datagridview显示行号

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);
}

另一种也是在这个事件下面下面 用了个for循环来做index+1的单元格赋值，效率太慢了。