Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!hydroplane.cis.ohio-state.edu!thitt
From: thitt@hydroplane.cis.ohio-state.edu (Todd A Hitt)
Newsgroups: comp.sys.mac.programmer
Subject: Terminal Emulator DA & ScrollRect
Message-ID: <52215@tut.cis.ohio-state.edu>
Date: 17 Jun 89 04:08:38 GMT
Sender: news@tut.cis.ohio-state.edu
Reply-To: <thitt@cis.ohio-state.edu>
Distribution: usa
Organization: Ohio State University Computer and Information Science
Lines: 38

I've been working for some time on a VT220 emulator Desk Accessory and am
nearing another release.  However, I have a problem:

I use ScrollRect to scroll the screen when necessary.  Currently, I ignore
the region that is returned (updateRgn).  This works fine and dandy as long
as the DA's window is not-occluded.

I would like to update the updateRgn except for the rectangle that doesn't
need updated without paying large performance penalties.  I've tried tactics
and have all failed miserably.

First I tried InvalRgn.  Unfortunately, by the time the ToolBox Event manager
had got around sending an UpdateEvent, I've already scrolled again.  This
results in a mess.

So, I tried re-drawing on the fly.  This worked better, but...  My algorithm
is smart enough not to redraw anything if the window isn't occluded.  However,
when the window is occluded, the rate I can service serial input appears to
slow down by about a factor of 100.

At this point in time, I only have two options left:

1. Simply redraw the whole window when it is activated.

2. Redraw the whole window when I got a call to accRun and there isn't any
serial input for a period of time.

Both of these options are unattactive.  I know a solution exists.  Smartcom
does it OK.

Ideas?  Help!!


-=-
Todd Hitt			thitt@cis.ohio-state.edu
Battelle Columbus/Ohio State	hitt%36.114@ohstpy.mps.ohio-state.edu
(614)424-3297			"You were not put on this earth to 'Get It'"
				 - "Lo Pan" in Big Trouble in Little China