Re: French typography is back

["Robert-André Mauchin" <zebob.m@pengzone.org>]

Le 22/05/2009 17:51, Arthur Reutenauer a écrit :
>>                                 but instead of arbitrary adding a 0.25em
>> before and 1em after the punctuation mark you should use the real nnbsp
>> (U+202F) before and real normal space (U+0020) after.
>
>    I don't think so.  Space characters don't mix very well with TeX glue
> and should best be avoided, generally speaking.  In particular, all
> inter-word spaces that are input in the TeX source as one or more of
> U+0020 are simply ignored, and replaced by normal inter-word glue, with
> its appropriate stretchability and shrinkability.  This has always been
> the case in TeX and is not going to change.  All other types of Unicode
> spaces should really, in my opinion, be processed in the same way, while
> respecting their additional properties in the case of non-breakable
> spaces, for instance.
>

Not knowing the internals, that's what I tried to say with adding a 
space after instead of 1em, i.e. "calculated by the engine". If w an em 
is added after, it is not stretchable and shrinkable, right?

>    In addition, characters like U+202F are very badly supported across
> fonts, and if you take in account the fact that the most appropriate
> width will probably change depending on the language, you're likely to
> observe much more arbitrary results if you use the glyph for that
> character in font.  I seriously doubt you want to rely on the font for
> that.
>
>> Why? Let me take your example again:
>>
>> {\setcharacterspacing[frenchpunctuation]a? aa? aaa? abba?}
>>
>> a\,? aa\,? aaa\,? abba\,?
>>
>> Surprise: the first line is longer than the second. It's because sizes of
>> the U+0020 and U+202F depend on the font design, their size are not exactly
>> 1em and 0.25em.
>
>    That's not the reason.  The reason is simply that \, is defined as a
> \kern by one sixth of an em (see core-spa.mkiv: it's equivalent to
> \thinspace, which is \kern .16667em).  In the first line, the value of
> .25em is defined in core-spa.mkiv; you can redefine it if you want.
> In any case, every space is completely controlled by ConTeXt, we don't
> let the font mess around.
>
>    For that matter, Latin Modern doesn't have a glyph for U+202F, so if
> we'd use it, we'd just see nothing: there would be no space at all, see
> attached file.
>

Thank you so much for the detailed technical explanation! So, AFAIK, I 
believe that the space before should be equivalent to thinspace.


>    All this really calls for more coordination in order to produce decent
> specifications, in my opinion.  If you think ConTeXt's default should be
> different, it's fine and I encourage you to contact Sébastien to discuss
> about it.  Report then to Hans and Peter for the implementation.
>

Thanks, I'll see that. Maybe I could write some detailled specs in the wiki.


Regards,

Bob.
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