How to select multiple rows OR columns keeping “Ctrl” pressed in DataGridView object

Question

I adapted code from this question how to select rows on cellclick, and also columns on column header click? into a single DataGridView1_MouseDown event, because it wasn't allowing me to select multiple rows/columns using the "Ctrl" key.

What I'd like, is to be able to select multiple rows (clicking on the row indices) OR multiple columns (clicking on the column headers) by selecting one after another keeping "Ctrl" pressed. I can easily get one OR the other (setting DataGridViewSelectionMode to either FullRowSelect or ColumnHeaderSelect) and then Ctrl works, but I'd like to have both functionality on the same DataGridView.

I feel like I'm so close. Thanks for any tips!

Private Sub DataGridView1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles DataGridView1.MouseDown
    Dim ht As DataGridView.HitTestInfo
    ht = Me.DataGridView1.HitTest(e.X, e.Y)
    If e.Button = Windows.Forms.MouseButtons.Left Then
        If ht.Type = DataGridViewHitTestType.Cell Then
            DataGridView1.SelectionMode = DataGridViewSelectionMode.CellSelect
            DataGridView1.CurrentCell.Selected = True
        ElseIf ht.Type = DataGridViewHitTestType.RowHeader Then
            DataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect
            DataGridView1.Rows(ht.RowIndex).Selected = True
        ElseIf ht.Type = DataGridViewHitTestType.ColumnHeader Then
            DataGridView1.SelectionMode = DataGridViewSelectionMode.ColumnHeaderSelect
            DataGridView1.Columns(ht.ColumnIndex).Selected = True
        End If
    End If
End Sub

soohoonigan soohoonigan · Accepted Answer · 2016-12-22T16:01:46

I don't think you will be able to use both full column and full row select at the same time, after running some tests, it seems that changing the datagridview's selectionmode is what's clearing selections when it is set...so unless you were to create a custom control that inherits from datagridview and overrides some of its internals, you may be stuck. Without doing that, the only way I was able to achieve the behavior you're trying to get was to leave the datagridview cellselection mode set to cellselect, and do the row/column selections manually:

Private Sub DataGridView1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) _
    Handles DataGridView1.MouseDown
    If e.Button = Windows.Forms.MouseButtons.Left Then
        Dim ht As DataGridView.HitTestInfo = Me.DataGridView1.HitTest(e.X, e.Y)
        If Not My.Computer.Keyboard.CtrlKeyDown Then DataGridView1.ClearSelection()
        If ht.Type = DataGridViewHitTestType.Cell Then
            DataGridView1.CurrentCell.Selected = True
        ElseIf ht.Type = DataGridViewHitTestType.RowHeader Then
            For i As Integer = 0 To DataGridView1.Columns.Count - 1
                DataGridView1.Rows(ht.RowIndex).Cells(i).Selected = True
            Next
        ElseIf ht.Type = DataGridViewHitTestType.ColumnHeader Then
            For i As Integer = 0 To DataGridView1.Rows.Count - 1
                DataGridView1.Rows(i).Cells(ht.ColumnIndex).Selected = True
            Next
        End If
    End If
End Sub

How to select multiple rows OR columns keeping “Ctrl” pressed in DataGridView object

1 Answers