MFC对话框绘制坐标轴和动态曲线的问题VS2010

void CfangzhenDlg::OnPaint()

{

	CPaintDC dc(this); // device context for painting 

   CString str;



   //强制更新绘图, 不可少, 否则绘图会出错

   pWnd->Invalidate(); //使static控件的区域无效

   pWnd->UpdateWindow();//更新窗口, 此时才真正向系统发送重绘消息

   CDC *pDC = pWnd->GetDC(); //获取控件的CDC指针

   pDC->Rectangle(0, 390, 700, 0); //画一个矩形框

   CPen *pPenRed = new CPen(); //创建画笔对象

   pPenRed ->CreatePen(PS_SOLID, 1, RGB(128, 128, 128)); //黑色画笔

   CPen *pPen = NULL;

   //选中当前红色画笔,并保存以前的画笔

   CGdiObject *pOldPen = pDC ->SelectObject(pPenRed);

   pDC ->MoveTo(20, 20); //绘制坐标轴

   pDC ->LineTo(20, 360); //竖起轴

   pDC ->LineTo(690, 360); //水平轴

   //写X轴刻度值

   for(int i = 0; i <= 25; i ++)

   {

      str.Format(_T("%d"), i);

      pDC ->TextOut(17 + 25 * i, 365, str);

      //绘制X轴刻度

      pDC ->MoveTo(i * 25 + 20, 360);

      pDC ->LineTo(i * 25 + 20, 355);

   }

   pDC ->TextOut(680,365,_T("t/s"));

   //写Y轴刻度值

   for(int i = 1; i <= 10; i ++)

   {

	  str.Format(_T("%d"), i);

      pDC ->TextOut(2, 360 - 30 * i - 5, str);

      //绘制Y轴刻度

      pDC ->MoveTo(25, 360 - 30 * i);

      pDC ->LineTo(20, 360 - 30 * i);

     }

   //绘制X箭头

   pDC ->MoveTo(680, 357);

   pDC ->LineTo(690, 360);

   pDC ->LineTo(680, 363);

   //绘制Y箭头 

   pDC ->MoveTo(17, 30);

   pDC ->LineTo(20, 20); //绘制左边箭头

   pDC ->LineTo(23, 30); //绘制右边箭头



   pDC ->SelectObject(pOldPen);//恢复以前的画笔

   

   delete pPenRed;

   if(pPen != NULL)

   delete pPen;

   ReleaseDC(pDC);



}