WPF 拖放 - 3 Treeview

Question

我正在尝试在 3 个树视图之间拖放项目。 每个树源都由相同的 class 定义。

public class TreeItem : TreeViewItemBase
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string SubstringedName { get; set; }
    public string Link { get; set; }
    public bool IsChecked { get; set; }

    public TreeItem Parent { get; set; }

    public bool IsSingle { get; set; }

    public List<TreeItem> TreeItems { get; set; }
}

但我不知道如何在这 3 棵树之间传递数据......这就是我现在所拥有的：

private void tree_view_current_slides_Drop(object sender, DragEventArgs e)
    {
        MessageBox.Show("YEY");
    }

    private void tree_view_current_slides_PreviewMouseMove(object sender, MouseEventArgs e)
    {
        if (e.LeftButton == MouseButtonState.Pressed ||
    e.RightButton == MouseButtonState.Pressed && !_IsDragging)
        {
            Point position = e.GetPosition(null);
            if (Math.Abs(position.X - _startPoint.X) >
                    SystemParameters.MinimumHorizontalDragDistance ||
                Math.Abs(position.Y - _startPoint.Y) >
                    SystemParameters.MinimumVerticalDragDistance)
            {
                StartDrag(e);
            }
        }
    }

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

    private void StartDrag(MouseEventArgs e)
    {
        _IsDragging = true;
        object temp = this.tree_view_current_slides.SelectedItem;
        DataObject data = null;

        data = new DataObject("inadt", temp);

        if (data != null)
        {
            DragDropEffects dde = DragDropEffects.Move;
            if (e.RightButton == MouseButtonState.Pressed)
            {
                dde = DragDropEffects.All;
            }
            DragDropEffects de = DragDrop.DoDragDrop(this.tree_view_current_slides, data, dde);
        }
        _IsDragging = false;
    }

我只需要知道如何将数据从一棵树获取到另一棵树以及它被丢弃的位置

Answer 1

这是我的演示，它指的是两个 TreeViews 之间的拖放。

XAMl 代码为：

 <StackPanel>
        <TreeView AllowDrop="True" Drop="OnDrop">
            <local:DragableTreeViewItem Header="Employee1">
                <local:DragableTreeViewItem Header="Jesper"/>
                <local:DragableTreeViewItem Header="Aaberg"/>
                <local:DragableTreeViewItem Header="12345"/>
            </local:DragableTreeViewItem>
            <local:DragableTreeViewItem Header="Employee2">
                <local:DragableTreeViewItem Header="Dominik"/>
                <local:DragableTreeViewItem Header="Paiha"/>
                <local:DragableTreeViewItem Header="98765"/>
            </local:DragableTreeViewItem>
        </TreeView>

        <TreeView AllowDrop="True" Drop="OnDrop">
            <local:DragableTreeViewItem Header="Employee3">
                <local:DragableTreeViewItem Header="Jesper3"/>
                <local:DragableTreeViewItem Header="Aaberg3"/>
                <local:DragableTreeViewItem Header="123453"/>
            </local:DragableTreeViewItem>
            <local:DragableTreeViewItem Header="Employee4">
                <local:DragableTreeViewItem Header="Dominik4"/>
                <local:DragableTreeViewItem Header="Paiha4"/>
                <local:DragableTreeViewItem Header="987654"/>
            </local:DragableTreeViewItem>
        </TreeView>
    </StackPanel>

它的cs代码是：

public void OnDrop(object sender, DragEventArgs e)
    {
        if (e.Data.GetData("DragableTreeViewItem") != null)
        {
            var item = e.Data.GetData("DragableTreeViewItem") as DragableTreeViewItem;
            DragableTreeViewItem newItem = new DragableTreeViewItem();
            newItem.Header = item.Header;
            foreach (var child in item.Items)
                newItem.Items.Add(child);
        }
    }

DragableTreeViewItem.cs 的代码是：

public class DragableTreeViewItem : TreeViewItem
{
    public DragableTreeViewItem()
    {
        this.Drop += (sender, e) =>
        {
            if (e.Data.GetData("DragableTreeViewItem") != null)
                ((DragableTreeViewItem)e.Data.GetData("DragableTreeViewItem")).SetParent(sender);
        };
    }

    public void SetParent(object newParent)
    {
        if (Parent is TreeView)
            ((TreeView)Parent).Items.Remove(this);
        if (Parent is DragableTreeViewItem)
            ((DragableTreeViewItem)Parent).Items.Remove(this);

        if (newParent is TreeView)
            ((TreeView)newParent).Items.Add(this);
        if (newParent is DragableTreeViewItem)
            ((DragableTreeViewItem)newParent).Items.Add(this);
    }

    protected override void OnMouseMove(System.Windows.Input.MouseEventArgs e)
    {
        if (e.LeftButton == System.Windows.Input.MouseButtonState.Pressed)
            DragDrop.DoDragDrop(this.Parent, new DataObject("DragableTreeViewItem", this, true), DragDropEffects.Move);

        base.OnMouseMove(e);
    }
}