NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/comp/os/msdos/programm/8142

Internet Message Format | 1992-07-28 | 2.1 KB

Path: sparky!uunet!cs.utexas.edu!ut-emx!ccwf.cc.utexas.edu
From: [e-mail] (paul)
Newsgroups: comp.os.msdos.programmer
Subject: Re: screen saver routines
Message-ID: <[e-mail]>
Date: 29 Jul 92 05:27:51 GMT
References: <[e-mail]> <[e-mail]>
Sender: [e-mail]
Organization: The University of Texas at Austin, Austin TX
Lines: 27

In article <[e-mail]> [e-mail] (Ya-Gui Wei ~{QG9p~}) writes:
>>>   I'm planning on incorporating a screen saver into my program.
>>>From what I gather, I'll need to hook onto 2 interrupts, 0x1C and
>>>0x09.  My hook to interrupt 0x1C will increment a counter every
>>>time it is called and if the counter is greater than a certain
>>>amount of time, blank the screen.  My hook to interrupt 0x09 will
>>>unblank the screen and clear the counter if the screen is already
>>>blanked, otherwise it will just clear the counter.  Can someone
>>>tell me if this will work or have any suggestions/improvements?
>
>  This is neccessary only if you are writing a TSR (memory resident
>program) or want the screen saver to act as a TSR. If you are not
>writing a TSR it is not neccessary (and not nice) to hook the
>interrupts.
This is not exactly true, either.  I have written a game that I felt inclined
to add a screen saver to (just for fun), and I did so exactly as the original
poster describes.  One main plus with that method (hooking interrupts) is that
the Pause key will not prevent the program from calling the Checking routine
that will determine if the program should blank the screen.  Among other things
that can go wrong with this method, the program should be careful not to be
doing any disk access or be in the middle of a particularly slow portion of
code where the users isn't needed (or capable) of typing... maybe sorting or
some other unwieldy task.  Since the application I wrote my saver into should
never need to worry about that, it was a simple matter of stealing the int hook
and patching it all together.

Jason