C# datagridview最左行显示序号

RowPostPaint事件

        private void datagridview1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
        {
            try
            {
                SolidBrush b = new SolidBrush(datagridview.RowHeadersDefaultCellStyle.ForeColor);
                e.Graphics.DrawString((e.RowIndex + 1).ToString(System.Globalization.CultureInfo.CurrentUICulture), datagridview.DefaultCellStyle.Font, b, e.RowBounds.Location.X + 20, e.RowBounds.Location.Y + 4);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }