Track changes to collections in ItemsControl.

And add a simple UI to test adding nodes to tree view.

Perspex/Controls/ItemsControl.cs

@@ -9,6 +9,8 @@ namespace Perspex.Controls
     using System;
     using System.Collections;
     using System.Collections.Generic;
+    using System.Collections.Specialized;
+    using System.ComponentModel;
     using System.Linq;
 
     public class ItemsControl : TemplatedControl
@@ -22,11 +24,13 @@ namespace Perspex.Controls
         public static readonly PerspexProperty<ItemsPanelTemplate> ItemsPanelProperty =
             PerspexProperty.Register<ItemsControl, ItemsPanelTemplate>("ItemsPanel", defaultValue: DefaultPanel);
 
-        private Dictionary<object, Control> itemControls = new Dictionary<object, Control>();
+        private Dictionary<object, Control> controlsByItem = new Dictionary<object, Control>();
+
+        private Dictionary<Control, object> itemsByControl = new Dictionary<Control, object>();
 
         public ItemsControl()
         {
-            this.GetObservable(ItemsProperty).Subscribe(this.ItemsChanged);
+            this.GetObservableWithHistory(ItemsProperty).Subscribe(this.ItemsChanged);
         }
 
         public IEnumerable Items
@@ -44,30 +48,61 @@ namespace Perspex.Controls
         public Control GetControlForItem(object item)
         {
             Control result;
-            this.itemControls.TryGetValue(item, out result);
+            this.controlsByItem.TryGetValue(item, out result);
+            return result;
+        }
+
+        public object GetItemForControl(Control control)
+        {
+            object result;
+            this.itemsByControl.TryGetValue(control, out result);
             return result;
         }
 
         public IEnumerable<Control> GetAllItemControls()
         {
-            return this.itemControls.Values;
+            return this.controlsByItem.Values;
         }
 
         internal Control CreateItemControl(object item)
         {
             Control control = this.CreateItemControlOverride(item);
-            this.itemControls.Add(item, control);
+            this.itemsByControl.Add(control, item);
+            this.controlsByItem.Add(item, control);
             return control;
         }
 
+        internal void RemoveItemControls(IEnumerable items)
+        {
+            foreach (object i in items)
+            {
+                Control control = this.GetControlForItem(i);
+                this.controlsByItem.Remove(i);
+                this.itemsByControl.Remove(control);
+            }
+        }
+
+        internal void ClearItemControls()
+        {
+            this.controlsByItem.Clear();
+            this.itemsByControl.Clear();
+        }
+
         protected virtual Control CreateItemControlOverride(object item)
         {
             return (item as Control) ?? this.GetDataTemplate(item).Build(item);
         }
 
-        private void ItemsChanged(IEnumerable items)
+        private void ItemsChanged(Tuple<IEnumerable, IEnumerable> value)
         {
-            if (items == null || !items.OfType<object>().Any())
+            INotifyPropertyChanged inpc = value.Item1 as INotifyPropertyChanged;
+
+            if (inpc != null)
+            {
+                inpc.PropertyChanged -= ItemsPropertyChanged;
+            }
+
+            if (value.Item2 == null || !value.Item2.OfType<object>().Any())
             {
                 this.Classes.Add(":empty");
             }
@@ -75,6 +110,28 @@ namespace Perspex.Controls
             {
                 this.Classes.Remove(":empty");
             }
+
+            inpc = value.Item2 as INotifyPropertyChanged;
+
+            if (inpc != null)
+            {
+                inpc.PropertyChanged += ItemsPropertyChanged;
+            }
+        }
+
+        private void ItemsPropertyChanged(object sender, PropertyChangedEventArgs e)
+        {
+            if (e.PropertyName == "Count")
+            {
+                if (((IList)sender).Count == 0)
+                {
+                    this.Classes.Add(":empty");
+                }
+                else
+                {
+                    this.Classes.Remove(":empty");
+                }
+            }
         }
     }
 }

Perspex/Controls/ItemsPresenter.cs

@@ -9,6 +9,7 @@ namespace Perspex.Controls
     using System;
     using System.Collections;
     using System.Collections.Generic;
+    using System.Collections.Specialized;
     using System.Linq;
     using Perspex.Layout;
 
