fonts

• March 19, 2013
• nightmorph

i think i’ve sorted out some of my desktop font issues, and created a few more in the process.

for a long time, i’ve had to deal with occasionally jagged, hard-to-read fonts when viewing webpages, because i ran my xfce desktop without any font antialiasing.

i’ve always hated the way modern desktop environments try to “fool” my eyes with antialiasing and subpixel hinting to convince me that a group of square pixels can be smoothed into round shapes. turning off antialiasing tends to make the rounder fonts, especially serif fonts, look pretty bad at large sizes, as seen here:

my preferred font for the desktop and the web is verdana, which looks pretty good without antialiasing. but most websites use other fonts, so rather than force one size of verdana everywhere (which causes flow/layout issues), i turned on antialiasing for my entire desktop, including my preferred browser, and started disabling antialiasing where needed.

before and after font settings:

i tried the infinality patchset for freetype, but unfortunately none of the eselect configurations produced the crisply rounded antialiased text the patches are known for. i rebuilt freetype without the patchset, and went into /etc/fonts to do some XML hacking.

while eselect-fontconfig offers painless management of existing presets, the only way to customize one’s setup is to get into nitty-gritty text editing, and font configs are in XML format. this is what i ended up with:

$ cat ~/.fonts.conf

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<match target="font">
    <edit name="antialias" mode="assign">
        <bool>false</bool>
    </edit>
</match>
<match target="font" >
    <test name="size" qual="any" compare="more">
        <double>11</double>
    </test>
    <edit name="antialias" mode="assign">
        <bool>true</bool>
    </edit>
</match>
<match target="font" >
    <test name="pixelsize" qual="any" compare="more">
        <double>16</double>
    </test>
    <edit name="antialias" mode="assign">
        <bool>true</bool>
    </edit>
</match>
<match target="pattern">
    <test qual="any" name="family"><string>Helvetica</string></test>
    <edit name="antialias" mode="assign">
      <bool>true</bool>
    </edit>
</match>

let’s step through the rules:

first, all antialiasing is disabled. then, any requested font size over 11, or anything that would display more than 16 pixels high, is antialiased. finally, since the common helvetica font really needs to be antialiased at all sizes, a rule turns that on. in theory, that is — firefox and xfce both seem to be ignoring this. unless antialiasing really is enabled at the smallest sizes with no visible effect, since there are only so many pixel spaces available at that scale to “fake” rounded corners.

a test webpage shows the antialiasing effect on different fonts and sizes:

besides the helvetica issue, there are a few xfce font display problems. xfce is known for mostly ignoring the “modern” xorg font config files, and each app in the desktop environment follows its own aliasing and hinting rules. gvim’s monospace font is occasionally antialiased, resulting in hard-to-read code. the terminal, which uses the exact same font and size, is not antialiased, since it has its own control for text display.

the rest of the gtk+ apps in the above screenshot are size 10 verdana, so they have no antialiasing, being under the “size 11″ rule. firefox doesn’t always obey the system’s font smoothing and hinting settings, even with the proper options in about:config set. unlike user stylesheets, there’s no way to enforce desktop settings with something like !important CSS code. i haven’t found any pattern in what firefox ignores or respects.

also, i haven’t found a workable fontconfig rule that enables antialiasing only for specific fonts at certain sizes. i’m not sure it’s even possible to set such a rule, despite putting together well-formed XML to do just that.

* * *

to sum up: font management on linux can be needlessly complicated, even if you don’t have special vision needs. my environment is overall a bit better, but i’m not ready to move entirely to antialiased text, not until it’s less blurry. i need crispy, sharp text.

fonts on my android phone’s screen look pretty good despite the antialiasing used everywhere, but the thing’s pixel density is so much higher than laptop and desktop LCDs that the display server doesn’t need to resort to complicated smoothing/hinting techniques to achieve that look.

as a general resource, the arch linux wiki page has very useful information on font configuration. there are some great ideas in there, even if they don’t all work on my system. the gentoo linux wiki page on fontconfig is a more basic; i didn’t use anything from it.