Re: MKIV Chinese typesetting

[Arthur Reutenauer <arthur.reutenauer@normalesup.org>]

	Hello,

  Thanks for this comprehensive review.  If I'm not mistaken, there is
no specific code for CJKV typesetting in Mark IV; the examples in mk.pdf
seem to use the generic font loading mechanism.

  I would like to answer more completely, but don't have much time for
the moment.  About some of your remarks:

> so I think a new feature should be added to map all the Chinese puncts
> into english while at the same time, a space should be added after the
> English punct marks.

  Would it not be better to automatically add shrinkable glue after
Chinese punctuation, rather than replacing the character by force?  This
would be very much in line with the general TeX philosophy of setting
text (and would probably suppress the need for half-width forms in the
font altogether).

> - pp118, penultimate example, box 2, line1, the ' punct mark should
> not appear at the end of the line

  This should be taken care of by adding an appropriate penalty before
the character.

> - pp118, ultimate example, box 2, line2, in fact, if you want do
> perfect Chinese typesetting, all the puncts which begin a line or end
> a line should be closed to the margin line

  Do you mean simply closer to the margin, or in the margin itself
(protruding)? Protruding is already possible in pdfTeX; I believe it is
available in LuaTeX as well, although it might be broken for the moment
(Taco?).  Setting the character closer to the margin should be possible
as well, as a modified form of protruding, I trust.

> A small skip should be left between Chinese and English which makes
> the result much better. usually the space is a quarter of a chinese
> character width. A TeX expression should like:
> \hspace{0.25em plus 0.125em minus 0.08em}

  Again, this can be taken care of by automatically adding this glue
between pairs of character of the appropriate category.

> The last important thing for English and Chinese bi-lingual
> typesetting is that: do not use English glyphs in Chinese fonts

  Sure, there should be a possibility of specifying a Western font to be
used inside Chinese text.

> - the following script produce an error: Invalid field id penalty for
> node type glyph (1).

  I don't have that error here.  This is very big font; are you sure it
has been read entirely and correctly written to the cache?  Lua crashed
on my machine when I first compiled your example, and only a partial
font hash was written to the cache (ConTeXt didn't crash, so the first
compilation apparently ended well, but the cache was already filled with
a partial font).  I can imagine that problems will arise in the presence
of a partially hashed font in the cache.

  Anyway, the code looks quite weird to me:

> \definefontfeature[chinese][mode=node,script=hang,lang=zht,script=hani,lang=dlft]

  This means that you activate two different scripts at the same time
(hang == Hangul and hani == Han ideographs), and also two languages at
the same time (zht == Chinese Traditional and dlft is probably a typo
for dflt == default).  I can't imagine what that is supposed to mean,
and activating Traditional Chinese is probably wrong with Adobe Song Std
which is a Simplified Chinese font.  A saner definition of that feature
would be in my opinion:

	\definefontfeature[chinese-traditional][mode=node,script=hani,lang=zhs]

  I know this code comes from mk.pdf, but I think it is a mistake.

  Finally, there is an interesting article by Jin-Hwan Cho (the dvipdfmx
author) and Haruhiko Okumura about CJKV typesetting with Omega a couple
of years ago.  They have implemented all of the rules you mention above
and a bit more; and although they used OTPs at the time, it should be
quite straighforward to transpose it in Lua code (actually, I've done it
a couple of months ago, but I have used plain LuaTeX, and in ConTeXt it
should probably done using node processors or something).

	http://project.ktug.or.kr/omega-cjk/tug2004-preprint.pdf

		Arthur
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