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ilblasco

Member

Registered: 2021-02-22

Posts: 7

Cannot set custom DPI under Plasma/Wayland session

Hello,
as the title suggest, I'm experimenting with Plasma/Wayland session. I followed the documentation and installed all required packages with Pacman.
I usually set a custom DPI value (120) because the HiDpi settings (in the official documentation) result in too big and blurry fonts.
The "Scale=125%" under "System Settings->Display Configuration" produces the same ugly result.

So, in order to set a custom dpi, I added "Xft.dpi: 120" in "$HOME/.Xresources"
- Under a standard X session, The file is correctly parsed and the fonts are correctly scaled.
- If I start a Wayland session, however, the fonts remain at the "default value" (dpi=96).

As a workaround, there should be a "Force Custom DPI" setting under "System Settings->Fonts", but the setting is not available in the same Wayland session.
Are you also experiencing the same behaviour? Do you know how to "reset" the Fonts configuration panel under System Settings?
Has any of you successfully set a custom DPI value under Plasma/Wayland session?

Please let me know if I have to provide further details. Thank you.

progandy

Member

Registered: 2012-05-17

Posts: 5,321

Re: Cannot set custom DPI under Plasma/Wayland session

Wayland does not support any dpi settings, and fractional scaling is done by the compositor as far as I know. Only integer scaling (1x 2x 3x, ... with a base of 1x ~= 96 dpi) can be forwarded to clients. There is currently no way to forward that to xwayland, so those are always scaled from the default resolution by the compositor.

I think it may have been the idea to calculate the dpi automatically from physical size and pixel size, but no applications have done that as far as I know and now we have a mess.

Last edited by progandy (2021-03-04 11:44:23)

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ilblasco

Member

Registered: 2021-02-22

Posts: 7

Re: Cannot set custom DPI under Plasma/Wayland session

Hi,

Thank you for replying.
I've made another test. I've added a startup script under "System Settings -> Startup and Shutdown" (sorry if this is not exactly the menu entry, I have the system in another language).
The script executes "xrdb -merge ~/.Xresources". The result is that the applications started after login, the ones that use XWayland (tested Firefox, Vlc, Atom, etc..), correctly scale the fonts.
But the desktop itself and all KDE applications (Dolphin, Konsole, ..) is not scaled.
Is there a way to force KDE apps to honor the dpi settings, before the login (I use SDDM as Display Manager)? Thank you.

d_fajardo

Member

Registered: 2017-07-28

Posts: 1,687

Re: Cannot set custom DPI under Plasma/Wayland session

Is there a way to force KDE apps to honor the dpi settings, before the login (I use SDDM as Display Manager)?

You can create a dpi.conf file in /etc/sddm.conf.d to set it. Refer to the SDDM wiki.

EDIT: Just dawned on me that you're trying to do this via Wayland. That dpi.conf is for X11.

Last edited by d_fajardo (2021-03-05 07:58:02)

ilblasco

Member

Registered: 2021-02-22

Posts: 7

Re: Cannot set custom DPI under Plasma/Wayland session

Hello,

the latest update on Plasma/Wayland added the option "Force Font DPI" in Plasma Fonts configuration back, so I decided to give it a try.

Unfortunately, after enabling the option and trying to change the value, no effect seems to happen. Even if I start a new app/plasma windows, the new app still has the same (small) fonts as before.
No effect after restarting the system too. Did anyone experienced this behavior as well? How did you fix the issue?

theringoffire

Member

Registered: 2014-01-25

Posts: 25

Re: Cannot set custom DPI under Plasma/Wayland session

I am also looking forward for the font DPI to work for Wayland sessions similar to X11. Including Xwayland applications would be perfect.
Display scaling is working OK as long as the Scale setting matches a supported output resolution. On other scaling factors it causes artifacts along the screen edges for my system (AMD Vega graphics). So e.g. 150% which equals a 1440p output on my 4K display works well. But not to be able to actually use the 4K screen resolution is meh to unacceptable.
For the moment I use manual Font setting which leaves a lot to be desired e.g. tiny address bar in Chromium.

So most likely it will be back to X11 :-(

ilblasco

Member

Registered: 2021-02-22

Posts: 7

Re: Cannot set custom DPI under Plasma/Wayland session

Hello all,

I just want to give you a quick update on this topic after the installation of Plasma 5.23.
I confirm that now the setting "Force Custom DPI" under "System Settings->Fonts" works as expected.
I hope this can be helpful. Have a great day!