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[css3-writing-modes] character orientation and text-combine-horizontal (was: [css3-writing-modes] i18n-ISSUE-275: Digit 1)

From: John Daggett <jdaggett@mozilla.com>
Date: Sun, 4 Aug 2013 21:10:49 -0700 (PDT)
To: www-style@w3.org
Cc: WWW International <www-international@w3.org>
Message-ID: <2079729704.1034328.1375675849449.JavaMail.zimbra@mozilla.com>
fantasai wrote:

>> 9.1. Horizontal-in-Vertical Composition: the ‘text-combine-horizontal’ property
>> http://dev.w3.org/csswg/css-writing-modes/#digits-ltinteger
>>
>> "Integers outside the range 1-4 are invalid."
>>
>> What if you set
>> date { text-combine-horizontal: digits 1; text-transform: full-width; }
>>
>> Does it make text-transform redundant?
>>
>> Isn't digits 1 equivalent to text-combine-horizontal: none?
>> Shouldn't the spec say "Integers outside the range 2-4 are
>> invalid."?
>>
>> Note added by Elika Etemad, 23 Jul 2013, 19:07:23:
>>
>> No, what that does is set each single digit as full-width and
>> upright. (It's a bit redundant because full-width glyphs are by
>> default upright.) The full-width transformation is only suppressed
>> when there is more than one character in the TCY.
>>
>> If you remove the full-width text-transform, then digits 1 will
>> effectively just put single digit numbers upright. It's not the
>> same as 'none'.

Looking at the wording for 'text-combine-horizontal', the precise
effective orientation of the combined glyph used in the tatechuyoko
case is not defined, nor is the interaction of this with
'text-orientation' clearly specified.

For example, what does happens in the case below?

  .tcy {
    text-combine-horizontal: digits 1;
    text-orientation: sideways;
  }

Are single digits upright or sideways? I think the spec needs to say
that the combined glyph is upright no matter what the value of
'text-orientation' is.

There's a related issue with the CSS3 Text spec which contains an
appendix listing the relative order of text processing operations [1].
The value of 'text-combine-horizontal' is used when dividing up runs
of vertical text into runs with a single orientation (i.e. upright,
sideways, inline horizontal), so it should be grouped with
'text-orientation' rather than listed above 'text transformation'.

Regards,

John Daggett

[1] http://dev.w3.org/csswg/css-text/#appendix-f-text-processing-order-of-oper
Received on Monday, 5 August 2013 04:11:16 UTC

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