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

A rather recent fix for CSS Text introduced a new line breaking
behavior in 5.1 Line Breaking Details[1], as quoted here:

> The line breaking behavior of a replaced element or other atomic inline
> is equivalent to that of the Object Replacement Character (U+FFFC) and
> introduces a soft wrap opportunityboth before and after itself. For
> Web-compatibility, this rule take precedence over WJ and GL handling;
> in terms of [UAX14], this shifts the CB rule (LB20) immediately above
> the WJ and GLrules (LB11/LB12).

Although this was done for web-compat, I found it has two unfortunate
side-effects:

1. Can break between image-based characters and, say, period or
closing parenthesis. Emoji is emerging as I understand. East Asian
Gaiji usage may decrease its use, but it'll still take a while.

2. text-combine-horizontal defines it to be U+FFFC for line breaking
purposes[2], and this change in CSS Text broke its assumptions to work
properly.

Fixing #2 is easy, we can change CSS Writing Modes to use one of
ideographic characters. Ruby has the same issue, I just replied to
that[3], but this can also be handled in ruby spec. Any ideographic
characters are fine with me, if I were to choose, let's say U+4E00,
the first ideographic character in the Unicode order.

Any ideas how to fix #1?

And/or opinions for how to fix #2?

[1] http://dev.w3.org/csswg/css-text-3/#line-break-details
[2] http://dev.w3.org/csswg/css-writing-modes-3/#text-combine-layout
[3] http://lists.w3.org/Archives/Public/www-style/2015Jan/0259.html

/koji

Received on Wednesday, 14 January 2015 13:02:28 UTC