每隔4行绘制一次Datagridview行

private void dataGridView1_Paint(object sender, PaintEventArgs e)
{
    DataGridView dgv = (DataGridView)sender;
    int rowIndex = 0;
    int rowHeight = dgv.RowTemplate.Height;

    foreach (DataGridViewRow row in dgv.Rows)
    {
        if (rowIndex % 4 == 0)
        {
            // 自定义绘制方式
            using (SolidBrush brush = new SolidBrush(Color.LightBlue))
            {
                e.Graphics.FillRectangle(brush, new Rectangle(0, row.Index * rowHeight, dgv.Width, rowHeight));
            }
        }

        rowIndex++;
    }
}