datagridview行号

[ToolboxBitmap(typeof(DataGridView))]
    public class DataGridViewEx : DataGridView
    {
        public DataGridViewEx()
            : base()
        { }

        protected override void OnRowPostPaint(DataGridViewRowPostPaintEventArgs e)
        {
            Rectangle rectangle = new Rectangle(e.RowBounds.Location.X, e.RowBounds.Location.Y, base.RowHeadersWidth - 4, e.RowBounds.Height);
            TextRenderer.DrawText(e.Graphics, Convert.ToInt32(e.RowIndex + 1).ToString(), base.RowHeadersDefaultCellStyle.Font, rectangle, base.RowHeadersDefaultCellStyle.ForeColor, TextFormatFlags.VerticalCenter | TextFormatFlags.Right);

            base.OnRowPostPaint(e);
        }
    }