[mythtv] Request - disable screensaver

[Cliff Draper]

I'm digging up an old thread, 'cause I finally got a few cycles to
look into it.

From: "Joseph A. Caputo" <jcaputo1 at comcast.net>
Date: Fri, 17 Oct 2003 15:48:08 +0000
> On Friday 17 October 2003 07:17 pm, Cliff Draper wrote:
> > From: "Joseph A. Caputo" <jcaputo1 at comcast.net>
> > Date: Fri, 17 Oct 2003 14:41:14 +0000
> > > I'm not sure it's as simple as that... while it will enable the 
> screensaver, I 
> > > think there might still be a problem.  In my experience before I disabled 
> the 
> > > screensaver, if the screensaver kicked in while I was watching something, 
> > > taking actions with my LIRC remote didn't clear the screensaver; I needed 
> to 
> > > plug in a real keyboard or mouse to get it to clear.  I think this is 
> because 
> > > the LIRC device is not recognized as an X input device; it merely runs 
> > > through a client program that fires off X-events.  So, yes, you could turn 
> on 
> > > the screensaver when in 'menu' mode, but if your only input is a remote 
> > > control you won't be able to clear the screensaver.
> > 
> > Yes, I think you're right here.  Well, I see 2 ways to save the `xset s on`
> > idea: figure out how to make LIRC better emulate a keyboard, or call
> > `xset s reset` for every keypress that myth gets.  I think the latter
> > would work, but the former would be more elegant.
> 
> Well, LIRC can't emulate a real X-input keyboard device (well, not without 
> rewriting LIRC), but it *can* emulate an X-input mouse device, so that would 
> be one way to go.
> 
> > > The real solution is to build screensaver calls directly into Myth.  
> Shouldn't 
> > > be that hard.
> > 
> > What do you mean by direct screensaver calls?
> 
> I mean code that uses the Xlib calls directly:
> XSetScreenSaver, XForceScreenSaver, XActivateScreenSaver,
> XResetScreenSaver, XGetScreenSaver
> 
> AFAIK, Ogle uses these to enable/disable the screensaver when playing a DVD.  
> Ideally, Myth would:
> 
> 	- Disable the screensaver whenever playing video/unpaused
> 	- Enable the screensaver if the video is paused
> 	- Enable the screensaver if Myth is showing a GUI screen (i.e., not playing 
> video
> 	- Reset the screensaver (i.e., leave it enabled but un-blank the screen) 
> whenever user input is detected.

So on my home machine, I've added some functions for disabling the
screensaver, restoring the screensaver, and reseting the timer.  When
the TV player's state transitions to playing video, I disable the
screensaver.  When the state transitions to not playing video, I
restore the screensaver.  And whenever a key is pressed, the timer
gets reset.

This all works fine except for 2 big issues.
  1. Key presses in MythTV do not all flow thru the same location.
  This class inherents from that class and overrides it's key press
  handler.  So far, I've editted 16 .cpp files to call the reset
  screensaver function (haven't touched any of the plugins yet).  If
  only there were 1 spot that all keys went thru before being sent off
  to the proper handler....  The delegator pattern might work well
  here.  And this would probably help any idea of having remappable
  keybindings.  Is there a simpler and more maintainable way of doing
  this?  (Change LIRC?)

  2. Screensavers are not consistent in X.  I'm a little disappointed
  with this, as there are 3 separate protocols.  There's the basic
  blanker done with XActivateScreenSaver (`xset s on`).  There's the
  DPMS calls which try to change the power state of the monitor (`xset
  +dpms`).  And finally, there's the xscreensaver daemon (the one with
  all of the pretty screensavers) which does not have an official C
  API for talking to it.  My changes deal well with the first two, but
  xscreensaver is questionable.  First, while it would be very cool to
  see real screensavers (toasters flying, etc), do you want this on a
  machine doing real time audio/video encoding where you're trying to
  squeeze every last cycle out of your machine?  It would probably be
  fine on a dedicated frontend.  Second, the way you reset the timer
  on xscreensaver is ugly.  See
  http://www.jwz.org/xscreensaver/faq.html#dvd   Basically to disable
  the screensaver, you're suppose to fork a process every minute and
  run the xscreensaver-command to reset the timer.  Any ideas on a
  good way to deal with this?

Cliff Draper    Sun Microsystems, Forte Tools
My opinions may or may not reflect those of my employer.
---------------------------- food for thought ---------------------------
Software is like entropy.  It is difficult to grasp, weighs nothing,
and obeys the Second Law of Thermodynamics, i.e., it always increases.