Printing from CFormView

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Printing from CFormView

There are several reasons for using a CFormView derived View Class, all of which are documented in the MFC documentation. As you may have found out, CFormView does not print the controls rendered in the View automatically. The code snippet below shows a quick way to get your CFormView application printing your screen, if that is all that you need. Please note, youll need a much better exception handling mechanism than my example. Nevertheless, this example demonstrates a quick way to get a printable CFormView View.
Our view class, called CPrintView is derived from CFormView; only 3 additional variables are needed to make CPrintView printable:
CDC * m_pMemDC;  //A memory device context compatible with our printer DC.
CRect m_rect;    //To hold the dimensions of our printing area while scaling.
CBitmap * m_pBm; //Capture the screen image as a Bitmap
Thats it. Lets see this in action:
In our views contructor, we initialize our variables:
CPrintView::CPrintView() : CFormView(CPrintView::IDD)
{	
	m_pMemDC = new CDC ;
	m_pBm = new CBitmap;
	
	//{{AFX_DATA_INIT(CPrintView)
		// NOTE: the ClassWizard will add member initialization here
	//}}AFX_DATA_INIT

}
Next we override CPrintView::OnBeginPrinting(..) as follows:
void CPrintView::OnBeginPrinting(CDC* pDC, CPrintInfo* /*pInfo*/)
{
	if (m_pMemDC->GetSafeHdc()) m_pMemDC->DeleteDC();
	m_pMemDC->CreateCompatibleDC(pDC);

	CClientDC dc(this);
	CRect rect;
	GetClientRect(rect);
	m_pMemDC->SetMapMode(MM_ANISOTROPIC);
	m_pMemDC->SetWindowExt(dc.GetDeviceCaps(LOGPIXELSX),dc.GetDeviceCaps(LOGPIXELSY));
	m_pMemDC->SetViewportExt(m_pMemDC->GetDeviceCaps(LOGPIXELSX),m_pMemDC->GetDeviceCaps(LOGPIXELSY));

	if (m_pBm->GetSafeHandle()) m_pBm->DeleteObject();
	m_pBm->CreateCompatibleBitmap(&dc,rect.Width(),rect.Height());
	m_pMemDC->SelectObject(m_pBm);
	dc.DPtoLP(rect); //Convert to Logical Coordinates
	m_rect = rect;   //Save Logical Coordinates
	m_pMemDC->BitBlt(0,0,rect.Width(),rect.Height(),&dc,0,0,SRCCOPY);
}
Next we need to override CPrintView::OnPrint(..)
void CPrintView::OnPrint(CDC* pDC, CPrintInfo*)
{
	//The Following code scales the image based on printer resolution.
	pDC->SetMapMode(MM_ANISOTROPIC);
	pDC->SetWindowExt(m_pMemDC->GetDeviceCaps(LOGPIXELSX),m_pMemDC->GetDeviceCaps(LOGPIXELSY));
	pDC->SetViewportExt(pDC->GetDeviceCaps(LOGPIXELSX),pDC->GetDeviceCaps(LOGPIXELSY));
	pDC->StretchBlt(0,0,m_rect.Width(),m_rect.Height(),m_pMemDC,0,0,m_rect.Width(),m_rect.Height(),SRCCOPY);

}
Lastly, we need to handle the destruction of our variables:
CPrintView::~CPrintView()
{
	delete m_pMemDC; //CLEAN UP OUR VARIABLES
	delete	m_pBm;
}
Thats it. Vinay Desai, Ph.D.

Note from section manager:
with this system you can print what is visible in the client area of the mainframe; it's a quick way to obtain a printed snapshot of the mainframe screen and so can have trouble with MDI formviews and cannot print what it's not show (if your formview is bigger than the mainframe, only portions will be printed; and that cannot be fixed with this approach). What is printed is influenced by the actual window size.

Last updated: 11 July 1998



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