Added VisualBrush support

src/Avalonia.Base/Rendering/Composition/CompositionDrawListVisual.cs

@@ -24,7 +24,7 @@ internal class CompositionDrawListVisual : CompositionContainerVisual
 
     private protected override IChangeSetPool ChangeSetPool => DrawListVisualChanges.Pool;
 
-    internal CompositionDrawListVisual(Compositor compositor, ServerCompositionContainerVisual server, Visual visual) : base(compositor, server)
+    internal CompositionDrawListVisual(Compositor compositor, ServerCompositionDrawListVisual server, Visual visual) : base(compositor, server)
     {
         Visual = visual;
     }

src/Avalonia.Base/Rendering/Composition/Drawing/CompositionDrawList.cs

@@ -1,5 +1,6 @@
 using System;
 using Avalonia.Collections.Pooled;
+using Avalonia.Rendering.Composition.Server;
 using Avalonia.Rendering.SceneGraph;
 using Avalonia.Utilities;
 
@@ -7,6 +8,8 @@ namespace Avalonia.Rendering.Composition.Drawing;
 
 internal class CompositionDrawList : PooledList<IRef<IDrawOperation>>
 {
+    public Size? Size { get; set; }
+    
     public CompositionDrawList()
     {
         
@@ -26,11 +29,22 @@ internal class CompositionDrawList : PooledList<IRef<IDrawOperation>>
 
     public CompositionDrawList Clone()
     {
-        var clone = new CompositionDrawList(Count);
+        var clone = new CompositionDrawList(Count) { Size = Size };
         foreach (var r in this)
             clone.Add(r.Clone());
         return clone;
     }
+
+    public void Render(CompositorDrawingContextProxy canvas)
+    {
+        foreach (var cmd in this)
+        {
+            canvas.VisualBrushDrawList = (cmd.Item as BrushDrawOperation)?.Aux as CompositionDrawList;
+            cmd.Item.Render(canvas);
+        }
+
+        canvas.VisualBrushDrawList = null;
+    }
 }
 
 internal class CompositionDrawListBuilder

src/Avalonia.Base/Rendering/Composition/Drawing/CompositionDrawingContext.cs

@@ -359,25 +359,30 @@ internal class CompositionDrawingContext : IDrawingContextImpl
             ? _builder.DrawOperations[_drawOperationIndex] as IRef<T>
             : null;
     }
-
-    private IDictionary<IVisual, Scene>? CreateChildScene(IBrush? brush)
+    
+    private IDisposable? CreateChildScene(IBrush? brush)
     {
-        /*
-        var visualBrush = brush as VisualBrush;
-
-        if (visualBrush != null)
+        if (brush is VisualBrush visualBrush)
         {
             var visual = visualBrush.Visual;
 
             if (visual != null)
             {
+                // TODO: This is a temporary solution to make visual brush to work like it does with DeferredRenderer
+                // We should directly reference the corresponding CompositionVisual (which should
+                // be attached to the same composition target) like UWP does.
+                // Render-able visuals shouldn't be dangling unattached
                 (visual as IVisualBrushInitialize)?.EnsureInitialized();
-                var scene = new Scene(visual);
-                _sceneBuilder.UpdateAll(scene);
-                return new Dictionary<IVisual, Scene> { { visualBrush.Visual, scene } };
-            }
-        }*/
 
+                var drawList = new CompositionDrawList() { Size = visual.Bounds.Size };
+                var recorder = new CompositionDrawingContext();
+                recorder.BeginUpdate(drawList);
+                ImmediateRenderer.Render(visual, new DrawingContext(recorder));
+                recorder.EndUpdate();
+
+                return drawList;
+            }
+        }
         return null;
     }
 }

src/Avalonia.Base/Rendering/Composition/Server/DrawingContextProxy.cs

@@ -2,6 +2,7 @@ using System.Numerics;
 using Avalonia.Media;
 using Avalonia.Media.Imaging;
 using Avalonia.Platform;
+using Avalonia.Rendering.Composition.Drawing;
 using Avalonia.Rendering.SceneGraph;
 using Avalonia.Utilities;
 
@@ -10,12 +11,21 @@ namespace Avalonia.Rendering.Composition.Server;
 internal class CompositorDrawingContextProxy : IDrawingContextImpl
 {
     private IDrawingContextImpl _impl;
+    private readonly VisualBrushRenderer _visualBrushRenderer;
 
