WPF 列表框 + 扩展器事件 [英] WPF Listbox + Expander events

问题描述

我在 ListBox 的 ItemTemplate 中有一个扩展器.渲染得很好.我遇到的问题是，我希望在展开和/或选择扩展器时触发 ListBox_SelectionChanged 事件.MouseDown 事件似乎没有冒泡到 ListBox.

I have an Expander in the ItemTemplate of a ListBox. Renders fine. The issue I have run into is that I would like the ListBox_SelectionChanged event to fire when the expander is expanded and/or selected. The MouseDown event does not seem to bubble up to the ListBox.

我需要的是 ListBox 的 SelectedIndex.因为 ListBox_SelectionChanged 没有被触发，所以索引为 -1，我无法确定选择了哪个项目.

What I need is the SelectedIndex of the ListBox. Because the ListBox_SelectionChanged does not get fired, the index is -1 and I cannot determine which item has been selected.

如果用户在展开器展开后单击其内容，则会触发 ListBox_SelectionChanged 事件.如果他们只单击扩展器，则不会触发该事件.这让用户感到困惑，因为从视觉上看，他们认为在实际单击 Expander Header 时已经单击了该项目.我需要在用户展开 Expander 时选择 ListBox 项目，因为就用户而言，现在该项目实际上不是被选择的.

The ListBox_SelectionChanged Event is fired if a user clicks on the Content of the Expander after it has been expanded. If they only click on the expander, the event is not fired. This is confusing to the user because visually, they think they have already clicked on that item when actually clicking on the Expander Header. I need the ListBox Item selected when the user Expands the Expander because as far as the user is concerned, the item is now selected when it really isn't.

关于如何使它工作或确定带有扩展器的列表框的 SelectedIndex 的替代方法有什么建议吗?

Any suggests on how to get this to work or alternate ways of determining the SelectedIndex of the list box with expanders in it?

简化代码供参考:

<Window x:Class="WpfApplication3.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300"
    Loaded="Window_Loaded">
    <Grid Name="Root">
        <ScrollViewer>
            <ListBox SelectionChanged="ListBox_SelectionChanged" ItemsSource="{Binding}">
                <ItemsControl.ItemTemplate >
                    <DataTemplate>
                        <Border>
                            <Expander>
                                <Expander.Header>
                                    <TextBlock Text="{Binding Path=Name}"/>
                                </Expander.Header>
                                <Expander.Content>
                                    <StackPanel>
                                        <TextBlock Text="{Binding Path=Age}"/>
                                        <TextBlock Text="Line 2"/>
                                        <TextBlock Text="Line 3"/>
                                    </StackPanel>
                                </Expander.Content>
                            </Expander>
                        </Border>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ListBox>
        </ScrollViewer>
    </Grid>
</Window>

简单的绑定类:

public class Person
{
    public string Name {
        get;
        set;
    }

    public int Age {
        get;
        set;
    }
}

为绑定创建和填充数据:

Creating and populating the data for binding:

private void Window_Loaded(object sender, RoutedEventArgs e) {

    data = new ObservableCollection<Person>();

    data.Add(new Person {
        Name = "One",
        Age=10
    });

    data.Add(new Person {
        Name = "Two",
        Age = 20
    });

    data.Add(new Person {
        Name = "Three",
        Age = 30
    });

    Root.DataContext = data;
}

这是我需要的事件(真的只是我需要的 SelectedIndex)

This is the event I need (really just the SelectedIndex I need)

private void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e) {
    ListBox box = (ListBox)sender;

    // This value is not set because events from Expander are not bubbled up to fire SelectionChanged Event
    int index = box.SelectedIndex;
}

推荐答案

另一种不依赖 IsSelected 的方法，你可以将 expander 的 Expanded/Collapsed 事件挂钩到后面的代码中，并使用以下代码找出您单击的 ListBox 索引.

An alternate way which doesnt depends on the IsSelected, You can hook an Expanded/Collapsed event of expander to the code behind and use the following code to find out the ListBox index on which you clicked.

DependencyObject dep = (DependencyObject)e.OriginalSource;

while ((dep != null) && !(dep is ListViewItem))
{
   dep = VisualTreeHelper.GetParent(dep);
}

if (dep == null)
     return;

int index = yourListBox.ItemContainerGenerator.IndexFromContainer(dep);

这篇关于WPF 列表框 + 扩展器事件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！