Silverlight获取子控件和父控件方法
在Silverlight项目开发中，经常会把一个独立功能的控件封装成一个UserControl，然后供其他页面或者控件进行调用。前一段时间，在项目中遇到一个问题，需要在同一个页面重复调用多个相同的UserControl控件，然后在父页面中控制这些重复生成的子控件。由于很多控件是动态生成，数量也是动态控制，所以所有的操作都需要使用后台代码进行实现。
在上面的需求中需要用到Silverlight API中的VisualTreeHelper类，对于VisualTreeHelper类，有不少文章已经介绍过，该类可以对Silverlight可视化树进行遍历，该可视化树是逻辑对象树的一个子集。我们可以通过VisualTreeHelper提供的方法GetChild()，GetParent()和GetChildrenCount()，分别获取子控件，父控件以及子控件数量。
在实际项目中，为满足实际开发需求，对VisualTreeHelper的方法重新进行封装是非常必要的。
首先要介绍的Hleper方法是GetParentObject方法，获取父控件方法。该方法将根据当前控件，遍历查找其父控件是否存在。参数1是表示当前子控件名，参数2是要查询父控件名；使用VisualTreeHelper.GetParent方法获取当前父控件。
1 public T GetParentObject<T>(DependencyObject obj, string name) where T : FrameworkElement
2 {
3 DependencyObject parent = VisualTreeHelper.GetParent(obj);
4
5 while (parent != null)
6 {
7 if (parent is T && (((T)parent).Name == name | string.IsNullOrEmpty(name)))
8 {
9 return (T)parent;
10 }
11
12 parent = VisualTreeHelper.GetParent(parent);
13 }
14
15 return null;
16 }
17
2 {
3 DependencyObject parent = VisualTreeHelper.GetParent(obj);
4
5 while (parent != null)
6 {
7 if (parent is T && (((T)parent).Name == name | string.IsNullOrEmpty(name)))
8 {
9 return (T)parent;
10 }
11
12 parent = VisualTreeHelper.GetParent(parent);
13 }
14
15 return null;
16 }
17
另外一个Helper方法是GetChildObject,获取子控件方法。该方法将根据当前控件，遍历查找其子控件是否存在。参数1是表示当前父控件名，参数2是要查询子控件名；
1 public T GetChildObject<T>(DependencyObject obj, string name) where T : FrameworkElement
2 {
3 DependencyObject child = null;
4 T grandChild = null;
5
6 for (int i = 0; i <= VisualTreeHelper.GetChildrenCount(obj) - 1; i++)
7 {
8 child = VisualTreeHelper.GetChild(obj, i);
9
10 if (child is T && (((T)child).Name == name | string.IsNullOrEmpty(name)))
11 {
12 return (T)child;
13 }
14 else
15 {
16 grandChild = GetChildObject<T>(child, name);
17 if (grandChild != null)
18 return grandChild;
19 }
20 }
21
22 return null;
23
24 }
2 {
3 DependencyObject child = null;
4 T grandChild = null;
5
6 for (int i = 0; i <= VisualTreeHelper.GetChildrenCount(obj) - 1; i++)
7 {
8 child = VisualTreeHelper.GetChild(obj, i);
9
10 if (child is T && (((T)child).Name == name | string.IsNullOrEmpty(name)))
11 {
12 return (T)child;
13 }
14 else
15 {
16 grandChild = GetChildObject<T>(child, name);
17 if (grandChild != null)
18 return grandChild;
19 }
20 }
21
22 return null;
23
24 }
最后介绍一个Helper方法是GetChildObjects方法，该方法将把所有子控件作为List集合返回到客户端。其中第一个参数是父控件参数，而第二个参数是特定子控件名称，如果需要遍历全部子控件，第二个参数留空即可。
1 public List<T> GetChildObjects<T>(DependencyObject obj, string name) where T : FrameworkElement
2 {
3 DependencyObject child = null;
4 List<T> childList = new List<T>();
5
6 for (int i = 0; i <= VisualTreeHelper.GetChildrenCount(obj) - 1; i++)
7 {
8 child = VisualTreeHelper.GetChild(obj, i);
9
10 if (child is T && (((T)child).Name == name || string.IsNullOrEmpty(name)))
11 {
12 childList.Add((T)child);
13 }
14
15 childList.AddRange(GetChildObjects<T>(child,""));
