Printing a text buffer

A lot of people have been asking questions about printing a simple straight multi-page text buffer to a user-selected printer, without using the docView framework. You could use the classes created by Richard Stringer, but quite often, this is a big overkill for what you want to do. A few suggestions have been made and Chris Maunder provided some samples on how to start with it. But no one gave a real world example. So I puzzled around abit, and finally came up with the code below.

It is far from perfect, and some additional function parameters would be cool. I will make a more advanced version when I find the time.

There is one major drawback to the method below : to find page breaks, it will start at the beginning of the buffer, and calculate the height needed for 1 character, 2 characters, 3 characters, ... and so on. When the height grows beyond the page size, a new page must be started with the previous character that didn't overflow yet. This method will have to call DrawText() for each character. A big calculation peak will be induced ! It would be a lot better to use entire words instead of characters. I intend to make such a version in the next few weeks.

Even better would be to use some statistics scheme and 'guess' where the page break will occur. Then jump back or forward with consecutively smaller blocks until you find the exact pagebreak location. (somewhat like the quicksort sorting algorithm) that's a problem for later. The routine works as it does now, and I hope someone can use it.



// p points to the start of the buffer, pSize holds the number of characters
void PrintString(char *p, DWORD pSize)
{
    CDC             dc;
    CPrintDialog    printDlg(FALSE);
    CRect           r;
    int             nHeight;
    
    // ask the user to select a printer
    if (printDlg.DoModal() == IDCANCEL)
        return;
    
    // Attach a printer DC
    dc.Attach(printDlg.GetPrinterDC());
    dc.m_bPrinting = TRUE;

    // use Textmappingmode, that's easiest to map the fontsize
    dc.SetMapMode(MM_TEXT);
    
    // setup font specifics
    LOGFONT LogFont;
    
    CFont	aFont, *oldFont;
    
    LogFont.lfHeight = -MulDiv(10, GetDeviceCaps(dc, LOGPIXELSY), 72);
    LogFont.lfWidth = 0;
    LogFont.lfEscapement = 0;
    LogFont.lfOrientation = 0;
    LogFont.lfWeight = 0;
    LogFont.lfItalic = false;
    LogFont.lfUnderline = 0;
    LogFont.lfStrikeOut = 0;
    LogFont.lfCharSet = ANSI_CHARSET;
    LogFont.lfOutPrecision = OUT_TT_PRECIS;
    LogFont.lfClipPrecision = CLIP_DEFAULT_PRECIS;
    LogFont.lfQuality = DEFAULT_QUALITY;
    LogFont.lfPitchAndFamily = DEFAULT_PITCH | FF_SWISS;
    lstrcpy (LogFont.lfFaceName, "MS Sans Serif");
    dc.SetBkMode(OPAQUE);
    aFont.CreateFontIndirect ( &LogFont );
    // ok, we've build the font, now use it
    oldFont = dc.SelectObject( &aFont );        
        
    // Get the application title
    CString strTitle;
    strTitle.LoadString(AFX_IDS_APP_TITLE);
    
    // Initialise print document details
    
    DOCINFO di;
    ::ZeroMemory (di, sizeof (DOCINFO));
    di.cbSize = sizeof (DOCINFO);
    // application title appears in the spooler view
    di.lpszDocName = strTitle;
    
    // Begin a new print job
    BOOL bPrintingOK = dc.StartDoc( &di );
        
    // Get the printing extents and store in the m_rectDraw field of a 
    // CPrintInfo object
    CPrintInfo Info;
    int w = dc.GetDeviceCaps(HORZRES);
    int h = dc.GetDeviceCaps(VERTRES);
    Info.m_rectDraw.SetRect(0,0, w, h);
    
    char *startAt = p;
    int totalDone = 0;
    int lengthToGo = pSize;
    
    for (UINT page = Info.GetMinPage();
    bPrintingOK & totalDone < lengthToGo; page++)
    {
        // begin new page
        dc.StartPage();
        Info.m_nCurPage = page;
        
        // calc how much text fits on one page
        r = Info.m_rectDraw;
        r.bottom = r.top;
        int i = 0;
        while (r.bottom < Info.m_rectDraw.bottom & totalDone + i < lengthToGo)
        {
            r.right = Info.m_rectDraw.right;
            nHeight = dc.DrawText(startAt, i++, r, 
                DT_CALCRECT|DT_WORDBREAK|DT_NOCLIP|DT_EXPANDTABS);
        }
        // go one back to assure correct height
        if (r.bottom >= Info.m_rectDraw.bottom)
            i--;
        
        
        // print that text
        dc.DrawText(startAt, i, r, DT_WORDBREAK|DT_NOCLIP|DT_EXPANDTABS);
        
        // go to next page
        startAt += i;
        totalDone += i;
        
        // end page
        bPrintingOK = (dc.EndPage() > 0);
    }
    
    // end a print job
    if (bPrintingOK)
        dc.EndDoc();
    else
        // abort job.
        dc.AbortDoc();
    
    
    // restore font
    dc.SelectObject(oldFont);
    // free font memory
    qFont.DeleteObject();
    // detach the printer DC
    dc.Detach();
}