box-shadow support

samples/RenderDemo/Pages/AnimationsPage.xaml

@@ -134,6 +134,23 @@
           </Animation>
         </Style.Animations>
       </Style>
+      <Style Selector="Border.Shadow">
+        <Style.Animations>
+          <Animation Duration="0:0:3"
+                     IterationCount="Infinite"
+                     PlaybackDirection="Alternate">
+            <KeyFrame Cue="0%">
+              <Setter Property="BoxShadow" Value="-15 -15 Red"/>
+            </KeyFrame>
+            <KeyFrame Cue="50%">
+              <Setter Property="BoxShadow" Value="20 20 0 0 Blue"/>
+            </KeyFrame>
+            <KeyFrame Cue="90%">
+              <Setter Property="BoxShadow" Value="20 20 10 20 Green"/>
+            </KeyFrame>
+          </Animation>
+        </Style.Animations>
+      </Style>
     </Styles>
   </UserControl.Styles>
   <Grid>
@@ -152,6 +169,8 @@
         <Border Classes="Test Rect4" Background="Navy"/>
         <Border Classes="Test Rect5" Background="SeaGreen"/>
         <Border Classes="Test Rect6" Background="Red"/>
+        <Border Classes="Test Shadow" Background="PaleGreen" CornerRadius="10" Child="{x:Null}" />
+        <Border Classes="Test Shadow" Background="PaleGreen" CornerRadius="0 30 60 0" Child="{x:Null}" />
       </WrapPanel>
     </StackPanel>
   </Grid>

src/Avalonia.Controls/Border.cs

@@ -33,6 +33,12 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<CornerRadius> CornerRadiusProperty =
             AvaloniaProperty.Register<Border, CornerRadius>(nameof(CornerRadius));
 
+        /// <summary>
+        /// Defines the <see cref="BoxShadow"/> property.
+        /// </summary>
+        public static readonly StyledProperty<BoxShadow> BoxShadowProperty =
+            AvaloniaProperty.Register<Border, BoxShadow>(nameof(BoxShadow));
+        
         private readonly BorderRenderHelper _borderRenderHelper = new BorderRenderHelper();
 
         /// <summary>
@@ -44,7 +50,8 @@ namespace Avalonia.Controls
                 BackgroundProperty,
                 BorderBrushProperty,
                 BorderThicknessProperty,
-                CornerRadiusProperty);
+                CornerRadiusProperty,
+                BoxShadowProperty);
             AffectsMeasure<Border>(BorderThicknessProperty);
         }
 
@@ -83,14 +90,24 @@ namespace Avalonia.Controls
             get { return GetValue(CornerRadiusProperty); }
             set { SetValue(CornerRadiusProperty, value); }
         }
-
+        
+        /// <summary>
+        /// Gets or sets the box shadow effect parameters
+        /// </summary>
+        public BoxShadow BoxShadow
+        {
+            get => GetValue(BoxShadowProperty);
+            set => SetValue(BoxShadowProperty, value);
+        }
+        
         /// <summary>
         /// Renders the control.
         /// </summary>
         /// <param name="context">The drawing context.</param>
         public override void Render(DrawingContext context)
         {
-            _borderRenderHelper.Render(context, Bounds.Size, BorderThickness, CornerRadius, Background, BorderBrush);
+            _borderRenderHelper.Render(context, Bounds.Size, BorderThickness, CornerRadius, Background, BorderBrush,
+                BoxShadow);
         }
 
         /// <summary>

src/Avalonia.Controls/Presenters/ContentPresenter.cs

@@ -40,7 +40,12 @@ namespace Avalonia.Controls.Presenters
         public static readonly StyledProperty<CornerRadius> CornerRadiusProperty =
             Border.CornerRadiusProperty.AddOwner<ContentPresenter>();
 