16 }
17
18 return childList;
19
20 }
2 {
3 DependencyObject child = null;
4 List<T> childList = new List<T>();
5
6 for (int i = 0; i <= VisualTreeHelper.GetChildrenCount(obj) - 1; i++)
7 {
8 child = VisualTreeHelper.GetChild(obj, i);
9
10 if (child is T && (((T)child).Name == name || string.IsNullOrEmpty(name)))
11 {
12 childList.Add((T)child);
13 }
14
15 childList.AddRange(GetChildObjects<T>(child,""));
16 }
17
18 return childList;
19
20 }
下面用一个例程演示使用方法：
使用方法很简单，首先创建基础控件：
1 <UserControl x:Class="SLVisualTreeHelper.MainPage"
2 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
5 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
6 mc:Ignorable="d"
7 d:DesignHeight="300" d:DesignWidth="400">
8
9 <Grid x:Name="LayoutRoot" Background="White">
10 <Grid.RowDefinitions>
11 <RowDefinition Height="Auto"></RowDefinition>
12 <RowDefinition Height="*"></RowDefinition>
13 </Grid.RowDefinitions>
14 <StackPanel x:Name="spDemoPanel" Orientation="Vertical" Grid.Row="0">
15 <TextBlock Margin="5">获取子控件和父控件演示</TextBlock>
16 <TextBlock Margin="5">专注Silverlight技术交流</TextBlock>
17 <TextBlock Margin="5">博客:http//jv9.cnblogs.com</TextBlock>
18 <Button x:Name="btDemoButton" Width="120" Height="40" Content="获取所有控件" Click="btDemoButton_Click" HorizontalAlignment="Left" Margin="5"/>
19 <Button x:Name="btModifyChild" Width="120" Height="40" Content="修改布局控件背景" Click="btModifyChild_Click" HorizontalAlignment="Left" Margin="5"/>
20 <Button x:Name="btModifyChilds" Width="120" Height="40" Content="批量修改控件字体尺寸" Click="btModifyChilds_Click" HorizontalAlignment="Left" Margin="5"/>
21 </StackPanel>
22
23 <StackPanel x:Name="spResult" Grid.Row="1">
24 <TextBlock x:Name="tbResult"/>
25 </StackPanel>
26
27 </Grid>
28 </UserControl>
29
2 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
5 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
6 mc:Ignorable="d"
7 d:DesignHeight="300" d:DesignWidth="400">
8
9 <Grid x:Name="LayoutRoot" Background="White">
10 <Grid.RowDefinitions>
11 <RowDefinition Height="Auto"></RowDefinition>
12 <RowDefinition Height="*"></RowDefinition>
13 </Grid.RowDefinitions>
14 <StackPanel x:Name="spDemoPanel" Orientation="Vertical" Grid.Row="0">
15 <TextBlock Margin="5">获取子控件和父控件演示</TextBlock>
16 <TextBlock Margin="5">专注Silverlight技术交流</TextBlock>
17 <TextBlock Margin="5">博客:http//jv9.cnblogs.com</TextBlock>
18 <Button x:Name="btDemoButton" Width="120" Height="40" Content="获取所有控件" Click="btDemoButton_Click" HorizontalAlignment="Left" Margin="5"/>
19 <Button x:Name="btModifyChild" Width="120" Height="40" Content="修改布局控件背景" Click="btModifyChild_Click" HorizontalAlignment="Left" Margin="5"/>
20 <Button x:Name="btModifyChilds" Width="120" Height="40" Content="批量修改控件字体尺寸" Click="btModifyChilds_Click" HorizontalAlignment="Left" Margin="5"/>
21 </StackPanel>
22
23 <StackPanel x:Name="spResult" Grid.Row="1">
24 <TextBlock x:Name="tbResult"/>
