[css‑text‑4] Multi‑value `white‑space` syntax proposal

[ExE-Boss]

Like how display now has a two value syntax, I’d like to propose a similar addition to the white‑space property:

white‑space

Syntax: [ <'text‑space‑collapse'> || <'text‑space‑trim'> || <'text‑wrap'> ] | <white‑space‑legacy>

<white‑space‑legacy>

Syntax: normal | pre | nowrap | pre-wrap | break-spaces | pre-line

<white‑space‑legacy>	<'text‑space‑collapse'>	<'text‑space‑trim'>	<'text‑wrap'>
normal	collapse	none	wrap
pre	preserve	none	no-wrap
nowrap	collapse	none	no-wrap
pre-wrap	preserve	none	wrap
break-spaces	preserve	none	wrap
pre-line	preserve‑breaks	none	wrap

text‑space‑collapse

Syntax: collapse | discard | preserve | preserve‑breaks | preserve‑spaces

text‑space‑trim

Syntax: none | [ trim‑inner || discard‑before || discard‑after ]

text‑wrap

Syntax: wrap | no‑wrap1 | balance | stable | pretty

Footnotes

1. https://github.com/w3c/csswg-drafts/issues/5376 ↩

[faceless2]

Thanks for suggesting this - I agree, this is a good idea for several reasons:

1. It's consistent with how other shorthand properties are handled.
2. It gives forward compatibility for the white-space property. If we don't do this, the white-space will be able to set some combinations of its components, but not all. This will eventually lead to be becoming a sort of legacy property, which I don't think we want.
3. It's removing one level of magic from the shortcuts - "pre" is just s shorter way of writing "preserve none nowrap", which is easier to explain than saying it sets text-space-collapse to preserve, text-space-trim to none and text-wrap to no-wrap.

I'm unconvinced on the value of renaming "nowrap" to "no-wrap" as part of this move - in particular, because it would make both white-space: nowrap and white-space: no-wrap evaluate to the same result. This could lead to a very confusing transition period until css-text-4 is fully implemented. But otherwise, great idea.

[fantasai]

I think this makes sense, but we need to have some mapping for break-spaces that isn't the exact same mapping as pre-wrap since they have different behavior. :)

[kojiishi]

we need to have some mapping for break-spaces

#3794

[cdoublev]

If I am not mistaken, this proposal seems to have been recently integrated via 4717dbc.

When white-space is not specified with a special keyword (<white‑space‑legacy>), I assume that sub-properties that are not given a value matching their syntax reset to their initial value?

[fantasai]

@cdoublev Yes, good catch. Clarified in b1f31d0

[fantasai]

This proposal is now edited into the ED, see https://drafts.csswg.org/css-text-4/#white-space-property
Agenda+ to ask the WG for review, if the resulting spec is indeed what we want.