dataGridView添加行号

private void dataGridView1_RowPostPaint( object sender, DataGridViewRowPostPaintEventArgs e)
{
Rectangle rectangle = new Rectangle(e.RowBounds.Location.X,
e.RowBounds.Location.Y,
dataGridView1.RowHeadersWidth - 4 ,
e.RowBounds.Height);

TextRenderer.DrawText(e.Graphics, (e.RowIndex + 1 ).ToString(),
dataGridView1.RowHeadersDefaultCellStyle.Font,
rectangle,
dataGridView1.RowHeadersDefaultCellStyle.ForeColor,
TextFormatFlags.VerticalCenter | TextFormatFlags.Right);
}