Re: [Fonts]Re: Font lookup ranges [was Re: Notes on Pango Xft backend]

[Owen Taylor <otaylor redhat com>]

Brian Stell <bstell ix netcom com> writes:

> Owen Taylor wrote:
> > ...
> > Pango already has the language tagging mechanism; the question is
> > how to use this to influence character lookup.
> > 
> >  a) Call FcFontSetSort() once, get a list, and then when finding
> >     a (language-tag, codepoint) pair, look first for a font with
> >     the language tag and the codepoint, then if that fails,
> >     look for a font without the language tag with the codepoint.
> > 
> >     Problems:
> > 
> >      - ...
> >      - I don't think we should ever fall back to a font that wasn't
> >        explicitely specified (*), just for a want of a language
> >        tag.
> 
> Please forgive me if I'm being slow but due to the triple negative
> I am not clear what the last statement means (I did read the 
> footnote). 

What I mean is if I'm trying to look up a traditional chinese font
for codepoint X, codepoint X also is present in japanese
fonts, and their are two choices:

 a) japanese font, explicitely specified
 b) traditional chinese, not explicitely specified

it seems to me that we should prefer a). Reasons:
 
 - Non-explicitely-specified fonts might differ in major
   ways (we might get a bold-italic font...)
 - There should be a way for users to override what we 
   are doing, especially if we are doing guesses for
   font language based on codepoint coverage.

Regards,
                                        Owen