From owner-freebsd-hackers  Wed Nov  4 16:14:06 1998
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From: Mikael Karpberg <karpen@ocean.campus.luth.se>
Message-Id: <199811050008.BAA06026@ocean.campus.luth.se>
Subject: Re: kld screensavers
In-Reply-To: <199811030302.MAA01789@zodiac.mech.utsunomiya-u.ac.jp> from Kazutaka YOKOTA at "Nov 3, 98 12:02:37 pm"
To: yokota@zodiac.mech.utsunomiya-u.ac.jp (Kazutaka YOKOTA)
Date: Thu, 5 Nov 1998 01:08:10 +0100 (CET)
Cc: hackers@FreeBSD.ORG, yokota@zodiac.mech.utsunomiya-u.ac.jp
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According to Kazutaka YOKOTA:
> >I haven't looked at the current code, I'm affraid, so go easy on me.
> >Example:
> >
> >Three screensavers:  (say default prio is 5)
> >
> >lock:     prio 1, 10 minutes, fallthrough  (Demands password...)
> >green:    prio 4, 20 minutes               (Turn screen off)
> >stars:    prio 5, 5 minutes                (Twinkle, twinkle, little star)
> [...]
> 
> I am not sure if we want to have this kind of screen saver stack.  It
> will complicate things a lot: multiple saver module management,
> priority management, flag checking...  Is this worth the effort?
> 
> If you want to lock the vty with password, you can always use
> `lock(1)'.  And it is easy to modify screen savers, `start' or
> whatever, and add them the ability to turn off the display after set
> period (the screen saver can check system time when it is called
> periodically); it will be far easier than implementing the screen
> saver stack thingy.

Yes, but I think I could offer to write the stack. I still haven't looked
at the current code, and i think I should before I attempt such a project,
but the stack itself is a very minor problem, I think. It's just coding. :-)

I imagine something with an interface like:

called_periodically_from_syscons();
called_by_syscons_at_char_pressed_when_in_screensaver_mode();
register_screensaver();
unregister_screensaver();
list_screensavers();

And have a couple of functions which gets called in the screensavers that
are registered, when appropriate. Again I haven't read the code yet, but
I guess the screensavers now just attack the hardware directly. This seems
undesirable, and I think for this to work well you would have to make
a couple of functions available to the screensavers. Syscons should provide
something like:

screensaver_set_mode();  /* normal (no saver), text, graphics, green */
screensaver_put_char();  /* for text mode */
screensaver_draw_line(); /* for graphics mode */

Umm... I actually can't think of anything else that would be needed.
If the screensavers were written to use this interface then syscons would
also know exactly what has happened to the screen, and would therefor
put it back easilly, when called with a screensaver_set_mode(normal),
I'm guessing. 

Umm... All this is not really well anchored in reality yet, but... comments
are welcome.

What do Søren and Kazutaka think? Anyone else?

  /Mikael

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