Winform 拖动画矩形框 闪烁问题

Question

大家好：
我使用如下代码，实现鼠标拖动画虚线框问题，但是鼠标在移动时，虚线框不断闪烁，不知如何处理，谢谢#region 框选对象
        bool MouseIsDown = false;
        Rectangle MouseRect = Rectangle.Empty;
        void frmMain_MouseUp(object sender, MouseEventArgs e)
        {
            this.FileListFlowLayoutPanel.Capture = false;
            Cursor.Clip = Rectangle.Empty;
            MouseIsDown = false;
            DrawRectangle();
            MouseRect = Rectangle.Empty;
        }
        void frmMain_MouseMove(object sender, MouseEventArgs e)
        {
            if (MouseIsDown)
                ResizeToRectangle(e.Location);
        }
        void frmMain_MouseDown(object sender, MouseEventArgs e)
        {
            MouseIsDown = true;
            DrawStart(e.Location);
        }
        private void ResizeToRectangle(Point p)
        {
            DrawRectangle();
            MouseRect.Width = p.X - MouseRect.Left;
            MouseRect.Height = p.Y - MouseRect.Top;
            DrawRectangle();
        }
        private void DrawRectangle()
        {
            Rectangle rect = this.FileListFlowLayoutPanel.RectangleToScreen(MouseRect);
            ControlPaint.DrawReversibleFrame(rect, Color.White, FrameStyle.Dashed);
        }
        private void DrawStart(Point StartPoint)
        {
            this.FileListFlowLayoutPanel.Capture = true;
            Cursor.Clip = this.FileListFlowLayoutPanel.RectangleToScreen(new Rectangle(0, 0, ClientSize.Width, ClientSize.Height));
            MouseRect = new Rectangle(StartPoint.X, StartPoint.Y, 0, 0);
        }
        #endregion

Answer 1

把所有东西先画在一个bitmap上，然后再把bitmap的内容复制到graphics上，

Answer 2

窗体的构造函数中添加this.DoubleBuffer = true;
或者
this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer, true);大概是这样，有些单词可能拼的不对