我正在使用 WPF ListView 控件，该控件显示了一个数据绑定的项目列表。
<ListView ItemsSource={Binding MyItems}>
<ListView.View>
<GridView>
<!-- declare a GridViewColumn for each property -->
</GridView>
</ListView.View>
</ListView>
我正在尝试获得与 ListView.SelectionChanged 事件类似的行为，但我还想检测当前选定的项目是否被单击。如果再次单击相同的项目，则SelectionChanged 事件不会触发（显然）。
什么是最好（最清晰）的方法来处理这个问题？
使用ListView.ItemContainerStyle属性为您的ListViewItems设置EventSetter，以处理PreviewMouseLeftButtonDown事件。然后，在处理程序中检查被点击的项是否已被选中。
XAML：
<ListView ItemsSource={Binding MyItems}>
<ListView.View>
<GridView>
<!-- declare a GridViewColumn for each property -->
</GridView>
</ListView.View>
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<EventSetter Event="PreviewMouseLeftButtonDown" Handler="ListViewItem_PreviewMouseLeftButtonDown" />
</Style>
</ListView.ItemContainerStyle>
</ListView>
后端代码：
private void ListViewItem_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var item = sender as ListViewItem;
if (item != null && item.IsSelected)
{
//Do your stuff
}
}
您可以处理 ListView 的 PreviewMouseLeftButtonUp 事件。原因是在处理事件时，ListView 的 SelectedItem 可能仍然为 null，因此不需要处理 PreviewMouseLeftButtonDown 事件。
XAML：
<ListView ... PreviewMouseLeftButtonUp="listView_Click"> ...
代码后端：
private void listView_Click(object sender, RoutedEventArgs e)
{
var item = (sender as ListView).SelectedItem;
if (item != null)
{
...
}
}
using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.CommandWpf;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
/// <summary>
/// Very basic model for example
/// </summary>
public class BasicModel
{
public string Id { get; set; }
public string Text { get; set; }
/// <summary>
/// Constructor
/// </summary>
/// <param name="text"></param>
public BasicModel(string text)
{
this.Id = Guid.NewGuid().ToString();
this.Text = text;
}
}
public class MainWindowViewModel : ViewModelBase
{
public MainWindowViewModel()
{
ModelsCollection = new ObservableCollection<BasicModel>(new List<BasicModel>() {
new BasicModel("Model one")
, new BasicModel("Model two")
, new BasicModel("Model three")
});
}
private BasicModel _selectedBasicModel;
/// <summary>
/// Stores the selected mode.
/// </summary>
/// <remarks>This is just an example, may be different.</remarks>
public BasicModel SelectedBasicModel
{
get { return _selectedBasicModel; }
set { Set(() => SelectedBasicModel, ref _selectedBasicModel, value); }
}
private ObservableCollection<BasicModel> _modelsCollection;
/// <summary>
/// List to bind to
/// </summary>
public ObservableCollection<BasicModel> ModelsCollection
{
get { return _modelsCollection; }
set { Set(() => ModelsCollection, ref _modelsCollection, value); }
}
}
private RelayCommand<string> _selectItemRelayCommand;
/// <summary>
/// Relay command associated with the selection of an item in the observablecollection
/// </summary>
public RelayCommand<string> SelectItemRelayCommand
{
get
{
if (_selectItemRelayCommand == null)
{
_selectItemRelayCommand = new RelayCommand<string>(async (id) =>
{
await selectItem(id);
});
}
return _selectItemRelayCommand;
}
set { _selectItemRelayCommand = value; }
}
/// <summary>
/// I went with async in case you sub is a long task, and you don't want to lock you UI
/// </summary>
/// <returns></returns>
private async Task<int> selectItem(string id)
{
this.SelectedBasicModel = ModelsCollection.FirstOrDefault(x => x.Id == id);
Console.WriteLine(String.Concat("You just clicked:", SelectedBasicModel.Text));
//Do async work
return await Task.FromResult(1);
}
public partial class MainWindow : Window
{
public MainWindowViewModel MyViewModel { get; set; }
public MainWindow()
{
InitializeComponent();
MyViewModel = new MainWindowViewModel();
this.DataContext = MyViewModel;
}
}
<Window x:Class="Basic_Binding.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:Custom="clr-namespace:GalaSoft.MvvmLight;assembly=GalaSoft.MvvmLight"
Title="MainWindow" Height="350" Width="525">
我添加了“i”和“Custom”。
这是ListView：
<ListView
Grid.Row="0"
Grid.Column="0"
HorizontalContentAlignment="Stretch"
ItemsSource="{Binding ModelsCollection}"
ItemTemplate="{DynamicResource BasicModelDataTemplate}">
</ListView>
<DataTemplate x:Key="BasicModelDataTemplate">
<Grid>
<TextBlock Text="{Binding Text}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="MouseLeftButtonUp">
<i:InvokeCommandAction
Command="{Binding DataContext.SelectItemRelayCommand,
RelativeSource={RelativeSource FindAncestor,
AncestorType={x:Type ItemsControl}}}"
CommandParameter="{Binding Id}">
</i:InvokeCommandAction>
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBlock>
</Grid>
</DataTemplate>
<ListView.ItemTemplate>
<DataTemplate>
<Button BorderBrush="Transparent" Background="Transparent" Focusable="False">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Click">
<i:InvokeCommandAction Command="{Binding DataContext.MyCommand, ElementName=ListViewName}" CommandParameter="{Binding}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
<Button.Template>
<ControlTemplate>
<Grid VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
...
这对我有效。
单击一行会触发后台代码。
XAML：
<ListView x:Name="MyListView" MouseLeftButtonUp="MyListView_MouseLeftButtonUp">
<GridView>
<!-- Declare GridViewColumns. -->
</GridView>
</ListView.View>
代码后台：
private void MyListView_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
System.Windows.Controls.ListView list = (System.Windows.Controls.ListView)sender;
MyClass selectedObject = (MyClass)list.SelectedItem;
// Do stuff with the selectedObject.
}
我无法按照自己的意愿使得被接受的答案起作用（请参见Farrukh的评论）。
我想出了一个稍微不同的解决方案，感觉更加本地化，因为它在鼠标按钮按下时选择项目，然后当鼠标按钮释放时，您可以对其做出反应：
XAML：
<ListView Name="MyListView" ItemsSource={Binding MyItems}>
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<EventSetter Event="PreviewMouseLeftButtonDown" Handler="ListViewItem_PreviewMouseLeftButtonDown" />
<EventSetter Event="PreviewMouseLeftButtonUp" Handler="ListViewItem_PreviewMouseLeftButtonUp" />
</Style>
</ListView.ItemContainerStyle>
代码后台：
private void ListViewItem_PreviewMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
MyListView.SelectedItems.Clear();
ListViewItem item = sender as ListViewItem;
if (item != null)
{
item.IsSelected = true;
MyListView.SelectedItem = item;
}
}
private void ListViewItem_PreviewMouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
ListViewItem item = sender as ListViewItem;
if (item != null && item.IsSelected)
{
// do stuff
}
}
private void listBox_MouseDoubleClick(object sender, MouseButtonEventArgs e)
{
try {
//Do your stuff here
listBox.SelectedItem = null;
listBox.SelectedIndex = -1;
} catch (Exception ex) {
System.Diagnostics.Debug.WriteLine(ex.Message);
}
}