From 6af31ecf43cffe837b85ffa45661fe81791e2a53 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Tue, 28 Jul 2015 21:42:08 +0200
Subject: [PATCH] Use modern Items property changed notification.

---
 Perspex.Controls/Deck.cs                      |  4 +-
 Perspex.Controls/ItemsControl.cs              | 68 ++++++++++++++++---
 .../Primitives/SelectingItemsControl.cs       |  6 +-
 3 files changed, 64 insertions(+), 14 deletions(-)

diff --git a/Perspex.Controls/Deck.cs b/Perspex.Controls/Deck.cs
index 8905d318a3..67d5a83c3d 100644
--- a/Perspex.Controls/Deck.cs
+++ b/Perspex.Controls/Deck.cs
@@ -35,9 +35,9 @@ namespace Perspex.Controls
             set { this.SetValue(TransitionProperty, value); }
         }
 
-        protected override void ItemsChanged(IEnumerable oldValue, IEnumerable newValue)
+        protected override void ItemsChanged(PerspexPropertyChangedEventArgs e)
         {
-            base.ItemsChanged(oldValue, newValue);
+            base.ItemsChanged(e);
 
             var items = this.Items;
 
diff --git a/Perspex.Controls/ItemsControl.cs b/Perspex.Controls/ItemsControl.cs
index aca64b2ea3..1fbfbacbf3 100644
--- a/Perspex.Controls/ItemsControl.cs
+++ b/Perspex.Controls/ItemsControl.cs
@@ -19,39 +19,57 @@ namespace Perspex.Controls
     using Perspex.Controls.Utils;
     using Perspex.Styling;
 
+    /// <summary>
+    /// Displays a collection of items.
+    /// </summary>
     public class ItemsControl : TemplatedControl, ILogical
     {
+        /// <summary>
+        /// The default value for the <see cref="ItemsPanel"/> property.
+        /// </summary>
         [SuppressMessage("Microsoft.StyleCop.CSharp.NamingRules", "SA1202:ElementsMustBeOrderedByAccess", Justification = "Needs to be before or a NullReferenceException is thrown.")]
         private static readonly ItemsPanelTemplate DefaultPanel =
             new ItemsPanelTemplate(() => new StackPanel());
 
+        /// <summary>
+        /// Defines the <see cref="Items"/> property.
+        /// </summary>
         public static readonly PerspexProperty<IEnumerable> ItemsProperty =
             PerspexProperty.Register<ItemsControl, IEnumerable>("Items");
 
+        /// <summary>
+        /// Defines the <see cref="ItemsPanel"/> property.
+        /// </summary>
         public static readonly PerspexProperty<ItemsPanelTemplate> ItemsPanelProperty =
             PerspexProperty.Register<ItemsControl, ItemsPanelTemplate>("ItemsPanel", defaultValue: DefaultPanel);
 
         private IItemContainerGenerator itemContainerGenerator;
 
-        private PerspexReadOnlyListView<IVisual, ILogical> logicalChildren = 
+        private PerspexReadOnlyListView<IVisual, ILogical> logicalChildren =
             new PerspexReadOnlyListView<IVisual, ILogical>(x => (ILogical)x);
 
         private IItemsPresenter presenter;
 
+        /// <summary>
+        /// Initializes static members of the <see cref="ItemsControl"/> class.
+        /// </summary>
         static ItemsControl()
         {
-            ItemsProperty.Changed.Subscribe(e =>
-            {
-                var control = e.Sender as ItemsControl;
-                control?.ItemsChanged((IEnumerable)e.OldValue, (IEnumerable)e.NewValue);
-            });
+            ItemsProperty.Changed.AddClassHandler<ItemsControl>(x => x.ItemsChanged);
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ItemsControl"/> class.
+        /// </summary>
         public ItemsControl()
         {
-            this.ItemsChanged(null, null);
+            this.Classes.Add(":empty");
         }
 
