Display settings on Hi/LoDPI devices?

[Duncan]

Kristian posted on Mon, 20 Nov 2023 06:30:39 +0100 as excerpted:

> Folks;
> wanting to try this again, wondering whether there are any good
> suggestions or starting points out there for me to try. Wanting to use
> KDE on a Dell Inspiron 2in1 convertible device, I'm without much success
> stuck wrestling the internal HiDPI display especially in my setup of
> working connected to a dock with a LoDPI display connected. Played
> around with some configuration tweaks already, but it always seems to
> boil down to optimizing display settings for _one_ particular device,
> meaning either:
> 
> - I set my system to work reasonably well with HiDPI - in this case,
> user interface (starting with SDDM for login) ist way too huge to really
> be usable.
> 
> - I set my system to work reasonably well with LoDPI - in this case, I
> hardly can even log in when just using the laptop without an external
> display attached.
> 
> On the other side, it seems at least GNOME somehow manages to handle
> this automatically so there apparently seems some way to detect the
> current configuration and use the "right" settings when booting the
> system. Is there anything I can do to make something like that work with
> KDE/SDDM login?

Not sure about the GUI login as I use a CLI login and a 1-line script that 
does dbus-run-session startplasma-wayland, but as RJVB suggested gnome was 
doing, kde/plasma multi-monitor different dpi works better on wayland.

So assuming you're running a reasonably current distro and kde where a 
wayland session should work, I'd try that for your session.  The scale 
along with resolutions, etc, are then separately settable per-monitor in 
the display configuration KCM.

(Alternatively, kscreen-doctor can be invoked from a script.  I haven't 
figured out a way to have the GUI config remember and restore my monitor 
layout and it's always reversed by default, for instance, so I have an 
autostart script setup that invokes kscreen-doctor to do it.)

No clue on SDDM, tho, as I've been doing a CLI login and if desired 
starting the GUI via a script from there for two decades now, and haven't 
even had a *DM installed since I switched to Gentoo back in 2004.

-- 
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