[Fontconfig] Improving Latin font selection for CJK locales

[Behdad Esfahbod]

On Tue, 2008-01-29 at 01:40 -0500, Qianqian Fang wrote:
> 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?

Well, it doesn't make much difference for Common, but will let you
choose to use the same font for Latin that you use for Chinese.  IIRC
that's what you initially wanted to achieve.  Right?

behdad

> 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?
> >
> >   
> 
-- 
behdad
http://behdad.org/

"Those who would give up Essential Liberty to purchase a little
 Temporary Safety, deserve neither Liberty nor Safety."
        -- Benjamin Franklin, 1759