C# DataGridView 在最左侧显示行号方法

代码：

        private void dataGridView1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
        {
            DataGridView dgv = sender as DataGridView;
            Rectangle rectangle = new Rectangle(e.RowBounds.Location.X,
                                                e.RowBounds.Location.Y,
                                                dgv.RowHeadersWidth - ,
                                                e.RowBounds.Height);

            TextRenderer.DrawText(e.Graphics, (e.RowIndex + ).ToString(),
                                    dgv.RowHeadersDefaultCellStyle.Font,
                                    rectangle,
                                    dgv.RowHeadersDefaultCellStyle.ForeColor,
                                    TextFormatFlags.VerticalCenter | TextFormatFlags.Right);
        }

效果：