如何获得Control中的Control

例子1 ：需要获得 ListBox 中的 Canvas

<ListBox x:Name="theListBox">
    <ListBox.ItemsPanel>
        <ItemsPanelTemplate>
            <Canvas Loaded="Canvas_Loaded"/>
        </ItemsPanelTemplate>
    </ListBox.ItemsPanel>
</ListBox>

 

方法1：Loaded 事件

private Canvas theCanvas = null;
private void Canvas_Loaded(object sender, RoutedEventArgs e)
{
    theCanvas = sender as Canvas;
}

方法2：

DependencyObject child = VisualTreeHelper.GetChild(theListBox, 0);
if (!(child is Canvas))
    return;
theCanvas = VisualTreeHelper.GetChild(child, 0) as Canvas;

 

 例子2：想获取一个可编辑的 ComboBox 中的 TextBox （顺便说一句，如果不可编辑，则是个 TextBlock，可以使用 SNOOP 来观察）

<ComboBox x:Name="MyComboBox"
          ItemsSource="{Binding X1}"
          SelectedItem="{Binding X2}"
          SelectedValuePath="X3"
          DisplayMemberPath="X4"
          Focusable="True"
          IsEditable="True"
          Loaded="MyComboBox_Loaded"
          />

 

private object FindFirstChild<T>(DependencyObject p)
{
    if (p == null)
        return null;

    int cnt = VisualTreeHelper.GetChildrenCount(p);
    for (int i = 0; i < cnt; ++i)
    {
        DependencyObject thisLevelChild = VisualTreeHelper.GetChild(p, i);
        if (thisLevelChild is T)
            return thisLevelChild;
        else
        {
            object obj = FindFirstChild<T>(thisLevelChild); // go to deeper level
            if (obj != null)
                return obj;
        }
    }

    return null;
}

private TextBox theTextBox = null;
private void MyComboBox_Loaded(object sender, RoutedEventArgs e)
{
    ComboBox bx = sender as ComboBox;

    object t = FindFirstChild<TextBox>(bx);
    if (t != null)
    {
        theTextBox = t as TextBox;
        theTextBox.TextChanged += new TextChangedEventHandler(theTextBox_TextChanged);
    }
}

void theTextBox_TextChanged(object sender, TextChangedEventArgs e)
{
    TextBox bx = sender as TextBox;
    string txt = bx.Text;
}