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Re: [CSS21][css3-text] letter-spacing, word-spacing and justification

From: Andrew Cunningham <lang.support@gmail.com>
Date: Sun, 7 Jul 2013 10:07:18 +1000
Message-ID: <CAGJ7U-XY5gpfp+dZcVXc1bC17NVx+EPg3d9h0BwmB31GZ=h4BA@mail.gmail.com>
To: fantasai <fantasai.lists@inkedblade.net>
Cc: www-style@w3.org
There is a sleeper here. Assuming that letter-spacing works as identified,
there definetely needs to be a way of disabling inter letter spacing.

For complex scripts that are not currently not speced  out in OT specs, are
supported by default rendering. Which usually means using mark, rlig, clig,
and liga features.

At least one rendering engine used by at least one browser will disable
optional features during letter spacing, breaking rendering.

As it is, in places where letter-spacing is non-zero, it is sometimes
necessary to reenable specific font features for certain fonts.

Andrew
On 06/26/2013 01:30 PM, Liam R E Quin wrote:

>
> The default needs to be that letter spacing is not used for
> justification of Latin scripts. I think the same is true for Devanagari
> and Thai. Enabling letter spacing should not affect justification either
> (although it should disable ligatures such as "ffi" and "fl").
>

I'm pretty sure Thai adjusts inter-cluster spacing for justification.
Spaces are uncommon enough that lines without them are reasonably common.
See for example https://www.sasin.edu/images/**
gallery/hrm-course-16jan13.jpg<https://www.sasin.edu/images/gallery/hrm-course-16jan13.jpg>

 Sample use case - a US English legal contract set in caps/small-caps
> with 0.1pt letterspacing should have the words justified to both margins
> and the word spaces adjusted accordingly, but with the 0.1pt letter
> spacing constant.
>

Nobody's disputing this. For English text, word spaces get first priority
at absorbing space for justification.

 For arabic and some indic scripts with connected characters, it's
> possible something like a kashida would be inserted but I don't know for
> sure.
>

Kashida are added for justification, but not evenly between each pair of
letters the way we add space in other scripts. I don't know of any examples
where Arabic is given any kind of tracking.

Devanagari appears to accept tracking (letter-spacing) between grapheme
clusters in the form of white space. See
  http://www.w3cindia.in/**cssdocument.html#horispace<http://www.w3cindia.in/cssdocument.html#horispace>

~fantasai
Received on Sunday, 7 July 2013 00:07:48 UTC

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