Re: [csswg-drafts] [css-view-transitions] Users need to be able to disable view transitions (#10267)

The CSS Working Group just discussed `[css-view-transitions] Users need to be able to disable view transitions https://github.com/w3c/csswg-drafts/issues/10267`, and agreed to the following:

* `RESOLVED: in cases of prefers-reduced-motion the UA stylesheet will define a cross-fade animation by default, without size/position animation`

<details><summary>The full IRC log of that discussion</summary>
&lt;matatk> subtopic: [css-view-transitions] Users need to be able to disable view transitions https://github.com/w3c/csswg-drafts/issues/10267<br>
&lt;astearns> github: https://github.com/w3c/csswg-drafts/issues/10267<br>
&lt;fantasai> matatk: We discussed in APA, idea of being able to do some kind of reduction on View Transitions we thought would be helpful<br>
&lt;fantasai> ... but also acknowledge that there is a subtle, but big, difference between reducing and disabling motion<br>
&lt;fantasai> ... wrt motion, there is good infrastruction for reducing but not disabling<br>
&lt;fantasai> ... so consistency issues<br>
&lt;fantasai> ... We're generally in favor of some sort of control, but wondering what is the latest from CSSWG<br>
&lt;khush> q+<br>
&lt;fantasai> vmpstr: We can respect prefers-reduced-motion and set up different default animation that doesn't have motion and does a cross-fade<br>
&lt;fantasai> ... but if authors customize, then that's a regular CSS animation -- they are responsible at that point<br>
&lt;PaulG> q+<br>
&lt;matatk> q+ to ask about 'one-sided' transitions<br>
&lt;matatk> q?<br>
&lt;matatk> ack khush<br>
&lt;fantasai> khush: There's another issue where flackr had a proposal for a forced no-motion mode<br>
&lt;PaulG> q-<br>
&lt;fantasai> ... that would disable all CSS animations completely<br>
&lt;fantasai> ... that seems better path for a CSS-wide fix for it<br>
&lt;fantasai> ... didn't want to do something specific for View Transitions<br>
&lt;fantasai> khush: one detail is that we do something generic for animating position and size<br>
&lt;matatk> q?<br>
&lt;fantasai> ... can adjust the defaults for that accordingly<br>
&lt;matatk> ack me<br>
&lt;Zakim> matatk, you wanted to ask about 'one-sided' transitions<br>
&lt;fantasai> matatk: if moving between documents and ...<br>
&lt;fantasai> vmpstr: Animation runs on one page only. The outgoing page doesn't control the animation in any shape or form<br>
&lt;fantasai> ... just specifies which parts will participate<br>
&lt;matatk> q?<br>
&lt;fantasai> ... incoming page controls the animation, so that's where prefers-reduced-motion would take effect<br>
&lt;fantasai> ...<br>
&lt;fantasai> matatk: OK, we'll take as homework on what to recommend<br>
&lt;fantasai> vmpstr: We can resolve now I guess<br>
&lt;fantasai> ... in cases of prefers-reduced-motion we will construct a cross-fade animation by default, without size/position animation<br>
&lt;fantasai> vmpstr: Thoughts? Objections?<br>
&lt;kbabbitt> q+<br>
&lt;fantasai> chrishtr: removing animation completely would be a separate feature<br>
&lt;matatk> ack kbabbitt<br>
&lt;fantasai> kbabbitt: Do we need to be concerned about whether this is detected as a user preference through timing or something?<br>
&lt;fantasai> fantasai: it's a media query<br>
&lt;fantasai> khush: by design, want authors to adapt to it<br>
&lt;fantasai> kbabbitt: but do we want the info to be detectable (concern wrt fingerprinting)<br>
&lt;fantasai> gregwhitworth: If mapping to prefers-reduced-motion, you can already get that info via JS<br>
&lt;fantasai> matatk: if document doesn't give an alternative, then you'd use the default cross-fade?<br>
&lt;fantasai> ... another option would be to not run the normal one, but that's not reducing it<br>
&lt;fantasai> ... I think that would surprise authors<br>
&lt;fantasai> khush: Firefox disables marquee animations in this mode already, so there's some precedent<br>
&lt;fantasai> chrishtr: UA stylesheet would normally do cross-fade + transform<br>
&lt;fantasai> ... with the second rule for prefers-reduced-motion would only do cross-fade<br>
&lt;fantasai> ... author's rules would always override<br>
&lt;matatk> ack fantasai<br>
&lt;TabAtkins> fantasai: Whatever we put in the default UA stylesheet<br>
&lt;TabAtkins> fantasai: Unless we specifically make it an override, it'll get overridden by the author<br>
&lt;matatk> q?<br>
&lt;TabAtkins> fantasai: so if they create a custom animation, it'll work in both modes. They'll have to create their own reduced one.<br>
&lt;TabAtkins> fantasai: This'll just change the default animation<br>
&lt;fantasai> matatk: So up to us to say if we think this is a good idea<br>
&lt;PaulG> +1 for the default<br>
&lt;fantasai> matatk: Motion doesn't come just from CSS<br>
&lt;fantasai> ... if the user says prefers-reduced-motion, is there any browser engine looking into reducing other forms of motion?<br>
&lt;fantasai> fantasai: prefers-reduced-motion is a MQ that the author has to adjust for; UA can oly adjust it's defaults<br>
&lt;fantasai> ... if adding a forced mode, we would take more heavy-handed approach to suppressing author-provided motion<br>
&lt;fantasai> s/provided/specified/<br>
&lt;fantasai> matatk: [missed]<br>
&lt;fantasai> flackr: smooth scrolling can get turned off, small example<br>
&lt;fantasai> emilio: we do that too<br>
&lt;fantasai> emilio: it's interesting to have different heuristics here, but similar to forced colors<br>
&lt;matatk> q?<br>
&lt;khush> q+<br>
&lt;fantasai> ... if was ? then we could take more aggressive measures<br>
&lt;fantasai> ... but right now no standard way to expose<br>
&lt;fantasai> ... so would need different settings or different browsers<br>
&lt;fantasai> ... may or may not be solveable<br>
&lt;fantasai> ... ideally we do something like that, where we have a forced-reduced-motion mode<br>
&lt;fantasai> ... but I don't think we're there yet<br>
&lt;zcorpan> q?<br>
&lt;matatk> ack khush<br>
&lt;fantasai> khush: Not all browsers have setting, try to infer from OS settings<br>
&lt;miriam> s/was ?/it was a need (not just a preference)/<br>
&lt;fantasai> ... e.g. Android no animations gets mapped to prefers-reduced-motion<br>
&lt;fantasai> ... so what was in the OS vs what's in the browser don't match very well<br>
&lt;astearns> proposed resolution: in cases of prefers-reduced-motion the UA stylesheet wil define a cross-fade animation by default, without size/position animation<br>
&lt;astearns> RESOLVED: in cases of prefers-reduced-motion the UA stylesheet will define a cross-fade animation by default, without size/position animation<br>
&lt;vmpstr> \o/<br>
</details>


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Received on Tuesday, 24 September 2024 01:01:40 UTC