redshift an app to avoid eye damage resulting from light emitted by screen in particular the blue component of light and in particular at day night.

You need to install
- redshift with yast software manager
- plasma 5 plasmoid redshift (gui for setting redshift)
you can get it here
https://software.opensuse.org/package/plasmoid-redshift

in "leap 15"
display "advanced packets" and click on "one click install"

in /etc/geoclue/geocclue.conf file
add these statements
Code:
[redshift]
allowed=true
system=false
users=
restart pc
open your kde session
go to systray settings
in "general" check "redshift control"

in the list of the systrayed apps
rigth click on the redshift icon for setting redshift

in "general"
check "autostart"

in "advanced"
in "location"
check "Automatic (geoclue)"

geoclue (geoclue2) is normaly installed when you install redshift
geoclue is used to get the geographical position of your pc according to know what are the hours of night

If you use a color manager as oyranos for example
according to redshift takes care of the selected icc profile (you need redshift >= 1.11)
in "advanced"
in "Mode"
choose "randr" and check "preserve screen color"


even if "randr" method works well i am not sure with 42.3 if the default method to manage screen is "randr" or "drm" by system thus by default by redshift.

there is some problem using redshift.
redshift modifies colors thus it's not good when managing/displaying photo or video with for example vlc , kdenlive , digikam

to avoid this with vlc for example
you must create in ~/bin/ a script vlc.sh with these statements:

Code:
#!/bin/bash
#
pkill -USR1 redshift
/usr/bin/vlc
pkill -USR1 redshift

"pkill -USR1 redshift" toggles redshift on/off.

don't forget to set script "executable".

you can create a second vlc item with "~/bin/vlc.sh" as command in the kde menu to facilitate the use of script.


useful links
http://jonls.dk/redshift/
https://github.com/jonls/redshift
https://wiki.archlinux.org/index.php/Redshift


Note:

in redshift plasmoid settings

when you set "Mode" to "randr" and check "preserve screen color" then click on "ok"
if you return to plasmoid settings you see "Mode" is set to "Auto"

you can think your settings is not recorded but they are recorded !

you can check this by launching by Ctrl_Esc the system activity monitor and search "redshift".
you will check that redshift is launched with

/usr/bin/redshift -m randr preserve 1 ...

you can also check this in
~/.config/plasma-org.kde.plasma.desktop-appletsrc
search "redshift" you will read something like that

Code:
[Containments][7][Applets][37]
immutability=1
plugin=org.kde.redshiftControl

[Containments][7][Applets][37][Configuration][Advanced]
geoclueLocationEnabled=true
preserveScreenColour=true
renderMode=randr
renderModeString=-m randr:preserve=1
Enjoy