[Fontconfig] Improving Latin font selection for CJK locales

[Qianqian Fang]

hi Behdad

the proposed method sounds quite interesting and useful.
For font developers, I think it will add the power to fine-tune
the font selections, particularly for massaging CJK fonts with
Latin fonts. I would like to give my full support on this effort.

In addition, I am not quite sure if this could be a possible remedy
for the common-script contextual formating issue that we have
discussed earlier (please forgive me if the connection is obvious)
https://www.redhat.com/archives/fedora-fonts-list/2007-December/msg00013.html

if they are connected, can you illustrate one scenario where
this mechanism can help to constrain the fonts for Common Scripts?

thank you

Qianqian


Behdad Esfahbod wrote:
> Hi,
>
> This keeps coming up again and again: CJK users want Pango to choose
> Latin fonts differently under a CJK locale than it does under a non-CJK
> locale.
>
> Making that work is currently impossible in Pango+fontconfig.  The
> reason being that Pango passes a Latin "lang" to fontconfig for Latin
> runs, and fontconfig and font configurations have no way to
> differentiate the Latin in CJK locale from Latin in Latin locale cases.
>
> I'd like to propose adding a new element named "locale" that holds the
> original locale language.  Fontconfig needs not know about this at all
> except that filling it in in FcDefaultSubstitute() like it does for
> "lang".  Then users can write configuration that is sensitive to locale.
>
> Pango then can pass PangoContext language as "locale".  PangoContext
> language defaults to the locale, so this is all consistent.
>
> I can do this all in Pango only, but given that I want to encourage CJK
> font developer/packagers to write such configuration for their fonts,
> would be nice to have it upstreamed.
>
> As an example, one would write:
>
>         <match>
>                 <test name="lang">
>                         <string>en</string>
>                 </test>
>                 <test name="locale">
>                         <string>ja</string>
>                 </test>
>                 <edit name="family" mode="prepend" binding="same">
>                         <string>SomeJapaneseFontWithGoodLatin</string>
>                 </edit>
>         </match>
>
> It could be easier if we could match on scripts instead of languages,
> but that's another issue.
>
> Keith, what do you think?
>
>