Re: [csswg-drafts] [css-color-4] Concerns about color() function fallback (#5931)

Hi @FremyCompany these are good questions. The complexities that I and others have noted are:

1. There is a recursive fallback, a `<color>` can have either another `<color>` or a legacy sRGB as fallback; that second `<color>` can also have a fallback and so on. It would not seem reasonable to limit the fallback to sRGB only, so this seems difficult to avoid.
2. Thus, the Typed Object Model for `<color>` needs to represent an arbitrarily-long list of fallbacks
3. CSS Color 5 proposes (as one alternative) [relative color syntax](https://drafts.csswg.org/css-color-5/#relative-colors) to extend `rgb()`, `lab()` and so on. Due to the complexity, this extension to `color()` has yet to be proposed as the grammar becomes tricky to write
4. There are questions about [`color-contrast()`](https://drafts.csswg.org/css-color-5/#colorcontrast) and the fallbacks. Does only the first color get tested? Do all of them? If so, how do we express the result, in that case? If not, what is the contrast if one of the fallbacks ends  up being used?
5. Similar questions for [`color-mix()'](https://drafts.csswg.org/css-color-5/#color-mix), is only the first color mixed? if so, what id the first color would not have been used? if not, is the mix result also a list, and how is that expressed?

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Received on Tuesday, 2 March 2021 13:18:16 UTC