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From: cmedley@wam.umd.edu (Charles Henry Medley)
Newsgroups: comp.sys.atari.st.tech
Subject: Traps on Resolution Change
Summary: How to cope with resolution dependent code on resolution change
Keywords: traps rez change resident code
Message-ID: <1991May12.024116.26326@wam.umd.edu>
Date: 12 May 91 02:41:16 GMT
Sender: usenet@wam.umd.edu (USENET Posting)
Organization: University of Maryland at College Park
Lines: 18
Nntp-Posting-Host: cville

I have been working on what I hope to be a commercial product for quite some
time, and what it does, running as an accessory, is steal the TRAP #5 vector.
I have often thought about making the TRAP #5 code an AUTO .PRG, but decided
against it for the sake of simplicity for the user.

What it boils down to is that this TRAP #5 code needs to know if the user
has changed resolutions from "Set Preferences" on the desktop.  Since all
of my code is legal under GEM (in fact, it counts on GEM!) I don't want to
use any dangerous hacks.  However, I've tried several methods and none work
realiably (i.e., checking for new sizes of the desktop window when about to
install a new trap handler, checking to see if the TRAP #5 is currently owned
by me, etc...).  Apparently, one source of my problem is that on a change
in the resolution, the ST does do a warm boot, but it does not affect system
vectors, like the various TRAP pointers or the hard drive vectors, etc... And
my accessory needs to know when the accessories are being flushed so it can
clear out, and when the system reloads ACCs, it can reinstall on the TRAP #5.

Any help is appreciated.