WPF VisualTreeHelper分析

Posted 2020-08-15 Ant-double

1、方法一

public static int GetChildrenCount(
	DependencyObject reference
)
可以看到接受任何为DependencyObject，wpf中的几乎所有的控件都继承自这个控件。
可以看到msdn上给的例子：

 1 // Enumerate all the descendants of the visual object.
 2 static public void EnumVisual(Visual myVisual)
 3 {
 4     for (int i = 0; i < VisualTreeHelper.GetChildrenCount(myVisual); i++)
 5     {
 6         // Retrieve child visual at specified index value.
 7         Visual childVisual = (Visual)VisualTreeHelper.GetChild(myVisual, i);
 8 
 9         // Do processing of the child visual object.
10 
11         // Enumerate children of the child visual object.
12         EnumVisual(childVisual);
13     }
14 }

下面是一封装的一个通用的方法

 1 /// <summary>
 2 /// 利用visualtreehelper寻找对象的子级对象
 3 /// </summary>
 4 /// <typeparam name="T"></typeparam>
 5 /// <param name="obj"></param>
 6 /// <returns></returns>
 7 List<T> FindVisualChild<T>(DependencyObject obj) where T : DependencyObject
 8 {
 9     try
10     {
11         List<T> TList = new List<T> { };
12         for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
13         {
14             DependencyObject child = VisualTreeHelper.GetChild(obj, i);
15             if (child != null && child is T)
16             {
17                 TList.Add((T)child);
18             }
19             else
20             {
21                 List<T> childOfChildren = FindVisualChild<T>(child);
22                 if (childOfChildren != null)
23                 {
24                     TList.AddRange(childOfChildren);
25                 }
26             }
27         }
28         return TList;
29     }
30     catch (Exception ee)
31     {
32         MessageBox.Show(ee.Message);
33         return null;
34     }
35 }

二、

public static DependencyObject GetParent(
	DependencyObject reference
)
可能看msdn上的例子：

 1 /// <summary>
 2 /// 利用VisualTreeHelper寻找指定依赖对象的父级对象
 3 /// </summary>
 4 /// <typeparam name="T"></typeparam>
 5 /// <param name="obj"></param>
 6 /// <returns></returns>
 7 public static List<T> FindVisualParent<T>(DependencyObject obj) where T : DependencyObject
 8 {
 9     try
10     {
11         List<T> TList = new List<T> { };
12         DependencyObject parent = VisualTreeHelper.GetParent(obj);
13         if (parent != null && parent is T)
14         {
15             TList.Add((T)parent);
16             List<T> parentOfParent = FindVisualParent<T>(parent);
17             if (parentOfParent !=null)
18             {
19                 TList.AddRange(parentOfParent);
20             }
21         }
22         else
23         {
24 
25         }
26         return TList;
27     }
28     catch (Exception ee)
29     {
30         MessageBox.Show(ee.Message);
31         return null;
32     }
33 }

给出一个使用的例子：

 1 private void btn_Two_Click(object sender, RoutedEventArgs e)
 2 {
 3     string parentName = "";
 4     List<Grid> gridList = FindVisualParent<Grid>(btn_Two);
 5     foreach (Grid item in gridList)
 6     {
 7         parentName += string.IsNullOrEmpty(parentName) ? item.Name.ToString() : "," + item.Name.ToString();
 8     }
 9     MessageBox.Show(string.Format(btn_Two.Name.ToString() + "共有{0}个逻辑父级,名称分别为{1}", gridList.Count, parentName));
10 }