Added IDrawingContextImpl.CreateLayer

samples/interop/Direct3DInteropSample/MainWindow.cs

@@ -253,7 +253,7 @@ namespace Direct3DInteropSample
 
             public IDrawingContextImpl CreateDrawingContext(IVisualBrushRenderer visualBrushRenderer)
             {
-                return new DrawingContextImpl(visualBrushRenderer, _window._d2dRenderTarget,
+                return new DrawingContextImpl(visualBrushRenderer, null, _window._d2dRenderTarget,
                     AvaloniaLocator.Current.GetService<SharpDX.DirectWrite.Factory>(),
                     AvaloniaLocator.Current.GetService<ImagingFactory>());
             }

src/Avalonia.Visuals/Platform/IDrawingContextImpl.cs

@@ -80,6 +80,20 @@ namespace Avalonia.Platform
         /// <param name="cornerRadius">The corner radius.</param>
         void FillRectangle(IBrush brush, Rect rect, float cornerRadius = 0.0f);
 
+        /// <summary>
+        /// Creates a new <see cref="IRenderTargetBitmapImpl"/> that can be used as a render layer
+        /// for the current render target.
+        /// </summary>
+        /// <param name="size">The size of the layer in DIPs.</param>
+        /// <returns>An <see cref="IRenderTargetBitmapImpl"/></returns>
+        /// <remarks>
+        /// Depending on the rendering backend used, a layer created via this method may be more
+        /// performant than a standard render target bitmap. In particular the Direct2D backend
+        /// 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);
+
         /// <summary>
         /// Pushes a clip rectange.
         /// </summary>

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

@@ -194,6 +194,11 @@ namespace Avalonia.Rendering.SceneGraph
             }
         }
 
+        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        {
+            throw new NotImplementedException();
+        }
+
         /// <inheritdoc/>
         public void PopClip()
         {

src/Gtk/Avalonia.Cairo/Media/DrawingContext.cs

@@ -227,6 +227,12 @@ namespace Avalonia.Cairo.Media
             }
         }
 
+        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        {
+            var surface = new Cairo.ImageSurface(Cairo.Format.Argb32, (int)size.Width, (int)size.Height);
+            return new RenderTargetBitmapImpl(surface);
+        }
+
         /// <summary>
         /// Pushes a clip rectange.
         /// </summary>

src/Skia/Avalonia.Skia/DrawingContextImpl.cs

@@ -349,6 +349,12 @@ namespace Avalonia.Skia
             }
         }
 
+        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        {
+            var pixelSize = size * (_dpi / 96);
+            return new BitmapImpl((int)pixelSize.Width, (int)pixelSize.Height, _dpi);
+        }
+
         public void PushClip(Rect clip)
         {
             Canvas.Save();

src/Windows/Avalonia.Direct2D1/ExternalRenderTarget.cs

@@ -1,5 +1,6 @@
 using System;
 using Avalonia.Direct2D1.Media;
+using Avalonia.Direct2D1.Media.Imaging;
 using Avalonia.Platform;
 using Avalonia.Rendering;
 using SharpDX;
@@ -7,7 +8,7 @@ using DirectWriteFactory = SharpDX.DirectWrite.Factory;
 
 namespace Avalonia.Direct2D1
 {
-    class ExternalRenderTarget : IRenderTarget
+    class ExternalRenderTarget : IRenderTarget, ILayerFactory
     {
         private readonly IExternalDirect2DRenderTargetSurface _externalRenderTargetProvider;
         private readonly DirectWriteFactory _dwFactory;
@@ -32,7 +33,7 @@ namespace Avalonia.Direct2D1
         {
             var target =  _externalRenderTargetProvider.GetOrCreateRenderTarget();
             _externalRenderTargetProvider.BeforeDrawing();
-            return new DrawingContextImpl(visualBrushRenderer, target, _dwFactory, _wicFactory, null, () =>
+            return new DrawingContextImpl(visualBrushRenderer, null, target, _dwFactory, _wicFactory, null, () =>
             {
                 try
                 {
@@ -44,5 +45,15 @@ namespace Avalonia.Direct2D1
                 }
             });
         }
+
+        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        {
+            var target = _externalRenderTargetProvider.GetOrCreateRenderTarget();
+            return D2DRenderTargetBitmapImpl.CreateCompatible(
+                _wicFactory,
+                _dwFactory,
+                target,
+                size);
+        }
     }
 }

