Firefox – Fix Awful Font Rendering in Debian Buster

firefoxfonts

I upgraded from Debian stable (Stretch) to testing (Buster) today, which went without a hitch. All applications work fine, except Firefox, which has awful font rendering: text is often hard to read and has artifacts. It gets better with (much) higher zoom values than 100%, but artifacts are always visible. (I'm still running Firefox 55 because I'm missing lots of add-ons in quantum. Many still cannot be implemented in the new system because APIs are todo.)

Screenshot I've found online with the same issue, except this is for Firefox 52:

http://z-issue.com/blog_imgs/tech/linux/fonts/mozilla_rendering/linux_firefox_thunderbird_ugly_fonts_skia_cairo.jpg

Best Answer

I figured out the solution by piecing together different sources, but later found that it's nicely described here: http://z-issue.com/wp/ugly-fonts-in-mozilla-firefox-and-thunderbird-under-linux-skia-and-cairo/

Basically, in about:config, change gfx.content.azure.backends and gfx.canvas.azure.backends from skia to cairo. Then restart Firefox.

This bug appears to be related, the target of which is 57. If you don't mind losing some addons, you should try upgrading.

Related Solutions

How to diagnose a font rendering problem

I had the same problem with Helvetica bitmap fonts. To avoid it, I have a file ~/.config/fontconfig/fonts.conf with:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<alias binding="same">
  <family>Helvetica</family>
  <prefer>
    <family>Arial</family>
  </prefer>
</alias>
</fontconfig>

EDIT: to find which font corresponds to Helvetica:

$ fc-match Helvetica
helvR12-ISO8859-1.pcf.gz: "Helvetica" "Regular"

This is a bitmap font. After the change in ~/.config/fontconfig/fonts.conf, I get:

$ fc-match Helvetica
Arial.ttf: "Arial" "Normal"

a TrueType font, i.e. antialiased.

Debian Fonts – How to Improve Font Rendering in Firefox

I've had this issue for ages, maybe it's time to do something about it!

It comes done to ClearType, Microsoft and patents from what I read. Most *nix distro's disable any patent protected font rendering by default.

Read about Debian and fonts here, you want Subpixel-hinting and Font-smoothing section.

There's a config file on that page but I will add here for future reference. Create a file called .fonts.conf in your home directory, and add the following:

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

Best Answer

Related Solutions

How to diagnose a font rendering problem

Debian Fonts – How to Improve Font Rendering in Firefox

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