WPF-wpf的可视化树操作

sing System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Windows.Controls.Primitives;
using System.Collections.ObjectModel;
using System.Collections.Generic;

namespace MyLib.Extensions {
    /// <summary>
    /// Description of WpfExt.
    /// </summary>
    public static class WpfExt    {
        public static List<childItem> FindVisualChildren<childItem>(this DependencyObject obj)
            where childItem : DependencyObject {

            List<childItem> children = new List<childItem>();

            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++) {
                DependencyObject child = VisualTreeHelper.GetChild(obj, i);
                if (child != null && child is childItem) {
                    children.Add(child as childItem);
                } else {
                    childItem childOfChild = FindVisualChild<childItem>(child);
                    if (childOfChild != null) {
                        children.Add(childOfChild as childItem);
                    }
                }
            }

            return children;
        }

        public static childItem FindVisualChild<childItem>(this DependencyObject obj)
            where childItem : DependencyObject {
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++) {
                DependencyObject child = VisualTreeHelper.GetChild(obj, i);
                if (child != null && child is childItem)
                    return (childItem)child;
                else {
                    childItem childOfChild = FindVisualChild<childItem>(child);
                    if (childOfChild != null)
                        return childOfChild;
                }
            }
            return null;
        }

    }
}