c# - 如果我选择另一个列表框，如何在列表框中设置 SeletedItems = null

Question

基本上我正在尝试做THIS

但你可以看到它不是 MVVM 所以我正在寻找一种方法来设置 SeletedItems = null或 clear()取决于什么是可行的

因为在我看来我会得到 N ListBoxes如果他按下 Button选择一些项目后，我将更改 SeletedItems 的一些属性但仅适用于最后一个事件 Listbox
所以我决定使用 SelectedItems所有 Listboxes 的属性(property)但由于我无法绑定(bind)到 SelectedItems 的 2 个问题，它不起作用基于此，我无法测试如何从其他 Listboxes 中删除选择

编辑:

给你一个简单的例子:

XAML

    <Window x:Class="Test.MainWindow"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Title="MainWindow" Height="350" Width="525">
        <StackPanel>
            <ListBox  Width="432" Height="67"
                      HorizontalAlignment="Left" VerticalAlignment="Top"
                      SelectionMode="Extended"   
<!-- SeletedItems="{Binding SelectedListItems}" ??? -->       
                      ItemsSource="{Binding Collection1}">
                <ListBox.ItemsPanel>
                    <ItemsPanelTemplate>
                        <StackPanel Orientation="Horizontal"/>
                    </ItemsPanelTemplate>
                </ListBox.ItemsPanel>
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <Grid>
                            <TextBlock Text="{Binding MyText}"
                                       Background="{Binding MyBackground}"/>
                        </Grid>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
            <ListBox  Width="432" Height="67"
                      HorizontalAlignment="Left" VerticalAlignment="Top"
                      SelectionMode="Extended"
<!-- SeletedItems="{Binding SelectedListItems}" ??? -->     
                      ItemsSource="{Binding Collection2}">
                <ListBox.ItemsPanel>
                    <ItemsPanelTemplate>
                        <StackPanel Orientation="Horizontal"/>
                    </ItemsPanelTemplate>
                </ListBox.ItemsPanel>
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <Grid>
                            <TextBlock Text="{Binding MyText}"
                                       Background="{Binding MyBackground}"/>
                        </Grid>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
            <Button Content="unselect" Width="80" Height="150"
                    HorizontalAlignment="Right" VerticalAlignment="Top"
                    Command="{Binding MyCommand}"/>
        </StackPanel>
    </Window>

代码

using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows;

namespace Test
{
    /// <summary>
    /// Interaktionslogik für MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new VM();
        }
    }

    public class VM : INotifyPropertyChanged
    {
        private ObservableCollection<DetailVM> _SelectedListItems = new ObservableCollection<DetailVM>();
        public ObservableCollection<DetailVM> SelectedListItems
        {
            get { return _SelectedListItems; }
            set
            {
                _SelectedListItems = value;
                OnPropertyChanged("SelectedListItems");
            }
        }

        public List<DetailVM> Collection1 { get; set; }
        public List<DetailVM> Collection2 { get; set; }

        private RelayCommand _myCommand;
        public ICommand MyCommand
        {
            get { return _myCommand?? (_myCommand= new RelayCommand(param => OnMyCommand())); }
        }
        public void OnMyCommand()
        {
            foreach DetailVM item in SelectedListItems
            {
                item.MyBackground ="Red";
            }
        }

        public VM()
        {
            Collection1 = new List<DetailVM>();
            Collection2 = new List<DetailVM>();

            for (int i = 0; i < 10; i++)
            {
                Collection1.Add(new DetailVM { MyText = "C1ITEM " + i });
                Collection2.Add(new DetailVM { MyText = "C2ITEM " + i });
            }
        }

        #region INotifyPropertyChanged Member

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

        #endregion
    }

    public class DetailVM
    {
        public string MyText { get; set; }
        public string MyBackground { get; set; }
    }
}

上面的代码应该将文本框背景的颜色更改为红色
如果用户在一个列表框中选择了一些项目，他应该只能同时选择一个列表框中的项目

那么该怎么做呢？ (请记住，这是一个简单的例子，但我需要这个用于将通过模板生成的 N 个列表框)

Answer 1

首先，我建议您扩展 ListView 以使其包含可绑定(bind)的 SelectedValues 属性(您不能使用名称 SelectedItems，因为它已经是 ListView 的不可绑定(bind)属性)。这是一个如何实现的示例。

public class MultiSelectListView : ListView
{
// Using a DependencyProperty as backing store
public static readonly DependencyProperty SelectedValuesProperty =
  DependencyProperty.Register("SelectedValues", typeof(IList), typeof(MultiSelectListView), new PropertyMetadata(default(IList), OnSelectedItemsChanged));

public IList SelectedValues
{
  get { return (IList)GetValue(SelectedValuesProperty); }
  set { SetValue(SelectedValuesProperty, value); }
}


private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
  // if selected items list implements INotifyCollectionChanged, we subscribe to its CollectionChanged event
  var element = (MultiSelectListView)d;
  if (e.OldValue != null && e.OldValue is INotifyCollectionChanged)
  {
    var list = e.OldValue as INotifyCollectionChanged;
    list.CollectionChanged -= element.OnCollectionChanged;
  }
  if (e.NewValue is INotifyCollectionChanged)
  {
    var list = e.NewValue as INotifyCollectionChanged;
    list.CollectionChanged += element.OnCollectionChanged;
  }

}

// when selection changes in the view, elements are added or removed from the underlying list
protected override void OnSelectionChanged(SelectionChangedEventArgs e)
{
  if (SelectedValues != null)
  {
    foreach (var item in e.AddedItems)
    {
      if (!SelectedValues.Contains(item))
        SelectedValues.Add(item);
    }
    foreach (var item in e.RemovedItems)
    {
      if (SelectedValues.Contains(item))
        SelectedValues.Remove(item);
    }
  }
  base.OnSelectionChanged(e);
}

// when underlying list changes, we set the control's selected items to the contents of the list
void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
  if (SelectedValues != null)
  {
    SetSelectedItems(SelectedValues);
  }
}

}

完成此操作后，您可以通过 View 模型控制列表中所选项目的行为。清除 View 模型列表会清除控件中的选定项。

接下来，您可以订阅所选项目列表的集合更改事件(在 View 模型中)，并在处理程序中检查您是否需要清除任何列表。