Documented/updated Decorator.

Perspex.Controls/Decorator.cs

@@ -1,65 +1,84 @@
 // -----------------------------------------------------------------------
 // <copyright file="Decorator.cs" company="Steven Kirk">
-// Copyright 2014 MIT Licence. See licence.md for more information.
+// Copyright 2015 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------
 
 namespace Perspex.Controls
 {
-    using System;
-    using System.Collections.Generic;
-    using System.Linq;
-    using System.Reactive.Linq;
     using Perspex.Collections;
-    using Perspex.Layout;
 
+    /// <summary>
+    /// Base class for controls which decorate a single child control.
+    /// </summary>
     public class Decorator : Control, IVisual, ILogical
     {
+        /// <summary>
+        /// Defines the <see cref="Child"/> property.
+        /// </summary>
         public static readonly PerspexProperty<Control> ChildProperty =
-            PerspexProperty.Register<Decorator, Control>("Child");
+            PerspexProperty.Register<Decorator, Control>(nameof(Child));
 
+        /// <summary>
+        /// Defines the <see cref="Padding"/> property.
+        /// </summary>
         public static readonly PerspexProperty<Thickness> PaddingProperty =
-            PerspexProperty.Register<Decorator, Thickness>("Padding");
+            PerspexProperty.Register<Decorator, Thickness>(nameof(Padding));
 
         private PerspexSingleItemList<ILogical> logicalChild = new PerspexSingleItemList<ILogical>();
 
-        public Decorator()
+        /// <summary>
+        /// Initializes static members of the <see cref="Decorator"/> class.
+        /// </summary>
+        static Decorator()
         {
-            this.GetObservableWithHistory(ChildProperty).Subscribe(x =>
-            {
-                if (x.Item1 != null)
-                {
-                    this.RemoveVisualChild(x.Item1);
-                    x.Item1.Parent = null;
-                }
-
-                if (x.Item2 != null)
-                {
-                    this.AddVisualChild(x.Item2);
-                    x.Item2.Parent = this;
-                }
-
-                this.logicalChild.SingleItem = x.Item2;
-            });
+            ChildProperty.Changed.AddClassHandler<Decorator>(x => x.ChildChanged);
         }
 
+        /// <summary>
+        /// Gets or sets the decorated control.
+        /// </summary>
         public Control Child
         {
             get { return this.GetValue(ChildProperty); }
             set { this.SetValue(ChildProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the padding to place around the <see cref="Child"/> control.
+        /// </summary>
         public Thickness Padding
         {
             get { return this.GetValue(PaddingProperty); }
             set { this.SetValue(PaddingProperty, value); }
         }
 
+        /// <summary>
+        /// Gets the logical children of the control.
+        /// </summary>
         IPerspexReadOnlyList<ILogical> ILogical.LogicalChildren
         {
             get { return this.logicalChild; }
         }
 
+        /// <inheritdoc/>
+        protected override Size MeasureOverride(Size availableSize)
+        {
+            var content = this.Child;
+            var padding = this.Padding;
+
+            if (content != null)
+            {
+                content.Measure(availableSize.Deflate(padding));
+                return content.DesiredSize.Inflate(padding);
+            }
+            else
+            {
+                return new Size(padding.Left + padding.Right, padding.Bottom + padding.Top);
+            }
+        }
+
+        /// <inheritdoc/>
         protected override Size ArrangeOverride(Size finalSize)
         {
             Control content = this.Child;
@@ -72,20 +91,28 @@ namespace Perspex.Controls
             return finalSize;
         }
 
-        protected override Size MeasureOverride(Size availableSize)
+        /// <summary>
+        /// Called when the <see cref="Child"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private void ChildChanged(PerspexPropertyChangedEventArgs e)
         {
-            var content = this.Child;
-            var padding = this.Padding;
+            var oldChild = (Control)e.OldValue;
+            var newChild = (Control)e.NewValue;
 
-            if (content != null)
+            if (oldChild != null)
             {
-                content.Measure(availableSize.Deflate(padding));
-                return content.DesiredSize.Inflate(padding);
+                oldChild.Parent = null;
+                this.RemoveVisualChild(oldChild);
             }
-            else
+
+            if (newChild != null)
             {
-                return new Size(padding.Left + padding.Right, padding.Bottom + padding.Top);
+                this.AddVisualChild(newChild);
+                newChild.Parent = this;
             }
+
+            this.logicalChild.SingleItem = newChild;
         }
     }
 }