-
+        /// <summary>
+        /// Defines the <see cref="BoxShadow"/> property.
+        /// </summary>
+        public static readonly StyledProperty<BoxShadow> BoxShadowProperty =
+            Border.BoxShadowProperty.AddOwner<ContentPresenter>();
+        
         /// <summary>
         /// Defines the <see cref="Child"/> property.
         /// </summary>
@@ -132,6 +137,15 @@ namespace Avalonia.Controls.Presenters
             set { SetValue(CornerRadiusProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the box shadow effect parameters
+        /// </summary>
+        public BoxShadow BoxShadow
+        {
+            get => GetValue(BoxShadowProperty);
+            set => SetValue(BoxShadowProperty, value);
+        }
+
         /// <summary>
         /// Gets the control displayed by the presenter.
         /// </summary>
@@ -274,7 +288,8 @@ namespace Avalonia.Controls.Presenters
         /// <inheritdoc/>
         public override void Render(DrawingContext context)
         {
-            _borderRenderer.Render(context, Bounds.Size, BorderThickness, CornerRadius, Background, BorderBrush);
+            _borderRenderer.Render(context, Bounds.Size, BorderThickness, CornerRadius, Background, BorderBrush,
+                BoxShadow);
         }
 
         /// <summary>

src/Avalonia.Controls/Utils/BorderRenderHelper.cs

@@ -1,5 +1,6 @@
 using System;
 using Avalonia.Media;
+using Avalonia.Platform;
 
 namespace Avalonia.Controls.Utils
 {
@@ -67,14 +68,17 @@ namespace Avalonia.Controls.Utils
             }
         }
 
-        public void Render(DrawingContext context, Size size, Thickness borders, CornerRadius radii, IBrush background, IBrush borderBrush)
+        public void Render(DrawingContext context, Size size, Thickness borders, CornerRadius radii, IBrush background,
+            IBrush borderBrush, BoxShadow boxShadow)
         {
             if (_useComplexRendering)
             {
                 var backgroundGeometry = _backgroundGeometryCache;
                 if (backgroundGeometry != null)
                 {
-                    context.DrawGeometry(background, null, backgroundGeometry);
+                    // We are using platform impl here because I'm not sure if we should
+                    // make the box shadow for geometries to be public API
+                    context.PlatformImpl.DrawGeometry(background, null, backgroundGeometry.PlatformImpl, boxShadow);
                 }
 
                 var borderGeometry = _borderGeometryCache;
@@ -97,7 +101,7 @@ namespace Avalonia.Controls.Utils
 
                 var rect = new Rect(top, top, size.Width - borderThickness, size.Height - borderThickness);
 
-                context.DrawRectangle(background, pen, rect, radii.TopLeft, radii.TopLeft);
+                context.DrawRectangle(background, pen, rect, radii.TopLeft, radii.TopLeft, boxShadow);
             }
         }    
 

src/Avalonia.Visuals/Animation/Animators/BoxShadowAnimator.cs

@@ -0,0 +1,21 @@
+using Avalonia.Media;
+
+namespace Avalonia.Animation.Animators
+{
+    public class BoxShadowAnimator : Animator<BoxShadow>
+    {
+        static ColorAnimator s_colorAnimator = new ColorAnimator();
+        static DoubleAnimator s_doubleAnimator = new DoubleAnimator();
+        public override BoxShadow Interpolate(double progress, BoxShadow oldValue, BoxShadow newValue)
+        {
+            return new BoxShadow
+            {
+                OffsetX = s_doubleAnimator.Interpolate(progress, oldValue.OffsetX, newValue.OffsetX),
+                OffsetY = s_doubleAnimator.Interpolate(progress, oldValue.OffsetY, newValue.OffsetY),
+                Blur = s_doubleAnimator.Interpolate(progress, oldValue.Blur, newValue.Blur),
+                Spread = s_doubleAnimator.Interpolate(progress, oldValue.Spread, newValue.Spread),
+                Color = s_colorAnimator.Interpolate(progress, oldValue.Color, newValue.Color)
+            };
+        }
+    }
+}

