如何从

Question

我试图从列表视图中删除Order类型的Object，该列表视图是从同一listview控件中的另一个listview发送的。这些列表视图的xaml是这样的：

 <ListView x:Name="listView" HorizontalAlignment="Left" Height="448" ItemsSource="{Binding}" VerticalAlignment="Top" Width="664" Margin="121,43,-2,0">
            <ListView.ItemsPanel>
                <ItemsPanelTemplate>
                    <StackPanel Orientation="Horizontal" Height="100"></StackPanel>
                </ItemsPanelTemplate>
            </ListView.ItemsPanel>
            <ListView.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Vertical">
                        <Button x:Name="Up" Content="^" Click="Up_Click"/>
                        <Button x:Name="Down" Content="v" Click="Down_Click"/>
                        <TextBlock Text="{Binding Chauffeur.Naam}" Width="50"/>
                        <ListView x:Name="Swagnek" ItemsSource="{Binding Orders}" Height="50" AllowDrop="True" DragEnter="ListView_DragEnter" PreviewDragOver="ListView_PreviewDragOver" Drop="ListView_Drop">
                            <ListView.ItemTemplate>
                                <DataTemplate>
                                    <TextBlock x:Name="HoiDoei" HorizontalAlignment="Stretch" Text="{Binding ID}" MouseRightButtonDown="HoiDoei_MouseRightButtonDown" MouseLeftButtonDown="HoiDoei_MouseLeftButtonDown" />
                                </DataTemplate>
                            </ListView.ItemTemplate>
                        </ListView>
                    </StackPanel>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>

所以我试图在两个列表视图之间拖放订单。 问题是，当我放弃它时，我必须从列表视图中删除拖动和删除顺序，我拖动它。

我正在使用这个c＃代码。

       private void ListView_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
            {

                var tb = (TextBlock)sender;
                DragDrop.DoDragDrop(this, (Order)tb.DataContext, DragDropEffects.Copy);
            }

   private void ListView_DragEnter(object sender, DragEventArgs e)
        {
            e.Effects = DragDropEffects.Move;
        }

        private void ListView_PreviewDragOver(object sender, DragEventArgs e)
        {
            e.Handled = true;
        }

        private void ListView_Drop(object sender, DragEventArgs e)
        {
            var lv = sender as ListView;
            if (lv.ItemsSource == null)
                lv.ItemsSource = new ObservableCollection<Order>();
            var order = e.Data.GetData(typeof(Order)) as Order;
            var items = lv.ItemsSource as ObservableCollection<Order>;
            items.Add(order);
            orderlist.Remove(order);
        }

也可以从列表框拖动到其中一个列表视图（不包含在代码中）

那是

的原因

 orderlist.Remove(order);

在那里

Answer 1

您从拖动对象的ListView的ItemsSource属性也应设置或绑定到ObservableCollection<Order>。然后，您应该能够在引用它之后从该集合中删除已删除的项目：

ObservableCollection<Order> _source;
private void ListView_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{

    var tb = (TextBlock)sender;
    ListView parentListView = FindParent<ListView>(tb);
    if (parentListView != null)
        _source = parentListView.ItemsSource as ObservableCollection<Order>;
    DragDrop.DoDragDrop(this, (Order)tb.DataContext, DragDropEffects.Copy);
}

public static T FindParent<T>(DependencyObject dependencyObject) where T : DependencyObject
{
    var parent = VisualTreeHelper.GetParent(dependencyObject);

    if (parent == null) return null;

    var parentT = parent as T;
    return parentT ?? FindParent<T>(parent);
}

private void ListView_Drop(object sender, DragEventArgs e)
{
    var lv = sender as ListView;
    if (lv.ItemsSource == null)
        lv.ItemsSource = new ObservableCollection<Order>();
    var order = e.Data.GetData(typeof(Order)) as Order;
    var items = lv.ItemsSource as ObservableCollection<Order>;
    items.Add(order);
    orderlist.Remove(order);
    if (_source != null && _source.Contains(order))
        _source.Remove(order);
}

Answer 2

而不是将TextBlock的DataContext作为数据传递给DragAndDrop动作，而不是传递TextBlock本身。

    private void ListView_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        DragDrop.DoDragDrop(this, (TextBlock)sender, DragDropEffects.Copy);
    }

然后在drop处理程序中，您现在可以访问包含TextBlock的ItemsControl（通过静态帮助器方法），并使用ItemsControl可以获取基础ItemsSource集合。

    private void ListView_Drop(object sender, DragEventArgs e)
    {
        var lv = (ListView)sender;
        if (lv.ItemsSource == null)
        {
            lv.ItemsSource = new ObservableCollection<Order>();
        }

        var tb = (TextBlock)e.Data.GetData(typeof(TextBlock));
        var order = (Order)tb.DataContext;

        var container = ItemsControl.ContainerFromElement(null, tb);
        var control = ItemsControl.ItemsControlFromItemContainer(container);
        (control.ItemsSource as ICollection<Order>)?.Remove(order);

        (lv.ItemsSource as ObservableCollection<Order>)?.Add(order);

        orderlist.Remove(order);
    }

这将从最初包含在其中的ItemsControl中删除拖动的订单。