获取屏幕dc并且将其画面显示在窗体中

  HWND hWnd = ::GetDesktopWindow();//获得屏幕的HWND.

 HDC hScreenDC = ::GetDC(hWnd);   //获得屏幕的HDC.

 HDC MemDC = ::CreateCompatibleDC(hScreenDC);

 RECT rect; 

 ::GetWindowRect(hWnd,&rect);

 SIZE screensize;

 screensize.cx=rect.right-rect.left;

 screensize.cy=rect.bottom-rect.top;

 hBitmap = ::CreateCompatibleBitmap(hScreenDC,screensize.cx,screensize.cy);

 HGDIOBJ hOldBMP = ::SelectObject(MemDC,hBitmap);

 ::BitBlt(MemDC,0,0,screensize.cx,screensize.cy,hScreenDC,rect.left,rect.top,SRCCOPY);//将屏幕画布拷贝到内存画布上

 ::SelectObject(MemDC,hOldBMP);

 ::DeleteObject(MemDC);

 ::ReleaseDC(hWnd,hScreenDC);

    CDC *pDC=GetDC();//获取窗体的cdc

 HDC dDlgDC=pDC->m_hDC;//获取窗体的hdc

 HDC MemDC1 = CreateCompatibleDC(dDlgDC);//创建画布

 HGDIOBJ hOldBMP1 = ::SelectObject(MemDC1,hBitmap);//选入画布

 ::StretchBlt(dDlgDC,0,0,600,400,MemDC1,0,0,screensize.cx,screensize.cy,SRCCOPY);//将内存画布缩略显示到窗体中

 ::SelectObject(MemDC1,hOldBMP1);//选出画布

 ::DeleteObject(MemDC1);//删除内存hdc

 ::ReleaseDC(m_hWnd,dDlgDC);//释放实际窗体的hdc

 

 

windows AP:

HDC GetDC( HWND // handle to window);

Parameters

hWnd

[in] Handle to the window whose DC is to be retrieved. If this value is NULL, GetDC retrieves the DC for the entire screen.