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Re: [css-ruby] Tone mark of bopomofo in ruby

From: Koji Ishii <kojiishi@gmail.com>
Date: Wed, 11 Feb 2015 22:28:40 +0900
Message-ID: <CAN9ydbV4qQFO7S87f1c0O36tRvGNS18avp_u7s=5KOo-cs4Eeg@mail.gmail.com>
To: Martin J. Dürst <duerst@it.aoyama.ac.jp>
Cc: Bobby Tung <bobbytung@wanderer.tw>, Xidorn Quan <quanxunzhen@gmail.com>, Richard Ishida <ishida@w3.org>, www-style list <www-style@w3.org>, CJK discussion <public-i18n-cjk@w3.org>
On Thu, Feb 5, 2015 at 7:43 PM, "Martin J. Dürst"
<duerst@it.aoyama.ac.jp> wrote:
> On 2015/02/04 00:13, Koji Ishii wrote:
>> 1. Do you want browsers to re-order the light tone marks, or do you
>> think it should be done in the source HTML files?
> I personally think it should be done in a font. I'm sure it can be done in a
> font, similar to vowel reordering in South Asian scripts if there's no
> simpler solution. That would make it straightforward because all four tone
> marks would be handled the same.
> But of course I'll leave it to the experts who are closer to the use cases.
>> 2. I recommend you to initiate an open source font project that
>> handles positioning of second/third/forth tone marks. Fonts only with
>> Bopomofo characters should not be too hard.
> As I say above, adding handling of the light tone mark should also be
> possible in a font.

It's a bit of technical details, but when you say a feature "can be
done in a font", there are two levels.

1. Algorithm is generalized, and the font engine reads the table in
the font file and render accordingly. Ligatures, vertical alternate,
diacritic marks fall into this category.

2. Algorithm is defined in OpenType spec, and the font engine handles
this without any data in the font file. Reordering in Devanagari is
one example of this category.

While the reordering could be handled in a font *system*, the
combination of font file and font engine, to do so, you will need to
update the font *engines* such as DirectWrite, CoreText, or HarfBuzz.
It's not something an open sourced OpenType font *file* can handle.

So my recommendations are:

1. An open source font handles 2nd/3rd/4th tone marks to position them
correctly, possibly with fine tunes depends on previous characters

2. If the reordering of the light tone marks is the right thing to do:
  2.1. Ask OpenType to add a spec (probably here[1]), and then expect
all font engines follow it someday.
  2.2. Since 2.1. will take really long, UA doing it automatically for
ruby text container looks reasonable approach to me. Even when 2.1. is
done, both UA and font engines doing it is no harm.

But I'm still unable to figure out whether the reordering is the right
thing to do or not. Bobby and Xidorn say it's not. Word does (thank
you Richard again for the investigation and updating the blog[2] as
always.) So, is Word doing what Taiwanese do not want? I have to admit
that it's quite possible ;) but I consider this question is still not
fully resolved yet.

[1] http://www.microsoft.com/en-us/Typography/SpecificationsOverview.aspx
[2] http://rishida.net/scripts/bopomofo/ontheweb#lighttoneposn

Received on Wednesday, 11 February 2015 13:29:08 UTC

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