Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!nucsrl!accuvax.nwu.edu!bob
From: bob@accuvax.nwu.edu (Bob Hablutzel)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Fast image changes
Message-ID: <10050074@accuvax.nwu.edu>
Date: 29 Jan 89 02:23:37 GMT
References: <243@usage.csd.unsw.oz>
Organization: Northwestern U, Evanston IL, USA
Lines: 12

> Another question about this 'CopyBits' inside VBL tasks.

> Is there a potential problem if the CopyBits decides to move memory
> around for you because it needs the space to draw a particularly difficult
> bitmap?  Or is this one of those places the Quickdraw cheats and uses
> memory between heap and stack that it thinks is fair game?


You cannot use CopyBits from a VBL task. CopyBits is on the list of traps
which might move or purge memory.

Bob Hablutzel	Wildwood Software	BOB@NUACC.ACNS.NWU.EDU