Getting decent font rendering on stock Debian

November 19, 2019

I recently converted one of my machines from a parabola installation to a Debian 10 system. I started from a text only interface - the bare minimum of packages - and installed the rest by hand. For reasons that aren’t entirely clear, the default font rendering is pretty hideous. It took me a while to track down how to properly configure font rendering. Perhaps this isn’t an issue for installs which include a desktop from the get go. If it is, maybe this can help. While I did this on Debian, there isn’t much Debian specific - I’ve opted for the text file editing approach to configuration instead of strange menu-driven or ncurses stuff. This allows me to version the configuration or do automation work later.

The very short version

Enter the following into /home/user/.config/fontconfig/fonts.conf.

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>

  <!-- Enable antialiasing for all fonts -->
  <match target="font">
    <edit mode="assign" name="antialias">
      <bool>true</bool>
    </edit>
  </match>

</fontconfig>

Restart an application (firefox, virtual terminal) to see the changes. For me, just adding anti-aliasing to font rendering made all the difference. There are more dials to tune, but this was enough to make the font rendering passable.

Beginning the art and craft of debugging fonts

I don’t know why fonts remain such a painful part of the linux experience. Perhaps it’s just me, but figuring out what’s going on, and how to configure the font rendering isn’t at all obvious. As such, I thought I’d make a list for my future self of tools to use to help determine what is going on.

fc-conflist lists all the files which are read to determine font configuration.
xterm launched from a terminal usefully prints out some errors in font configuration (e.g. unrecognised entries). There ought to be a better way than this, but I don’t know it (I discovered this by accident).
fc-cache builds font information caches.
fc-list lists all fonts on the system.

Using these together with restarting a test application can help get the fonts to render as you would like.

I also noticed taking screenshots was well worthwhile, or at least doing a side-by-side comparison of different settings. I thought my settings had made one program render very strangely compared to previous settings, but direct comparison showed no difference! In fact, anti-aliasing was the only change I made where I could tell the difference in the font rendering (it’s possible all other settings I tried were already set in the other configuration files). Now text doesn’t look like total garbage.

At a future point, when I can find the will to do it, I’ll tune the rendering further still, and expand these notes.