Screensaver to be or not to be (was: Re: Security Audit Request for Screenlocker Branch)

Thomas L├╝bking thomas.luebking at gmail.com
Thu Oct 13 19:21:35 BST 2011


Am Wed, 12 Oct 2011 16:37:41 -0400
schrieb Michael Pyne <mpyne at kde.org>:

> Sure it can. Just click "Test" in the Display & Monitor screen saver
> options. ;) There's probably some DBus call to do the same thing.
i thought about "kstart --fullscreen kdeasciiquarium", fails because
the window us resized externally (configure request) rather than by the
screensaver class which probably sets the window fullscreen before
the derived constructor is called.

> I will admit that resize is not supported, mostly because scaling
> down the text makes it completely impossible to see.
From what i can say, the size impacts the amount of fishes and the
area size, so it's not just a scale up/down (which should be done
adjusting the font size, never by naive pixmap/image scaling. Hinting
will more or less ensure the font remains visible)

> > If you happen to meet him and he should actually require guidance
> > in how to fix that, he may just call back. *cough*
> 
> I'm open to suggestions.
from a rough look on the code (still no git?) it seems to be sufficient
to catch resize events on Screen (eg. with an eventfilter in AASaver),
remove all sprites and do the addAll* from the constructor again.

For scaling, the new size would be exposed to the sprites so they can
wipe the caches and recreate them with a new font size.

> I guess my point is pretty much the same actually: Locking and
> screensaver animations should be orthogonal -- it should continue to
> be possible to kick off the screensaver without forcing on the lock.
"No" - it should be possible to run nice little animations for personal
joy whenever you want, but the "screensaver" just kicks in because the
system is idle - it now had the chance to save a lot of energy AND the
screen by simply turning the screen off, since nobody is watching.
Instead it's keeping the screen turned on and also peaks the CPU/GPU
for really amazing visual things - that unfortunately nobody sees (or
wants to see, because otherwise he'd just activated them)

=> The screensaver hacks (ie. the nifty shows) need some propagation
elsewhere, eg. some dropdown "your 5 minutes of zen" plasmoid.

Launching the screensaver kcm and click the demo button is
as cumbersome as taking away hands from keyboard and mouse and just wait
five minutes or so.
Video players usually trigger some action to prevent the screensavers
from activation and if you steer on eg. a complex formula, it'd be more
than annoying if it suddenly disappears (while xdpms shares this issue
with "screensavers")

So the only sane reason these things to show up "automatically" is that
the system is abandoned and than it's no more sane to run them.

Cheers,
Thomas




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