[HarfBuzz] Question about HarfBuzz-ng CTL Shaper Status

Kenichi Handa handa at m17n.org
Mon Sep 20 23:51:25 PDT 2010

In article <AANLkTim8v3cTx_sSKVTOh6LmV1s3NZkt3AERhU3VQPhN at mail.gmail.com>, Ed <ed.trager at gmail.com> writes:

> Yes, Tai Tham is encoded in logical order like Devanagari and other
> Indic scripts.

> The problem with that is of course that not a single rendering engine
> exists which will deal with Tai Tham reordering (except perhaps
> Graphite).

> For certain combinations, such as Tai Tham's "Medial R" which needs to
> precede the base consonant, using ccmp substitutions will work.  This
> requires creating a lot of "ligature" glyphs.  But it works.

> For all the vowels which also precede base consonants (U+1A6E through
> U+1A72), I may have to use the same approach.  If I do it that way,
> the font will become filled up with hundreds of "ligature" glyphs.
> The file size will become large - not at all ideal for what I
> originally intended to be a "web font".  But that may be the tradeoff,
> because it is a solution that will work today.  Maybe.

I think it's far from:
  a "pure" version of the font that uses only proper OpenType features

The right approach will be:

(1) Write a specification document something like what
Microsoft does for various scripts:
This should be a base of Tai Tham font & layout-engine
developpers, and for that, it may be good that this document
is officially approved by a proper Tai Tham authority
(perhaps by the one who proposed Tai Tham script to Unicode
or ISO10646).

(2) Implement a Tai Tham layout engine as a pango module or
a harfbuzz-ng's shaper according to (1).

(3) Urge Microsoft to implement Tai Tham support in
uniscribe according to (1).

I admit that (3) is not easy.  :-(

By the way, have you tried oftview?

Kenichi Handa
handa at m17n.org

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