Regarding the outputdevice Wayland protocol

[Sebastian Kügler]

Hi Drew,

On woensdag 8 november 2017 15:12:03 CET Drew DeVault wrote:
> Thanks for the info, guys!
> 
> My main use-case for this protocol is to be able to share an
> arandr-like tool between KDE and any compositor using wlroots (Sway,
> way-cooler, waymonad, etc).
> 
> Did you guys write a screen configuration tool that leverages this
> protocol? Can it be easily detached from the rest of KDE?

Yes, we did.

We have a library (libkscreen) which has backends for xrandr and
wayland). It uses our kwayland frameworks (which is a wayland
abstraction and depends on Qt). libkscreen has a high-level screen
management API. In Plasma, there's a systemsettings module, which
probably is a bit too Plasma specific for your case), but libkscreen
also contains a command-line program (called kscreen- doctor) that
allows screen configuration, it looks like this:

iro.sebas(~/.config/QtProject): kscreen-doctor
--help [15:53:58]
Usage: kscreen-doctor [options] [output.<name>.<setting>
output.<name>.setting [...]]
kscreen-doctor allows to change the screen setup from the command-line.

Setting the output configuration is done in an atomic fashion, all
settings are applied in a single command.
kscreen-doctor can be used to enable and disable outputs, to position
screens, change resolution (mode setting), etc.. You should put all
your options into a single invocation of kscreen-doctor, so they can
all be applied at once.

Usage examples:

   Show output information:
   $ kscreen-doctor -o
   Output: 1 eDP-1 enabled connected Panel Modes: Modes: 1:800x600 at 60
   [...] Geometry: 0,0 1280x800
   Output: 70 HDMI-2 enabled connected  HDMI Modes: 1:800x600 at 60 [...] 
Geometry: 1280,0 1920x1080

   Disable the hdmi output, enable the laptop panel and set it to a
   specific mode
   $ kscreen-doctor output.HDMI-2.disable output.eDP-1.mode.1 
output.eDP-1.enable

   Position the hdmi monitor on the right of the laptop panel
   $ kscreen-doctor output.HDMI-2.position.0,1280
   output.eDP-1.position.0,0

   Set resolution mode
   $ kscreen-doctor output.HDMI-2.mode.1920x1080 at 60 


Options:
  -h, --help           Displays this help.
  -i, --info           Show runtime information: backends, logging, etc.
  -j, --json           Show configuration in JSON format
  -o, --outputs        Show outputs
  -d, --dpms <off>     Display power management (wayland only)
  -l, --log <comment>  Write a comment to the log file

Arguments:
  config               Specific output settings are separated by
spaces, each setting is in the form of
                       output.<name>.<setting>[.<value>]
                       For example:
                       $ kscreen-doctor output.HDMI-2.enable \ 
                                      output.eDP-1.mode.4 \ 
                                      output.eDP-1.position.1280,0
                       Multiple settings are passed in order to have
                       kscreen-doctor apply these settings in one go.
 

libkscreen can be used to create a GUI to manage screens.

There's also a Plasma specific daemon which tracks screen configuration 
changes and handles hotplugging (it detects plugged and unplugged
screens and then applies a config that the user has previously set up.
It also does some sensible things around lid close and suspend events.

kwayland and libkscreen are unit-tested, libkscreens xrandr backend's
unit tests are somewhat spotty, but the wayland / kwayland coverage is
actually really good, since it's much easier to synthesize a wayland
server than an X11 server, and the protocols are of course much more
reliant.

If you have any questions, please let me know. 

Cheers,
-- 
sebas

http://www.kde.org | http://vizZzion.org