[HarfBuzz] Mai Kang Lai in Tai Tham, summary draft

[Andrew Cunningham]

On 23/05/2013 5:04 AM, "Richard Wordingham" <richard.wordingham at ntlworld.com>
wrote:
>
> On Wed, 22 May 2013 11:23:14 +1000
> Andrew Cunningham <lang.support at gmail.com> wrote:
>
> > I need to think about it and see how variation in positioning has been
> > handled in other contexts, i.e. MYANMAR SIGN DOT BELOW in its
> > positioning in Karen languages vs Burmese and Mon.
> >
> > Although I think the Tai Tham discussion and the way the fonts are
> > evolving has already taken us to the stage where the fonts will be
> > designed for Barfbuzz and will not render correctly on Uniscribe.
>
> Is there yet a Tai Tham definition for Uniscribe?  Is there an embargoed
> definition?
>

No shaper for Tai Tham in Uniscribe, so no official implementation notes. I
hope it will be similar to .myanmar.

The issue is that it is an unsupported script on Uniscribe, so Uniscribe
will only apply the features acessible to the default scripr, whick
basically means using rlig, mark and mkmk only. There are some other
features like clig, liga, etc which can be used but sipport for these are
optional.

> > Regarding the choice between solution one and solution two; are there
> > examples of the positioning being contrastive, i.e. the same document
> > using two or three of the differening conventions to mark
> > distinctions between works? Or is it purely stylistic i.e. differing
> > calligraphic and typographic conventions?
>
> I don't understand your question, unless 'works' is a typo for
> 'words'.  If you meant 'words', then I would say 'no', though it may be
> possible to devise arrangements of glyphs whose meaning depends on which
> convention is in use.

Yes typo

>
> The short answer is that these are stylistic differences.
>
> > If the difference is purely stylistic .. that leads us to solution 2.
>
> > For solution 2 there seems to be two options:
>
> > 1) fonts tailored for a specific typographic/stylistic convention; or
> >
> > 2) more typographically advanced fonts using graphite or opentype
> > features to accommodate the variations, would it be possible to
> > handle it as a variant glyph or stylistic set?
>
> It would be possible in graphite; the problem comes with technologies

Yep, graphite can do it. But useful if a way exists in opentype.

I have seen fonts that contain visual reordering of characters dependant on
language. The question is wether this would work for the example you give.

The second issue is, which is more important is how do we expose this
feature.

> that can't transpose glyphs while keeping track of the backing store
> correspondences.  The problem is epitomised by Pali nominative singular
> _saṅgho_ 'the community of Buddhist monks'. One style wants the glyph
> order <HIGH SA, MAI KANG LAI, SIGN E, LOW KHA, SIGN AA> and the other
> wants the glyph order <HIGH SA, SIGN E, LOW KHA, MAI KANG LAI, SIGN
> AA>.  (The encoding is <HIGH SA, MAI KANG LAI, LOW KHA, SIGN E, SIGN
> AA>.
>
> The problem is not that we need different fonts for the various styles;
> the problem is that we seem to need different *reordering* rules.
>

I am aware of that, maybe poor choice of words on my part.

> > I hope with a bit of spare time next week I can sit down and try
> > experimenting with a minimal font, and see what could be done.
>
> The question is whether GPOS can sensibly convert one of the two orders
> above to the other.
>
> Richard.
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