src/Avalonia.Visuals/Media/BoxShadow.cs

@@ -0,0 +1,88 @@
+using System;
+using Avalonia.Animation.Animators;
+using Avalonia.Utilities;
+
+namespace Avalonia.Media
+{
+    public struct BoxShadow
+    {
+        public double OffsetX { get; set; }
+        public double OffsetY { get; set; }
+        public double Blur { get; set; }
+        public double Spread { get; set; }
+        public Color Color { get; set; }
+
+        static BoxShadow()
+        {
+            Animation.Animation.RegisterAnimator<BoxShadowAnimator>(prop =>
+                typeof(BoxShadow).IsAssignableFrom(prop.PropertyType));
+        }
+        
+        public bool Equals(BoxShadow other)
+        {
+            return OffsetX.Equals(other.OffsetX) && OffsetY.Equals(other.OffsetY) && Blur.Equals(other.Blur) && Spread.Equals(other.Spread) && Color.Equals(other.Color);
+        }
+
+        public override bool Equals(object obj)
+        {
+            return obj is BoxShadow other && Equals(other);
+        }
+
+        public override int GetHashCode()
+        {
+            unchecked
+            {
+                var hashCode = OffsetX.GetHashCode();
+                hashCode = (hashCode * 397) ^ OffsetY.GetHashCode();
+                hashCode = (hashCode * 397) ^ Blur.GetHashCode();
+                hashCode = (hashCode * 397) ^ Spread.GetHashCode();
+                hashCode = (hashCode * 397) ^ Color.GetHashCode();
+                return hashCode;
+            }
+        }
+
+        public bool IsEmpty => OffsetX == 0 && OffsetY == 0 && Blur == 0 && Spread == 0;
+
+        public static unsafe BoxShadow Parse(string s)
+        {
+            if (s == "none")
+                return default;
+            
+            var separatorCount = 0;
+            var separators = stackalloc char[4];
+            for(var c = 0; c<s.Length; c++)
+                if (s[c] == ',' || s[c] == ' ')
+                {
+                    if (separatorCount == 4)
+                        throw new FormatException("Invalid box-shadow format");
+                    separators[separatorCount] = s[c];
+                    separatorCount++;
+                }
+
+            if (separatorCount != 2 && separatorCount > 4)
+                throw new FormatException("Invalid box-shadow format");
+
+            var tokenizer = new StringTokenizer(s);
+            var offsetX = tokenizer.ReadDouble(separators[0]);
+            var offsetY = tokenizer.ReadDouble(separators[1]);
+            double blur = 0;
+            double spread = 0;
+            if (separatorCount > 2)
+                blur = tokenizer.ReadDouble(separators[2]);
+            if (separatorCount > 3)
+                spread = tokenizer.ReadDouble(separators[3]);
+            var color = Media.Color.Parse(tokenizer.ReadString());
+            return new BoxShadow
+            {
+                OffsetX = offsetX,
+                OffsetY = offsetY,
+                Blur = blur,
+                Spread = spread,
+                Color = color
+            };
+        }
+
+        public Rect TransformBounds(in Rect rect) 
+            => rect.Translate(new Vector(OffsetX, OffsetY)).Inflate(Spread + Blur);
+    }
+}

src/Avalonia.Visuals/Media/Color.cs

@@ -118,6 +118,50 @@ namespace Avalonia.Media
             throw new FormatException($"Invalid color string: '{s}'.");
         }
 
+        /// <summary>
+        /// Parses a color string.
+        /// </summary>
+        /// <param name="s">The color string.</param>
+        /// <param name="color">The parsed color</param>
+        /// <returns>The status of the operation.</returns>
+        public static bool TryParse(Span<char> s, out Color color)
+        {
+            color = default;
+            if (s == null)
+                return false;
+            if (s.Length == 0)
+                return false;
+
+            if (s[0] == '#')
+            {
+                var or = 0u;
+
+                if (s.Length == 7)
+                {
+                    or = 0xff000000;
+                }
+                else if (s.Length != 9)
+                {
+                    return false;
+                }
+
+                if(!uint.TryParse(s.Slice(1).ToString(), NumberStyles.HexNumber, CultureInfo.InvariantCulture, out var parsed))
+                    return false;
+                color = FromUInt32(parsed| or);
+                return true;
+            }
+
+            var knownColor = KnownColors.GetKnownColor(s.ToString());
+
+            if (knownColor != KnownColor.None)
+            {
+                color = knownColor.ToColor();
+                return true;
+            }
+
+            return false;
+        }
+
         /// <summary>
         /// Returns the string representation of the color.
         /// </summary>

src/Avalonia.Visuals/Media/DrawingContext.cs

@@ -125,7 +125,7 @@ namespace Avalonia.Media
 
             if (brush != null || PenIsVisible(pen))
             {
-                PlatformImpl.DrawGeometry(brush, pen, geometry.PlatformImpl);
+                PlatformImpl.DrawGeometry(brush, pen, geometry.PlatformImpl, default);
             }
         }
 
