Add 'motion-preference' media feature

[inoas]

Implements Issue: #442
Alternative to #586

Having a good wording of the feature also gets around default value evaluating to true instead of false. Ref: #586 (comment)

[nattarnoff]

This makes sense to me as solid way to implement in CSS. By default motion is on, and we can reduce action from there. I'm struggling to see how this gets implemented though in a real world example.
For instance, as a media query, I expect something like:

@medis (motion-preference: none {
  // Base CSS - no motion
}
@media (motion-preference: reduced) {
  // CSS for limited motion
}
 // Balance of CSS with full animation

Of course this is an ideal, and most folks will probably retrofit and use these in the opposite manner initially. Is there anyway this can be read and acted upon by WAAPI/JS animation implementations?

[cookiecrook]

Why split the conversation into this alternative PR? Please just continue in either of the original threads: #442 or #586. PR #586 was raised because the CSSWG hadn't taken action in over two years, since this was proposed in 2014. We can come to an agreement in a single thread I believe.

[inoas]

The suggestion already is in #442 - precisely here: #442 (comment)

However it wasn't picked and as far as I can see there wasn't any argument against it (yet!).

Do you see any issues with this PR here?
Does it not solve anything?
Is it anywhere unclear?
@grorg Where would this not work for you?

[cookiecrook]

@inoas wrote:

as far as I can see there wasn't any argument against it

Your last comment in that thread suggested all as a falsey value which doesn't seem right to me.

You also seemed to agree with the "prefers-" prefix over your suggested "-preference" suffix with the following comment:

the idea with the prefers- prefix seems to be a good one!

[cookiecrook]

@inoas wrote:

Where would this not work for you?

I think the forced-all-animation-off idea (motion-preference: disable;) is unlikely to be implemented because it would break too many things, which is why I proposed the opt-in. I'd rather see that forced-all-animation-off idea incubated. If you get author and browser support, bring it back.

[cookiecrook]

As for the motion-preference versus prefers-reduced-motion property name, let's keep discussing that in PR #586.

[cookiecrook]

Also I think your proposal would not be backwards compatible:

@media (motion-preference: all) /* this would be the default, but works in no browsers today */

[cookiecrook]

I suggest closing this one and duping it to #586

[inoas]

• I think it is really bad to design keywords around what is currently possible. If you think it is not the right time to support 'disabled' then either the browser-vendor can decide so or the PR can be restricted to values default and reduced leaving the OPTION to later have disabled. However personally I'd love to be able to know if a user does not like any animations. It is still a preference setting. E.g. you can still offer animations, but maybe .1s long instead of .3s.
• There is no all but only default, reduced and disable. Where would this not work in browsers?
• I am perfectly fine discussing in Add 'prefers-reduced-motion' media feature #586 I was just setting up a PR so that it isn't just words.
• I don't understand what you mean by duping it to Add 'prefers-reduced-motion' media feature #586.

[frivoal]

This discussion is kind of spreading over a bunch of places. I made a comment in #442 (comment) to try and summarize all that's been said in terms of naming options, and try to find a winner.

[inoas]

Closing as there has been made a decision.