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w3c / jlreq

Text Layout Requirements for Japanese
https://w3c.github.io/jlreq/
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Line start and end prohibition rule not fully supported #274

Open himorin opened 3 years ago

himorin commented 3 years ago

Some characters are listed in line start and end prohibition rule, and some levels exist for set of prohibited characters.

Specs: css-text-3 defines line-break property with three levels strict, normal, and loose to switch among sets of prohibited characters.

Tests & results: web platform test, lists test for three levels

Gecko, Chromium, and Webkit partially support three levels.

Browser bug reports: Chromium • Webkit, Webkit

Priority: The impact of this is probably more important for advanced layout.

himorin commented 3 years ago

_The first comment in this issue contains text that will automatically appear in the Japanese gap-analysis document as a topic with the same title as this issue. Any edits made to that comment will be immediately available in the Editor's draft of the document. Proposals for changes or discussion of the content can be made in comments below this point._

r12a commented 3 years ago

What's the problem being described here? Can you describe, briefly, what are the relevant results of the tests?

himorin commented 3 years ago

In Chromium and Gecko, when strict or normal is specified, inseparable characters (IN) like U+2025 or U+2026 is not separated but also taken as prohibited at line start. (noted as ICU bug in Chromium bug report) I currently don't have information for Webkit.

r12a commented 3 years ago

@himorin i looked into this a little, and found that the test results you point to are suspect. See https://github.com/web-platform-tests/wpt/issues/31021 Could you do some more research on this, before we let it appear in the gap-analysis document? (I'll remove some tags in the meantime.)

himorin commented 3 years ago

Will do. With rough going through, seems almost correct for chrome...

r12a commented 3 years ago

Don't forget that we have a set of tests of our own, with results at https://www.w3.org/International/i18n-tests/results/line-breaks-jazh#ja

In particular, see https://www.w3.org/International/i18n-tests/run?base=css-text/line-break-property&batch=line-breaks-jazh&test=ja/css-text-line-break-ja-in-loose.html

If it's just that one particular combination we're concerned about, we should probably make it clear that this generally works fine, with the exception of this one bug.