[css-text] Ideographic spaces at the beginning or end of lines

[xfq]

In Chinese text layout, IDEOGRAPHIC SPACE (U+3000) may appear at the beginning or end of a line, and should not be collapsed or moved. See w3c/clreq#411 (comment) and the following comment for details. I think that conflicts with the default rules in the current css-text spec. Is there anything we can do for this use case?

[xfq]

(Also adding the i18n-jlreq label. Although this is mainly a use case for Chinese, since U+3000 is also used in Japanese, it may affect the use of Japanese, so it is an FYI for the jlreq folks.)

[himorin]

U+3000 is used in Japanese text sometimes - mostly in two cases, one major is the full-width line head indent at the beginning of a paragraph (which could be replaced with css-text feature now), and another is the full-width spacing right after dividing punctuation marks (e.g. ！). For latter, usually U+3000 will be collapsed at the line end. (cf. https://w3c.github.io/jlreq/#positioning_of_dividing_punctuation_marks)

[frivoal]

I think that conflicts with the default rules in the current css-text spec.

I don't think it does. The current spec does not remove or collapse ideographic spaces and the start or end of lines, that only happens to collapsible spaces, and ideographic spaces aren't part of that.

Ideographic spaces at the end of the line do hang (by default), but that's a separate question, which I believe is appropriate.

[xfq]

I think that conflicts with the default rules in the current css-text spec.

I don't think it does. The current spec does not remove or collapse ideographic spaces and the start or end of lines, that only happens to collapsible spaces, and ideographic spaces aren't part of that.

Indeed. However, for line breaking, U+3000 is currently BA (tailorable) per UAX #14 and that conflicts with the requirements of Nuo tai. Perhaps this is something that should be tailored by the UA when lang is zh.

[frivoal]

The BA class suppresses breaks before the character. In addition to that, css-text requires end-of-lines U+3000 to hang. For general use, I think that's the expected behavior. The 　神 usage is very specific, and doesn't follow the usual rules. I would expect text intending to use that convention to adopt special markup. Maybe something like

起初<span class=god>　神</span>创造天地

which is then styled as

.god {
  white-space: break-spaces;
  line-break: anywhere;
}

[xfq]

For the Nuo tai use case

The BA class suppresses breaks before the character. In addition to that, css-text requires end-of-lines U+3000 to hang. For general use, I think that's the expected behavior.

I might be missing something, but it looks like what BA does is the opposite of Nuo tai does. The BA class suppresses breaks before the character, while U+3000 in Nuo tai suppresses breaks after the character. After reading the definition of hang in css-text, I am not sure how it will help this use case either.

The person's name and the ideographic space in Nuo tai, like Arabic numerals and the minus sign or currency symbol before them, cannot be split into two lines. What BA prohibits is the line break before the space, not the line break after the space.

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For the 　神 use case

The 　神 usage is very specific, and doesn't follow the usual rules. I would expect text intending to use that convention to adopt special markup. Maybe something like

起初<span class=god>　神</span>创造天地

which is then styled as

.god {
  white-space: break-spaces;
  line-break: anywhere;
}

Sounds fine to me. Thanks.