Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mailrus!cornell!biar!trebor
From: trebor@biar.UUCP (Robert J Woodhead)
Newsgroups: comp.sys.mac.programmer
Subject: Re: 3K "limitation" for CopyBits
Message-ID: <669@biar.UUCP>
Date: 22 Jun 89 10:12:46 GMT
References: <3224@ncsuvx.ncsu.edu> <7731@hoptoad.uucp>
Reply-To: trebor@biar.UUCP (Robert J Woodhead)
Organization: Biar Games, Inc.
Lines: 18

In article <7731@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes:
>In article <3224@ncsuvx.ncsu.edu> jnh@ecemwl.UUCP (Joseph N. Hall) writes:
>>Does the 3K-byte suggested restriction for CopyBits (mentioned in IM I)
>>still apply?
>I have it on fairly good authority that what happens in CopyBits is
>that each row gets pushed onto the stack.  therefore, it is not so much
>the total size of the bitmap, but the width, that determines the
>safety.

According to something I read many moons ago:

The 3K limit applies only on 64k ROMS.  Later ROMS (and perhaps System Files)
have had QuickDraw patched so that it detects situations where a QD operation
will potentially causes a Stack Heap crash, and ``subdivides'' the operation
into 2 or more subcalls so as to reduce the stack requirements.-- 
(^;-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-;^)
Robert J Woodhead, Biar Games, Inc.   !uunet!biar!trebor | trebor@biar.UUCP
  ``I can read your mind - right now, you're thinking I'm full of it...''