+        /// <summary>
+        /// Gets the <see cref="IItemContainerGenerator"/> for the control.
+        /// </summary>
+        public IItemContainerGenerator ItemContainerGenerator
         {
             get
             {
@@ -64,18 +82,27 @@ namespace Perspex.Controls
             }
         }
 
+        /// <summary>
+        /// Gets or sets the items to display.
+        /// </summary>
         public IEnumerable Items
         {
             get { return this.GetValue(ItemsProperty); }
             set { this.SetValue(ItemsProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the panel used to display the items.
+        /// </summary>
         public ItemsPanelTemplate ItemsPanel
         {
             get { return this.GetValue(ItemsPanelProperty); }
             set { this.SetValue(ItemsPanelProperty, value); }
         }
 
+        /// <summary>
+        /// Gets the items presenter control.
+        /// </summary>
         public IItemsPresenter Presenter
         {
             get
@@ -90,6 +117,12 @@ namespace Perspex.Controls
             }
         }
 
+        /// <summary>
+        /// Gets the logical children of the control.
+        /// </summary>
+        /// <remarks>
+        /// The logical children of an <see cref="ItemsControl"/> are the item containers.
+        /// </remarks>
         IPerspexReadOnlyList<ILogical> ILogical.LogicalChildren
         {
             get
@@ -99,25 +132,36 @@ namespace Perspex.Controls
             }
         }
 
+        /// <summary>
+        /// Creates the <see cref="ItemContainerGenerator"/> for the control.
+        /// </summary>
+        /// <returns>An <see cref="IItemContainerGenerator"/>.</returns>
         protected virtual IItemContainerGenerator CreateItemContainerGenerator()
         {
             return new ItemContainerGenerator(this);
         }
 
+        /// <inheritdoc/>
         protected override void OnTemplateApplied()
         {
             this.Presenter = this.FindTemplateChild<IItemsPresenter>("itemsPresenter");
         }
 
-        protected virtual void ItemsChanged(IEnumerable oldValue, IEnumerable newValue)
+        /// <summary>
+        /// Caled when the <see cref="Items"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected virtual void ItemsChanged(PerspexPropertyChangedEventArgs e)
         {
-            var incc = oldValue as INotifyCollectionChanged;
+            var incc = e.OldValue as INotifyCollectionChanged;
 
             if (incc != null)
             {
                 incc.CollectionChanged += this.ItemsCollectionChanged;
             }
 
+            var newValue = e.NewValue as IEnumerable;
+
             if (newValue == null || newValue.Count() == 0)
             {
                 this.Classes.Add(":empty");
@@ -135,6 +179,12 @@ namespace Perspex.Controls
             }
         }
 
+        /// <summary>
+        /// Called when the <see cref="INotifyCollectionChanged.CollectionChanged"/> event is
+        /// raised on <see cref="Items"/>.
+        /// </summary>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event args.</param>
         protected virtual void ItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
         {
             var collection = sender as ICollection;
diff --git a/Perspex.Controls/Primitives/SelectingItemsControl.cs b/Perspex.Controls/Primitives/SelectingItemsControl.cs
index 8f2b8e1363..2b465e0319 100644
--- a/Perspex.Controls/Primitives/SelectingItemsControl.cs
+++ b/Perspex.Controls/Primitives/SelectingItemsControl.cs
@@ -86,10 +86,10 @@ namespace Perspex.Controls.Primitives
         }
 
         /// <inheritdoc/>
-        protected override void ItemsChanged(IEnumerable oldValue, IEnumerable newValue)
+        protected override void ItemsChanged(PerspexPropertyChangedEventArgs e)
         {
-            base.ItemsChanged(oldValue, newValue);
-            this.SelectedIndex = IndexOf(newValue, this.SelectedItem);
+            base.ItemsChanged(e);
+            this.SelectedIndex = IndexOf((IEnumerable)e.NewValue, this.SelectedItem);
         }
 
         /// <inheritdoc/>