having trouble with drag-n-drop of multiple items

3 May 2007 1:59 PM

Dan Morrow

I'm having trouble handling drag-n-drop of rows from a DataGridView.

The SelectionMode is FullRowSelect, so when I click, the whole row gets
selected, not just cells.

What I'd like to do is select rows 1, 3 and 5 (by control-clicking) and
then click one more time, and drag all three rows.

The problem that occurs is that when I do that last click (to perform
the drag) all the rows unhilite, and only the row that I clicked on
stays hilited. This is not desirable behavior, obviously.

I'd really like my DataGridView to do drags the same way that Outlook or
Windows Explorer (or any program that has a list of things like this).
But I can't seem to find the right way to do this.

If I'm just dragging one row, then this works fine, but I need to
support dragging multiple rows.

Thanks for any help in this matter,
-Dan.

P.S. - I've been a programmer for many years, but I'm a relative newbie
to VB.

3 May 2007 3:17 PM

ClayB

Try deriving the DataGridView and overriding OnMouseDown to start your
drag if you are over a seelcted row.

Public Class MyDataGridView
   Inherits DataGridView

   Protected Overrides Sub OnMouseDown(e As MouseEventArgs)
      Dim hti As HitTestInfo = Me.HitTest(e.X, e.Y)
      If Me.SelectedRows.Contains(Me.Rows(hti.RowIndex)) Then
          'Not calling the baseclass prevents unselecting the selected
rows
          'Start your drag here
      Else
         MyBase.OnMouseDown(e)
      End If
   End Sub 'OnMouseDown
End Class 'MyDataGridView

==============================
Clay Burch
Syncfusion, Inc.