datagridview行号

private void dataGridView1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
        {
            Rectangle rectangle = new Rectangle(e.RowBounds.Location.X, e.RowBounds.Location.Y, dataGridView1.RowHeadersWidth, e.RowBounds.Height);
                TextRenderer.DrawText(e.Graphics, (e.RowIndex + 1).ToString(),
                    dataGridView1.RowHeadersDefaultCellStyle.Font, rectangle, dataGridView1.RowHeadersDefaultCellStyle.ForeColor,
                    TextFormatFlags.VerticalCenter | TextFormatFlags.HorizontalCenter);
        }