Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!agate!pasteur!ames!mailrus!umix!umich!mibte!gamma!ulysses!thumper!faline!bellcore!tness7!tness1!nuchat!wombat
From: wombat@nuchat.UUCP (Scott Lindsey)
Newsgroups: comp.sys.apple
Subject: Re: Quickdraw
Message-ID: <943@nuchat.UUCP>
Date: 15 Apr 88 16:39:56 GMT
References: <8804122040.aa11841@SMOKE.BRL.ARPA>
Organization: Mental Pogo-sticks, LTD
Lines: 37

From article <8804122040.aa11841@SMOKE.BRL.ARPA>, by STEIN@UCONNVM.BITNET:
> 
> I've started playing around with assembly language using the
> GS Toolbox and am having some difficulty deciphering some
> facts about Quickdraw's coordinate system from the
> documentation I am using -- Michael Fischer's Apple IIGS
> Technical Reference and Gary Little's Exploring the Apple
> IIGS.  

In my opinion, the technical references published by Apple through
Addison-Wesley are far superior. (And they're finally available in bookstores)
They are still not without errors and just plain wrong information, but
they are much more current than Fischer's reference, which is based on
drafts of Apple's documentation.

	[various discussion on coordinates and rect's]

In a nutshell, the boundsRect defines the size of the document, or pixel
image.  The portRect defines the port (possibly a window) looking in on
the document.  If the two are equal, then the document fits in the port.
If not, you see a portion of the document in the port.  If the port is a
window with scrollbars, then the scrollbars reflect the ratio of the
portRect to the boundsRect (by the size of the thumbs) and the location of
the portRect on the boundsRect (by the location of the thumbs).
	The Apple IIGS Toolbox Reference Volume 2 offers a much more in
depth discussion.  One comment I think that should be made is the
documentation of the tool calls LineTo and MoveTo.  I have yet to see it
documented correctly.  These take LOCAL coordinates, not global as the
manual claims.  If that was the case, local coordinate systems would be
of far less use, and bloody near impossible to use.


-- 
 Scott Lindsey      uunet!nuchat!wombat  | These are my opinions.
 StyleWare, Inc.                         | No one else claims responsibility
 5250 Gulfton 2E                         | for them.  If you agree with them,
 Houston, TX 77081                       | then you're as sick as I am.