@@ -141,11 +141,13 @@ namespace Avalonia.Media
         /// <param name="radiusY">The radius in the Y dimension of the rounded corners.
         ///     This value will be clamped to the range of 0 to Height/2
         /// </param>
+        /// <param name="boxShadow">Box shadow effect parameters</param>
         /// <remarks>
         /// The brush and the pen can both be null. If the brush is null, then no fill is performed.
         /// If the pen is null, then no stoke is performed. If both the pen and the brush are null, then the drawing is not visible.
         /// </remarks>
-        public void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX = 0, double radiusY = 0)
+        public void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX = 0, double radiusY = 0,
+            BoxShadow boxShadow = default)
         {
             if (brush == null && !PenIsVisible(pen))
             {
@@ -162,7 +164,7 @@ namespace Avalonia.Media
                 radiusY = Math.Min(radiusY, rect.Height / 2);
             }
 
-            PlatformImpl.DrawRectangle(brush, pen, rect, radiusX, radiusY);
+            PlatformImpl.DrawRectangle(brush, pen, rect, radiusX, radiusY, boxShadow);
         }
 
         /// <summary>

src/Avalonia.Visuals/Platform/IDrawingContextImpl.cs

@@ -55,7 +55,8 @@ namespace Avalonia.Platform
         /// <param name="brush">The fill brush.</param>
         /// <param name="pen">The stroke pen.</param>
         /// <param name="geometry">The geometry.</param>
-        void DrawGeometry(IBrush brush, IPen pen, IGeometryImpl geometry);
+        /// <param name="boxShadow">The box shadow parameters</param>
+        void DrawGeometry(IBrush brush, IPen pen, IGeometryImpl geometry, BoxShadow boxShadow);
 
         /// <summary>
         /// Draws a rectangle with the specified Brush and Pen.
@@ -69,11 +70,13 @@ namespace Avalonia.Platform
         /// <param name="radiusY">The radius in the Y dimension of the rounded corners.
         ///     This value will be clamped to the range of 0 to Height/2
         /// </param>
+        /// <param name="boxShadow">Box shadow effect parameters</param>
         /// <remarks>
         /// The brush and the pen can both be null. If the brush is null, then no fill is performed.
         /// If the pen is null, then no stoke is performed. If both the pen and the brush are null, then the drawing is not visible.
         /// </remarks>
-        void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX = 0, double radiusY = 0);
+        void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX = 0, double radiusY = 0,
+            BoxShadow boxShadow = default);
 
         /// <summary>
         /// Draws text.

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

@@ -97,13 +97,13 @@ namespace Avalonia.Rendering.SceneGraph
         }
 
         /// <inheritdoc/>
-        public void DrawGeometry(IBrush brush, IPen pen, IGeometryImpl geometry)
+        public void DrawGeometry(IBrush brush, IPen pen, IGeometryImpl geometry, BoxShadow boxShadow)
         {
             var next = NextDrawAs<GeometryNode>();
 
-            if (next == null || !next.Item.Equals(Transform, brush, pen, geometry))
+            if (next == null || !next.Item.Equals(Transform, brush, pen, geometry, boxShadow))
             {
-                Add(new GeometryNode(Transform, brush, pen, geometry, CreateChildScene(brush)));
+                Add(new GeometryNode(Transform, brush, pen, geometry, boxShadow, CreateChildScene(brush)));
             }
             else
             {
@@ -149,13 +149,14 @@ namespace Avalonia.Rendering.SceneGraph
         }
 
         /// <inheritdoc/>
-        public void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX = 0, double radiusY = 0)
+        public void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX = 0D, double radiusY = 0D,
+            BoxShadow boxShadow = default)
         {
             var next = NextDrawAs<RectangleNode>();
 
-            if (next == null || !next.Item.Equals(Transform, brush, pen, rect, radiusX, radiusY))
+            if (next == null || !next.Item.Equals(Transform, brush, pen, rect, radiusX, radiusY, boxShadow))
             {
-                Add(new RectangleNode(Transform, brush, pen, rect, radiusX, radiusY, CreateChildScene(brush)));
+                Add(new RectangleNode(Transform, brush, pen, rect, radiusX, radiusY, boxShadow, CreateChildScene(brush)));
             }
             else
             {

