Re: [csswg-drafts] [css-color-adjust] Clarify expectations re forced-color mode, system colors, and transitions (#5419)

The CSS Working Group just discussed `[css-color-adjust] Clarify expectations re forced-color mode, system colors, and transitions`, and agreed to the following:

* `RESOLVED: colors assigned due to forced-colors mode are not interpolatable`

<details><summary>The full IRC log of that discussion</summary>
&lt;dael> Topic: [css-color-adjust] Clarify expectations re forced-color mode, system colors, and transitions<br>
&lt;dael> github: https://github.com/w3c/csswg-drafts/issues/5419<br>
&lt;dael> Rossen_: I know AmeliaBR sent regrets. Seems consensus on issue. alisonmaher can you summerize?<br>
&lt;dael> alisonmaher: General issues are specifically when you change forced-color-adjust to aut or none do we trigger transition. If to or from are forced we would not trigger transitions is the proposal<br>
&lt;fremy> sounds like the right call to me<br>
&lt;emilio> q+<br>
&lt;dael> TabAtkins: Simplifies impl and happy to have in spec<br>
&lt;dael> Rossen_: Also support. Makes behavior predictable<br>
&lt;AmeliaBR> no need to wait for me: my opinion was “please pick what works best for implementations &amp; spec it!”<br>
&lt;dael> emilio: Other than display is the precedent for such a thing?<br>
&lt;dael> TabAtkins: There's a couple of non-interpolatable properties. Some have values that cannot be interpolated though others can.<br>
&lt;dael> emilio: This is different. This isn't about interpolable but about if triggers transitions on other arbitrary properties<br>
&lt;dael> TabAtkins: Yes. If the stuff is forced or not controls if other properties can interp certain values. That is novel. Seems easier on out impl to handle it.<br>
&lt;dael> emilio: Why?<br>
&lt;dael> TabAtkins: Don't know. Rune would have more details<br>
&lt;dael> emilio: To me seems it would make; this would need to be a special case<br>
&lt;dael> Rossen_: Impl aside from user or author PoV which behavior would you prefer<br>
&lt;fremy> q+<br>
&lt;dael> emilio: If author has spec BG transitions I don't see why it shouldn't?<br>
&lt;dael> Rossen_: How if in middle of transition you go to or from forced colors. You're going off a cliff for expected. But continuing to transition means some thigns change. These are dissonant to me.<br>
&lt;dael> emilio: To make sure I understand saying that changing forced-color adjust stops in progress particular property values?<br>
&lt;dael> TabAtkins: Not quite. Any colors comping from forced color mode don't interpolate. In general it's forced vs not and that's outside the property.<br>
&lt;dael> emilio: Agree with Rossen_ similar that stopping transition when element stops making boxes makes sense it does make sense when you change to stop animations and transitions. I need to look deeper into implications.<br>
&lt;dael> Rossen_: We do have a resolution on animations<br>
&lt;dael> fremy: An example of why don't want to transition colors. When in forced-colors the backplate is on top of text. Will disappear when set to none. Previous text color contrasts backplate so you don't want text color to transition because it's a completely different background. Text could disappear for a few seconds. I think stopping transitions makes the most sense<br>
&lt;dael> emilio: Could make argument with a bunch of different property combos, right? Not just forced-colors.<br>
&lt;dael> Rossen_: Is this something you want to object emilio, discuss more?<br>
&lt;dael> emilio: colors from forced-colors and colors don't interpolate?<br>
&lt;dael> TabAtkins: Prop: Colors assigned due to forced-colors mode are not interpolable<br>
&lt;dael> emilio: I won't object. I need to look more<br>
&lt;dael> emilio: When you revert a property and it goes to color from UA sheet I assume that counts as assigned b/c forced color mode?<br>
&lt;dael> emilio: You have forced colors. That can cause you to revert some properties to UA level. If you use a color; it's not just default colors you assign but also the ones you get when revert to a value from UA stylesheet. They shouldn't interp. But same as if author spec revert<br>
&lt;dael> TabAtkins: Should have been from set of forced system colors so yes<br>
&lt;dael> emilio: I don't know. Feels awkward resolution. I would be curious about constraints that simplify this in Chrome<br>
&lt;dael> emilio: I won't object<br>
&lt;dael> Rossen_: If you have a better proposal and want to re-open please do<br>
&lt;dael> Rossen_: Let's make progress now<br>
&lt;dael> Rossen_: Objections to colors assigned due to forced-colors mode are not interpolable<br>
&lt;TabAtkins> https://github.com/w3c/csswg-drafts/issues/5419#issue-677260327 lays out some initial thoughts, from Amelia, and subsequent comments from Alison and Rune<br>
&lt;dael> RESOLVED: colors assigned due to forced-colors mode are not interpolatable<br>
&lt;Rossen_> q?<br>
&lt;Rossen_> ack emilio<br>
&lt;Rossen_> ack fremy<br>
</details>


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Received on Wednesday, 30 September 2020 16:52:25 UTC