How to drag and drop row within the same datagridview

Question

In a Windows App (Visual Studio)(VB) how do you drag and drop a single row to another postition to allow for the user to re-order the row? I haven't found any worthy examples for this yet.

Answer 1

Here is a vb version from this C# answer: How could I Drag and Drop DataGridView Rows under each other?

The form class variables:

Private fromIndex As Integer
Private dragIndex As Integer
Private dragRect As Rectangle

The drag events:

Private Sub DataGridView1_DragDrop(ByVal sender As Object, _
                                   ByVal e As DragEventArgs) _
                                   Handles DataGridView1.DragDrop
  Dim p As Point = DataGridView1.PointToClient(New Point(e.X, e.Y))
  dragIndex = DataGridView1.HitTest(p.X, p.Y).RowIndex
  If (e.Effect = DragDropEffects.Move) Then
    Dim dragRow As DataGridViewRow = e.Data.GetData(GetType(DataGridViewRow))
    DataGridView1.Rows.RemoveAt(fromIndex)
    DataGridView1.Rows.Insert(dragIndex, dragRow)
  End If
End Sub

Private Sub DataGridView1_DragOver(ByVal sender As Object, _
                                   ByVal e As DragEventArgs) _
                                   Handles DataGridView1.DragOver
  e.Effect = DragDropEffects.Move
End Sub

The mouse events:

Private Sub DataGridView1_MouseDown(ByVal sender As Object, _
                                    ByVal e As MouseEventArgs) _
                                    Handles DataGridView1.MouseDown
  fromIndex = DataGridView1.HitTest(e.X, e.Y).RowIndex
  If fromIndex > -1 Then
    Dim dragSize As Size = SystemInformation.DragSize
    dragRect = New Rectangle(New Point(e.X - (dragSize.Width / 2), _
                                       e.Y - (dragSize.Height / 2)), _
                             dragSize)
  Else
    dragRect = Rectangle.Empty
  End If
End Sub

Private Sub DataGridView1_MouseMove(ByVal sender As Object, _
                                    ByVal e As MouseEventArgs) _
                                    Handles DataGridView1.MouseMove
  If (e.Button And MouseButtons.Left) = MouseButtons.Left Then
    If (dragRect <> Rectangle.Empty _
    AndAlso Not dragRect.Contains(e.X, e.Y)) Then
      DataGridView1.DoDragDrop(DataGridView1.Rows(fromIndex), _
                               DragDropEffects.Move)
    End If
  End If
End Sub

Make sure you have the grids AllowDrop property set to true.

Answer 2

UPDATE:

Instead of

 If dragIndex < 0 Then dragIndex = DataGridView1.RowCount - 1

change to

 If dragIndex > -1 Then 
      'action if not selected in the row header and blank space
 else
      'return error if selected in the column header and blank space
 end if

then a error occurs when you drag a row to the "blank zone", if you don't believe me, you must to try it.

the final code (Only for the part "The drag events") is this:

  Private Sub DataGridView1_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles DataGridView1.DragDrop
        Dim p As Point = DataGridView1.PointToClient(New Point(e.X, e.Y))
        dragIndex = DataGridView1.HitTest(p.X, p.Y).RowIndex
    'Determine if dragindex is valid row index       
    If dragIndex > -1 Then
        If (e.Effect = DragDropEffects.Move) Then
            Dim dragRow As DataGridViewRow = CType(e.Data.GetData(GetType(DataGridViewRow)), DataGridViewRow)
            DataGridView1.Rows.RemoveAt(fromIndex)
            DataGridView1.Rows.Insert(dragIndex, dragRow)
            'Add this line of code if you want to put selected rows to the rows that change
            DataGridView1.Rows(dragIndex).Selected = True
        End If 
       Else 'Do any message here if selected in column header and blank space. 
       End If
    End Sub