Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!cmcl2!lanl!opus!ksitze
From: ksitze@nmsu.edu (Kevin Sitze)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Flickering cursor
Message-ID: <KSITZE.89Apr19150833@bonito.nmsu.edu>
Date: 19 Apr 89 21:08:33 GMT
Sender: news@nmsu.edu
Distribution: comp.sys.mac.programmer
Organization: NMSU Computer Science
Lines: 44


<I'm working on an LSC program that is very calculation intensive.  My
<event loop checks for the usual events and after processing any makes
<a call to my calculation routine.  This routine takes a small fraction
<of a second (typically about .1 - .2, I'd guess)[...]

<The problem is that my mouse cursor flickers horribly.  [...]
<It seems to me that the problem is just because I'm not calling
<WaitNextEvent frequently enough, but it will take some serious 
<rewriting to check for events between every calculation instead of
<between groups of calculations.

<Am I correctly assessing the problem?  Is there some general guideline
<about how frequently GetNextEvent must be called?  Thanks for any help.

You might check your drawing, if you do a large amount of drawing to
the screen then (if the mouse is over the area being drawn to) you'll
see the cursor 'flicker' as it's being erased and redrawn.

If you just are doing calculations and virtually no drawing, VBL tasks
may be the culprit.  GetNextEvent never affects the cursor updating
(assuming a DA isn't asking for time).  WaitNextEvent may or may not
affect the mouse (I would say not) if you are passing a non-nil mouse
region to it. (I personally can't see any reason for WaitNextEvent to
be changing the cursor sense it only needs to check the mouse location
but who knows, I've seen Apple do stranger things...)

--
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