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Re: [css-text][css-writing-modes] Line breaking around Emoji, Gaiji, U+FFFC, and text-combine-horizontal

From: Koji Ishii <kojiishi@gmail.com>
Date: Sat, 17 Jan 2015 19:53:24 +0900
Cc: CJK discussion <public-i18n-cjk@w3.org>, Henrik Andersson <henke@henke37.cjb.net>
Message-Id: <1362BD2A-ADB3-43E3-967A-F22E6C73BE54@gmail.com>
To: "www-style@w3.org" <www-style@w3.org>
Iím revising the proposal after discussed with Unicode experts.

1. Change the 5th bullet of 5.1 Line Breaking Details[1] to force a soft wrap opportunity both before and after a replaced element and other atomic inline for web-compatibility, but not by changing the behavior of U+FFFC nor the rule orders of UAX#14.

2. Add Ďline-break-stringí property. When this property is set to a string of 1 character length, the element looks as if its text is the character to line breakers and justification algorithms.

TL;DR; changing the order of rules are usually not allowed in libraries such as ICU, and therefore makes implementations hard. Itís better to handle application specific behavior outside of the UAX#14 if desired for backward compatibilities or for any other reasons.

One of the experts recommended ID (Ideographic) class[2] for inline images such as Emoji. One idea is to have a boolean property to opt-in to this behavior. Another idea was to for authors to specify UAX#14 class. Among the three options, I think the 1 character length string gives the best flexibility.

Iíll try edits to the ED and will let you know, but any feedback are appreciated anytime.

[1] http://dev.w3.org/csswg/css-text-3/#line-break-details
[2] http://unicode.org/reports/tr14/#ID

/koji

On Jan 15, 2015, at 12:53 PM, Koji Ishii <kojiishi@gmail.com> wrote:

> On Thu, Jan 15, 2015 at 12:36 AM, Henrik Andersson
> <henke@henke37.cjb.net> wrote:
>> Koji Ishii skrev:
>> 
>> I vote "pass the bucket". "Can" does not mean "should" or "must". Let a
>> higher level line breaking deal with it.
> 
> I was ambiguous, "Can break" here means that it's a break opportunity,
> and therefore lines break if Emoji is at the end of line but no
> otherwise.
> 
> It's a MUST to break before and after Emoji (and any other replaced
> elements) from the spec perspective.
> 
> One idea that came up in my mind is to add the "line-break-string"
> property, that can set a string to use to determine line-breaking and
> justification opportunity purposes.
> 
> What do you think?
> 
> /koji
Received on Saturday, 17 January 2015 10:52:34 UTC

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