WPF常用代码：Visual Logical Tree

1. 自定义路由事件

   // Register the routed event
   public static readonly RoutedEvent SelectedEvent = 
       EventManager.RegisterRoutedEvent( "Selected", RoutingStrategy.Bubble, 
       typeof(RoutedEventHandler), typeof(MyCustomControl));
    
   // .NET wrapper
   public event RoutedEventHandler Selected
   {
       add { AddHandler(SelectedEvent, value); } 
       remove { RemoveHandler(SelectedEvent, value); }
   }
   
   // Raise the routed event "selected"
   RaiseEvent(new RoutedEventArgs(MyCustomControl.SelectedEvent));

2. 查找特定的Parent元素或Child元素

    // walk up the visual tree to find object of type T, starting from initial object
           public static T FindUpVisualTree<T>(DependencyObject initial) where T : DependencyObject
           {
               DependencyObject current = initial;
   
               while (current != null && current.GetType() != typeof(T))
               {
                   current = VisualTreeHelper.GetParent(current);
               }
               return current as T;
           }
   
           public static T FindDownVisualTree<T>(Visual parent) where T : Visual
           {
               T child = default(T);
               int numVisuals = VisualTreeHelper.GetChildrenCount(parent);
               for (int i = 0; i < numVisuals; i++)
               {
                   Visual v = (Visual)VisualTreeHelper.GetChild(parent, i);
                   child = v as T;
                   if (child == null)
                   {
                       child = FindDownVisualTree<T>(v);
                   }
                   if (child != null)
                   {
                       break;
                   }
               }
               return child;
           }