后台截屏

HBITMAP GetWindowBitmap(HWND hWnd)  {  typedef BOOL ( __stdcall *pPrintWindow )(HWND ,HDC ,UINT );      RECT rect;   HMODULE h;  h = LoadLibrary( "user32.dll" );  pPrintWindow p;  if( h )  {  p = ( pPrintWindow )::GetProcAddress( h, "PrintWindow" );  }      ::GetWindowRect(hWnd,&rect);      HDC hScrDC=::GetDC(hWnd);                            //创建屏幕DC      HDC hMemDC=CreateCompatibleDC(hScrDC);                //创建内存DC      HBITMAP bitmap=::CreateCompatibleBitmap(hScrDC,rect.right-rect.left,rect.bottom-rect.top); //创建兼容位图      HBITMAP OldBitmap=(HBITMAP)::SelectObject(hMemDC,bitmap);    //把位图选进内存DC      p(hWnd,hMemDC,0);    HDC d;  HWND hw;  hw = ::GetDesktopWindow();  d = ::GetWindowDC( hw );  ::BitBlt( d, 0, 0, 200, 200, hMemDC, 0, 0, SRCCOPY );      ::SelectObject(hMemDC,OldBitmap);       ::DeleteDC(hMemDC) ;            //删除内存DC      ::ReleaseDC(NULL,hScrDC) ;    //释放屏幕DC      return bitmap;  }