Question

Basically in the treeview, I have a list of items, if the item is of type “Group”, then I can add / drag drop items into it.

How can I achieve that in code? I tried DragEnter, DragOver events and setting the allowdrop property to false if the target item is not a group object but to no avail. Any advice please?

Cheers

Answer 1

You’ll want to set the Effects to None (or turn off Copy/Link/Move more specifically).

A good example of doing this programmatically is within TreeViewDragDropTarget itself, as it contains logic to similarly disable if you’re trying to drag an item under itself.

http://silverlight.codeplex.com/SourceControl/changeset/view/56962#779753

The relevant snippet:

        if (itemsControl == null || IsTreeViewItemDraggedInDescendent(args) || IsTreeViewItemDraggedDirectlyAboveOrBelowSelf(args))
        {
            SW.DragDropEffects effects = args.AllowedEffects & (~(SW.DragDropEffects.Copy | SW.DragDropEffects.Link | SW.DragDropEffects.Move));
            args.Effects = effects;
            if (args.Effects != args.AllowedEffects)
            {
                args.Handled = true;
            }
        }