src/Windows/Avalonia.Direct2D1/ICreateLayer.cs

@@ -1,10 +0,0 @@
-using System;
-using Avalonia.Platform;
-
-namespace Avalonia.Direct2D1
-{
-    internal interface ICreateLayer
-    {
-        IRenderTargetBitmapImpl CreateLayer(int pixelWidth, int pixelHeight);
-    }
-}

src/Windows/Avalonia.Direct2D1/ILayerFactory.cs

@@ -0,0 +1,10 @@
+using System;
+using Avalonia.Platform;
+
+namespace Avalonia.Direct2D1
+{
+    public interface ILayerFactory
+    {
+        IRenderTargetBitmapImpl CreateLayer(Size size);
+    }
+}

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

@@ -18,6 +18,7 @@ namespace Avalonia.Direct2D1.Media
     public class DrawingContextImpl : IDrawingContextImpl, IDisposable
     {
         private readonly IVisualBrushRenderer _visualBrushRenderer;
+        private readonly ILayerFactory _layerFactory;
         private readonly SharpDX.Direct2D1.RenderTarget _renderTarget;
         private readonly SharpDX.DXGI.SwapChain1 _swapChain;
         private readonly Action _finishedCallback;
@@ -29,12 +30,17 @@ namespace Avalonia.Direct2D1.Media
         /// </summary>
         /// <param name="visualBrushRenderer">The visual brush renderer.</param>
         /// <param name="renderTarget">The render target to draw to.</param>
+        /// <param name="layerFactory">
+        /// An object to use to create layers. May be null, in which case a
+        /// <see cref="WicRenderTargetBitmapImpl"/> will created when a new layer is requested.
+        /// </param>
         /// <param name="directWriteFactory">The DirectWrite factory.</param>
         /// <param name="imagingFactory">The WIC imaging factory.</param>
         /// <param name="swapChain">An optional swap chain associated with this drawing context.</param>
         /// <param name="finishedCallback">An optional delegate to be called when context is disposed.</param>
         public DrawingContextImpl(
             IVisualBrushRenderer visualBrushRenderer,
+            ILayerFactory layerFactory,
             SharpDX.Direct2D1.RenderTarget renderTarget,
             SharpDX.DirectWrite.Factory directWriteFactory,
             SharpDX.WIC.ImagingFactory imagingFactory,
@@ -42,6 +48,7 @@ namespace Avalonia.Direct2D1.Media
             Action finishedCallback = null)
         {
             _visualBrushRenderer = visualBrushRenderer;
+            _layerFactory = layerFactory;
             _renderTarget = renderTarget;
             _swapChain = swapChain;
             _finishedCallback = finishedCallback;
@@ -285,6 +292,25 @@ namespace Avalonia.Direct2D1.Media
             }
         }
 
+        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        {
+            if (_layerFactory != null)
+            {
+                return _layerFactory.CreateLayer(size);
+            }
+            else
+            {
+                var platform = AvaloniaLocator.Current.GetService<IPlatformRenderInterface>();
+                var dpi = new Vector(_renderTarget.DotsPerInch.Width, _renderTarget.DotsPerInch.Height);
+                var pixelSize = size * (dpi / 96);
+                return platform.CreateRenderTargetBitmap(
+                    (int)pixelSize.Width,
+                    (int)pixelSize.Height,
+                    dpi.X,
+                    dpi.Y);
+            }
+        }
+
         /// <summary>
         /// Pushes a clip rectange.
         /// </summary>

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

@@ -9,7 +9,7 @@ using DirectWriteFactory = SharpDX.DirectWrite.Factory;
 
 namespace Avalonia.Direct2D1.Media.Imaging
 {
-    public class D2DRenderTargetBitmapImpl : D2DBitmapImpl, IRenderTargetBitmapImpl, ICreateLayer
+    public class D2DRenderTargetBitmapImpl : D2DBitmapImpl, IRenderTargetBitmapImpl, ILayerFactory
     {
         private readonly DirectWriteFactory _dwriteFactory;
         private readonly BitmapRenderTarget _target;
@@ -31,13 +31,12 @@ namespace Avalonia.Direct2D1.Media.Imaging
             ImagingFactory imagingFactory,
             DirectWriteFactory dwriteFactory,
             SharpDX.Direct2D1.RenderTarget renderTarget,
-            int pixelWidth,
-            int pixelHeight)
+            Size size)
         {
             var bitmapRenderTarget = new BitmapRenderTarget(
                 renderTarget,
                 CompatibleRenderTargetOptions.None,
-                new Size2F(pixelWidth, pixelHeight));
+                new Size2F((float)size.Width, (float)size.Height));
             return new D2DRenderTargetBitmapImpl(imagingFactory, dwriteFactory, bitmapRenderTarget);
         }
 
