Revert "Removed PerspexReadOnlyListView<T>"

This reverts commit 0359f8c9a3.

Perspex.Base/Collections/PerspexReadOnlyListView.cs

@@ -13,6 +13,134 @@ namespace Perspex.Collections
     using System.ComponentModel;
     using System.Linq;
 
+    public class PerspexReadOnlyListView<T> : IPerspexReadOnlyList<T>, IDisposable
+    {
+        private IPerspexReadOnlyList<T> source;
+
+        public PerspexReadOnlyListView()
+            : this(null)
+        {
+        }
+
+        public PerspexReadOnlyListView(IPerspexReadOnlyList<T> source)
+        {
+            this.source = source;
+
+            if (source != null)
+            {
+                this.source.CollectionChanged += this.SourceCollectionChanged;
+            }
+        }
+
+        public event NotifyCollectionChangedEventHandler CollectionChanged;
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        public int Count
+        {
+            get { return this.source?.Count ?? 0; }
+        }
+
+        public IPerspexReadOnlyList<T> Source
+        {
+            get
+            {
+                return this.source;
+            }
+
+            set
+            {
+                if (this.source != null)
+                {
+                    this.source.CollectionChanged -= this.SourceCollectionChanged;
+
+                    if (this.CollectionChanged != null)
+                    {
+                        var ev = new NotifyCollectionChangedEventArgs(
+                            NotifyCollectionChangedAction.Remove,
+                            this.source,
+                            0);
+                        this.CollectionChanged(this, ev);
+                    }
+                }
+
+                this.source = value;
+
+                if (this.source != null)
+                {
+                    this.source.CollectionChanged += this.SourceCollectionChanged;
+
+                    if (this.CollectionChanged != null)
+                    {
+                        var ev = new NotifyCollectionChangedEventArgs(
+                            NotifyCollectionChangedAction.Add,
+                            this.source.ToList(),
+                            0);
+                        this.CollectionChanged(this, ev);
+                    }
+                }
+            }
+        }
+
+        public T this[int index]
+        {
+            get { return this.source[index]; }
+        }
+
+        public void Dispose()
+        {
+            this.source.CollectionChanged -= this.SourceCollectionChanged;
+        }
+
+        public IEnumerator<T> GetEnumerator()
+        {
+            return (this.source != null) ? 
+                this.source.GetEnumerator() : 
+                Enumerable.Empty<T>().GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return this.GetEnumerator();
+        }
+
+        private void SourceCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            if (this.CollectionChanged != null)
+            {
+                NotifyCollectionChangedEventArgs ev;
+
+                switch (e.Action)
+                {
+                    case NotifyCollectionChangedAction.Add:
+                        ev = new NotifyCollectionChangedEventArgs(
+                            NotifyCollectionChangedAction.Add,
+                            e.NewItems,
+                            e.NewStartingIndex);
+                        break;
+                    case NotifyCollectionChangedAction.Remove:
+                        ev = new NotifyCollectionChangedEventArgs(
+                            NotifyCollectionChangedAction.Remove,
+                            e.OldItems,
+                            e.OldStartingIndex);
+                        break;
+                    case NotifyCollectionChangedAction.Replace:
+                        ev = new NotifyCollectionChangedEventArgs(
+                            NotifyCollectionChangedAction.Replace,
+                            e.NewItems,
+                            e.OldItems,
+                            e.OldStartingIndex);
+                        break;
+
+                    default:
+                        throw new NotSupportedException("Action not yet implemented.");
+                }
+
+                this.CollectionChanged(this, ev);
+            }
+        }
+    }
+
     public class PerspexReadOnlyListView<TIn, TOut> : IPerspexReadOnlyList<TOut>, IDisposable
     {
         private IPerspexReadOnlyList<TIn> source;

Perspex.Controls/ContentControl.cs

@@ -24,7 +24,7 @@ namespace Perspex.Controls
         public static readonly PerspexProperty<VerticalAlignment> VerticalContentAlignmentProperty =
             PerspexProperty.Register<ContentControl, VerticalAlignment>("VerticalContentAlignment");
 
-        private IPerspexReadOnlyList<ILogical> logicalChildren = new PerspexList<ILogical>();
+        private PerspexReadOnlyListView<ILogical> logicalChildren = new PerspexReadOnlyListView<ILogical>();
 
         public ContentControl()
         {
@@ -63,7 +63,11 @@ namespace Perspex.Controls
 
             if (presenter != null)
             {
-                this.logicalChildren = ((ILogical)presenter)?.LogicalChildren;
+                this.logicalChildren.Source = ((ILogical)presenter).LogicalChildren;
+            }
+            else
+            {
+                this.logicalChildren.Source = null;
             }
         }
 

Perspex.Controls/DropDown.cs

@@ -28,7 +28,7 @@ namespace Perspex.Controls
         public static readonly PerspexProperty<bool> IsDropDownOpenProperty =
             PerspexProperty.Register<DropDown, bool>("IsDropDownOpen");
 
-        private IPerspexReadOnlyList<ILogical> logicalChildren = new PerspexSingleItemList<ILogical>();
+        private PerspexReadOnlyListView<ILogical> logicalChildren = new PerspexReadOnlyListView<ILogical>();
 
         public DropDown()
         {
@@ -77,7 +77,7 @@ namespace Perspex.Controls
         {
             var container = this.GetTemplateChild<Panel>("container");
             ((IItemsPanel)container).ChildLogicalParent = this;
-            this.logicalChildren = ((ILogical)container).LogicalChildren;
+            this.logicalChildren.Source = ((ILogical)container).LogicalChildren;
         }
 
         private void SetContentParent(Tuple<object, object> change)

Perspex.Controls/TabControl.cs

@@ -25,7 +25,8 @@ namespace Perspex.Controls
         public static readonly PerspexProperty<IPageTransition> TransitionProperty =
             Deck.TransitionProperty.AddOwner<TabControl>();
 
-        private IPerspexReadOnlyList<ILogical> logicalChildren = new PerspexSingleItemList<ILogical>();
+        private PerspexReadOnlyListView<ILogical> logicalChildren = 
+            new PerspexReadOnlyListView<ILogical>();
 
         static TabControl()
         {
@@ -80,7 +81,7 @@ namespace Perspex.Controls
             base.OnTemplateApplied();
 
             this.deck = this.GetTemplateChild<Deck>("deck");
-            this.logicalChildren = ((ILogical)deck).LogicalChildren;
+            this.logicalChildren.Source = ((ILogical)deck).LogicalChildren;
         }
     }
 }