C＃ - PictureBox图形闪烁

Question

我尝试制作像PingPong一样的动画球，它正在工作，但有图形闪烁。我搜索网络没什么帮助我。我有双缓冲表单，我尝试使用绘图与位图，但然后球不会显示。 这是我的球动画代码：

        protected PictureBox pictureBox;
    protected Graphics graphics;
    //
    public MoveBall(PictureBox pictureBox)
    {
        this.pictureBox = pictureBox;
        graphics = pictureBox.CreateGraphics();
    }
    //
    public void AnimateBall(List<Point> positions, Ball ball)
    {
        foreach (Point point in positions)
        {
            graphics.FillEllipse(new SolidBrush(pictureBox.BackColor), new Rectangle(ball.Position.X - Convert.ToInt32(Convert.ToDouble(ball.Width) * 0.5), ball.Position.Y - Convert.ToInt32(Convert.ToDouble(ball.Height) * 0.5), ball.Width, ball.Height));
            ball.Position = point;
            graphics.FillEllipse(new SolidBrush(ball.Color), new Rectangle(point.X - Convert.ToInt32(Convert.ToDouble(ball.Width) * 0.5), point.Y - Convert.ToInt32(Convert.ToDouble(ball.Height) * 0.5), ball.Width, ball.Height));
            Thread.Sleep(1);
        }
    }