Arch Linux

piedro

Member

Registered: 2013-04-11

Posts: 218

How to set the DPI via sddm.conf?

Hello!

My monitor is a 1920x1200 which has a screen dpi of 82 pixels per inch.

Now I cannot read anything on this resolution, my eyes need huge fonts and enlarged UI elements like window buttons...

One thing I can do is set the screen resolution in the DE to 1440x900 and then scale up my fonts.
But that doesn't help with the login manager which is SDDM.

The Arch WIki says:

DPI settings

Sometimes it's useful to set up correct monitor's PPI settings on a "Display Manager" level. To do so you need to find "ServerArguments" parameter in sdd.conf and add -dpi %YOUR RESOLUTION at the end of the string.

For example:

/etc/sddm.conf

ServerArguments=-nolisten tcp -dpi 94

My questions are:

1. There is no [X11] or [Wayland] section in my sddm.conf.
How can I correctly add the above line to the sddm.conf file?
(I tried before to add "MinimumVT=3" to get the graphical output to another virtual terminal but it had no effect at all..)

2. How can I use the scaling mechanism in KDE > sytemsettings > display > scaling ... this has no effect on my desktop at all (yes, I relogged in)?

Thanks for your help,
p.

GrimBandito

Member

Registered: 2016-12-04

Posts: 41

Re: How to set the DPI via sddm.conf?

Backup your old sddm config file:-

sudo mv /etc/sddm.conf /etc/sddm.conf.bak

You can then generate a sample sddm.conf file by using the following command (ref: https://wiki.archlinux.org/index.php/SDDM#Configuration) :-

su
sddm --example-config > /etc/sddm.conf

You can then modify the relevant lines such as themes, cursors and finally tag your dpi settings to the ServerArguments line. This should start the XServer with the required DPI setting.

Within KDE Plasma the only setting to alter DPI is found at System Settings -> Font -> Force Fonts DPI. But, afaik this only affects font scaling. A better solution would be to ensure Xorg is configured correctly, specifically in the monitor section you need to make sure either your dpi is specified there or that the correct dimensions (mm) of your monitor are specified. Xorg can then correctly calculate your DPI.

Hope this helps.

Last edited by GrimBandito (2016-12-11 18:03:54)

jaergenoth

Member

Registered: 2015-01-16

Posts: 85

Re: How to set the DPI via sddm.conf?

...

sudo sddm --example-config > /etc/sddm.conf

...

This command will not work as the redirection is done as a regular user, and you will get a permission denied error.
It should be something like this:

sudo sddm --example-config | sudo tee /etc/sddm.conf

GrimBandito

Member

Registered: 2016-12-04

Posts: 41

Re: How to set the DPI via sddm.conf?

...

sudo sddm --example-config > /etc/sddm.conf

...

This command will not work as the redirection is done as a regular user, and you will get a permission denied error.
It should be something like this:

sudo sddm --example-config | sudo tee /etc/sddm.conf

Thanks for the info, post updated.