c#在Winform下如何实现在picturebox中高频率绘制大量矩形不闪烁

平台是winform，用的C#。
背景：实时（20毫秒刷新周期）获取在线检测进度，每1000为一个单位，循环刷新。合格品在进度条中显示绿色，不合格品在进度条中显示红色，当前检测单位（1000为一个单位）内的检测数量在进度条中显示棕色。
个人解决方案：我用了一个picturebox来绘制整个进度条，初始化时把picturebox分割成了1000个矩形。定义了一个容量为1000的数组，包括矩形的位置，以及绘制矩形的颜色。用多线程BackgroundWorker每20毫秒刷新获取检测数据，并在进度条中绘制检测结果。我在picturebox的Paint函数中用FillRectangle实现绘制，每次调用picturebox.refresh，就是绘制当前1000个矩形的颜色。
问题：1.绘制的指示进度的矩形会闪烁（我即使只绘制进度矩形，也会闪烁）。双缓冲也开了，无效。
2.如果多条生产线，生成多个进度条，占用系统资源较多。
请高手帮看看代码，或者指点其它途径，多谢！

    public partial class Form1 : Form

    {

        public struct CheckProgress

        {//检测进度

            public System.Drawing.RectangleF[] DrawRect; // 矩形数组

            public System.Drawing.Brush[] DrawBush;//   每个矩形对应的Brush

        }

        CheckProgress m_DrawCheckProgress;

        int CheckProgressLength;    //进度条总长度

        int m_DrawCounter;  //检测进度游标

        public Form1()

        {

            InitializeComponent();

            CheckProgressLength = 1000;

            m_DrawCounter = 0;

        }



        Color[] DrawColor = new Color[3] { Color.Red, Color.Green, Color.Yellow };

        int rand()

        {// 调试用随机数, 用于随机生成大约2%的不合格品

            Random r = new Random();

            if (r.Next(100) < 97)

            {

                return 1;

            }

            else return 0;

        }



        

        private void Form1_Load(object sender, EventArgs e)

        {

            //  Initialize Struct CheckProgressBar

            m_DrawCheckProgress = new CheckProgress();

            m_DrawCheckProgress.DrawRect = new System.Drawing.RectangleF[CheckProgressLength];

            m_DrawCheckProgress.DrawBush = new System.Drawing.Brush[CheckProgressLength];



            //将Picturebox分割成1000个小矩形

            for (int i = 0; i < m_DrawCheckProgress.DrawRect.Length; i++)

            {

                m_DrawCheckProgress.DrawRect[i] = new RectangleF(PicMainProgress.Width * i * 1.0f / CheckProgressLength, 0, PicMainProgress.Width * 1.0f / CheckProgressLength, PicMainProgress.Height);

                m_DrawCheckProgress.DrawBush[i] = new SolidBrush(PicMainProgress.BackColor);

            }

          

              //Start Thread

            if (false == Bgw_CheckResult.IsBusy)

            {

                Bgw_CheckResult.RunWorkerAsync();

            }

        }

        //

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)

        {

            Random random = new Random(); //调试用随机数, 用于随机生成大约2%的不合格品

            while (false == Bgw_CheckResult.CancellationPending)

            {//调试用

                Color c;

                int rd = rand();

                if (1 == rd)

                {

                    c = Color.Green;

                }

                else

                {

                    c = Color.Red;

                }

                m_DrawCheckProgress.DrawBush[m_DrawCounter % CheckProgressLength] = new SolidBrush(c);



                //  设置游标颜色(占据2个矩形)

                int n = 2;

                for (int i = 0; i < n; i++)

                {//防止溢出

                    if (m_DrawCounter % CheckProgressLength + n < CheckProgressLength)

                    {

                        m_DrawCheckProgress.DrawBush[m_DrawCounter % CheckProgressLength + (i+1)] = new SolidBrush(Color.Blue);

                    }

                }

               //              

                Bgw_CheckResult.ReportProgress(1);

                m_DrawCounter++;

                Thread.Sleep(20);

            }

        }

        //

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)

        {

            //  Refresh Picturebox

            PicMainProgress.Refresh();

        }

        //进度条绘制函数

        private void PicMainProgress_Paint(object sender, PaintEventArgs e)

        {

            e.Graphics.Clear(SystemColors.Control);

            for (int i = 0; i < m_DrawCheckProgress.DrawRect.Length; i++)

            {

                e.Graphics.FillRectangle(m_DrawCheckProgress.DrawBush[i], m_DrawCheckProgress.DrawRect[i]);

            }

            e.Dispose();

        }



    }