Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!decwrl!ucbvax!hoptoad!tim
From: tim@hoptoad.uucp (Tim Maroney)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Finding the size of the screen under Multifinder/Color QD
Message-ID: <9490@hoptoad.uucp>
Date: 5 Jan 90 05:17:58 GMT
References: <10139@saturn.ucsc.edu> <9429@hoptoad.uucp> <1102@urbana.mcd.mot.com> <10164@saturn.ucsc.edu>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Organization: Eclectic Software, San Francisco
Lines: 41

In article <1102@urbana.mcd.mot.com> willcox@urbana.mcd.mot.com
(David A Willcox) writes:
>>This sounds a bit like what happened when I tried to use screenBits
>>from within an XCMD.  The problem, of course, was that I hadn't called
>>InitGraf() (I hope that's the right name) from within my XCMD, and I
>>was seeing a local copy of screenBits that had not been initialized.

In article <10164@saturn.ucsc.edu> sirkm@ssyx.ucsc.edu (Greg Anderson) writes:
>I know  it's illegal to call InitGraf() from within XCMD's, but can I
>call it from within a DA?  It seems like I would have the same problems
>you experienced.

It sounds like your problem is with THINK C.  If you'll look on page 78
of the THINK C 3.0 Manual, you'll find that this issue is explicitly
addressed.  "If you access these globals from a driver, you'll find
that they aren't the real QuickDraw globals but simply the driver's own
globals that QuickDraw knows ntohing about.  You can access the real
QuickDraw globals from a driver by observing that 0(A5) holds the
address of the last of the QuickDraw globals, thePort.  The remaining
QuickDraw globals are at descending addresses from thePort; refer to
Inside Macintosh I, Chapter 6, 'QuickDraw', for more information."

This is what I told you in my last message, but perhaps you'll take it
more seriously from the compiler manual.  You haven't been looking at
screenBits.bounds at all....

>If I cannot call InitGraf() from within my DA, then how can I find the
>size of the screen?  screenbits.bounds can be used under UniFinder, and
>I can look at the main screen's gDevice on a system with color quickdraw,
>but that still leaves me stuck in Multifinder systems that don't have
>color quickdraw.

Use inline assembly language in THINK C to access the QD globals from
non-applications.  Use screenBits.bounds to find the size of the screen.
-- 
Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, tim@toad.com

FROM THE FOOL FILE:
"I wouldn't work for Dukakis if my life depended on it.  I've worked for
 Greeks and I know just how filthy and stinking they can be."
    -- Caller, KGO-AM, 8 Nov 88