Refactored DrawingContext and VisualBrush, added DrawingBrush (#10419)

Refactored DrawingContext and VisualBrush, added DrawingBrush

samples/RenderDemo/Pages/CustomSkiaPage.cs

@@ -1,29 +1,35 @@
 using System;
 using System.Diagnostics;
 using System.Globalization;
+using System.Linq;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.Rendering.SceneGraph;
 using Avalonia.Skia;
 using Avalonia.Threading;
+using Avalonia.Utilities;
 using SkiaSharp;
 
 namespace RenderDemo.Pages
 {
     public class CustomSkiaPage : Control
     {
+        private readonly GlyphRun _noSkia;
         public CustomSkiaPage()
         {
             ClipToBounds = true;
+            var text = "Current rendering API is not Skia";
+            var glyphs = text.Select(ch => Typeface.Default.GlyphTypeface.GetGlyph(ch)).ToArray();
+            _noSkia = new GlyphRun(Typeface.Default.GlyphTypeface, 12, text.AsMemory(), glyphs);
         }
 
         class CustomDrawOp : ICustomDrawOperation
         {
-            private readonly FormattedText _noSkia;
+            private readonly GlyphRun _noSkia;
 
-            public CustomDrawOp(Rect bounds, FormattedText noSkia)
+            public CustomDrawOp(Rect bounds, GlyphRun noSkia)
             {
                 _noSkia = noSkia;
                 Bounds = bounds;
@@ -42,10 +48,7 @@ public void Render(IDrawingContextImpl context)
             {
                 var leaseFeature = context.GetFeature<ISkiaSharpApiLeaseFeature>();
                 if (leaseFeature == null)
-                    using (var c = new DrawingContext(context, false))
-                    {
-                        c.DrawText(_noSkia, new Point());
-                    }
+                    context.DrawGlyphRun(Brushes.Black, _noSkia.PlatformImpl);
                 else
                 {
                     using var lease = leaseFeature.Lease();
@@ -114,10 +117,7 @@ static int Animate(int d, int from, int to)
 
         public override void Render(DrawingContext context)
         {
-            var noSkia = new FormattedText("Current rendering API is not Skia", CultureInfo.CurrentCulture,
-                FlowDirection.LeftToRight, Typeface.Default, 12, Brushes.Black);
-
-            context.Custom(new CustomDrawOp(new Rect(0, 0, Bounds.Width, Bounds.Height), noSkia));
+            context.Custom(new CustomDrawOp(new Rect(0, 0, Bounds.Width, Bounds.Height), _noSkia));
             Dispatcher.UIThread.InvokeAsync(InvalidateVisual, DispatcherPriority.Background);
         }
     }

samples/RenderDemo/Pages/PathMeasurementPage.cs

@@ -37,11 +37,8 @@ protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs
 
         public override void Render(DrawingContext context)
         {
-            using (var ctxi = _bitmap.CreateDrawingContext(null))
-            using (var bitmapCtx = new DrawingContext(ctxi, false))
+            using (var bitmapCtx = _bitmap.CreateDrawingContext())
             {
-                ctxi.Clear(default);
-
                 var basePath = new PathGeometry();
 
                 using (var basePathCtx = basePath.Open())

samples/RenderDemo/Pages/RenderTargetBitmapPage.cs

@@ -28,13 +28,11 @@ protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs
         readonly Stopwatch _st = Stopwatch.StartNew();
         public override void Render(DrawingContext context)
         {
-            using (var ctxi = _bitmap.CreateDrawingContext(null))
-            using(var ctx = new DrawingContext(ctxi, false))
+            using (var ctx = _bitmap.CreateDrawingContext())
             using (ctx.PushPostTransform(Matrix.CreateTranslation(-100, -100)
                                          * Matrix.CreateRotation(_st.Elapsed.TotalSeconds)
                                          * Matrix.CreateTranslation(100, 100)))
             {
-                ctxi.Clear(default);
                 ctx.FillRectangle(Brushes.Fuchsia, new Rect(50, 50, 100, 100));
             }
 

src/Avalonia.Base/Media/DrawingBrush.cs

@@ -0,0 +1,66 @@
+using Avalonia.Media.Immutable;
+using Avalonia.Rendering;
+using Avalonia.Rendering.Composition;
+using Avalonia.Rendering.Composition.Drawing;
+
+namespace Avalonia.Media
+{
+    /// <summary>
+    /// Paints an area with an <see cref="Drawing"/>.
+    /// </summary>
+    public class DrawingBrush : TileBrush, ISceneBrush, IAffectsRender
+    {
+        /// <summary>
+        /// Defines the <see cref="Drawing"/> property.
+        /// </summary>
+        public static readonly StyledProperty<Drawing?> DrawingProperty =
+            AvaloniaProperty.Register<DrawingBrush, Drawing?>(nameof(Drawing));
+
+        static DrawingBrush()
+        {
+            AffectsRender<DrawingBrush>(DrawingProperty);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DrawingBrush"/> class.
+        /// </summary>
+        public DrawingBrush()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DrawingBrush"/> class.
+        /// </summary>
+        /// <param name="visual">The visual to draw.</param>
+        public DrawingBrush(Drawing visual)
+        {
+            Drawing = visual;
+        }
+
+        /// <summary>
+        /// Gets or sets the visual to draw.
+        /// </summary>
+        public Drawing? Drawing
+        {
+            get { return GetValue(DrawingProperty); }
+            set { SetValue(DrawingProperty, value); }
+        }
+
+        ISceneBrushContent? ISceneBrush.CreateContent()
+        {
+            if (Drawing == null)
+                return null;
+
+
+            var recorder = new CompositionDrawingContext();
+            recorder.BeginUpdate(null);
+            Drawing?.Draw(recorder);
+            var drawList = recorder.EndUpdate();
+            if (drawList == null)
+                return null;
+
+            return new CompositionDrawListSceneBrushContent(new ImmutableSceneBrush(this), drawList,
+                drawList.CalculateBounds(), true);
+        }
+    }
+}