一般拖放ListBoxItems

Question

我想使用MVVM模式在多个数据绑定的列表框上实现拖放.我不是想在列表框之间拖放,而是希望用户能够在每个列表框中拖放listboxitems,以便他们可以重新排列排序顺序.我在SO上发现这篇帖子非常有帮助:

WPF C#:通过拖放重新排列列表框中的项目

我想尝试使这些方法更"通用",以便它可以在任何绑定到不同类型的Observable Collections的列表框上工作.所以说这是我在VIEW中的XAML:

<Window x:Class="WpfApplication1.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">

    <Window.Resources>
        <Style TargetType="{x:Type ListBoxItem}" x:Key="ListBoxItemDragDrop">
            <Setter Property="AllowDrop" Value="True" />
            <EventSetter Event="PreviewMouseMove" Handler="ListBoxItem_PreviewMouseMoveEvent" />
            <EventSetter Event="Drop" Handler="listbox1_Drop" />
        </Style>
    </Window.Resources>

    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>

        <ListBox Name="listbox1"
                 ItemsSource="{Binding OCofType1}"
                 ItemContainerStyle="{StaticResource ListBoxItemDragDrop}" />

        <ListBox Name="listbox2" Grid.Column="1"
                 ItemsSource="{Binding OCofType2}"
                 ItemContainerStyle="{StaticResource ListBoxItemDragDrop}"/>
    </Grid>

</Window>

OC绑定的位置是ObservalbeCollection <Type1>和ObservalbeCollection <Type2>.这是VIEW中抓取鼠标移动事件并检查它是否是拖动的方法:

void ListBoxItem_PreviewMouseMoveEvent(object sender, MouseEventArgs e)
{
    if (e.LeftButton == MouseButtonState.Pressed && sender is ListBoxItem)
    {
        ListBoxItem draggedItem = (ListBoxItem)sender;
        DragDrop.DoDragDrop(draggedItem, draggedItem.DataContext, DragDropEffects.Move);
        draggedItem.IsSelected = true;
    }
}

这似乎是"通用的".接下来是方法,也在VIEW中,处理drop,这就是我遇到的问题:

void ListBoxItem_Drop(object sender, DragEventArgs e)
{
    object Target = ((ListBoxItem)(sender)).DataContext;
    object Dropped = e.Data.GetData(Target.GetType());

    int RemoveIndex = listbox1.Items.IndexOf(Dropped);
    int TargetIndex = listbox1.Items.IndexOf(Target);

    ListBox container = ((DependencyObject)sender).GetAncestor<ListBox>();

    if (RemoveIndex < TargetIndex)
    {
        //THESE WILL NOT WORK IF I AM DOING BINDINGS THROUGH THE ITEMSSOURCE
        //container.Items.Insert(RemoveIndex + 1, Dropped);
        //container.Items.RemoveAt(RemoveIndex);

        //SO HAVE TO USE THE ITEMSSOURCE DIRECTLY BUT HOW WITHOUT A SPECIFIC CAST TO THE OC<TYPE#>
        container.ItemsSource.Insert(RemoveIndex + 1, Dropped);  //ERROR: IENUMERATOR DOES NOT CONTAIN A DEFINITION FOR INSERT....
        container.ItemsSource.RemoveAt(RemoveIndex); //ERROR: IENUMERATOR DOES NOT CONTAIN A DEFINITION FOR REMOVEAT....
    }
    else
        if (container.Items.Count > RemoveIndex)
        {
            //THESE WILL NOT WORK IF I AM DOING BINDINGS THROUGH THE ITEMSSOURCE                    
            //container.Items.Insert(TargetIndex, Dropped);
            //container.Items.RemoveAt(RemoveIndex + 1); 

            //SO HAVE TO USE THE ITEMSSOURCE DIRECTLY BUT HOW WITHOUT A SPECIFIC CAST TO THE OC<TYPE#>
            container.ItemsSource.Insert(TargetIndex, Dropped);  //ERROR: IENUMERATOR DOES NOT CONTAIN A DEFINITION FOR INSERT....
            container.ItemsSource.RemoveAt(RemoveIndex + 1);  //ERROR: IENUMERATOR DOES NOT CONTAIN A DEFINITION FOR REMOVEAT....

        }
}

找到祖先功能就是这个(来自SO的另一篇文章):

static T FindAnchestor<T>(DependencyObject current) where T : DependencyObject
{
    do
    {
        if (current is T)
            return (T)current;

        current = VisualTreeHelper.GetParent(current);
    }
    while (current != null);
    return null;
}

在drop函数中,如果我直接添加到ListBox的List集合中,这可能会起作用.但是因为我正在对VIEWMODEL中的集合进行绑定,所以我将不得不通过ItemsSource处理这些对象.但是,如果我使用ItemsSource,我将不得不为每个OC类型创建该函数的可疑版本,因为我不会在运行时投射ItemsSource.我可以使用if语句将其保持为1函数,该语句确定将其强制转换为显式内容,但如果对于应用于每个新OC的情况,则不必记得更新.

接下来的问题是如何添加/移动项目到的ItemsSource不知道究竟投什么呢？

谢谢你的帮助.

Answer 1

这是一个非常方便的工具/框架.龚WPF拖放