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

@@ -19,18 +19,20 @@ namespace Avalonia.Rendering.SceneGraph
         /// <param name="pen">The stroke pen.</param>
         /// <param name="geometry">The geometry.</param>
         /// <param name="childScenes">Child scenes for drawing visual brushes.</param>
-        public GeometryNode(
-            Matrix transform,
+        /// <param name="boxShadow"></param>
+        public GeometryNode(Matrix transform,
             IBrush brush,
             IPen pen,
             IGeometryImpl geometry,
+            BoxShadow boxShadow,
             IDictionary<IVisual, Scene> childScenes = null)
-            : base(geometry.GetRenderBounds(pen), transform, null)
+            : base(boxShadow.TransformBounds(geometry.GetRenderBounds(pen)), transform, null)
         {
             Transform = transform;
             Brush = brush?.ToImmutable();
             Pen = pen?.ToImmutable();
             Geometry = geometry;
+            BoxShadow = boxShadow;
             ChildScenes = childScenes;
         }
 
@@ -54,6 +56,8 @@ namespace Avalonia.Rendering.SceneGraph
         /// </summary>
         public IGeometryImpl Geometry { get; }
 
+        public BoxShadow BoxShadow { get; }
+
         /// <inheritdoc/>
         public override IDictionary<IVisual, Scene> ChildScenes { get; }
 
@@ -64,24 +68,27 @@ namespace Avalonia.Rendering.SceneGraph
         /// <param name="brush">The fill of the other draw operation.</param>
         /// <param name="pen">The stroke of the other draw operation.</param>
         /// <param name="geometry">The geometry of the other draw operation.</param>
+        /// <param name="boxShadow">The box shadow parameters</param>
         /// <returns>True if the draw operations are the same, otherwise false.</returns>
         /// <remarks>
         /// The properties of the other draw operation are passed in as arguments to prevent
         /// allocation of a not-yet-constructed draw operation object.
         /// </remarks>
-        public bool Equals(Matrix transform, IBrush brush, IPen pen, IGeometryImpl geometry)
+        public bool Equals(Matrix transform, IBrush brush, IPen pen, IGeometryImpl geometry,
+            BoxShadow boxShadow)
         {
             return transform == Transform &&
-                Equals(brush, Brush) && 
-                Equals(Pen, pen) &&
-                Equals(geometry, Geometry);
+                   BoxShadow.Equals(boxShadow, boxShadow) &&
+                   Equals(brush, Brush) &&
+                   Equals(Pen, pen) &&
+                   Equals(geometry, Geometry);
         }
 
         /// <inheritdoc/>
         public override void Render(IDrawingContextImpl context)
         {
             context.Transform = Transform;
-            context.DrawGeometry(Brush, Pen, Geometry);
+            context.DrawGeometry(Brush, Pen, Geometry, BoxShadow);
         }
 
         /// <inheritdoc/>

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

@@ -29,8 +29,9 @@ namespace Avalonia.Rendering.SceneGraph
             Rect rect,
             double radiusX,
             double radiusY,
+            BoxShadow boxShadow,
             IDictionary<IVisual, Scene> childScenes = null)
-            : base(rect, transform, pen)
+            : base(boxShadow.TransformBounds(rect), transform, pen)
         {
             Transform = transform;
             Brush = brush?.ToImmutable();
@@ -39,6 +40,7 @@ namespace Avalonia.Rendering.SceneGraph
             RadiusX = radiusX;
             RadiusY = radiusY;
             ChildScenes = childScenes;
+            BoxShadow = boxShadow;
         }
 
         /// <summary>
@@ -70,6 +72,11 @@ namespace Avalonia.Rendering.SceneGraph
         /// The radius in the Y dimension of the rounded corners.
         /// </summary>
         public double RadiusY { get; }
+        
+        /// <summary>
+        /// The parameters for the box-shadow effect
+        /// </summary>
+        public BoxShadow BoxShadow { get; }
 
         /// <inheritdoc/>
         public override IDictionary<IVisual, Scene> ChildScenes { get; }
@@ -88,11 +95,12 @@ namespace Avalonia.Rendering.SceneGraph
         /// The properties of the other draw operation are passed in as arguments to prevent
         /// allocation of a not-yet-constructed draw operation object.
         /// </remarks>
-        public bool Equals(Matrix transform, IBrush brush, IPen pen, Rect rect, double radiusX, double radiusY)
+        public bool Equals(Matrix transform, IBrush brush, IPen pen, Rect rect, double radiusX, double radiusY, BoxShadow boxShadow)
         {
             return transform == Transform &&
                    Equals(brush, Brush) &&
                    Equals(Pen, pen) &&
+                   Media.BoxShadow.Equals(BoxShadow, boxShadow) &&
                    rect == Rect &&
                    Math.Abs(radiusX - RadiusX) < double.Epsilon &&
                    Math.Abs(radiusY - RadiusY) < double.Epsilon;
@@ -103,7 +111,7 @@ namespace Avalonia.Rendering.SceneGraph
         {
             context.Transform = Transform;
 
