[lltx] luaotfload update

[Ulrike Fischer]

Am Thu, 6 Oct 2011 17:18:03 +1030 schrieb Will Robertson:

> On 06/10/2011, at 5:10 PM, Khaled Hosny wrote:
 
>> Hans keeps those two IIRC because em and en dashes are hard to
>> distinguish in monospaced fonts while editing, but even those are not
>> supported now in luaotfload as I stated earlier.
 
> Frankly, this is crazy. LuaLaTeX *cannot* drop support entirely
> for these features. There have been countless requests for how
> these should be activated in the XeTeX mailing list, even after
> that feature was implemented there. Can't we just keep the old
> code lying around?

Well "keeping the old code" means that the development of the font
loader code in lualatex doesn't keep pace with the development of
the code in context. 

But before the discussion gets to hot I think it would be a good
idea to check what works and what doesn't. 

I think there are three cases:

1. "Real" ligatures ff, fi, ffl etc which are features of the fonts
and implemented through "real" open type features. I'm certain that
these still works.

2. The "faked" (so called TeX)-ligatures for en-dash and em-dash: -- 
and ---. Last time I heard about them in the context list Hans just
implemented a fix to get around a bug in connections with this
ligatures. So I'm quite confident that they still work in context
and so too with the newest luaotfload. But it must be tested. 

3. The other "faked" (TeX)-ligatures: ``, `?, and so on: I think
these will no longer work. (I personnally don't care. I even did
find e.g. `? quite irritating.)

> Otherwise, XeTeX supports these features with its Unicode input
> mapping feature -- what are the chances this could be written
> with a Lua callback? It's a useful feature in itself, and the big
> reason polyglossia is currently XeTeX-only.

You could use a fea-file as a replacement, e.g. to implement  such
ligatures. If you search the mailing list you will find some
examples where they have been used to adjust the kerning. Works even
easier than with xetex as you don't have to compile the files, they
are simple text files. 

-- 
Ulrike Fischer