Added corner radius for RadShadow

Controls/Primitives/Primitives.UWP/Shadow/RadShadow.cs

@@ -1,9 +1,11 @@
-using System.Numerics;
+using System;
+using System.Numerics;
 using Windows.Foundation;
 using Windows.UI;
 using Windows.UI.Composition;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Data;
 using Windows.UI.Xaml.Hosting;
 using Windows.UI.Xaml.Markup;
 using Windows.UI.Xaml.Shapes;
@@ -51,7 +53,13 @@ namespace Telerik.UI.Xaml.Controls.Primitives
         /// Identifies the <see cref="Content"/> dependency property.
         /// </summary>
         public static readonly DependencyProperty ContentProperty =
-            DependencyProperty.Register(nameof(Content), typeof(object), typeof(RadShadow), new PropertyMetadata(null, new PropertyChangedCallback((d, e) => ((RadShadow)d).OnContentPropertyChanged())));
+            DependencyProperty.Register(nameof(Content), typeof(object), typeof(RadShadow), new PropertyMetadata(null, new PropertyChangedCallback((d, e) => ((RadShadow)d).Invalidate())));
+
+        /// <summary>
+        /// Identifies the <see cref="CornerRadius"/> dependency property.
+        /// </summary>
+        public static readonly DependencyProperty CornerRadiusProperty =
+            DependencyProperty.Register(nameof(CornerRadius), typeof(int), typeof(RadShadow), new PropertyMetadata(0, new PropertyChangedCallback((d, e) => ((RadShadow)d).OnCornerRadiusPropertyChanged())));
 
         private const string PartShadowName = "PART_Shadow";
 
@@ -59,6 +67,7 @@ namespace Telerik.UI.Xaml.Controls.Primitives
         private SpriteVisual shadowVisual;
         private DropShadow dropShadow;
         private Canvas shadowView;
+        private Rectangle radiusMask;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="RadShadow"/> class.
@@ -122,6 +131,15 @@ namespace Telerik.UI.Xaml.Controls.Primitives
             set { this.SetValue(ContentProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the corner radius of the shadow.
+        /// </summary>
+        public int CornerRadius
+        {
+            get { return (int)this.GetValue(CornerRadiusProperty); }
+            set { this.SetValue(CornerRadiusProperty, value); }
+        }
+
         /// <summary>
         /// Use to get the shadow mask if the Content has such mask. Views like Shapes, TextBlock and Image provide masks - you can get them through the GetAlphaMask methods.
         /// </summary>
@@ -147,7 +165,7 @@ namespace Telerik.UI.Xaml.Controls.Primitives
                 return image.GetAlphaMask();
             }
 
-            return null;
+            return this.radiusMask?.GetAlphaMask();
         }
 
         /// <inheritdoc />
@@ -158,13 +176,27 @@ namespace Telerik.UI.Xaml.Controls.Primitives
             var content = this.GetVisualContent();
             if (content != null)
             {
-                this.ApplyShadowMaskIfNeeded(content);
-
                 var contentPosition = content.TransformToVisual(this);
                 var offset = contentPosition.TransformPoint(new Point(0, 0));
 
-                this.shadowVisual.Offset = new Vector3((float)offset.X - (float)this.BorderThickness.Left, (float)offset.Y - (float)this.BorderThickness.Top, 0);
-                this.shadowVisual.Size = new Vector2((float)content.ActualWidth, (float)content.ActualHeight);
+                var x = (float)offset.X - (float)this.BorderThickness.Left;
+                var y = (float)offset.Y - (float)this.BorderThickness.Top;
+                this.shadowVisual.Offset = new Vector3(x, y, 0);
+
+                var width = content.ActualWidth;
+                var height = content.ActualHeight;
+                this.shadowVisual.Size = new Vector2((float)width, (float)height);
+
+                if (this.radiusMask != null)
+                {
+                    this.radiusMask.Width = width;
+                    this.radiusMask.Height = height;
+
+                    Canvas.SetTop(this.radiusMask, y);
+                    Canvas.SetLeft(this.radiusMask, x);
+                }
+
+                this.ApplyShadowMaskIfNeeded(content);
             }
 
             return size;
@@ -196,6 +228,7 @@ namespace Telerik.UI.Xaml.Controls.Primitives
             this.OnOffsetPropertyChanged();
             this.OnBlurRadiusPropertyChanged(this.BlurRadius);
             this.OnShadowOpacityPropertyChanged(this.ShadowOpacity);
+            this.OnCornerRadiusPropertyChanged();
 
             this.shadowVisual.Shadow = this.dropShadow;
 
@@ -263,10 +296,54 @@ namespace Telerik.UI.Xaml.Controls.Primitives
             }
         }
 
-        private void OnContentPropertyChanged()
+        private void OnCornerRadiusPropertyChanged()
+        {
+            if (this.shadowView == null)
+            {
+                return;
+            }
+
+            var cornerRadius = this.CornerRadius;
+            if (cornerRadius < 0)
+            {
+                throw new ArgumentException($"{cornerRadius} is an invalid value for {nameof(this.CornerRadius)}");
+            }
+
+            if (cornerRadius > 0)
+            {
+                if (this.radiusMask == null)
+                {
+                    this.radiusMask = new Rectangle();
+                    this.radiusMask.SetBinding(Rectangle.FillProperty, new Binding() 
+                    {
+                        Path = new PropertyPath(nameof(this.Background)),
+                        Source = this, Mode = BindingMode.TwoWay
+                    });
+
+                    this.shadowView.Children.Add(this.radiusMask);
+                }
+               
+                this.radiusMask.RadiusY = cornerRadius;
+                this.radiusMask.RadiusX = cornerRadius;
+            }
+            else
+            {
+                if (this.shadowView.Children.Contains(this.radiusMask))
+                {
+                    this.shadowView.Children.Remove(this.radiusMask);
+                }
+
+                this.radiusMask.ClearValue(Rectangle.FillProperty);
+                this.radiusMask = null;
+            }
+
+            this.Invalidate();
+        }
+
+        private void Invalidate()
         {
             this.invalidateShadowMask = true;
             this.InvalidateArrange();
         }
     }
-}
+}