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：

 1 using system;
 2 using system.windows;
 3 using system.windows.controls;
 4 
 5 namespace johar.core
 6 {
 7     public static class bringintoviewbehavior
 8     {
 9         public static bool getisbringintoviewwhenselected(dependencyobject obj)
10         {
11             return (bool)obj.getvalue(isbringintoviewwhenselectedproperty);
12         }
13 
14         public static void setisbringintoviewwhenselected(dependencyobject obj, bool value)
15         {
16             obj.setvalue(isbringintoviewwhenselectedproperty, value);
17         }
18 
19         // using a dependencyproperty as the backing store for isbringintoviewwhenselected.  this enables animation, styling, binding, etc...
20         public static readonly dependencyproperty isbringintoviewwhenselectedproperty =
21             dependencyproperty.registerattached("isbringintoviewwhenselected", 
22             typeof(bool), typeof(bringintoviewbehavior), 
23             new frameworkpropertymetadata(false, new propertychangedcallback(onisbringintoviewwhenselected)));
24 
25         private static void onisbringintoviewwhenselected(dependencyobject d, dependencypropertychangedeventargs e)
26         {
27             treeviewitem item = d as treeviewitem;
28             if (item == null)
29             {
30                 return;
31             }
32 
33             if (e.newvalue is bool == false)
34             {
35                 return;
36             }
37 
38             if ((bool)e.newvalue)
39             {
40                 item.selected -= item_selected;
41                 item.selected += item_selected;
42             }
43             else
44             {
45                 item.selected -= item_selected;
46             }
47         }
48 
49         private static void item_selected(object sender, routedeventargs e)
50         { 
59             treeviewitem item = e.originalsource as treeviewitem;
60             if (item != null)
61             {
62                 item.bringintoview();
63             }
64         }
65     }
66 }

然后在treeview中设置一下这个依赖属性为true即可上述要求。