-            context.DrawRectangle(Brush, Pen, Rect, RadiusX, RadiusY);
+            context.DrawRectangle(Brush, Pen, Rect, RadiusX, RadiusY, BoxShadow);
         }
 
         /// <inheritdoc/>

src/Skia/Avalonia.Skia/DrawingContextImpl.cs

@@ -164,11 +164,21 @@ namespace Avalonia.Skia
         }
 
         /// <inheritdoc />
-        public void DrawGeometry(IBrush brush, IPen pen, IGeometryImpl geometry)
+        public void DrawGeometry(IBrush brush, IPen pen, IGeometryImpl geometry, BoxShadow boxShadow)
         {
             var impl = (GeometryImpl) geometry;
             var size = geometry.Bounds.Size;
 
+            if(!boxShadow.IsEmpty)
+                using (var shadow = BoxShadowFilter.Create(boxShadow, _currentOpacity, false))
+                {
+                    Canvas.Save();
+                    Canvas.ClipPath(impl.EffectivePath, SKClipOperation.Difference);
+                    Canvas.DrawPath(impl.EffectivePath, shadow.Paint);
+                    Canvas.Restore();
+
+                }
+            
             using (var fill = brush != null ? CreatePaint(_fillPaint, brush, size) : default(PaintWrapper))
             using (var stroke = pen?.Brush != null ? CreatePaint(_strokePaint, pen, size) : default(PaintWrapper))
             {
@@ -184,12 +194,65 @@ namespace Avalonia.Skia
             }
         }
 
+        struct BoxShadowFilter : IDisposable
+        {
+            public SKPaint Paint;
+            private SKImageFilter _filter;
+            private SKImageFilter _dilate;
+
+            public static BoxShadowFilter Create(BoxShadow shadow, double opacity, bool skipDilate)
+            {
+                var ac = shadow.Color;
+                var spread = (int)shadow.Spread;
+                var dilate = !skipDilate && spread != 0 ? SKImageFilter.CreateDilate(spread, spread) : null;
+                var filter = SKImageFilter.CreateDropShadow(
+                    (float)shadow.OffsetX,
+                    (float)shadow.OffsetY,
+                    (float)shadow.Blur / 2,
+                    (float)shadow.Blur / 2,
+                    new SKColor(ac.R, ac.G, ac.B, (byte)(ac.A * opacity)),
+                    SKDropShadowImageFilterShadowMode.DrawShadowOnly, dilate);
+                var paint = new SKPaint { Color = SKColors.White, ImageFilter = filter };
+                return new BoxShadowFilter { Paint = paint, _filter = filter, _dilate = dilate };
+            }
+
+            public void Dispose()
+            {
+                Paint.Dispose();
+                _filter.Dispose();
+                _dilate?.Dispose();
+            }
+        }
+        
         /// <inheritdoc />
-        public void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX, double radiusY)
+        public void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX = 0D, double radiusY = 0D,
+            BoxShadow boxShadow = default)
         {
             var rc = rect.ToSKRect();
             var isRounded = Math.Abs(radiusX) > double.Epsilon || Math.Abs(radiusY) > double.Epsilon;
 
+            if (!boxShadow.IsEmpty)
+            {
+                using(var shadow = BoxShadowFilter.Create(boxShadow, _currentOpacity, true))
+                {
+                    var shadowRect = rc;
+                    shadowRect.Inflate((float)boxShadow.Spread, (float)boxShadow.Spread);
+                    Canvas.Save();
+                    if (isRounded)
+                    {
+                        Canvas.ClipRoundRect(new SKRoundRect(rc, (float)radiusX, (float)radiusY),
+                            SKClipOperation.Difference, true);
+                        Canvas.DrawRoundRect(shadowRect, (float)radiusX, (float)radiusY, shadow.Paint);
+                    }
+                    else
+                    {
+                        Canvas.ClipRect(shadowRect, SKClipOperation.Difference);
+                        Canvas.DrawRect(shadowRect, shadow.Paint);
+                    }
+                    Canvas.Restore();
+                }
+            }
+            
             if (brush != null)
             {
                 using (var paint = CreatePaint(_fillPaint, brush, rect.Size))

