DataGridViewのヘッダー部に行番号を付ける方法

DataGridViewのヘッダー部に行番号を付ける方法
VB.NET

Private Sub dgv1_CellPainting(ByVal sender As Object, _
        ByVal e As DataGridViewCellPaintingEventArgs) _
        Handles dgv1.CellPainting
    If e.ColumnIndex < 0 And e.RowIndex >= 0 Then
        e.Paint(e.ClipBounds, DataGridViewPaintParts.All)
        Dim indexRect As Rectangle = e.CellBounds
        indexRect.Inflate(-2, -2)
        TextRenderer.DrawText(e.Graphics, _
            (e.RowIndex + 1).ToString(), _
            e.CellStyle.Font, _
            indexRect, _
            e.CellStyle.ForeColor, _
            TextFormatFlags.Right Or TextFormatFlags.VerticalCenter)
        e.Handled = True
    End If
End Sub

C#

private void dgv1_CellPainting(object sender,
    DataGridViewCellPaintingEventArgs e)
{
    if (e.ColumnIndex < 0 && e.RowIndex >= 0)
    {
        e.Paint(e.ClipBounds, DataGridViewPaintParts.All);

        Rectangle indexRect = e.CellBounds;
        indexRect.Inflate(-2, -2);
        TextRenderer.DrawText(e.Graphics,
            (e.RowIndex + 1).ToString(),
            e.CellStyle.Font,
            indexRect,
            e.CellStyle.ForeColor,
            TextFormatFlags.Right | TextFormatFlags.VerticalCenter);
        e.Handled = true;
    }
}

RowPostPaintイベントを活用する方法
VB.NET

Private Sub dgv1_RowPostPaint(ByVal sender As Object, _
        ByVal e As DataGridViewRowPostPaintEventArgs) _
        Handles dgv1.RowPostPaint
    Dim dgv As DataGridView = CType(sender, DataGridView)
    If dgv.RowHeadersVisible Then
        Dim rect As New Rectangle(e.RowBounds.Left, e.RowBounds.Top, _
            dgv.RowHeadersWidth, e.RowBounds.Height)
        rect.Inflate(-2, -2)
        TextRenderer.DrawText(e.Graphics, _
            (e.RowIndex + 1).ToString(), _
            e.InheritedRowStyle.Font, _
            rect, _
            e.InheritedRowStyle.ForeColor, _
            TextFormatFlags.Right Or TextFormatFlags.VerticalCenter)
    End If
End Sub

C#

private void dgv1_RowPostPaint(object sender,
    DataGridViewRowPostPaintEventArgs e)
{
    DataGridView dgv = (DataGridView)sender;
    if (dgv.RowHeadersVisible)
    {
        Rectangle rect = new Rectangle(
            e.RowBounds.Left, e.RowBounds.Top,
            dgv.RowHeadersWidth, e.RowBounds.Height);
        rect.Inflate(-2, -2);
        TextRenderer.DrawText(e.Graphics,
            (e.RowIndex + 1).ToString(),
            e.InheritedRowStyle.Font,
            rect,
            e.InheritedRowStyle.ForeColor,
            TextFormatFlags.Right | TextFormatFlags.VerticalCenter);
    }
}