VC Double Canvas eliminates screen flicker

In VC mapping, the direct mapping to the screen of the CDC, because the surface of the time is stuck in different times caused the screen flicker. The solution to this problem is to first draw the picture onto the memory canvas, at once to the screen, memory mapped to the screen quickly, so it does not cause flicker.

　CDC　m_dcMem;　　　　　　　　　　　　　　//创建内存画布
　 CBitmap　m_bmpMemDC;　　　　　　　　　//创建内存画布的
//初始化内存画布
CDC* pDC = GetDC();
　 if(pDC->GetSafeHdc())
　 {
　　 if(!m_dcMem.CreateCompatibleDC(pDC))
　　 {
　　　 ReleaseDC(pDC);
　　　 return;
　　 }
　　 if(!m_bmpMemDC.CreateCompatibleBitmap(pDC, rect.Width(), rect.Height()))
　　 {
　　　 ReleaseDC(pDC);
　　　 return;
　　 }
　　 m_dcMem.SelectObject(&m_bmpMemDC);
　　 ReleaseDC(pDC);
//把图像画到内存画布上
//内存画布映射到屏幕
pDC->BitBlt(0,0,rect.Width(),rect.Height(),&m_dcMem,0,0,SRCCOPY);