        class HeadlessBitmapStub : IBitmapImpl, IDrawingContextLayerImpl, IWriteableBitmapImpl
         {
             public Size Size { get; }
 
@@ -267,6 +267,11 @@ namespace Avalonia.Headless
                 return new HeadlessDrawingContextStub();
             }
 
+            public void Blit(IDrawingContextImpl context)
+            {
+                
+            }
+
             public Vector Dpi { get; }
             public PixelSize PixelSize { get; }
             public int Version { get; set; }
@@ -307,7 +312,7 @@ namespace Avalonia.Headless
 
             }
 
-            public IRenderTargetBitmapImpl CreateLayer(Size size)
+            public IDrawingContextLayerImpl CreateLayer(Size size)
             {
                 return new HeadlessBitmapStub(size, new Vector(96, 96));
             }

src/Avalonia.Visuals/ApiCompatBaseline.txt

@@ -9,7 +9,11 @@ TypesMustExist : Type 'Avalonia.Media.Fonts.FontKey' does not exist in the imple
 CannotAddAbstractMembers : Member 'public Avalonia.Media.TextFormatting.TextLineBreak Avalonia.Media.TextFormatting.TextLine.TextLineBreak' is abstract in the implementation but is missing in the contract.
 MembersMustExist : Member 'public Avalonia.Media.TextFormatting.TextLineBreak Avalonia.Media.TextFormatting.TextLine.LineBreak.get()' does not exist in the implementation but it does exist in the contract.
 CannotAddAbstractMembers : Member 'public Avalonia.Media.TextFormatting.TextLineBreak Avalonia.Media.TextFormatting.TextLine.TextLineBreak.get()' is abstract in the implementation but is missing in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.IDrawingContextLayerImpl Avalonia.Platform.IDrawingContextImpl.CreateLayer(Avalonia.Size)' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.IRenderTargetBitmapImpl Avalonia.Platform.IDrawingContextImpl.CreateLayer(Avalonia.Size)' is present in the contract but not in the implementation.
+MembersMustExist : Member 'public Avalonia.Platform.IRenderTargetBitmapImpl Avalonia.Platform.IDrawingContextImpl.CreateLayer(Avalonia.Size)' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public System.Boolean Avalonia.Platform.IFontManagerImpl.TryMatchCharacter(System.Int32, Avalonia.Media.FontStyle, Avalonia.Media.FontWeight, Avalonia.Media.FontFamily, System.Globalization.CultureInfo, Avalonia.Media.Fonts.FontKey)' is present in the contract but not in the implementation.
 MembersMustExist : Member 'public System.Boolean Avalonia.Platform.IFontManagerImpl.TryMatchCharacter(System.Int32, Avalonia.Media.FontStyle, Avalonia.Media.FontWeight, Avalonia.Media.FontFamily, System.Globalization.CultureInfo, Avalonia.Media.Fonts.FontKey)' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public System.Boolean Avalonia.Platform.IFontManagerImpl.TryMatchCharacter(System.Int32, Avalonia.Media.FontStyle, Avalonia.Media.FontWeight, Avalonia.Media.FontFamily, System.Globalization.CultureInfo, Avalonia.Media.Typeface)' is present in the implementation but not in the contract.
-Total Issues: 13
+MembersMustExist : Member 'public Avalonia.Utilities.IRef<Avalonia.Platform.IRenderTargetBitmapImpl> Avalonia.Rendering.RenderLayer.Bitmap.get()' does not exist in the implementation but it does exist in the contract.
+Total Issues: 17

src/Avalonia.Visuals/Platform/IDrawingContextImpl.cs

@@ -99,7 +99,7 @@ namespace Avalonia.Platform
         /// has to do a format conversion each time a standard render target bitmap is rendered,
         /// but a layer created via this method has no such overhead.
         /// </remarks>
-        IRenderTargetBitmapImpl CreateLayer(Size size);
+        IDrawingContextLayerImpl CreateLayer(Size size);
 
         /// <summary>
         /// Pushes a clip rectangle.
@@ -156,4 +156,13 @@ namespace Avalonia.Platform
         /// <param name="custom">Custom draw operation</param>
         void Custom(ICustomDrawOperation custom);
     }
+
+    public interface IDrawingContextLayerImpl : IRenderTargetBitmapImpl
+    {
+        /// <summary>
+        /// Does optimized blit with Src blend mode
+        /// </summary>
+        /// <param name="context"></param>
+        void Blit(IDrawingContextImpl context);
+    }
 }

src/Avalonia.Visuals/Rendering/DeferredRenderer.cs

@@ -489,6 +489,7 @@ namespace Avalonia.Rendering
 
             var clientRect = new Rect(scene.Size);
 
