更新:2007 年 11 月
下面的示例演示如何查找由 DataTemplate 生成的元素。
示例
在本示例中,有一个绑定到某些 XML 数据的 ListBox:
<ListBox Name="myListBox" ItemTemplate="{StaticResource myDataTemplate}"
IsSynchronizedWithCurrentItem="True">
<ListBox.ItemsSource>
<Binding Source="{StaticResource InventoryData}" XPath="Books/Book"/>
</ListBox.ItemsSource>
</ListBox>
ListBox 使用以下 DataTemplate:
<DataTemplate x:Key="myDataTemplate">
<TextBlock Name="textBlock" FontSize="14" Foreground="Blue">
<TextBlock.Text>
<Binding XPath="Title"/>
</TextBlock.Text>
</TextBlock>
</DataTemplate>
如果要检索由某个 ListBoxItem 的 DataTemplate 生成的 TextBlock 元素,您需要获得 ListBoxItem,在该 ListBoxItem 内查找 ContentPresenter,然后对在该 ContentPresenter 上设置的 DataTemplate 调用 FindName。下面的示例演示如何执行这些步骤。出于演示的目的,本示例创建一个消息框,用于显示由 DataTemplate 生成的文本块的文本内容。
// Getting the currently selected ListBoxItem
// Note that the ListBox must have
// IsSynchronizedWithCurrentItem set to True for this to work
ListBoxItem myListBoxItem =
(ListBoxItem)(myListBox.ItemContainerGenerator.ContainerFromItem(myListBox.Items.CurrentItem));
// Getting the ContentPresenter of myListBoxItem
ContentPresenter myContentPresenter = FindVisualChild<ContentPresenter>(myListBoxItem);
// Finding textBlock from the DataTemplate that is set on that ContentPresenter
DataTemplate myDataTemplate = myContentPresenter.ContentTemplate;
TextBlock myTextBlock = (TextBlock)myDataTemplate.FindName("textBlock", myContentPresenter);
// Do something to the DataTemplate-generated TextBlock
MessageBox.Show("The text of the TextBlock of the selected list item: "
+ myTextBlock.Text);
下面是 FindVisualChild 的实现,使用的是 VisualTreeHelper 方法:
private childItem FindVisualChild<childItem>(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;
}
有关完整示例,请参见 查找由模板生成的元素的示例。