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 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.