W3C home > Mailing lists > Public > www-style@w3.org > January 2015

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

From: fantasai <fantasai.lists@inkedblade.net>
Date: Sun, 25 Jan 2015 17:29:42 -0500
Message-ID: <54C56E56.7040804@inkedblade.net>
To: www-style@w3.org
On 01/14/2015 08:01 AM, Koji Ishii wrote:
> A rather recent fix for CSS Text introduced a new line breaking
> behavior in 5.1 Line Breaking Details[1], as quoted here:
> [...]
> Although this was done for web-compat, I found it has two unfortunate
> side-effects: [...]

OK, so I think there are several issues raised in this thread.
Let me try to summarize:

1. text-combine-upright
-----------------------

    Result of text-combine-upright should break as ID, not as U+FFFC.
    Current spec requires treating as actual contents for line-breaking.
    So there is some misunderstanding of the text;
    unclear whether there is an issue here to fix.

    Proposal A: Leave spec as-is: TCY treated as its own text.
    Proposal B: Make TCY always treated as ideographic character.

2. UAX#14 Rules for Atomic Inlines Problematic
----------------------------------------------

    Changing the rule order for UAX#14 is a difficult tailoring.
    Spec should just create a special rule for atomic inlines.

    Proposal A: Change spec wording to fix this.
    Proposal B: Change spec wording to fix issue #3.

    Remaining Issue: Should U+FFFC match images?

3. Images as Emoji / Gaiji Should Break as ID
---------------------------------------------

    Images used as emoji/gaiji need to break as ID in CJK contexts.

    Proposal A: Add new property in L4 to switch behaviors.
    Proposal B: Treat all images as ID.

    Ideographic characters (ID class) can break in most places,
    but not around certain punctuation like commas, enclosing
    parens, or non-breaking characters (GL) like nbsp.
    This behavior is, afaict, 100% more sensible than the current
    behavior. The question is, is it Web-compatible?

Koji, did I miss anything?

[There was a mention of a ruby issue on line breaking, but that
has its own thread, so won't address here.]

~fantasai
Received on Sunday, 25 January 2015 22:30:14 UTC

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