Run render tests with deferred renderer.

Make render tests run all tests with both the deferred and immediate
renderer.

src/Avalonia.Visuals/Rendering/DeferredRenderer.cs

@@ -14,7 +14,7 @@ namespace Avalonia.Rendering
     {
         private readonly IDispatcher _dispatcher;
         private readonly IRenderLoop _renderLoop;
-        private readonly IRenderRoot _root;
+        private readonly IVisual _root;
         private readonly ISceneBuilder _sceneBuilder;
         private readonly RenderLayers _layers;
         private readonly IRenderLayerFactory _layerFactory;
@@ -51,6 +51,23 @@ namespace Avalonia.Rendering
             }
         }
 
+        public DeferredRenderer(
+            IVisual root,
+            IRenderTarget renderTarget,
+            ISceneBuilder sceneBuilder = null,
+            IRenderLayerFactory layerFactory = null)
+        {
+            Contract.Requires<ArgumentNullException>(root != null);
+            Contract.Requires<ArgumentNullException>(renderTarget != null);
+
+            _root = root;
+            _renderTarget = renderTarget;
+            _sceneBuilder = sceneBuilder ?? new SceneBuilder();
+            _scene = new Scene(root);
+            _layerFactory = layerFactory ?? new DefaultRenderLayerFactory();
+            _layers = new RenderLayers(_layerFactory);
+        }
+
         public bool DrawFps { get; set; }
         public bool DrawDirtyRects { get; set; }
         public string DebugFramesPath { get; set; }
@@ -81,6 +98,8 @@ namespace Avalonia.Rendering
 
         public void Render(Rect rect)
         {
+            UpdateScene();
+            Render(_scene);
         }
 
         private void Render(Scene scene)
@@ -198,7 +217,7 @@ namespace Avalonia.Rendering
             {
                 if (_renderTarget == null)
                 {
-                    _renderTarget = _root.CreateRenderTarget();
+                    _renderTarget = ((IRenderRoot)_root).CreateRenderTarget();
                 }
 
                 using (var context = _renderTarget.CreateDrawingContext())
@@ -259,7 +278,7 @@ namespace Avalonia.Rendering
                 }
 
                 _dirty.Clear();
-                _root.Invalidate(new Rect(scene.Size));
+                (_root as IRenderRoot)?.Invalidate(new Rect(scene.Size));
             }
             finally
             {

src/Avalonia.Visuals/Rendering/DirtyVisuals.cs

@@ -14,7 +14,7 @@ namespace Avalonia.Rendering
 
         public void Add(IVisual visual)
         {
-            var distance = visual.IsAttachedToVisualTree ? visual.CalculateDistanceFromVisualRoot() : -1;
+            var distance = visual.CalculateDistanceFromAncestor(visual.VisualRoot);
             int existingDistance;
 
             if (_index.TryGetValue(visual, out existingDistance))

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

@@ -12,7 +12,11 @@ namespace Avalonia.Rendering.SceneGraph
         private Dictionary<IVisual, IVisualNode> _index;
 
         public Scene(IVisual rootVisual)
-            : this(new VisualNode(rootVisual, null), new Dictionary<IVisual, IVisualNode>(), new SceneLayers(), 0)
+            : this(
+                new VisualNode(rootVisual, null),
+                new Dictionary<IVisual, IVisualNode>(),
+                new SceneLayers(rootVisual),
+                0)
         {
             _index.Add(rootVisual, Root);
         }

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

@@ -5,14 +5,7 @@ namespace Avalonia.Rendering.SceneGraph
 {
     public class SceneLayer
     {
-        public SceneLayer(IVisual layerRoot)
-        {
-            LayerRoot = layerRoot;
-            Dirty = new DirtyRects();
-            DistanceFromRoot = layerRoot.CalculateDistanceFromVisualRoot();
-        }
-
-        internal SceneLayer(IVisual layerRoot, int distanceFromRoot)
+        public SceneLayer(IVisual layerRoot, int distanceFromRoot)
         {
             LayerRoot = layerRoot;
             Dirty = new DirtyRects();

