Drag & Drop in Treeview wpf

Question

Hi All, im trying to drag and drop files in my treeview but i have no idea why its breaking down if i run it and try dragind a file.

i'm basically a newby in wpf and the code below is as far i can try please somebody help me on this.

    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;
        }
    }

Thanx in advance

Austin

Answer 1

This article is very helpful. Drag drop wpf

This code may be of use to you as well.

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;
}