+            var firstLayer = true;
             foreach (var layer in scene.Layers)
             {
                 var bitmap = Layers[layer.LayerRoot].Bitmap;
@@ -501,7 +502,10 @@ namespace Avalonia.Rendering
 
                 if (layer.OpacityMask == null)
                 {
-                    context.DrawBitmap(bitmap, layer.Opacity, sourceRect, clientRect);
+                    if (firstLayer)
+                        bitmap.Item.Blit(context);
+                    else
+                        context.DrawBitmap(bitmap, layer.Opacity, sourceRect, clientRect);
                 }
                 else
                 {
@@ -512,6 +516,8 @@ namespace Avalonia.Rendering
                 {
                     context.PopGeometryClip();
                 }
+
+                firstLayer = false;
             }
 
             if (_overlay != null)

src/Avalonia.Visuals/Rendering/RenderLayer.cs

@@ -20,7 +20,7 @@ namespace Avalonia.Rendering
             IsEmpty = true;
         }
 
-        public IRef<IRenderTargetBitmapImpl> Bitmap { get; private set; }
+        public IRef<IDrawingContextLayerImpl> Bitmap { get; private set; }
         public bool IsEmpty { get; set; }
         public double Scaling { get; private set; }
         public Size Size { get; private set; }

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

@@ -218,7 +218,7 @@ namespace Avalonia.Rendering.SceneGraph
                 ++_drawOperationindex;
             }
         }
-        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        public IDrawingContextLayerImpl CreateLayer(Size size)
         {
             throw new NotSupportedException("Creating layers on a deferred drawing context not supported");
         }

src/Skia/Avalonia.Skia/DrawingContextImpl.cs

@@ -422,7 +422,7 @@ namespace Avalonia.Skia
         }
 
         /// <inheritdoc />
-        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        public IDrawingContextLayerImpl CreateLayer(Size size)
         {
             return CreateRenderTarget( size);
         }

src/Skia/Avalonia.Skia/Gpu/OpenGl/GlSkiaGpu.cs

@@ -1,4 +1,6 @@
+using System;
 using System.Collections.Generic;
+using Avalonia.Logging;
 using Avalonia.OpenGL;
 using Avalonia.OpenGL.Imaging;
 using Avalonia.OpenGL.Surfaces;
@@ -10,6 +12,7 @@ namespace Avalonia.Skia
     {
         private GRContext _grContext;
         private IGlContext _glContext;
+        private bool? _canCreateSurfaces;
 
         public GlSkiaGpu(IPlatformOpenGlInterface openGl, long? maxResourceBytes)
         {
@@ -45,7 +48,22 @@ namespace Avalonia.Skia
 
         public ISkiaSurface TryCreateSurface(PixelSize size)
         {
-            return new FboSkiaSurface(_grContext, _glContext, size);
+            size = new PixelSize(Math.Max(size.Width, 1), Math.Max(size.Height, 1));
+            if (_canCreateSurfaces == false)
+                return null;
+            try
+            {
+                var surface = new FboSkiaSurface(_grContext, _glContext, size);
+                _canCreateSurfaces = true;
+                return surface;
+            }
+            catch (Exception e)
+            {
+                Logger.TryGet(LogEventLevel.Error, "OpenGL")
+                    ?.Log(this, "Unable to create a Skia-compatible FBO manually");
+                _canCreateSurfaces ??= false;
+                return null;
+            }
         }
 
         public IOpenGlBitmapImpl CreateOpenGlBitmap(PixelSize size, Vector dpi) => new GlOpenGlBitmapImpl(_glContext, size, dpi);

src/Skia/Avalonia.Skia/SurfaceRenderTarget.cs

@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using System.Reactive.Disposables;
+using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.Rendering;
 using Avalonia.Skia.Helpers;
@@ -11,7 +12,7 @@ namespace Avalonia.Skia
     /// <summary>
     /// Skia render target that writes to a surface.
     /// </summary>
-    internal class SurfaceRenderTarget : IRenderTargetBitmapImpl, IDrawableBitmapImpl
+    internal class SurfaceRenderTarget : IDrawingContextLayerImpl, IDrawableBitmapImpl
     {
         private readonly ISkiaSurface _surface;
         private readonly SKCanvas _canvas;
@@ -133,23 +134,33 @@ namespace Avalonia.Skia
             }
         }
 
-        /// <inheritdoc />
-        public void Draw(DrawingContextImpl context, SKRect sourceRect, SKRect destRect, SKPaint paint)
+        public void Blit(IDrawingContextImpl contextImpl)
         {
-            if (sourceRect.Left == 0 && sourceRect.Top == 0 && sourceRect.Size == destRect.Size)
+            var context = (DrawingContextImpl)contextImpl;
+
+            if (_surface.CanBlit)
             {
                 _surface.Surface.Canvas.Flush();
-                if (context.Canvas.TotalMatrix.IsIdentity && _surface.CanBlit && destRect.Top == 0 &&
-                    destRect.Left == 0)
-                    _surface.Blit();
-                else
-                    _surface.Surface.Draw(context.Canvas, destRect.Left, destRect.Top, paint);
+                
+                // This should set the render target as the current FBO
+                context.Canvas.Clear();
+                context.Canvas.Flush();
+                _surface.Blit();
             }
             else
-                using (var image = SnapshotImage())
-                {
-                    context.Canvas.DrawImage(image, sourceRect, destRect, paint);
-                }
+            {
+                var oldMatrix = context.Canvas.TotalMatrix;
+                context.Canvas.ResetMatrix();
+                _surface.Surface.Draw(context.Canvas, 0, 0, null);
+                context.Canvas.SetMatrix(oldMatrix);
+            }
+        }
+        
+        /// <inheritdoc />
+        public void Draw(DrawingContextImpl context, SKRect sourceRect, SKRect destRect, SKPaint paint)
+        {
+            using var image = SnapshotImage();
+            context.Canvas.DrawImage(image, sourceRect, destRect, paint);
         }
         
