在树视图中拖放

Posted 2023-05-08

【中文标题】在树视图中拖放

【英文标题】：Drag & Drop in Treeview

【发布时间】：2010-11-04 19:12:01

【问题描述】：

我正在尝试在树形视图中拖放文件，但我不知道如果我运行它并尝试拖动文件，它为什么会崩溃。

下面的代码是我尝试过的。请帮忙。

private void TreeViewItem_Drop( object sender, DragEventArgs e)

    TreeViewItem treeViewItem = e.Source as TreeViewItem;
    TreeViewItem obj = e.Data.GetData(typeof(TreeViewItem)) as TreeViewItem;

    if ((obj.Parent as TreeViewItem) != null)
    
        (obj.Parent as TreeViewItem).Items.Remove(obj);
    
    else
    
        treeViewItem.Items.Remove(obj);
        treeViewItem.Items.Insert(0, obj);
        e.Handled = true;
    


private void TreeViewItem_MouseLeftButtonDown( object sender,MouseButtonEventArgs e)

    DependencyObject dependencyObject = _treeview.InputHitTest(e.GetPosition(_treeview)) as DependencyObject;

    Debug.Write(e.Source.GetType().ToString());

    if (dependencyObject is TextBlock)
    
        TreeViewItem treeviewItem = e.Source as TreeViewItem;

        DragDrop.DoDragDrop(_treeview, _treeview.SelectedValue, DragDropEffects.Move);
        e.Handled = true;
    

【参考方案1】：

这篇文章很有帮助。 Drag drop wpf

此代码也可能对您有用。

Point _startPoint;
bool _IsDragging = false;

void TemplateTreeView_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);
        
               


void TemplateTreeView_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)

    _startPoint = e.GetPosition(null);


private void StartDrag(MouseEventArgs e)

    _IsDragging = true;
    object temp = this.TemplateTreeView.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.TemplateTreeView, data, dde);
    
    _IsDragging = false;

【讨论】：

感谢 Erin 代码确实帮助我们意识到出了什么问题。在我的 MousePreviewDown 中有几件事是错误的，比如我没有使用 Math.Abs​​()。抱歉反馈来晚了:)

如果您愿意，请将其标记为答案。