c# - 如何将项目从一个列表框拖放到另一个列表框

Question

是否可以将项目从一个 Listbox 拖放到另一个？不是删除而是复制。从这个 Listbox。实际上，我有三个列表框，它们非常相似，我需要能够将一个项目(每个 Listbox 中的一个)拖放到 Listbox listHero

<ListBox x:Name="listhelmets" Height="214" Width="248" ItemsSource="{Binding ListHelmets}"
         IsSynchronizedWithCurrentItem="True" Canvas.Left="464" Canvas.Top="37" PreviewMouseDown="helmet_MouseDown1"
        PreviewMouseLeftButtonDown="helmet_PreviewMouseLeftButtonDown" DragLeave="helmet_DragLeave"
        PreviewMouseMove="helmet_PreviewMouseMove" SelectedValuePath="protection">
            <ListBox.ItemTemplate >
                <DataTemplate >
                    <StackPanel Orientation="Horizontal">
                        <Image Source="{Binding Path=Image}" Width="56" Height="61"/>
                        <TextBox Height="30" Width="30">
                          <Binding Path="protection" />
                           </TextBox>
                       </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

这个

 <ListBox x:Name="listHero" Height="148" Width="158" 
            <ListBox.ItemTemplate >
                <DataTemplate >
                    <StackPanel Orientation="Horizontal">
                     </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

拖放第一个列表框:

private void helmet_MouseDown1(object sender, MouseButtonEventArgs e)
{
    _startPoint = e.GetPosition(null);


}

private void helmet_PreviewMouseMove(object sender, MouseEventArgs e)
{
    Point mousePos = e.GetPosition(null);
    Vector diff = _startPoint - mousePos;
    if (e.LeftButton == MouseButtonState.Pressed &&
  (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
   Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance))
    {

        var listBox = sender as ListBox;
        var listBoxItem = listBox.SelectedItem;

        DataObject dragData = new DataObject(_dropIdentifier, listBoxItem);
        DragDrop.DoDragDrop(listBox, dragData, DragDropEffects.Move);
    }

Answer 1

As MSDN says 关于枚举DragDropEffects:

• All - 数据被复制，从拖动源中移除，并在其中滚动下降目标。
• 复制 - 数据被复制到放置目标。
• 链接 - 拖动源中的数据链接到放置目标。
• 移动 - 将拖动源中的数据移动到放置目标。
• 无 - 放置目标不接受数据。
• 滚动 - 滚动即将开始或当前正在放置目标中进行。

为了仅复制项目，您只需将值 DragDropEffects 从 Move 更改为 Copy:

private void helmet_PreviewMouseMove(object sender, MouseEventArgs e)
{
    //the code omitted for the brevity
    if (e.LeftButton == MouseButtonState.Pressed &&
  (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
   Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance))
    {    
        //the code omitted for the brevity
        DragDrop.DoDragDrop(listBox, dragData, DragDropEffects.Copy);
    }
}

XAML:

<ListBox x:Name="DropList" 
          Drop="DropList_Drop" 
          DragEnter="DropList_DragEnter" 
          AllowDrop="True" />

C#:

private void DropList_DragEnter(object sender, DragEventArgs e)
{
    if (!e.Data.GetDataPresent("myFormat") ||
        sender == e.Source)
    {
        e.Effects = DragDropEffects.None;
    }
}

    private void DropList_Drop(object sender, DragEventArgs e)
{
    if (e.Data.GetDataPresent("myFormat"))
    {
        Contact contact = e.Data.GetData("myFormat") as Contact;
        ListView listView = sender as ListView;
        listView.Items.Add(contact);
    }
}