-    public CompositorDrawingContextProxy(IDrawingContextImpl impl)
+    public CompositorDrawingContextProxy(IDrawingContextImpl impl, VisualBrushRenderer visualBrushRenderer)
     {
         _impl = impl;
+        _visualBrushRenderer = visualBrushRenderer;
     }
 
+    // This is a hack to make it work with the current way of handling visual brushes
+    public CompositionDrawList? VisualBrushDrawList
+    {
+        get => _visualBrushRenderer.VisualBrushDrawList;
+        set => _visualBrushRenderer.VisualBrushDrawList = value;
+    }
+    
     public Matrix PreTransform { get; set; } = Matrix.Identity;
     
     public void Dispose()
@@ -135,4 +145,22 @@ internal class CompositorDrawingContextProxy : IDrawingContextImpl
     {
         _impl.Custom(custom);
     }
+
+    public class VisualBrushRenderer : IVisualBrushRenderer
+    {
+        public CompositionDrawList? VisualBrushDrawList { get; set; }
+        public Size GetRenderTargetSize(IVisualBrush brush)
+        {
+            return VisualBrushDrawList?.Size ?? Size.Empty;
+        }
+
+        public void RenderVisualBrush(IDrawingContextImpl context, IVisualBrush brush)
+        {
+            if (VisualBrushDrawList != null)
+            {
+                foreach (var cmd in VisualBrushDrawList)
+                    cmd.Item.Render(context);
+            }
+        }
+    }
 }

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionDrawListVisual.cs

@@ -51,10 +51,7 @@ internal class ServerCompositionDrawListVisual : ServerCompositionContainerVisua
     {
         if (_renderCommands != null)
         {
-            foreach (var cmd in _renderCommands)
-            {
-                cmd.Item.Render(canvas);
-            }
+            _renderCommands.Render(canvas);
         }
         base.RenderCore(canvas, transform);
     }

src/Avalonia.Base/Rendering/Composition/Server/ServerCompositionTarget.cs

@@ -75,11 +75,12 @@ namespace Avalonia.Rendering.Composition.Server
 
                 if (!_dirtyRect.IsEmpty)
                 {
-                    using (var context = _layer.CreateDrawingContext(null))
+                    var visualBrushHelper = new CompositorDrawingContextProxy.VisualBrushRenderer();
+                    using (var context = _layer.CreateDrawingContext(visualBrushHelper))
                     {
                         context.PushClip(_dirtyRect);
                         context.Clear(Colors.Transparent);
-                        Root.Render(new CompositorDrawingContextProxy(context), Root.CombinedTransformMatrix);
+                        Root.Render(new CompositorDrawingContextProxy(context, visualBrushHelper), Root.CombinedTransformMatrix);
                         context.PopClip();
                     }
                 }

src/Avalonia.Base/Rendering/DeferredRenderer.cs

@@ -272,16 +272,18 @@ namespace Avalonia.Rendering
             }
         }
 
+        Scene? TryGetChildScene(IRef<IDrawOperation>? op) => (op?.Item as BrushDrawOperation)?.Aux as Scene;
+        
         /// <inheritdoc/>
         Size IVisualBrushRenderer.GetRenderTargetSize(IVisualBrush brush)
         {
-            return (_currentDraw?.Item as BrushDrawOperation)?.ChildScenes?[brush.Visual]?.Size ?? Size.Empty;
+            return TryGetChildScene(_currentDraw)?.Size ?? Size.Empty;
         }
 
         /// <inheritdoc/>
         void IVisualBrushRenderer.RenderVisualBrush(IDrawingContextImpl context, IVisualBrush brush)
         {
-            var childScene = (_currentDraw?.Item as BrushDrawOperation)?.ChildScenes?[brush.Visual];
+            var childScene = TryGetChildScene(_currentDraw);
 
             if (childScene != null)
             {

src/Avalonia.Base/Rendering/SceneGraph/BrushDrawOperation.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using Avalonia.Media;
 using Avalonia.VisualTree;
 
@@ -9,14 +10,21 @@ namespace Avalonia.Rendering.SceneGraph
     /// </summary>
     internal abstract class BrushDrawOperation : DrawOperation
     {
-        public BrushDrawOperation(Rect bounds, Matrix transform)
+        public BrushDrawOperation(Rect bounds, Matrix transform, IDisposable? aux)
             : base(bounds, transform)
         {
+            Aux = aux;
         }
 
