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From: earleh@dartvax.UUCP (Earle R. Horton)
Newsgroups: comp.sys.mac
Subject: Writing a Printing Manager (sarcastic portions rot13'd)
Message-ID: <6933@dartvax.UUCP>
Date: Mon, 24-Aug-87 13:41:27 EDT
Article-I.D.: dartvax.6933
Posted: Mon Aug 24 13:41:27 1987
Date-Received: Fri, 28-Aug-87 02:00:53 EDT
Organization: disorganized
Lines: 54
Keywords: help, where is the documentation?

I am currently attempting to write a Printing Manager for use with the
Macintosh and letter quality daisy wheel printers.  I have some problems
with the documentation and with details of implementation, however.

For example, what is my printer driver supposed to do when it receives a
control or status call which it does not support?  This is not at all
obvious.  When I am doing draft mode printing, I have to supply a
GrafPort.  It is not at all clear to me what goes in the
portBits.baseAddr field of this GrafPort (nil, or what?) when using
draft mode printing.  The function PrOpen is supposed to "prepare the
Printing Manager for use.  It opens the Printer Driver and the printer
resource file."  Exactly whose responsibility is this?  Will my printer
resource file be open when my driver receives its first open call, or am
I to assume it is not, and open it myself?  There are fields in the
TPrPort data structure that are "for internal use only".  Are these
fields reserved for use by Apple, or do I get full access to them?  It
is not very clear how I am supposed to fill in the font characterization
table for the Font Manager when I receive a control call with csCode = 
iFMgrCtl.  This is not an exhaustive list, of course.

I could, of course, obtain the answers to these and many more questions
by resorting to use of MacsBug.  It would be nicer, however, if Apple or
someone at Apple would take the time to provide the information
necessary to write a Printer Manager, in a more digestible form than 
currently exists.  The information I really want is certainly of the 
type which is not made public (i.e. source code for ImageWriter driver),
but there must be some way Apple could find to help out those who want
to write serial printer drivers.  (Especially since they do not support
a large number of serial printers themselves.)

Inside Macintosh, Promotional Edition:

"an application uses the same routine calls to print with all varieties
of printers."                                             ^^^

Apple:
**SYNZR BA**

Gunaxf sbe gur rkgrafvir qbphzragngvba ba ubj gb qb guvf cebcreyl.  V qb
abg zvaq gung gur cevagre vagresnpr pbqr vf pbzcyvpngrq naq uneq gb jevgr,
orpnhfr V frr gung vg vf hygvzngryl gb gur hfre'f orarsvg, naq nyfb nyybjf
sbe pbzzhavpngvba jvgu znal qvssrerag glcrf bs qrivprf.  Jung V qb zvaq vf
gung gur qbphzragngvba ba ubj gb jevgr gur pbqr sbe gur cevagre erfbhepr
svyr vf fxvzcl naq nccrnef gb or jevggra va nf bofpher n snfuvba nf 
cbffvoyr.  V fhccbfr vs V unq jevggra DhvpxQenj zlfrys, gura gur jubyr
guvat jbhyq or boivbhf gb zr.  Ubjrire, V qvq abg, naq vg vf abg, naq V
nz ernyyl gvpxrq bss nobhg guvf.

**SYNZR BSS**

-- 
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*Earle R. Horton, H.B. 8000, Dartmouth College, Hanover, NH 03755   *
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