使用多选列表框在 DataTemplate 中查找控件

Question

我有一个多选列表框，用户可以在其中勾选列表中的多个项目。目前我有它，所以当一个复选框被勾选时，它所在的 ListBoxItem 也会被选中：

private void CheckBox_Checked(object sender, RoutedEventArgs e)
            {
                //Select the Item using the DataContext of the Button
                object clicked = (e.OriginalSource as FrameworkElement).DataContext;
                var lbi = LstDistro.ItemContainerGenerator.ContainerFromItem(clicked) as ListBoxItem;
                lbi.IsSelected = true;
            }

现在我正在尝试另一种方式。 Whenever a ListBoxItem is selected the checkbox within it gets ticked.到目前为止，我拥有它，因此您选择的第一个项目将被勾选，但之后您选择的其他项目都不会被勾选。我需要以某种方式让它遍历所有当前选定的项目。

我当前的代码：

WPF：

<ListBox x:Name="LstDistro" HorizontalAlignment="Left" Margin="10,10,0,42" Width="235" BorderBrush="Black" BorderThickness="2,2,1,1" SelectionMode="Multiple" SelectionChanged="LstDistro_SelectionChanged">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid>
                        <Canvas x:Name="EventItem" HorizontalAlignment="Left" Height="42" VerticalAlignment="Top" Width="215" Background="{Binding Path=LBackground}">
                            <Label Content="{Binding LInits}" HorizontalAlignment="Left" Height="33" VerticalAlignment="Top" Width="40" FontWeight="Bold" FontSize="12" Canvas.Top="5"/>
                            <Label Content="{Binding LFullName}" HorizontalAlignment="Left" Height="33" VerticalAlignment="Top" Width="164" FontSize="12" Canvas.Left="40" Canvas.Top="5"/>
                            <CheckBox x:Name="ChkName" Height="20" Width="20" Canvas.Left="190" Canvas.Top="12" Checked="CheckBox_Checked"  IsChecked="False"/>
                        </Canvas>
                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

C#：

private void CheckBox_Checked(object sender, RoutedEventArgs e)
            {
                //Select the Item using the DataContext of the Button
                object clicked = (e.OriginalSource as FrameworkElement).DataContext;
                var lbi = LstDistro.ItemContainerGenerator.ContainerFromItem(clicked) as ListBoxItem;
                lbi.IsSelected = true;
            }

            private void LstDistro_SelectionChanged(object sender, SelectionChangedEventArgs e)
            {

                //Get the current selected item
                ListBoxItem item = LstDistro.ItemContainerGenerator.ContainerFromIndex(LstDistro.SelectedIndex) as ListBoxItem;
                CheckBox ChkName = null;

                //Get the item's template parent
                ContentPresenter templateParent = GetFrameworkElementByName<ContentPresenter>(item);
                //Get the DataTemplate that the Checkbox is in.
                DataTemplate dataTemplate = LstDistro.ItemTemplate;
                ChkName = dataTemplate.FindName("ChkName", templateParent) as CheckBox;
                ChkName.IsChecked = true;
            }

            private static T GetFrameworkElementByName<T>(FrameworkElement referenceElement) where T : FrameworkElement
            {
                FrameworkElement child = null;
                for (Int32 i = 0; i < VisualTreeHelper.GetChildrenCount(referenceElement); i++)
                {
                    child = VisualTreeHelper.GetChild(referenceElement, i) as FrameworkElement;
                    System.Diagnostics.Debug.WriteLine(child);
                    if (child != null && child.GetType() == typeof(T))
                    { break; }
                    else if (child != null)
                    {
                        child = GetFrameworkElementByName<T>(child);
                        if (child != null && child.GetType() == typeof(T))
                        {
                            break;
                        }
                    }
                }
                return child as T;
            }

Answer 1

您应该像这样设置 Checkbox IsChecked 绑定：

IsChecked="{Binding Path=IsSelected, RelativeSource={RelativeSource AncestorType={x:Type ListBoxItem}}}"

这意味着每当您选择一个 ListBoxItem 时，您的复选框也会被选中。

希望这有帮助:)

Answer 2

见VisualHelper class here

提供了扩展方法FindVisualChild、FindVisualChilds

var checkedCheckBoxes= LstDistro.FindVisualChilds<CheckBox>().Where(s=>s.IsChecked==true);

Answer 3

好的。删除所有代码并重新开始。

如果您正在使用 WPF，您确实需要了解并接受 The WPF Mentality。

这就是你在适当的 WPF 中做你正在寻找的事情的方式：

<Window x:Class="WpfApplication14.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication14"
        Title="MainWindow" Height="350" Width="525">
    <DockPanel>
        <Button Content="Show Selected Item Count" Click="Button_Click"
                DockPanel.Dock="Top"/>

        <Button Content="Select All" Click="SelectAll"
                DockPanel.Dock="Top"/>

        <Button Content="Select All" Click="UnSelectAll"
                DockPanel.Dock="Top"/>

        <ListBox ItemsSource="{Binding}" SelectionMode="Multiple">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <CheckBox IsChecked="{Binding IsSelected}" Content="{Binding DisplayName}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>

            <ListBox.ItemContainerStyle>
                <Style TargetType="ListBoxItem">
                    <Setter Property="IsSelected" Value="{Binding IsSelected}"/>
                </Style>
            </ListBox.ItemContainerStyle>
        </ListBox>
    </DockPanel>
</Window>

后面的代码：

public partial class MainWindow : Window
{
    private ObservableCollection<SelectableItem> Items { get; set; } 

    public MainWindow()
    {
        InitializeComponent();

        //Create dummy items, you will not need this, it's just part of the example.
        var dummyitems = Enumerable.Range(0, 100)
                                   .Select(x => new SelectableItem()
                                   {
                                       DisplayName = x.ToString()
                                   });

        DataContext = Items = new ObservableCollection<SelectableItem>(dummyitems);
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        MessageBox.Show(Items.Count(x => x.IsSelected).ToString());
    }

    private void SelectAll(object sender, RoutedEventArgs e)
    {
        foreach (var item in Items)
            item.IsSelected = true;
    }

    private void UnSelectAll(object sender, RoutedEventArgs e)
    {
        foreach (var item in Items)
            item.IsSelected = false;
    }
}

数据项：

public class SelectableItem:INotifyPropertyChanged
{
    private bool _isSelected;
    public bool IsSelected
    {
        get { return _isSelected; }
        set
        {
            _isSelected = value;
            OnPropertyChanged("IsSelected");
        }
    }

    public string DisplayName { get; set; }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
}

结果：

• 注意当您使用 WPF 的功能而不是手动、程序化、类似 winforms 的方法时，生活是多么简单和幸福。
• 简单、简单的属性和INotifyPropertyChanged。这就是您在 WPF 中编程的方式。无需复杂的VisualTreeHelper.Whatever() 东西，无需在程序代码中操作 UI。简单漂亮的DataBinding。
• 看看我是如何在SelectAll() 和UnSelectAll() 方法而不是UI 中对我的Data 进行操作的。 UI 不负责维护数据的状态，只负责显示它。
• 复制我的代码并将其粘贴到 File -> New Project -> WPF Application 中，然后亲自查看结果。
• WPF 摇滚