[Development] Question to fonts and styles

2015-05-09 Thread Martin Koller
I got a question from a kolourpaint user (KDE painting program) why he can not 
see
the same fonts he finds in e.g. libreoffice.

Checking my own system (openSuse 13.2), I see some differences where I hope 
someone here can answer
why Qt does list some fonts.

E.g. fc-list finds also these fonts
/usr/share/fonts/truetype/DejaVuSans-ExtraLight.ttf: DejaVu Sans,DejaVu Sans 
Light:style=ExtraLight
/usr/share/fonts/truetype/DejaVuSansCondensed.ttf: DejaVu Sans,DejaVu Sans 
Condensed:style=Condensed,Book
but in a QFontComboBox I only get DejaVu Sans and also DejaVu Sans Mono, 
but I do not get
the two above DejaVu Sans Light and DejaVu Sans Condensed both of which 
libreoffice shows.

(This happens with Qt4.8.6 and with Qt5.4.1)

Is this because the two mentioned above are just styles of DejaVu Sans ?

Intersting is that fc-list also lists DejaVu Sans Condensed as family name, 
e.g.
family: DejaVu Sans(s) DejaVu Sans Condensed(s)
familylang: en(s) en(s)
style: Condensed(s) Book(s)
stylelang: en(s) en(s)
fullname: DejaVu Sans Condensed(s)

Shouldn't Qt list all fonts as different fonts which are listed with a unique 
family name ?
-- 
Best regards/Schöne Grüße

Martin
A: Because it breaks the logical sequence of discussion
Q: Why is top posting bad?

()  ascii ribbon campaign - against html e-mail 
/\- against proprietary attachments

Geschenkideen, Accessoires, Seifen, Kulinarisches: www.lillehus.at
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Re: [Development] Question to fonts and styles

2015-05-09 Thread René J . V . Bertin
On Saturday May 09 2015 13:26:49 Martin Koller wrote:

 I got a question from a kolourpaint user (KDE painting program) why he can 
 not see
 the same fonts he finds in e.g. libreoffice.

I'm afraid the answer is that Qt's handling of not-so-common font styles and 
weights is incomplete, not to say flaky. This is especially noticeable with Qt 
4.x on OS X, but I'm glad to see I'm not the only one who's noticed it on Linux 
too.

The code is evolving, though. I've been working on a patch to improve things, 
and it's been getting smaller from Qt 4.8.7 to 5.4 to 5.5 .

I'm not claiming that this patch will bring Qt on par with GTk though. The 
fundamental approach feels flawed to me, and I fear the code will always be 
trying to catch up with fonts no one ever thought of checking.
I cannot affirm that the situation is actually that much better with GTk, but 
it seems safe to say that given its heritage (the GIMP Toolkit...), flaky font 
handling was never acceptable.

 /usr/share/fonts/truetype/DejaVuSans-ExtraLight.ttf: DejaVu Sans,DejaVu Sans 
 Light:style=ExtraLight
 /usr/share/fonts/truetype/DejaVuSansCondensed.ttf: DejaVu Sans,DejaVu Sans 
 Condensed:style=Condensed,Book
 but in a QFontComboBox I only get DejaVu Sans and also DejaVu Sans Mono, 
 but I do not get
 the two above DejaVu Sans Light and DejaVu Sans Condensed both of which 
 libreoffice shows.
 
 (This happens with Qt4.8.6 and with Qt5.4.1)
 
 Is this because the two mentioned above are just styles of DejaVu Sans ?
 
 Intersting is that fc-list also lists DejaVu Sans Condensed as family name, 
 e.g.
 family: DejaVu Sans(s) DejaVu Sans Condensed(s)
 familylang: en(s) en(s)
 style: Condensed(s) Book(s)
 stylelang: en(s) en(s)
 fullname: DejaVu Sans Condensed(s)
 
 Shouldn't Qt list all fonts as different fonts which are listed with a unique 
 family name ?

This actually depends on what's in the font files. Typically, Condensed/Narrow 
and Mono/Typewriter are a different (variant) family that can have as many 
weights/styles (bold, italic/slanted/oblique, medium/demibold/semibold, 
book/light, thin, black, heavy, etc) as the normal family. That is because the 
outlines are considered different, not just the result of a transformation. 
It's clearer with the Mono variant of course. But ultimately it depends on how 
this information is stored in the font files that you have installed. I'm sure 
everyone has seen cases where even the bold and italic weight/styles show up as 
different fonts ... and that is actually how foundries and font experts think 
of typefaces. The whole grouping into families, styles and weights is a 
convenience feature.

R.


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