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

@@ -199,7 +199,8 @@ namespace Avalonia.Direct2D1.Media
         /// <param name="brush">The fill brush.</param>
         /// <param name="pen">The stroke pen.</param>
         /// <param name="geometry">The geometry.</param>
-        public void DrawGeometry(IBrush brush, IPen pen, IGeometryImpl geometry)
+        public void DrawGeometry(IBrush brush, IPen pen, IGeometryImpl geometry,
+            BoxShadow boxShadow)
         {
             if (brush != null)
             {
@@ -228,7 +229,8 @@ namespace Avalonia.Direct2D1.Media
         }
 
         /// <inheritdoc />
-        public void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX, double radiusY)
+        public void DrawRectangle(IBrush brush, IPen pen, Rect rect, double radiusX = 0D, double radiusY = 0D,
+            BoxShadow boxShadow = default)
         {
             var rc = rect.ToDirect2D();
             var isRounded = Math.Abs(radiusX) > double.Epsilon || Math.Abs(radiusY) > double.Epsilon;

tests/Avalonia.Visuals.UnitTests/Rendering/DeferredRendererTests.cs

@@ -473,7 +473,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering
                 var animation = new BehaviorSubject<double>(0.5);
 
                 context.Verify(x => x.PushOpacity(0.5), Times.Once);
-                context.Verify(x => x.DrawRectangle(Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0), Times.Once);
+                context.Verify(x => x.DrawRectangle(Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0, default), Times.Once);
                 context.Verify(x => x.PopOpacity(), Times.Once);
             }
         }
@@ -503,7 +503,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering
                 var animation = new BehaviorSubject<double>(0.5);
 
                 context.Verify(x => x.PushOpacity(0.5), Times.Never);
-                context.Verify(x => x.DrawRectangle(Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0), Times.Never);
+                context.Verify(x => x.DrawRectangle(Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0, default), Times.Never);
                 context.Verify(x => x.PopOpacity(), Times.Never);
             }
         }
@@ -528,7 +528,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering
                 var animation = new BehaviorSubject<double>(0.5);
 
                 context.Verify(x => x.PushOpacityMask(Brushes.Green, new Rect(0, 0, 100, 100)), Times.Once);
-                context.Verify(x => x.DrawRectangle(Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0), Times.Once);
+                context.Verify(x => x.DrawRectangle(Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0, default), Times.Once);
                 context.Verify(x => x.PopOpacityMask(), Times.Once);
             }
         }
@@ -653,7 +653,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering
                 var context = GetLayerContext(target, border);
 
                 context.Verify(x => x.PushOpacity(0.5), Times.Never);
-                context.Verify(x => x.DrawRectangle(Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0), Times.Once);
+                context.Verify(x => x.DrawRectangle(Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0, default), Times.Once);
                 context.Verify(x => x.PopOpacity(), Times.Never);
             }
         }

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

@@ -111,7 +111,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         public void Should_Not_Replace_Identical_DrawOperation()
         {
             var node = new VisualNode(new TestRoot(), null);
-            var operation = RefCountable.Create(new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0));
+            var operation = RefCountable.Create(new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0, default));
             var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(null, layers);
 
@@ -133,7 +133,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         public void Should_Replace_Different_DrawOperation()
         {
             var node = new VisualNode(new TestRoot(), null);
-            var operation = RefCountable.Create(new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0));
+            var operation = RefCountable.Create(new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0, default));
             var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(null, layers);
 
@@ -155,7 +155,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         public void Should_Update_DirtyRects()
         {
             var node = new VisualNode(new TestRoot(), null);
-            var operation = new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0);
+            var operation = new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0, default);
             var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(null, layers);
 
@@ -206,7 +206,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
         public void Trimmed_DrawOperations_Releases_Reference()
         {
             var node = new VisualNode(new TestRoot(), null);
-            var operation = RefCountable.Create(new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0));
+            var operation = RefCountable.Create(new RectangleNode(Matrix.Identity, Brushes.Red, null, new Rect(0, 0, 100, 100), 0, 0, default));
             var layers = new SceneLayers(node.Visual);
             var target = new DeferredDrawingContextImpl(null, layers);
 

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

@@ -69,7 +69,7 @@ namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
                 new Matrix(),
                 Brushes.Black,
                 null,
-                geometry);
+                geometry, default);
 
             geometryNode.HitTest(new Point());
         }