效果如图，代码如下：
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Public Class Form1
'Circle类
Class Circle
Public Center As Point
Public Radius As Single
Public Sub New(c As Point, r As Single)
Center = c
Radius = r
End Sub
'绘制
Public Sub Draw(g As Graphics, pen As Pen)
g.DrawEllipse(pen, New RectangleF(Center.X - Radius, Center.Y - Radius, Radius * 2, Radius * 2))
End Sub
End Class
Private downPoint As Point '记录鼠标按下位置
Private circleList As New List(Of Circle) '已存放圆的列表
Private tmpCircle As Circle '临时圆（正在拖动）
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
DoubleBuffered = True '启用双缓冲绘图，避免闪烁
End Sub
Private Sub Form1_MouseDown(sender As Object, e As MouseEventArgs) Handles Me.MouseDown
downPoint = e.Location '记下位置
End Sub
Private Sub Form1_MouseMove(sender As Object, e As MouseEventArgs) Handles Me.MouseMove
If e.Button Windows.Forms.MouseButtons.Left Then Return '左键没按下则退出
Dim r As Single = Math.Sqrt((e.X - downPoint.X) ^ 2 + (e.Y - downPoint.Y) ^ 2) '算出半径
tmpCircle = New Circle(downPoint, r) '更新临时圆
Refresh() '先刷新掉之前绘制的临时圆
tmpCircle.Draw(Me.CreateGraphics, Pens.Black) '绘制临时圆
End Sub
Private Sub Form1_MouseUp(sender As Object, e As MouseEventArgs) Handles Me.MouseUp
circleList.Add(tmpCircle) '鼠标弹起，把临时圆加入圆列表
End Sub
Private Sub Form1_Paint(sender As Object, e As PaintEventArgs) Handles Me.Paint
For Each c As Circle In circleList
c.Draw(e.Graphics, Pens.Black) '绘制出每个圆
Next
End Sub
End Class
上位机软件接收大量数据并显示，会造成界面卡顿，可采用双缓冲技术，即将数据存到内存，再将其绘制到界面，比将数据直接绘制到界面要省很多时间
添加在子进程里面，就加在你批量传输代码里的每一个传输后面，也就是大批量中的每传输一个数据就暂停一下，而不是每一个大批量才暂停一下。
VB.NET画图是不能设置双缓冲的，双缓冲是指窗体，从来没说是针对控件。
不用graphic.clear清理重画就不会闪烁。你可以先把容器删了再重新建立一个再去画。
简单举例：
Graphics g;
Pen p;
Panel pl;
构造函数初始化：
p=new Pen(Color.Red,2);
pl=panel1;
造成闪烁的画法：
g=pl.CreateGraphics();
g.Clear(SystemColor.ButtonFace);
//.....画新的
不会闪烁的办法：
this.Controls.ReMoveAt(panel1);
pl=new Panel();
pl.Name="panel1";
//....创建容器控件
this.Controls.Add(pl);
//继续画
