Re: Arabic support

[Kenichi Handa]

In article <address@hidden>, Eli Zaretskii <address@hidden> writes:

> > Doesn't it mean uniscribe_shape reorders glyphs?

> This reorders a single LGSTRING, according to my reading.  Isn't an
> LGSTRING a single grapheme cluster, rather than several distinct
> characters?

No, LGSTRING may contain multiple grapheme clusters.  In the
case of arabic, we make LGSTRING for one Arabic word then
shape it (otherwise, the shaper can't know where in a word a
consonant appears).  So, usually LGSTRING contains multiple
grapheme clusters for Arabic.  Glyphs constituting a
grapheme cluster has the same value in LGLYPH_FROM (G) and
LGLYPH_TO (G) where G is a LGRYPH given by LGSTRING_GLYPH
(LGLYPH, IDX).

> Btw, where's the documentation of LGSTRING?  The commentary to
> uniscribe_shape says to look in font-make-gstring, but I cannot find
> that, neither as function nor as variable.  In general, everything
> about compositions and lgstrings needs a lot more of documentation.

I renamed font-make-gstring to composition-get-gstring and
moved the code to composite.c.  The above macros for
accessing LGSTRING and LGLYPH are in composite.h.

---
Kenichi Handa
address@hidden