Different font rendering for native packages and flatpaks using fractional scaling

Bluefin
1

I’m using Bluefin on a Framework laptop with the original display with a resolution of 2256x1504. Using fractional scaling, I usually have it set at 125% or 150%. I have noticed that the font rendering in flatpaks is really fuzzy, and after some testing around I’ve noticed that:

  • Font rendering in native apps is always good, no matter how the scaling is set.
  • Flatpaks have fuzzy rendering at fractional scaling (175%, 150%, 125%, etc…), but look good at 100% or 200%.
  • Aurora does not seem to be affected.

This is most obvious when viewing PDFs.

Nicht gespeichertes Bild 1
Nicht gespeichertes Bild 1603×477 75.4 KB

Top part is with the native viewer Evince. The lower bit is with the flatpak installation of Foliate.

Anybody have an idea why this is?

2

It is most probably not specific to Blufin. I suggest to ask flatpak like questions to flathub.org forum, because you will most probably get way better feedback from flatpak experts.

3

Flatpaks do not import complete host fonconfig because fontconfig versions between host and flatpak might differ and config file formats are not compatible: [feature] Expose xdg-config/fontconfig to sandbox by default · Issue #3947 · flatpak/flatpak · GitHub

I was unhappy with flatpak Brave font rendering and it helped to create local customized fonts.conf in ~/.var/app/com.brave.Browser/config/fontconfig/

4

How does your fonts.conf look like? I copied over my configuration from ~/.config/fontconfig and it did nothing.

5

My fonts.conf looks like this:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
<fontconfig>
  <match target="font">
    <edit mode="assign" name="antialias">
      <bool>true</bool>
    </edit>
    <edit mode="assign" name="embeddedbitmap">
      <bool>false</bool>
    </edit>
    <edit mode="assign" name="hinting">
      <bool>true</bool>
    </edit>
    <edit mode="assign" name="autohint">
      <bool>false</bool>
    </edit>
    <edit mode="assign" name="hintstyle">
      <const>hintslight</const>
    </edit>
    <edit mode="assign" name="lcdfilter">
      <const>lcddefault</const>
    </edit>
    <edit mode="assign" name="rgba">
      <const>rgb</const>
    </edit>
  </match>
</fontconfig>