如何使用 DataTemplate 访问列表框中的特定项目? [英] How to access a specific item in a Listbox with DataTemplate?
问题描述
我有一个 ListBox,其中包含一个带有 2 个 StackPanel 的 ItemTemplate.我想访问的第二个 StackPanel 中有一个 TextBox.(将其可见性更改为 true 并接受用户输入)触发器应该是 SelectionChangedEvent.因此,如果用户单击 ListBoxItem,则 TextBlock 不可见,而 TextBox 可见.
I have a ListBox including an ItemTemplate with 2 StackPanels. There is a TextBox in the second StackPanel i want to access. (Change it's visibility to true and accept user input) The trigger should be the SelectionChangedEvent. So, if a user clicks on an ListBoxItem, the TextBlock gets invisible and the TextBox gets visible.
XAML 代码:
<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这个问题,但我尝试过的方法都没有奏效.
I guess there are several ways to solve this, but nothing I tried worked.
我目前的方法是这样的
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;
}
推荐答案
感谢你们的帮助!!最后我得到了它.解决了 VisualTreeHelper 的问题.好棒的功能^^
Thank you for your help guys!! Finally i got it. Solved the problem with the VisualTreeHelper. What a great function ^^
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);
helperFunction
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;
}
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