         /// <summary>

src/Windows/Avalonia.Direct2D1/ExternalRenderTarget.cs

@@ -38,7 +38,7 @@ namespace Avalonia.Direct2D1
             });
         }
 
-        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        public IDrawingContextLayerImpl CreateLayer(Size size)
         {
             var renderTarget = _externalRenderTargetProvider.GetOrCreateRenderTarget();
             return D2DRenderTargetBitmapImpl.CreateCompatible(renderTarget, size);

src/Windows/Avalonia.Direct2D1/ILayerFactory.cs

@@ -4,6 +4,6 @@ namespace Avalonia.Direct2D1
 {
     public interface ILayerFactory
     {
-        IRenderTargetBitmapImpl CreateLayer(Size size);
+        IDrawingContextLayerImpl CreateLayer(Size size);
     }
 }

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

@@ -334,7 +334,7 @@ namespace Avalonia.Direct2D1.Media
             }
         }
 
-        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        public IDrawingContextLayerImpl CreateLayer(Size size)
         {
             if (_layerFactory != null)
             {
@@ -345,7 +345,7 @@ namespace Avalonia.Direct2D1.Media
                 var platform = AvaloniaLocator.Current.GetService<IPlatformRenderInterface>();
                 var dpi = new Vector(_deviceContext.DotsPerInch.Width, _deviceContext.DotsPerInch.Height);
                 var pixelSize = PixelSize.FromSizeWithDpi(size, dpi);
-                return platform.CreateRenderTargetBitmap(pixelSize, dpi);
+                return (IDrawingContextLayerImpl)platform.CreateRenderTargetBitmap(pixelSize, dpi);
             }
         }
 

src/Windows/Avalonia.Direct2D1/Media/Imaging/D2DRenderTargetBitmapImpl.cs

@@ -8,7 +8,7 @@ using D2DBitmap = SharpDX.Direct2D1.Bitmap;
 
 namespace Avalonia.Direct2D1.Media.Imaging
 {
-    public class D2DRenderTargetBitmapImpl : D2DBitmapImpl, IRenderTargetBitmapImpl, ILayerFactory
+    public class D2DRenderTargetBitmapImpl : D2DBitmapImpl, IDrawingContextLayerImpl, ILayerFactory
     {
         private readonly BitmapRenderTarget _renderTarget;
 
@@ -34,7 +34,14 @@ namespace Avalonia.Direct2D1.Media.Imaging
             return new DrawingContextImpl(visualBrushRenderer, this, _renderTarget, null, () => Version++);
         }
 
-        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        public void Blit(IDrawingContextImpl context)
+        {
+            var rc = new Rect(0, 0, PixelSize.Width, PixelSize.Height);
+            context.DrawBitmap(RefCountable.CreateUnownedNotClonable(this),
+                1, rc, rc);
+        }
+
+        public IDrawingContextLayerImpl CreateLayer(Size size)
         {
             return CreateCompatible(_renderTarget, size);
         }

src/Windows/Avalonia.Direct2D1/RenderTarget.cs

@@ -30,7 +30,7 @@ namespace Avalonia.Direct2D1
             return new DrawingContextImpl(visualBrushRenderer, this, _renderTarget);
         }
 
-        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        public IDrawingContextLayerImpl CreateLayer(Size size)
         {
             return D2DRenderTargetBitmapImpl.CreateCompatible(_renderTarget, size);
         }

src/Windows/Avalonia.Direct2D1/SwapChainRenderTarget.cs

@@ -35,7 +35,7 @@ namespace Avalonia.Direct2D1
             return new DrawingContextImpl(visualBrushRenderer, this, _deviceContext, _swapChain);
         }
 
-        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        public IDrawingContextLayerImpl CreateLayer(Size size)
         {
             if (_deviceContext == null)
             {

tests/Avalonia.UnitTests/TestRoot.cs

@@ -72,7 +72,7 @@ namespace Avalonia.UnitTests
             dc.Setup(x => x.CreateLayer(It.IsAny<Size>())).Returns(() =>
             {
                 var layerDc = new Mock<IDrawingContextImpl>();
-                var layer = new Mock<IRenderTargetBitmapImpl>();
+                var layer = new Mock<IDrawingContextLayerImpl>();
                 layer.Setup(x => x.CreateDrawingContext(It.IsAny<IVisualBrushRenderer>())).Returns(layerDc.Object);
                 return layer.Object;
             });