如何使用DataTemplate访问列表框中的特定项目？

Z时代
2024-01-10
分类：问答

我有一个包含2个StackPanels的ItemTemplate的ListBox。我要访问的第二个StackPanel中有一个TextBox。（将其可见性更改为true并接受用户输入）触发器应为SelectionChangedEvent。因此，如果用户单击ListBoxItem，则TextBlock变为不可见，而TextBox变为可见。

<ListBox Grid.Row="1" Name="ContactListBox" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" ItemsSource="{Binding Contacts}" Margin="0,36,0,0" SelectionChanged="ContactListBox_SelectionChanged">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal" Margin="0,0,0,0">
                        <toolkit:ContextMenuService.ContextMenu>
                            <toolkit:ContextMenu>
                                <toolkit:MenuItem Header="Edit Contact" Click="ContactMenuItem_Click"/>
                                <toolkit:MenuItem Header="Delete Contact" Click="ContactMenuItem_Click"/>
                            </toolkit:ContextMenu>
                        </toolkit:ContextMenuService.ContextMenu>
                        <Grid>
                            <Rectangle Fill="{StaticResource PhoneAccentBrush}"
                                           Width="72" Height="72">
                                <Rectangle.OpacityMask>
                                    <ImageBrush ImageSource="/Images/defaultContactImage.png" Stretch="UniformToFill"/>
                                </Rectangle.OpacityMask>
                            </Rectangle>
                        </Grid>
                        <StackPanel>
                            <TextBox Text="{Binding Name}" TextWrapping="Wrap" Visibility="Collapsed"/>
                            <TextBlock Text="{Binding Name}" TextWrapping="Wrap" Style="{StaticResource PhoneTextExtraLargeStyle}" />
                            <TextBlock Text="{Binding Number}" TextWrapping="Wrap" Margin="12,-6,12,0" Style="{StaticResource PhoneTextAccentStyle}"/>
                        </StackPanel>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

我想有几种方法可以解决此问题，但是我没有尝试过。

    private void ContactListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        ListBoxItem listBoxItem = ContactListBox.SelectedItem as ListBoxItem;
        DataTemplate listBoxTemplate = listBoxItem.ContentTemplate;
        // How to access the DataTemplate content?
        StackPanel outerStackPanel = listBoxTemplate.XXX as StackPanel;
        StackPanel innerStackPanel = outerStackPanel.Children[1] as StackPanel;
        TextBox nameBox = innerStackPanel.Children[0] as TextBox;
        TextBlock nameBlock = innerStackPanel.Children[1] as TextBlock;
        nameBox.Visibility = System.Windows.Visibility.Visible;
        nameBlock.Visibility = System.Windows.Visibility.Collapsed;
    }

回答：

谢谢您的帮助！！终于我明白了。使用VisualTreeHelper解决了该问题。多么出色的功能^^

private void ContactListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (ContactListBox.SelectedIndex == -1)
            return;
        currentSelectedListBoxItem = this.ContactListBox.ItemContainerGenerator.ContainerFromIndex(ContactListBox.SelectedIndex) as ListBoxItem;
        if (currentSelectedListBoxItem == null)
            return;
        // Iterate whole listbox tree and search for this items
        TextBox nameBox = helperClass.FindDescendant<TextBox>(currentSelectedListBoxItem);
        TextBlock nameBlock = helperClass.FindDescendant<TextBlock>(currentSelectedListBoxItem);

public T FindDescendant<T>(DependencyObject obj) where T : DependencyObject
    {
        // Check if this object is the specified type
        if (obj is T)
            return obj as T;
        // Check for children
        int childrenCount = VisualTreeHelper.GetChildrenCount(obj);
        if (childrenCount < 1)
            return null;
        // First check all the children
        for (int i = 0; i < childrenCount; i++)
        {
            DependencyObject child = VisualTreeHelper.GetChild(obj, i);
            if (child is T)
                return child as T;
        }
        // Then check the childrens children
        for (int i = 0; i < childrenCount; i++)
        {
            DependencyObject child = FindDescendant<T>(VisualTreeHelper.GetChild(obj, i));
            if (child != null && child is T)
                return child as T;
        }
        return null;
    }