[Fontconfig-bugs] [Bug 95428] Subfamilies with different OpenType 'size' should not be merged

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=95428

Akira TAGOH <akira at tagoh.org> changed:

           What    |Removed                     |Added
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                 CC|                            |akira at tagoh.org

--- Comment #1 from Akira TAGOH <akira at tagoh.org> ---
Hm, that sounds like a side-effect of the multiple family names in those fonts.
strictly speaking, those fonts are recognized separately in fontconfig itself.
but due to the unified family name for those, when applications queries it to
fontconfig, fontconfig just returns the better font sets against the requested
patterns. but if that pattern isn't enough, say, if asking for only family name
once and reuse it for any size for rendering, it may not works as expected
right.

(In reply to gm from comment #0)
> == Issues: ==
> 
> * The gnome font selector (for instance in the preferences of gedit) shows
> all the fonts, but they all display the same as Arno Pro Caption, i.e. if
> one chooses Arno Pro Regular one gets Arno Pro Caption instead.

I can't say off hand but if "fc-match 'Arno Pro Regular'" returns it as is,
maybe fontconfig decided it isn't a best font for the certain pattern. I can't
say more without logs containing what applications actually requested.

> * Inkscape only lists Arno Pro as a family. One can enter "Arno Pro Display"
> (and Caption, etc.) by hand, however this produces strange results: the
> metrics of Arno Pro Display are used, but the glyphs from the initial font
> are used. I noticed it used to work better in older versions of Inkscape
> (from Ubuntu 11.04, if my memory serves well).

That should be the inkscape issue.

>   This is the relevant fontconfig debug output when requesting "Arno Pro" in
> weight 50 with QFont in lyx:
> 
> '''
> FC_DEBUG=3:

Well, I can't figure out if that really explain what you say because FC_DEBUG=3
doesn't show the original request and hard to estimate it from the debugging
log, but that looks like lyx doesn't request weight=50 really. try FC_DEBUG=4
or =7 instead.

> == Expected behaviour: ==
> 
> * At the very least, the font selection should be consistent and preferably
> select the regular variant by default. However, it is hard to know for sure
> which one should be selected, because nothing in the opentype specification
> of the 'size' feature indicates that there must be a reference variant, such
> as Arno Pro Regular in the example of Arno Pro.
> 
> * Preferably, Arno Pro Caption, Arno Pro SmText, Arno Pro Regular, Arno Pro
> Subhead, and Arno Pro Display should be recognised as distinct font families
> such that user interfaces would let the user choose every variant, and this
> variant should be correctly selected when asked for. (In the case of Arno
> Pro, they all come with bold, semi-bold and italic variants.)

For a workaround, you could get rid of "Arno Pro" from those fonts. for
example:

<match target="scan">
  <test name="family">Arno Pro</test>
  <edit name="family" mode="delete"/>
</match>

Once add it into the config, run fc-cache -f.

> * Alternatively, the opentype 'size' feature should be implemented. However,
> the example of qt, above, where size 25.9 is requested while it looks like
> 12pt on screen shows that the 'size' feature is not viable without a way to
> fine-tune or disable the feature.
> 
> Implementing the opentype 'size' feature looks like a complicated
> enhancement. I think it is reasonable in the meanwhile to request a way to
> make fonts with 'size' variants at least usable.

That may needs to be discussed, including it should be dealt with fontconfig or
upper layer.

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