         /// <summary>
-        /// Gets a collection of child scenes that are needed to draw visual brushes.
+        /// Auxiliary data required to draw the brush
         /// </summary>
-        public abstract IDictionary<IVisual, Scene>? ChildScenes { get; }
+        public IDisposable? Aux { get; }
+
+        public override void Dispose()
+        {
+            Aux?.Dispose();
+            base.Dispose();
+        }
     }
 }

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

@@ -457,7 +457,7 @@ namespace Avalonia.Rendering.SceneGraph
             return _drawOperationindex < _node!.DrawOperations.Count ? _node.DrawOperations[_drawOperationindex] as IRef<T> : null;
         }
 
-        private IDictionary<IVisual, Scene>? CreateChildScene(IBrush? brush)
+        private IDisposable? CreateChildScene(IBrush? brush)
         {
             var visualBrush = brush as VisualBrush;
 
@@ -470,7 +470,7 @@ namespace Avalonia.Rendering.SceneGraph
                     (visual as IVisualBrushInitialize)?.EnsureInitialized();
                     var scene = new Scene(visual);
                     _sceneBuilder.UpdateAll(scene);
-                    return new Dictionary<IVisual, Scene> { { visualBrush.Visual, scene } };
+                    return scene;
                 }
             }
 

src/Avalonia.Base/Rendering/SceneGraph/EllipseNode.cs

@@ -17,14 +17,13 @@ namespace Avalonia.Rendering.SceneGraph
             IBrush? brush, 
             IPen? pen, 
             Rect rect, 
-            IDictionary<IVisual, Scene>? childScenes = null) 
-            : base(rect.Inflate(pen?.Thickness ?? 0), transform)
+            IDisposable? aux = null) 
+            : base(rect.Inflate(pen?.Thickness ?? 0), transform, aux)
         {
             Transform = transform;
             Brush = brush?.ToImmutable();
             Pen = pen?.ToImmutable();
             Rect = rect;
-            ChildScenes = childScenes;
         }
 
         /// <summary>
@@ -47,8 +46,6 @@ namespace Avalonia.Rendering.SceneGraph
         /// </summary>
         public Rect Rect { get; }
 
-        public override IDictionary<IVisual, Scene>? ChildScenes { get; }
-
         public bool Equals(Matrix transform, IBrush? brush, IPen? pen, Rect rect)
         {
             return transform == Transform &&

src/Avalonia.Base/Rendering/SceneGraph/GeometryNode.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using Avalonia.Media;
 using Avalonia.Media.Immutable;
 using Avalonia.Platform;
@@ -23,14 +24,13 @@ namespace Avalonia.Rendering.SceneGraph
             IBrush? brush,
             IPen? pen,
             IGeometryImpl geometry,
-            IDictionary<IVisual, Scene>? childScenes = null)
-            : base(geometry.GetRenderBounds(pen).CalculateBoundsWithLineCaps(pen), transform)
+            IDisposable? aux)
+            : base(geometry.GetRenderBounds(pen).CalculateBoundsWithLineCaps(pen), transform, aux)
         {
             Transform = transform;
             Brush = brush?.ToImmutable();
             Pen = pen?.ToImmutable();
             Geometry = geometry;
-            ChildScenes = childScenes;
         }
 
         /// <summary>
@@ -53,9 +53,6 @@ namespace Avalonia.Rendering.SceneGraph
         /// </summary>
         public IGeometryImpl Geometry { get; }
 
-        /// <inheritdoc/>
-        public override IDictionary<IVisual, Scene>? ChildScenes { get; }
-
         /// <summary>
         /// Determines if this draw operation equals another.
         /// </summary>

src/Avalonia.Base/Rendering/SceneGraph/GlyphRunNode.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 
 using Avalonia.Media;
 using Avalonia.Media.Immutable;
@@ -23,13 +24,12 @@ namespace Avalonia.Rendering.SceneGraph
             Matrix transform,
             IBrush foreground,
             GlyphRun glyphRun,
-            IDictionary<IVisual, Scene>? childScenes = null)
-            : base(new Rect(glyphRun.Size), transform)
+            IDisposable? aux = null)
+            : base(new Rect(glyphRun.Size), transform, aux)
         {
             Transform = transform;
             Foreground = foreground.ToImmutable();
             GlyphRun = glyphRun;
-            ChildScenes = childScenes;
         }
 
