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Re: Shaping characters in upright orientation in vertical text flow

From: John Daggett <jdaggett@mozilla.com>
Date: Wed, 18 Jan 2012 18:25:45 -0800 (PST)
To: Koji Ishii <kojiishi@gluesoft.co.jp>
Cc: "'WWW International' (www-international@w3.org)" <www-international@w3.org>, public-i18n-bidi@w3.org
Message-ID: <c140a558-4002-43f1-89a4-05de7e86b684@zimbra1.shared.sjc1.mozilla.com>
Koji Ishii wrote:

> CSS Writing Modes Level 3 has the "text-orientation" property[1]. With
> that, you can set glyph orientation in vertical text flow.
> 
> The issue is about how to render shaping characters when
> "text-orientation: upright" is applied. Please scroll down the spec a
> little bit to see "Figure 12. 'text-orientation' values"; "upright" is
> the one I'm talking about. You see all characters including Latin are
> upright in this style.
> 
> How do you expect shaping characters look in this case?

I don't think you're giving proper context here.  Vertical text layout
is different from horizontal text layout in that the "natural" way to
layout text involves a mixture of directions depending upon the
script; within Japanese text, strings of Latin text can either be
displayed rotated sideways or upright.  This "natural" way is the
default value for the proposed text-orientation property:

  text-orientation: upright-right;

With this value, the decision about whether to rotate right or leave
upright is based on the codepoint; Han characters will be displayed
upright, Latin characters rotated.  I have pushed in the past that 
this be labeled 'auto', since it's behavior is largely determined by
the script.  The use of 'upright-right' and 'upright' property values
doesn't really communicate the differences clearly.

There are several other values which are used to set the orientation
explicitly. 

  text-orientation: upright;
  text-orientation: sideways;
  text-orientation: sideways-right;
  text-orientation: sideways-left;

The 'upright' value is intended to always set characters
upright and the 'sideways-xxx' values are intended to set characters
sideways.  For Latin text, using 'upright' will explicitly specify
that characters are display upright, as in a vertical sign or a book
spine.  But the ripple here, is that for Arabic nobody is quite
sure that showing isolated forms upright really makes sense.

I think the real question for the folks in the internationalization
group is whether there are existing traditions for vertical display of
Arabic, in signage or otherwise that would give us some guidance here.
To me, using isolated forms seems somewhat nonsensical but if it
reflects a widespread tradition we should respect it.

Regards,

John Daggett
Received on Thursday, 19 January 2012 02:26:21 GMT

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