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Re: [csswg-drafts] [css-text-3] Segment Break Transformation Rules for East Asian Width property of A (#337)

From: Florian Rivoal via GitHub <sysbot+gh@w3.org>
Date: Thu, 20 Dec 2018 06:12:43 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-448885375-1545286362-sysbot+gh@w3.org>
Here's an attempt at stating the problem independently of the solution:

* We want to identify cases where the fact that a line break is allowed, as evidenced by the fact that one was used in the source code, does not imply that a space would be acceptable in the rendered document if the text was wrapped elsewhere (or not at all).

* A rule that only finds a subset of cases where this is true is both acceptable and unavoidable. Acceptable because authors can refrain from using line breaks in the source code even if that's inconvenient, unavoidable because of too much linguistic and typographic diversity and too many corner cases.

* On the other hand, false positives *must* be avoided, as it would likely break existing pages.

* This is only useful to authors to the extent that it is consistent across browsers, as otherwise the result would be unwanted spaces in some browsers.

* The results *should* be unsurprising, otherwise authors risk shying away from using it.

* To the extent it relies on classifying characters, it *must* do so based on properties and classifications maintained by Unicode (or combination thereof), as the CSS-WG cannot maintain character by character classifications while Unicode continues to expand.

* It *may* rely on things other than classifying characters, such as the content language.

* It *must* be practical to implement performantly.


On the last point, I trust implementors' judgement better than mine. But that aside, I believe each of the proposed rules in [section 4.1.2](https://drafts.csswg.org/css-text-3/#line-break-transform) satisfy all these criteria.

I also don't think I've heard any other proposal (except adopting a subset of these rules) that does.

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Received on Thursday, 20 December 2018 06:12:44 UTC

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