How do I use kscreen?

[Duncan]

Nikos Chantziaras posted on Mon, 03 Nov 2014 19:47:01 +0200 as excerpted:

> On 03/11/14 15:08, Kevin Krammer wrote:
>> On Monday, 2014-11-03, 15:02:43, Nikos Chantziaras wrote:
>>> I upgraded my KDE installation to 4.11.13/4.14.2. I am now no longer
>>> able to configure my monitor through KDE System Settings.
>>> [...]
>>
>> I think kscreen is just the name of the project. The configuration is
>> still available through system settings.
>>
>> Sounds more like something has gone wrong during your upgrade.
>>
>> Does
>>
>> kcmshell4 display
>>
>> work for you?
> 
> It brings up an empty dialog:
> 
>    http://s28.postimg.org/zcyf9ugvx/display.png


While Nikos hasn't indicated distro yet on this thread, in the past he 
has indicated gentoo, which is what I run...

Apparently, upstream kde now recommends the kscreen interface for screen 
management instead of the old krandr interface, and with the kde-
workspace-4.11.13 based ebuilds, gentoo/kde has switched the default to 
kscreen as well.

Among other things, the kscreen interface is supposed to keep multiple 
profiles based on detected attached screens, and to automatically enable 
the configuration last used with that set of screens when it re-
encounters it.  This allows laptop users, for instance, to have kde 
remember and reenable the last used configuration for their work setup, 
probably with one external monitor config, their home working setup, with 
another external monitor config, their gaming and/or home movie setup, 
probably with a big-screen TV connected as external monitor, their 
detached setup, with just the laptop's own monitor, and possibly one or 
more presentation setups, each with different projection devices or big-
screen TVs setup.  This was the big failure for the old krandr solution, 
as it had only a single profile, and while you could (ideally) configure 
it as desired, each new configuration replaced the single stored 
configuration, so even if you were regularly using the same few setups in 
consistently the same way, you'd consistently have to re-setup each time 
you reconnected, since only the single profile was stored and any time 
you connected or disconnected something it was a change.

@ Nikos: You should be able to read more about that in the two 
documentation files kscreen installs in (assuming gentoo)
/usr/share/doc/kscreen-*/, one gentoo-based and one generic.

A second, more personal problem with the old krandr based setup is that 
it could never get my main workstation's Radeon-based config correct, 
from the first introduction back in kde3 times, thru multiple kde updates 
including from kde3 to kde4 and all the way to current kde4 now nearing 
kde5/frameworks, thru multiple Radeon-based graphics card generations, 
thru both two and three monitor setups, etc.  At one point even simply 
accidentally entering the display configuration kcontrol module would 
wreak havoc, before I had a chance to touch the config at all!  Luckily 
that stage passed, but while the current krandr based setup mostly works, 
it still had a gap between two of the displays that can wreak havoc if I 
get too bold with my experiments using it.

The kscreen interface, however, "just works" for me.  The monitors appear 
positioned as the should, and I can play with resolution/orientation/
positioning without having everything go whacky on me and having to 
restart kde to get back to my default xorg configuration.

But it's possible the kscreen interface doesn't work for Nikos with his 
servantware nVidia drivers, in much the same way the krandr interface 
never worked correctly for me, with the freedomware radeon drivers, even 
tho xrandr using supposedly the same interface, and now kscreen, works 
just fine for me.  Hopefully the kscreen folks fix it to work correctly 
for him; krandr never /did/ work correctly for me, tho sometimes it was 
broken worse than others.


Anyway... to a practical solution:

@ Nikos (still assuming gentoo):

What about (from a konsole or other terminal window)...

kcmshell4 kcm_kscreen


If that gives an error about a missing module, kscreen isn't properly 
installed on your system.

Here, run from a konsole session, it does print a warning:

This backend is only for XRandR 1.1, your version is:  1 . 4

But as I said it works just fine, unlike krandr.

If that runs and pops up the kscreen kcm module in a window just fine, 
then you know what it looks like and should be able to spot it in your 
normal kde systemsettings choices as well.  If not, well, something isn't 
working correctly, as it shows up fine here.


Meanwhile, the kde-base/systemsettings package now (4.11.13+) has the 
"kscreen" USE flag.  If you look at the ebuild, the effect of this flag 
is to toggle the cmake option -DBUILD_KCM_RANDR.  USE=kscreen (the IUSE 
default due to the +kscreen) toggles this to FALSE, while USE=-kscreen 
toggles it to TRUE.  USE=kscreen additionally adds an RDEPEND on kde-misc/
kscreen.

If you set USE=-kscreen and rebuild kde-base/systemsettings, you should 
get the old krandr kcm and krandrtray applet back.

Both the kscreen and krandr kcms can be installed at the same time, and 
in fact, I was running that way here from the time I first installed 
kscreen, until the kde4-live kde-base/systemsettings ebuild I'm running 
from the gentoo/kde overlay changed, adding that USE flag.  Since I 
religiously track kde overlay changes via git log every time I update, I 
immediately saw that in the git log, and decided to set USE=kscreen here 
(I have USE=-* beginning my global USE settings so the IUSE default 
setting wouldn't have affected me), thus eliminating krandr, which as I 
said never did work correctly for me anyway.  But with them both 
installed, you should be able to use whichever one you want.  I did here, 
tho of course I chose kscreen most of the time since unlike krandr, it 
actually worked correctly for me.  But you should be able to choose krandr 
if it works better for you, instead.

Of course with USE=-kscreen set, kde-base/systemsettings won't be pulling 
kscreen into the dependency chain any longer, so if you don't have it in 
your world file, an emerge --depclean should unmerge it, leaving only 
krandr once again.

So in true gentoo fashion, the choice is up to you.  Depending on your 
USE flag and world set, you can have krandr or kscreen or both. =:^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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