Hacky keyboard navigation for TreeView.

Perspex.Controls/TreeView.cs

@@ -6,10 +6,9 @@
 
 namespace Perspex.Controls
 {
-    using System.Linq;
-    using System.Reactive.Linq;
+    using System.Collections;
+    using System.Collections.Generic;
     using Perspex.Controls.Generators;
-    using Perspex.Controls.Presenters;
     using Perspex.Controls.Primitives;
     using Perspex.Input;
 
@@ -20,28 +19,77 @@ namespace Perspex.Controls
             return new TreeItemContainerGenerator<TreeViewItem>(this);
         }
 
-        //protected override void OnPointerPressed(PointerEventArgs e)
-        //{
-        //    IVisual source = (IVisual)e.Source;
-        //    ContentPresenter contentPresenter = source.GetVisualAncestors()
-        //        .OfType<ContentPresenter>()
-        //        .FirstOrDefault();
-
-        //    if (contentPresenter != null)
-        //    {
-        //        TreeViewItem container = contentPresenter.TemplatedParent as TreeViewItem;
-
-        //        if (container != null)
-        //        {
-        //            foreach (var i in this.GetVisualDescendents().OfType<TreeViewItem>())
-        //            {
-        //                i.IsSelected = i == container;
-        //            }
-
-        //            this.SelectedItem = this.ItemContainerGenerator.GetItemForContainer(container);
-        //        }
-        //    }
-
-        //}
+        protected override void MoveSelection(FocusNavigationDirection direction)
+        {
+            // TODO: Up and down movement is a *HACK* and probably pretty slow. Probably needs
+            // rewriting at some point.
+            if (this.SelectedItem != null)
+            {
+                switch (direction)
+                {
+                    case FocusNavigationDirection.Up:
+                        {
+                            var list = this.Flatten();
+                            var index = list.IndexOf(this.SelectedItem);
+
+                            if (index > 0)
+                            {
+                                this.SelectedItem = list[index - 1];
+                            }
+                            break;
+                        }
+
+                    case FocusNavigationDirection.Down:
+                        {
+                            var list = this.Flatten();
+                            var index = list.IndexOf(this.SelectedItem);
+
+                            if (index + 1 < list.Count)
+                            {
+                                this.SelectedItem = list[index + 1];
+                            }
+                            break;
+                        }
+
+                    case FocusNavigationDirection.Left:
+                        {
+                            var node = (TreeViewItem)this.ItemContainerGenerator.GetContainerForItem(this.SelectedItem);
+                            node.IsExpanded = false;
+                            break;
+                        }
+
+                    case FocusNavigationDirection.Right:
+                        {
+                            var node = (TreeViewItem)this.ItemContainerGenerator.GetContainerForItem(this.SelectedItem);
+                            node.IsExpanded = true;
+                            break;
+                        }
+                }
+            }
+        }
+
+        List<object> Flatten()
+        {
+            var result = new List<object>();
+            this.Flatten(this.Items, result);
+            return result;
+        }
+
+        void Flatten(IEnumerable items, List<object> result)
+        {
+            if (items != null)
+            {
+                foreach (object item in items)
+                {
+                    var container = (TreeViewItem)this.ItemContainerGenerator.GetContainerForItem(item);
+                    result.Add(item);
+
+                    if (container.IsExpanded)
+                    {
+                        this.Flatten(container.Items, result);
+                    }
+                }
+            }
+        }
     }
 }