[Pkg-fonts-bugs] Bug#409472: ttf-dejavu: Condensed fonts not working

[Ben Laenen]

> I have also a laptop running sid, and kde.  I am able to use DejaVu
> Serif Condensed font.  I don't fully understand why desktop is unable
> to use the font.
>
> Please advise.

Two possible causes:
* you're using an old DejaVu version (< 2.9)
* you're not using the newest fontconfig (2.4.2).

The reason why:
we set in DejaVu 2.9 the so called "preferred family" and "preferred 
subfamily" tags. That didn't really affect anyone back then since there 
was nothing that supported it in the Linux world. The idea behind these 
preferred families is that some environments only support four styles 
of the same font (regular, italic, bold and bold italic). Any other 
style that would belong to that family cannot be accessed. Hence we 
have two different "family" names for the normal and the condensed 
faces.

example in dejavu:
sans book: family: dejavu sans; subfamily: book
sans condensed book: family: dejavu condensed sans; subfamily: book

However, more advanced programs can handle more than four font styles, 
so you want to be able to tell in a font that condensed fonts are 
really from the same family as the regular ones. That's why "preferred 
family/subfamily" was added: these ones have the names advanced 
programs should use.

example in dejavu:
sans book: pref. family: dejavu sans; pref. subfamily: book
sans condensed book: pref. family: dejavu sans; pref. subfamily: 
condensed

As said, no-one probably noticed these new tags until fontconfig 2.4.2 
came out: fontconfig now suddenly started using the preferred families 
of a font. Which had the consequence that all software depending on 
fontconfig now all saw the condensed sans fonts in the one big "dejavu 
sans" family.

Now, unfortunately Qt (and thus also KDE) doesn't support condensed 
fonts variants in the same family. Consequence: no condensed fonts from 
dejavu in KDE anymore.

So after this little history, the possible solutions if you want to have 
condensed:

* fix Qt -- the only proper way, but the most difficult one of course.
* patch fontconfig to disable preferred families, bug #401411 can help, 
but then you'll disable them for all other fonts and for gnome (which 
supports more styles in the same font a little bit better)
* or just don't upgrade to fontconfig 2.4.2 and keep using 2.4.1
* patch DejaVu to remove the preferred family tags.

I hope this clarifies the complete situation about this and explains why 
people get different results sometimes.

Greetings
Ben