Question Treeview: only allow children to parent node, no children of children

[sous2817]

Hello everyone,

I'm working on a drag-and-drop method to copy items from a listview control to a treeview. I've got the drag and drop working, but I'm hoping to limit the ability to drag items that create a child of a child. Ideally, if someone drags an item from the listview to the Treeview and the drop the listview item over a child, it would drop the dragged item to the parent.

Hope I've explained it and any help is appreciated.

Thanks in advance

 

[JohnH]

Use the DragOver event and hittest current location against the node level, this will provide proper feedback to the user about where drops is allowed, for example:

Dim pt = Me.ATreeView.PointToClient(New Point(e.X, e.Y))
Dim node = Me.ATreeView.GetNodeAt(pt)
If node IsNot Nothing AndAlso node.Level = 0 Then
    e.Effect = DragDropEffects.Copy
Else
    e.Effect = DragDropEffects.None
End If

Same GetNodeAt code in DragDrop to find the root node to add node to.

 

[sous2817]

Thank you for the code JohnH,

This is my hack that seemed to work as well:

Dim position As New Point(0, 0)
Dim oparent As TreeNode
Dim dNode As TreeNode
position.X = e.X
position.Y = e.Y
position = Tree1.PointToClient(position)
oparent = Tree1.GetNodeAt(position)
If IsNothing(oparent) Then
     Exit Sub
Else
 
Dim node As TreeNode = oparent
 
If node.Parent IsNot Nothing Then
     node.Parent.Nodes.Add(lbSource.SelectedItems(0).Text)
Else
oparent.Nodes.Add(lbSource.SelectedItems(0).Text)
End If
End If

Your way is way cleaner...

Thanks again!