VC双缓冲画图实例

void CTest::OnPaint()

{

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

     // TODO: Add your message handler code here

     // Do not call CWnd::OnPaint() for painting messages

     CPoint ptCenter;

     CRect rect,ellipseRect;

     GetClientRect(&rect);

     ptCenter = rect.CenterPoint();

     //用于缓冲作图的内存DC

     CDC dcMem; 

     //内存中承载临时图象的位图

     CBitmap bmp;

     //依附窗口DC创建兼容内存DC

     dcMem.CreateCompatibleDC(&dc);

     //创建兼容位图

     bmp.CreateCompatibleBitmap(&dc,rect.Width(),rect.Height());

     //将位图选择进内存DC

     dcMem.SelectObject(&bmp); 

     //按原来背景填充客户区，不然会是黑色

     dcMem.FillSolidRect(rect,dc.GetBkColor());

     //在内存DC上做同样的同心圆图象

     for(int i=20;i>0;i--) 

     {

         ellipseRect.SetRect(ptCenter,ptCenter);

         ellipseRect.InflateRect(i*10,i*10);

         dcMem.Ellipse(ellipseRect);

     }

     //将内存DC上的图象拷贝到前台

     dc.BitBlt(0,0,rect.Width(),rect.Height(), &dcMem,0,0,SRCCOPY);

     //删除DC

     dcMem.DeleteDC();

     //删除位图

     bmp.DeleteObject();

}