@@ -24,7 +25,7 @@ namespace Perspex.Controls
 
         public ItemsPresenter()
         {
-            this.GetObservable(ItemsProperty).Subscribe(this.ItemsChanged);
+            this.GetObservableWithHistory(ItemsProperty).Subscribe(this.ItemsChanged);
         }
 
         public IEnumerable Items
@@ -91,23 +92,55 @@ namespace Perspex.Controls
             }
         }
 
+        private void ClearItemControls()
+        {
+            ItemsControl i = this.TemplatedParent as ItemsControl;
+
+            if (i != null)
+            {
+                i.ClearItemControls();
+            }
+        }
+
+        private void RemoveItemControls(IEnumerable items)
+        {
+            ItemsControl i = this.TemplatedParent as ItemsControl;
+
+            if (i != null)
+            {
+                i.RemoveItemControls(items);
+            }
+        }
+
         private Panel GetPanel()
         {
             if (this.panel == null && this.ItemsPanel != null)
             {
                 this.panel = this.ItemsPanel.Build();
                 ((IVisual)this.panel).VisualParent = this;
-                this.ItemsChanged(this.Items);
+                this.ItemsChanged(Tuple.Create(default(IEnumerable), this.Items));
             }
 
             return this.panel;
         }
 
-        private void ItemsChanged(IEnumerable items)
+        private void ItemsChanged(Tuple<IEnumerable, IEnumerable> value)
         {
+            if (value.Item1 != null)
+            {
+                INotifyCollectionChanged incc = value.Item1 as INotifyCollectionChanged;
+
+                if (incc != null)
+                {
+                    incc.CollectionChanged -= this.ItemsCollectionChanged;
+                }
+            }
+
+            this.ClearItemControls();
+
             if (this.panel != null)
             {
-                var controls = this.CreateItemControls(items).ToList();
+                var controls = this.CreateItemControls(value.Item2).ToList();
 
                 foreach (var control in controls)
                 {
@@ -115,6 +148,42 @@ namespace Perspex.Controls
                 }
 
                 this.panel.Children = new Controls(controls);
+
+                INotifyCollectionChanged incc = value.Item2 as INotifyCollectionChanged;
+
+                if (incc != null)
+                {
+                    incc.CollectionChanged += this.ItemsCollectionChanged;
+                }
+            }
+        }
+
+        private void ItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            if (this.panel != null)
+            {
+                // TODO: Handle Move and Replace.
+                switch (e.Action)
+                {
+                    case NotifyCollectionChangedAction.Add:
+                        var controls = this.CreateItemControls(e.NewItems).ToList();
+
+                        foreach (var control in controls)
+                        {
+                            control.TemplatedParent = null;
+                        }
+
+                        this.panel.Children.AddRange(controls);
+                        break;
+
+                    case NotifyCollectionChangedAction.Remove:
+                        this.RemoveItemControls(e.OldItems);
+                        break;
+                        
+                    case NotifyCollectionChangedAction.Reset:
+                        this.ItemsChanged(Tuple.Create(this.Items, this.Items));
+                        break;
+                }
             }
         }
     }

Perspex/Controls/Panel.cs

@@ -17,7 +17,7 @@ namespace Perspex.Controls
     /// <summary>
     /// Base class for controls that can contain multiple children.
     /// </summary>
-    public class Panel : Control, IVisual
+    public class Panel : Control, ILogical, IVisual
     {
         private Controls children;
 
@@ -51,6 +51,11 @@ namespace Perspex.Controls
             }
         }
 
+        IEnumerable<ILogical> ILogical.LogicalChildren
+        {
+            get { return this.children ?? Enumerable.Empty<ILogical>(); }
+        }
+
         IEnumerable<IVisual> IVisual.VisualChildren
         {
             get { return this.children ?? Enumerable.Empty<IVisual>(); }

Perspex/Controls/TabControl.cs

@@ -7,10 +7,11 @@
 namespace Perspex.Controls
 {
     using System;
+    using System.Collections.Generic;
     using System.Linq;
     using System.Reactive.Linq;
 
-    public class TabControl : SelectingItemsControl
+    public class TabControl : SelectingItemsControl, ILogical
     {
         public static readonly PerspexProperty<object> SelectedContentProperty =
             PerspexProperty.Register<TabControl, object>("SelectedContent");
@@ -22,6 +23,11 @@ namespace Perspex.Controls
             this.GetObservable(SelectedItemProperty).Skip(1).Subscribe(this.SelectedItemChanged);
         }
 
+        IEnumerable<ILogical> ILogical.LogicalChildren
+        {
+            get { return this.Items.OfType<TabItem>(); }
+        }
+
         protected override void OnTemplateApplied()
         {
             this.tabStrip = this.GetTemplateControls()