@@ -45,14 +44,15 @@ namespace Avalonia.Direct2D1.Media.Imaging
         {
             return new DrawingContextImpl(
                 visualBrushRenderer,
+                this,
                 _target,
                 _dwriteFactory,
                 WicImagingFactory);
         }
 
-        public IRenderTargetBitmapImpl CreateLayer(int pixelWidth, int pixelHeight)
+        public IRenderTargetBitmapImpl CreateLayer(Size size)
         {
-            return CreateCompatible(WicImagingFactory, _dwriteFactory, _target, pixelWidth, pixelHeight);
+            return CreateCompatible(WicImagingFactory, _dwriteFactory, _target, size);
         }
 
         public override void Dispose()

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

@@ -47,7 +47,12 @@ namespace Avalonia.Direct2D1.Media
 
         public IDrawingContextImpl CreateDrawingContext(IVisualBrushRenderer visualBrushRenderer)
         {
-            return new DrawingContextImpl(visualBrushRenderer, _target, _dwriteFactory, WicImagingFactory);
+            return new DrawingContextImpl(
+                visualBrushRenderer,
+                null,
+                _target,
+                _dwriteFactory,
+                WicImagingFactory);
         }
     }
 }

src/Windows/Avalonia.Direct2D1/RenderTarget.cs

@@ -3,6 +3,7 @@
 
 using System;
 using Avalonia.Direct2D1.Media;
+using Avalonia.Direct2D1.Media.Imaging;
 using Avalonia.Platform;
 using Avalonia.Rendering;
 using SharpDX.Direct2D1;
@@ -11,7 +12,7 @@ using WicFactory = SharpDX.WIC.ImagingFactory;
 
 namespace Avalonia.Direct2D1
 {
-    public class RenderTarget : IRenderTarget
+    public class RenderTarget : IRenderTarget, ILayerFactory
     {
         /// <summary>
         /// The render target.
@@ -40,7 +41,16 @@ namespace Avalonia.Direct2D1
         /// <returns>An <see cref="Avalonia.Platform.IDrawingContextImpl"/>.</returns>
         public IDrawingContextImpl CreateDrawingContext(IVisualBrushRenderer visualBrushRenderer)
         {
-            return new DrawingContextImpl(visualBrushRenderer, _renderTarget, DirectWriteFactory, WicFactory);
+            return new DrawingContextImpl(visualBrushRenderer, this, _renderTarget, DirectWriteFactory, WicFactory);
+        }
+
+        public IRenderTargetBitmapImpl CreateLayer(Size size)
+        {
+            return D2DRenderTargetBitmapImpl.CreateCompatible(
+                WicFactory,
+                DirectWriteFactory,
+                _renderTarget,
+                size);
         }
 
         public void Dispose()

src/Windows/Avalonia.Direct2D1/SwapChainRenderTarget.cs

@@ -14,7 +14,7 @@ using Avalonia.Direct2D1.Media.Imaging;
 
 namespace Avalonia.Direct2D1
 {
-    public abstract class SwapChainRenderTarget : IRenderTarget, ICreateLayer
+    public abstract class SwapChainRenderTarget : IRenderTarget, ILayerFactory
     {
         private Size2 _savedSize;
         private Size2F _savedDpi;
@@ -56,13 +56,14 @@ namespace Avalonia.Direct2D1
 
             return new DrawingContextImpl(
                 visualBrushRenderer,
+                this,
                 _deviceContext,
                 DirectWriteFactory,
                 WicImagingFactory,
                 _swapChain);
         }
 
-        public IRenderTargetBitmapImpl CreateLayer(int pixelWidth, int pixelHeight)
+        public IRenderTargetBitmapImpl CreateLayer(Size size)
         {
             if (_deviceContext == null)
             {
@@ -73,8 +74,7 @@ namespace Avalonia.Direct2D1
                 WicImagingFactory,
                 DirectWriteFactory,
                 _deviceContext,
-                pixelWidth,
-                pixelHeight);
+                size);
         }
 
         public void Dispose()