Letters of some fonts are placed with incorrect distance

Question

Hello.
I'm trying quite hard to configure my fonts, but installing ms fonts always breaks the websites look.
What is strange is that some fonts are looking brilliant for me, but some (at some conditions) are really eye-breakable.
Here is an example of arial with russian letters at different sizes:
10px
11px (this is the main issue)
12px
13px
So, the distance is going to change quite insane and i don't know what to do.
And that is not only related to russian arial, or russian ms, or vodka, etc. The problem is more common, because it is also quite observable with inconsolata-g (english):
screenshot - this is shot of firefox@archlinux wiki part. "font-size:  12.7px", firefox said. Other sizes look sane.
And all this stuff is only firefox related. Other applications (leafpad, writer) draw arial, well, sane, at least. That may be a bit upexpectable, but ok, usable=)
Im using firefox on cinnamon on archlinux, with infinality-ultimate default config (from infinality repos).
Edit: oh no. That is not firefox-only related. I just forgot that font sizes are measured in points, not in pixels, in font-choosers.
So this bug is presented in leafpad, too.
Last edited by foobarrior (2013-09-09 10:40:39)

Answer 1

The is not really a problem with hinting but with stem alignment and fitting and the pixel manipulation they are responsible for. With pre 2.5.0 freetype2, I experienced constant problems when trying to 'clean' the fonts: I never managed to achieve a sharp picture that would be readable at all sizes and didn't produce painful inconsistencies between even small size ranges. Only after changing the strategy, the rendering became mostly acceptable and further fine tuning didn't involve creation of multiple additional rules for the same family for different use scenarios.
In this particular case, many font families treat Cyrillic and Latin scripts in the same manner, which means they apply the same letter positioning patterns to incompatible language systems. The problem could be easily solved if we could treat various language specific glyphs differently, i.e. apply
<match target="font">
<test name="family">
<string>Arial</string>
</test>
<test name="pixelsize" compare="less">
<double>13</double>
</test>
<edit name="hintstyle" mode="assign">
<const>hintslight</const>
</edit>
<edit name="autohint" mode="assign">
<bool>false</bool>
</edit>
</match>
to the Latin script and
<match target="font">
<test name="family">
<string>Arial</string>
</test>
<test name="pixelsize" compare="less">
<double>13</double>
</test>
<edit name="hintstyle" mode="assign">
<const>hintslight</const>
</edit>
<edit name="autohint" mode="assign">
<bool>true</bool>
</edit>
</match>
to the Cyrillic one. Unfortunately, using the <charset>0022</charset> property has never worked for me, leaving the glitches exactly where they were…
What you can do:
Choose between global settings that favour Cyrillic script over the Latin one (see above). The solution is based on the "either … or" choice which isn't exactly what you may want when both Latin and non-Latin languages have the same priority for you.
Use a dedicated sans-serif font for Cyrillic based languages. This should be a preferred solution if you choose a proper font family (Arimo or Liberastika for instance). The substitution is only done when a particular language is detected, and for anything else the default sans family will be used. You should add
<match>
<test name="lang" compare="contains">
<string>ru</string>
</test>
<test name="family">
<string>sans-serif</string>
</test>
<edit name="family" mode="prepend_first" binding="strong">
<string>Arimo</string>
</edit>
</match>
to /etc/fonts/conf.avail.infinality/93-final-lang-spec.conf and additionaly, if you choose Liberastika,
<match target="font">
<test name="family">
<string>Liberastika</string>
</test>
<test name="pixelsize" compare="less">
<double>13</double>
</test>
<test name="weight" compare="more_eq">
<const>regular</const>
</test>
<edit name="autohint" mode="assign">
<bool>true</bool>
</edit>
<edit name="hintstyle" mode="assign">
<const>hintslight</const>
</edit>
</match>
to /etc/fonts/conf.avail.infinality/92-selective-rendering.conf.
In either case, the previously appended
<match target="font">
<test name="pixelsize" compare="less">
<double>11</double>
</test>
<edit name="hintstyle" mode="assign">
<const>hintslight</const>
</edit>
<edit name="autohint" mode="assign">
<bool>true</bool>
</edit>
</match>
should be removed.
Additional fonts are available in a dedicated repository:
[infinality-bundle-any]
Server = http://ibn.net63.net/infinality-bundle-any
Simply add the above to your pacman.conf, run 'pacman -Syyu' and install whatever you like.