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

@@ -7,11 +7,13 @@ namespace Avalonia.Rendering.SceneGraph
 {
     public class SceneLayers : IEnumerable<SceneLayer>
     {
-        private List<SceneLayer> _inner = new List<SceneLayer>();
-        private Dictionary<IVisual, SceneLayer> _index = new Dictionary<IVisual, SceneLayer>();
+        private readonly IVisual _root;
+        private readonly List<SceneLayer> _inner = new List<SceneLayer>();
+        private readonly Dictionary<IVisual, SceneLayer> _index = new Dictionary<IVisual, SceneLayer>();
 
-        public SceneLayers()
+        public SceneLayers(IVisual root)
         {
+            _root = root;
         }
 
         public int Count => _inner.Count;
@@ -39,7 +41,8 @@ namespace Avalonia.Rendering.SceneGraph
         {
             Contract.Requires<ArgumentNullException>(layerRoot != null);
 
-            var layer = new SceneLayer(layerRoot);
+            var distance = layerRoot.CalculateDistanceFromAncestor(_root);
+            var layer = new SceneLayer(layerRoot, distance);
             var insert = FindInsertIndex(layer);
             _index.Add(layerRoot, layer);
             _inner.Insert(insert, layer);
@@ -48,7 +51,7 @@ namespace Avalonia.Rendering.SceneGraph
 
         public SceneLayers Clone()
         {
-            var result = new SceneLayers();
+            var result = new SceneLayers(_root);
 
             foreach (var src in _inner)
             {

src/Avalonia.Visuals/VisualTree/VisualExtensions.cs

@@ -17,28 +17,24 @@ namespace Avalonia.VisualTree
         /// Calculates the distance from a visual's <see cref="IRenderRoot"/>.
         /// </summary>
         /// <param name="visual">The visual.</param>
-        /// <returns>The number of steps from the visual to the render root.</returns>
-        /// <exception cref="ArgumentException">The visual is not rooted.</exception>
-        public static int CalculateDistanceFromVisualRoot(this IVisual visual)
+        /// <param name="ancestor">The ancestor visual.</param>
+        /// <returns>
+        /// The number of steps from the visual to the ancestor or -1 if
+        /// <paramref name="visual"/> is not a descendent of <paramref name="ancestor"/>.
+        /// </returns>
+        public static int CalculateDistanceFromAncestor(this IVisual visual, IVisual ancestor)
         {
             Contract.Requires<ArgumentNullException>(visual != null);
 
-            var root = visual.VisualRoot;
-
-            if (root == null)
-            {
-                throw new ArgumentException("Visual is not rooted.");
-            }
-
             var result = 0;
 
-            while (visual != root)
+            while (visual != null && visual != ancestor)
             {
                 ++result;
                 visual = visual.VisualParent;
             }
 
-            return result;
+            return visual != null ? result : -1;
         }
 
         /// <summary>

tests/Avalonia.RenderTests/TestBase.cs

@@ -9,6 +9,7 @@ using Avalonia.Media.Imaging;
 using Avalonia.Rendering;
 
 using Xunit;
+using Avalonia.Platform;
 
 #if AVALONIA_CAIRO
 using Avalonia.Cairo;
@@ -63,7 +64,9 @@ namespace Avalonia.Direct2D1.RenderTests
                 Directory.CreateDirectory(OutputPath);
             }
 
-            string path = Path.Combine(OutputPath, testName + ".out.png");
+            var immediatePath = Path.Combine(OutputPath, testName + ".immediate.out.png");
+            var deferredPath = Path.Combine(OutputPath, testName + ".deferred.out.png");
+            var factory = AvaloniaLocator.Current.GetService<IPlatformRenderInterface>();
 
             using (RenderTargetBitmap bitmap = new RenderTargetBitmap(
                 (int)target.Width,
@@ -73,22 +76,41 @@ namespace Avalonia.Direct2D1.RenderTests
                 target.Measure(size);
                 target.Arrange(new Rect(size));
                 bitmap.Render(target);
-                bitmap.Save(path);
+                bitmap.Save(immediatePath);
+            }
+
+            using (var rtb = factory.CreateRenderTargetBitmap((int)target.Width, (int)target.Height, 96, 96))
+            using (var renderer = new DeferredRenderer(target, rtb))
+            {
+                Size size = new Size(target.Width, target.Height);
+                target.Measure(size);
+                target.Arrange(new Rect(size));
+                renderer.Render(target.Bounds);
+                rtb.Save(deferredPath);
             }
         }
 
