WPF TreeView BringIntoViewBehavior

由于项目需要，需要能够定位TreeView中的点，TreeView的节点数过多的情况下，即使找到了对应的节点并选中展示了，由于不在可视区域内，给用户的感觉还是不好，因此设计如下的Behavior，来实现选中的TreeViewItem显示在可见区域：

 using System;
 using System.Windows;
 using System.Windows.Controls;

 namespace Johar.Core
 {
     public static class BringIntoViewBehavior
     {
         public static bool GetIsBringIntoViewWhenSelected(DependencyObject obj)
         {
             return (bool)obj.GetValue(IsBringIntoViewWhenSelectedProperty);
         }

         public static void SetIsBringIntoViewWhenSelected(DependencyObject obj, bool value)
         {
             obj.SetValue(IsBringIntoViewWhenSelectedProperty, value);
         }

         // Using a DependencyProperty as the backing store for IsBringIntoViewWhenSelected.  This enables animation, styling, binding, etc...
         public static readonly DependencyProperty IsBringIntoViewWhenSelectedProperty =
             DependencyProperty.RegisterAttached("IsBringIntoViewWhenSelected",
             typeof(bool), typeof(BringIntoViewBehavior),
             new FrameworkPropertyMetadata(false, new PropertyChangedCallback(OnIsBringIntoViewWhenSelected)));

         private static void OnIsBringIntoViewWhenSelected(DependencyObject d, DependencyPropertyChangedEventArgs e)
         {
             TreeViewItem item = d as TreeViewItem;
             if (item == null)
             {
                 return;
             }

             if (e.NewValue is bool == false)
             {
                 return;
             }

             if ((bool)e.NewValue)
             {
                 item.Selected -= item_Selected;
                 item.Selected += item_Selected;
             }
             else
             {
                 item.Selected -= item_Selected;
             }
         }

         private static void item_Selected(object sender, RoutedEventArgs e)
         {
             TreeViewItem item = e.OriginalSource as TreeViewItem;
             if (item != null)
             {
                 item.BringIntoView();
             }
         }
     }
 }

然后在TreeView中设置一下这个依赖属性为True即可上述要求。