25 </StackPanel>
26
27 </Grid>
28 </UserControl>
29
然后在后台代码，声明实例进行调用，
1 namespace SLVisualTreeHelper
2 {
3 public partial class MainPage : UserControl
4 {
5
6 public MainPage()
7 {
8 InitializeComponent();
9 }
10
11 private void btDemoButton_Click(object sender, RoutedEventArgs e)
12 {
13 Globals VTHelper = new Globals();
14 StackPanel sp = VTHelper.GetChildObject<StackPanel>(this.LayoutRoot, "spDemoPanel");
15 Grid layoutGrid = VTHelper.GetParentObject<Grid>(this.spDemoPanel, "LayoutRoot");
16 List<TextBlock> textblock = VTHelper.GetChildObjects<TextBlock>(this.LayoutRoot, "");
17
18
19 if (sp != null)
20 {
21 if (layoutGrid != null)
22 {
23
24 if (textblock.Count > 0)
25 {
26 tbResult.Text = "包含TextBlock控件数量为: " + textblock.Count.ToString() + "/n";
27 }
28 tbResult.Text += "获取父控件成功..../n" ;
29 }
30 tbResult.Text += "获取子控件成功..../n";
31 }
32 }
33
34 private void btModifyChild_Click(object sender, RoutedEventArgs e)
35 {
36 Globals VTHelper = new Globals();
37 StackPanel sp = VTHelper.GetChildObject<StackPanel>(this.LayoutRoot, "spDemoPanel");
38 sp.Background = new SolidColorBrush(Colors.Purple);
39 }
40
41 private void btModifyChilds_Click(object sender, RoutedEventArgs e)
42 {
43 Globals VTHelper = new Globals();
44 List<TextBlock> textblock = VTHelper.GetChildObjects<TextBlock>(this.LayoutRoot, "");
45 foreach (TextBlock tmpTextblock in textblock)
46 {
47 tmpTextblock.FontSize += 6;
48 }
49 }
50 }
51 }
2 {
3 public partial class MainPage : UserControl
4 {
5
6 public MainPage()
7 {
8 InitializeComponent();
9 }
10
11 private void btDemoButton_Click(object sender, RoutedEventArgs e)
12 {
13 Globals VTHelper = new Globals();
14 StackPanel sp = VTHelper.GetChildObject<StackPanel>(this.LayoutRoot, "spDemoPanel");
15 Grid layoutGrid = VTHelper.GetParentObject<Grid>(this.spDemoPanel, "LayoutRoot");
16 List<TextBlock> textblock = VTHelper.GetChildObjects<TextBlock>(this.LayoutRoot, "");
17
18
19 if (sp != null)
20 {
21 if (layoutGrid != null)
22 {
23
24 if (textblock.Count > 0)
25 {
26 tbResult.Text = "包含TextBlock控件数量为: " + textblock.Count.ToString() + "/n";
27 }
28 tbResult.Text += "获取父控件成功..../n" ;
29 }
30 tbResult.Text += "获取子控件成功..../n";
31 }
32 }
33
34 private void btModifyChild_Click(object sender, RoutedEventArgs e)
35 {
36 Globals VTHelper = new Globals();
37 StackPanel sp = VTHelper.GetChildObject<StackPanel>(this.LayoutRoot, "spDemoPanel");
38 sp.Background = new SolidColorBrush(Colors.Purple);
39 }
40
41 private void btModifyChilds_Click(object sender, RoutedEventArgs e)
42 {
43 Globals VTHelper = new Globals();
44 List<TextBlock> textblock = VTHelper.GetChildObjects<TextBlock>(this.LayoutRoot, "");
45 foreach (TextBlock tmpTextblock in textblock)
46 {
47 tmpTextblock.FontSize += 6;
48 }
49 }
50 }
51 }
其中Globals类中包含前文介绍的几个获取代码。
在线演示：
最后是源代码下载，项目是VS2010+Silverlight 4，点击下载
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