Advanced MFC Programming

Chapter 12. Screen Capturing & Printing
……
);
-rect.Height(),
(LPSTR)lpBi+dwBitOffset,
lpBi,
DIB_RGB_COLORS,
SRCCOPY
Calculating the Number of Pages when the Printing Is Undergoing
Sample 12.5-3\GDI uses an alternate method to calculate the number of required pages for printing. It
is based on sample 12.4\GDI. Instead of calculating the number of pages before printing begins, we can set
the number of pages to the maximum value then start printing. Each time a page is printed, we check if all
of the image has been output to the printer. If so, we can stop printing.
The advantage of this method is that the actual number of required pages need not to be decided
beforehand. This is especially useful for the situation when data cannot be formatted before being printed.
By applying this method, we do not need to calculate the number of required pages in function
CGDIView::OnPrepareDC(…). Instead, we can first set it to the maximum possible value in function
CGDIView::OnPreparePrinting(…):
BOOL CGDIView::OnPreparePrinting(CPrintInfo *pInfo)
{
if(DoPreparePrinting(pInfo) == FALSE)return FALSE;
pInfo->SetMaxPage(0xFFFFFFFE);
return TRUE;
}
Please note that we must use 0xFFFFFFFE instead of 0xFFFFFFFF to set the maximum page range,
the latter will result in printing only the first page.
If we do not add further control, the printing will not stop until 0xFFFFFFFE pages have been printed.
To stop printing after all the image has been printed out, we need to calculate the total required number of
pages and check if the page currently being printed is the last page in function CGDIView::OnPrint(…). If
so, we set the page range again to stop printing:
……
……
uNumPages=
(
((lpBi->bmiHeader.biWidth-1)/abs(rectDC.Width())+1)*
((lpBi->bmiHeader.biHeight-1)/abs(rectDC.Height())+1)
);
if(uNumPages == pInfo->m_nCurPage)
{
pInfo->SetMaxPage(uNumPages);
}
In our case the number of pages can actually be decided before the printing begins, so it seems not
necessary to stop printing this way. However, for applications that the number of pages cannot be decided
beforehand, this is the only method to implement multiple-page printing.
12.6 Customizing Print Dialog Box
In this section, we will discuss the topics on how to enhance the user interface for implementing print
set up, which has nothing to do with GDI.
Customizing Common Controls
One customization we want to make is to disable radio buttons labeled “Pages” and “Selection”, along
with the edit boxes labeled “from:” and “to:” after the user executes “File | Print” command (Figure 12-8).
This dialog box is implemented by print common dialog box, which was not discussed in Chapter 7. The
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