Re: Arabic support

[Kenichi Handa]

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

> > In Emacs, bidi reordering is done by Emacs itself, so the `shape'
> > method of font backend should not reorder glyphs.  But, perhaps
> > Uniscribe backend reorders Arabic text, right?

> No, not AFAIK.  We call the ScriptItemize API of Uniscribe with NULL
> as the 4th and 5th arguments, which AFAIU should disable reordering.
> Perhaps Jason could chime in and tell if I'm right here.

I read the function uniscribe_shape roughly.  It has this
code:

  for (i = 0; i < nitems; i++)
    {
      int nglyphs, nchars_in_run, rtl = items[i].a.fRTL ? -1 : 1;
[...]
          if (SUCCEEDED (result))
            {
              int j, nclusters, from, to;

              from = rtl > 0 ? 0 : nchars_in_run - 1;

Doesn't it mean uniscribe_shape reorders glyphs?

> Btw, does the current code support Arabic ligatures and shaping on
> GNU/Linux?

I don't know about ligatures, but at least these should be
supported by libotf and m17n-lib with OpenType fonts.

o glyph substitution of consonants depending on where it is;
  beginning, middle, or end of a word.
o glyph positioning of vowels

---
Kenichi Handa
address@hidden