         /// <summary>
@@ -47,9 +47,6 @@ namespace Avalonia.Rendering.SceneGraph
         /// </summary>
         public GlyphRun GlyphRun { get; }
 
-        /// <inheritdoc/>
-        public override IDictionary<IVisual, Scene>? ChildScenes { get; }
-
         /// <inheritdoc/>
         public override void Render(IDrawingContextImpl context)
         {

src/Avalonia.Base/Rendering/SceneGraph/LineNode.cs

@@ -25,14 +25,13 @@ namespace Avalonia.Rendering.SceneGraph
             IPen pen,
             Point p1,
             Point p2,
-            IDictionary<IVisual, Scene>? childScenes = null)
-            : base(LineBoundsHelper.CalculateBounds(p1, p2, pen), transform)
+            IDisposable? aux = null)
+            : base(LineBoundsHelper.CalculateBounds(p1, p2, pen), transform, aux)
         {
             Transform = transform;
             Pen = pen.ToImmutable();
             P1 = p1;
             P2 = p2;
-            ChildScenes = childScenes;
         }
 
         /// <summary>
@@ -55,9 +54,6 @@ namespace Avalonia.Rendering.SceneGraph
         /// </summary>
         public Point P2 { get; }
 
-        /// <inheritdoc/>
-        public override IDictionary<IVisual, Scene>? ChildScenes { get; }
-
         /// <summary>
         /// Determines if this draw operation equals another.
         /// </summary>

src/Avalonia.Base/Rendering/SceneGraph/OpacityMaskNode.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.VisualTree;
@@ -17,12 +18,11 @@ namespace Avalonia.Rendering.SceneGraph
         /// <param name="mask">The opacity mask to push.</param>
         /// <param name="bounds">The bounds of the mask.</param>
         /// <param name="childScenes">Child scenes for drawing visual brushes.</param>
-        public OpacityMaskNode(IBrush mask, Rect bounds, IDictionary<IVisual, Scene>? childScenes = null)
-            : base(Rect.Empty, Matrix.Identity)
+        public OpacityMaskNode(IBrush mask, Rect bounds, IDisposable? aux = null)
+            : base(Rect.Empty, Matrix.Identity, aux)
         {
             Mask = mask.ToImmutable();
             MaskBounds = bounds;
-            ChildScenes = childScenes;
         }
 
         /// <summary>
@@ -30,7 +30,7 @@ namespace Avalonia.Rendering.SceneGraph
         /// opacity mask pop.
         /// </summary>
         public OpacityMaskNode()
-            : base(Rect.Empty, Matrix.Identity)
+            : base(Rect.Empty, Matrix.Identity, null)
         {
         }
 
@@ -44,8 +44,6 @@ namespace Avalonia.Rendering.SceneGraph
         /// </summary>
         public Rect? MaskBounds { get; }
 
-        /// <inheritdoc/>
-        public override IDictionary<IVisual, Scene>? ChildScenes { get; }
 
         /// <inheritdoc/>
         public override bool HitTest(Point p) => false;

src/Avalonia.Base/Rendering/SceneGraph/RectangleNode.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using Avalonia.Media;
 using Avalonia.Media.Immutable;
 using Avalonia.Platform;
@@ -26,14 +27,13 @@ namespace Avalonia.Rendering.SceneGraph
             IPen? pen,
             RoundedRect rect,
             BoxShadows boxShadows,
-            IDictionary<IVisual, Scene>? childScenes = null)
-            : base(boxShadows.TransformBounds(rect.Rect).Inflate((pen?.Thickness ?? 0) / 2), transform)
+            IDisposable? aux = null)
+            : base(boxShadows.TransformBounds(rect.Rect).Inflate((pen?.Thickness ?? 0) / 2), transform, aux)
         {
             Transform = transform;
             Brush = brush?.ToImmutable();
             Pen = pen?.ToImmutable();
             Rect = rect;
-            ChildScenes = childScenes;
             BoxShadows = boxShadows;
         }
 
@@ -62,9 +62,6 @@ namespace Avalonia.Rendering.SceneGraph
         /// </summary>
         public BoxShadows BoxShadows { get; }
 
-        /// <inheritdoc/>
-        public override IDictionary<IVisual, Scene>? ChildScenes { get; }
-
         /// <summary>
         /// Determines if this draw operation equals another.
         /// </summary>