Re: [csswg-drafts] [css-color-5] Behavior of `none` in relative color syntax (#10151)

Hmm that line [was added here](https://github.com/w3c/csswg-drafts/commit/d629921597dd55f076105d4f8717fcfe82a5d77a) in response to

 - https://github.com/w3c/csswg-drafts/issues/7771

and, earlier,

 - https://github.com/w3c/csswg-drafts/issues/7771#issue-1380029170

Re-reading this issue, @mirisuzanne supported the [proposal by @nex](https://github.com/w3c/csswg-drafts/issues/7771#issue-1380029170)  to have the result be `none`; this had earlier been [proposed by @weinig ](https://github.com/w3c/csswg-drafts/issues/6920). Having it be `none` was also supported by myself and by @LeaVerou but opposed by @tabatkins 

@tabatkins  argued that 

> doing color-space conversion on a color that already has missing components treats those components as zero, rather than specially handling them. 

(which is incorrect; I suspect that understanding was not informed by (or predated) the concept of analogous components and carrying-forward).

@mirisuzanne argued that

> The relative color syntax use-cases are very similar to interpolation use-cases (where we also define a way for none to be maintained across conversions). 

which is persuasive (and the model I used in this refactoring), and also @weinig [argued that](https://github.com/w3c/csswg-drafts/issues/6920#issuecomment-1003426142)

> There is a small argument for having some way to preserve the "missing" concept into calc() so that users could match the interpolation rules the engine uses in a custom interpolation they might implement using the relative color syntax 

and

> if one of the components was 'none', what the user probably really wanted was to just the other component, but if they always lose that information they are out of luck.

In conclusion, if five people argue one position while one argues the contrary, then there wasn't consensus and the issue should not have been closed.

In terms of the utility, I know @LeaVerou has been working in that area for responsive color scales that cope with dark/light mode, so invite her to comment further.


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Received on Friday, 12 April 2024 21:48:16 UTC