Perspex/Controls/TreeView.cs

@@ -66,6 +66,8 @@ namespace Perspex.Controls
                     {
                         i.IsSelected = i == item;
                     }
+
+                    this.SelectedItem = this.GetItemForControl(item);
                 }
             }
 

Perspex/LogicalExtensions.cs

@@ -0,0 +1,37 @@
+// -----------------------------------------------------------------------
+// <copyright file="LogicalExtensions.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using Perspex.Controls;
+    using Perspex.Styling;
+
+    public static class LogicalExtensions
+    {
+        public static T FindControl<T>(this ILogical control, string id) where T : Control
+        {
+            return control.GetLogicalDescendents()
+                .OfType<T>()
+                .FirstOrDefault(x => x.Id == id);
+        }
+
+        public static IEnumerable<ILogical> GetLogicalDescendents(this ILogical control)
+        {
+            foreach (ILogical child in control.LogicalChildren)
+            {
+                yield return child;
+
+                foreach (ILogical descendent in child.GetLogicalDescendents())
+                {
+                    yield return descendent;
+                }
+            }
+        }
+    }
+}

Perspex/Perspex.csproj

@@ -218,6 +218,7 @@
     <Compile Include="Visual.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="ControlExtensions.cs" />
+    <Compile Include="LogicalExtensions.cs" />
     <Compile Include="VisualExtensions.cs" />
   </ItemGroup>
   <ItemGroup>

TestApplication/Program.cs

@@ -1,5 +1,6 @@
 using System.Collections;
 using System.Collections.Generic;
+using System.Linq;
 using Perspex;
 using Perspex.Controls;
 using Perspex.Layout;
@@ -34,18 +35,23 @@ namespace TestApplication
 
     class Node
     {
+        public Node()
+        {
+            this.Children = new PerspexList<Node>();
+        }
+
         public string Name { get; set; }
-        public IEnumerable<Node> Children { get; set; }
+        public PerspexList<Node> Children { get; set; }
     }
 
     class Program
     {
-        private static Node[] treeData = new[]
+        private static PerspexList<Node> treeData = new PerspexList<Node>
         {
             new Node
             {
                 Name = "Root 1",
-                Children = new[]
+                Children = new PerspexList<Node>
                 {
                     new Node
                     {
@@ -54,7 +60,7 @@ namespace TestApplication
                     new Node
                     {
                         Name = "Child 2",
-                        Children = new[]
+                        Children = new PerspexList<Node>
                         {
                             new Node
                             {
@@ -176,7 +182,7 @@ namespace TestApplication
                             IsSelected = true,
                             Content = new StackPanel
                             {
-                                Orientation = Orientation.Vertical,
+                                Orientation = Orientation.Horizontal,
                                 HorizontalAlignment = HorizontalAlignment.Center,
                                 VerticalAlignment = VerticalAlignment.Center,
                                 Gap = 8,
@@ -184,8 +190,27 @@ namespace TestApplication
                                 {
                                     new TreeView
                                     {
+                                        Id = "treeView",
                                         Items = treeData,
                                     },
+                                    new StackPanel
+                                    {
+                                        Orientation = Orientation.Vertical,
+                                        Gap = 2.0,
+                                        Children = new Controls
+                                        {
+                                            new TextBox
+                                            {
+                                                Id = "newTreeViewItemText",
+                                                Text = "New Item"
+                                            },
+                                            new Button
+                                            {
+                                                Id = "addTreeViewItem",
+                                                Content = "Add",
+                                            },
+                                        }
+                                    },
                                 }
                             },
                         },
@@ -193,7 +218,20 @@ namespace TestApplication
                 }
             };
 
-            //System.Console.WriteLine(Perspex.Diagnostics.Debug.PrintVisualTree(window));
+            var treeView = window.FindControl<TreeView>("treeView");
+            var newTreeViewItemText = window.FindControl<TextBox>("newTreeViewItemText");
+            var addTreeViewItem = window.FindControl<Button>("addTreeViewItem");
+
+            addTreeViewItem.Click += (s, e) =>
+            {
+                if (treeView.SelectedItem != null)
+                {
+                    ((Node)treeView.SelectedItem).Children.Add(new Node
+                    {
+                        Name = newTreeViewItemText.Text,
+                    });
+                }
+            };
 
             window.Show();
             Dispatcher.Run();