         protected void CompareImages([CallerMemberName] string testName = "")
         {
-            string expectedPath = Path.Combine(OutputPath, testName + ".expected.png");
-            string actualPath = Path.Combine(OutputPath, testName + ".out.png");
-            using (MagickImage expected = new MagickImage(expectedPath))
-            using (MagickImage actual = new MagickImage(actualPath))
+            var expectedPath = Path.Combine(OutputPath, testName + ".expected.png");
+            var immediatePath = Path.Combine(OutputPath, testName + ".immediate.out.png");
+            var deferredPath = Path.Combine(OutputPath, testName + ".deferred.out.png");
+
+            using (var expected = new MagickImage(expectedPath))
+            using (var immediate = new MagickImage(immediatePath))
+            using (var deferred = new MagickImage(deferredPath))
             {
-                double error = expected.Compare(actual, ErrorMetric.RootMeanSquared);
+                double immediateError = expected.Compare(immediate, ErrorMetric.RootMeanSquared);
+                double deferredError = expected.Compare(deferred, ErrorMetric.RootMeanSquared);
+
+                if (immediateError > 0.022)
+                {
+                    Assert.True(false, immediatePath + ": Error = " + immediateError);
+                }
 
-                if (error > 0.022)
+                if (deferredError > 0.022)
                 {
-                    Assert.True(false, actualPath + ": Error = " + error);
+                    Assert.True(false, deferredPath + ": Error = " + deferredError);
                 }
             }
         }

tests/Avalonia.Visuals.UnitTests/Rendering/SceneGraph/DeferredDrawingContextImplTests.cs

@@ -16,7 +16,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         {
             var parent = new VisualNode(new TestRoot(), null);
             var child = new VisualNode(Mock.Of<IVisual>(), null);
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(parent.Visual);
             var target = new DeferredDrawingContextImpl(layers);
 
             target.BeginUpdate(parent);
@@ -31,7 +31,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         {
             var parent = new VisualNode(new TestRoot(), null);
             var child = new VisualNode(Mock.Of<IVisual>(), null);
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(parent.Visual);
 
             parent.AddChild(child);
 
@@ -50,7 +50,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
             var parent = new VisualNode(new TestRoot(), null);
             var child1 = new VisualNode(Mock.Of<IVisual>(), null);
             var child2 = new VisualNode(Mock.Of<IVisual>(), null);
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(parent.Visual);
 
             parent.AddChild(child1);
 
@@ -74,7 +74,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
             node.AddChild(new VisualNode(Mock.Of<IVisual>(), node) { LayerRoot = root });
             node.AddChild(new VisualNode(Mock.Of<IVisual>(), node) { LayerRoot = root });
 
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(root);
             var target = new DeferredDrawingContextImpl(layers);
             var child1 = new VisualNode(Mock.Of<IVisual>(), null) { LayerRoot = root };
             var child2 = new VisualNode(Mock.Of<IVisual>(), null) { LayerRoot = root };
@@ -91,7 +91,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         public void Should_Add_DrawOperations()
         {
             var node = new VisualNode(new TestRoot(), null);
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(layers);
 
             node.LayerRoot = node.Visual;
@@ -112,7 +112,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         {
             var node = new VisualNode(new TestRoot(), null);
             var operation = new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0);
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(layers);
 
             node.LayerRoot = node.Visual;
@@ -134,7 +134,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         {
             var node = new VisualNode(new TestRoot(), null);
             var operation = new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0);
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(layers);
 
             node.LayerRoot = node.Visual;
@@ -156,7 +156,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         {
             var node = new VisualNode(new TestRoot(), null);
             var operation = new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0);
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(layers);
 
             node.LayerRoot = node.Visual;
@@ -180,7 +180,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
             node.AddDrawOperation(new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 30, 100), 0));
             node.AddDrawOperation(new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 40, 100), 0));
 
-            var layers = new SceneLayers();
+            var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(layers);
 
             using (target.BeginUpdate(node))

tests/Avalonia.Visuals.UnitTests/Rendering/SceneGraph/SceneLayersTests.cs

@@ -23,7 +23,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
                 }
             };
 
-            var target = new SceneLayers();
+            var target = new SceneLayers(root);
             target.Add(root);
             target.Add(decorator);
             target.Add(border);