bug#29364: 27.0.50; Word Wrap doesn't support CJK

[Eli Zaretskii]

> From: Chunyang Xu <mail@xuchunyang.me>
> Date: Mon, 20 Nov 2017 20:34:48 +0800
> 
> the point is, Chinese doesn't have to rely on space to break, it can
> break at anywhere but with some exceptions, such as, after breaking, the
> punctuation mark can not be at the beginning of the line, so the
> following is also incorrect:
> 
> -----------------------------------------------------
> 文字文字 English 文字文字文字文字文字文字文字文字文字
> 文字文字文字文字文字文字文字文字文字文字文字文字文字
> 。
> -----------------------------------------------------
> 
> for this width, it should display:
> 
> -----------------------------------------------------
> 文字文字 English 文字文字文字文字文字文字文字文字文字
> 文字文字文字文字文字文字文字文字文字文字文字文字文
> 字。
> -----------------------------------------------------
> 
> 
> Some applications such as Chrome (web browser) and Atom (text edit) can
> wrap CJK text, and Atom added CJK wrapping support by this patch:
> 
> - https://github.com/atom/atom/pull/9162
> 
> There is an article from Wikipedia explaining how to break CJK text:
> 
> - https://en.wikipedia.org/wiki/Line_breaking_rules_in_East_Asian_languages

Emacs has an implementation of those rules in kinsoku.el.  Word-wrap
is done on the C level in the display engine; volunteers are welcome
to submit patches for honoring Kinsoku rules on that level.  The
challenge is to do so without slowing down redisplay.

Thanks.