Re: [csswg-drafts] [css-variables] When does substitution occur, before or after animation interopolation?

@tabatkins @shans and myself spoke about animating custom properties 
and how many substitutions you need in order to support use cases the 
authors would expect to work. I recommend adding the following copy as
 a note for an example implementation to ensure the spirit of the 
specification is followed by all implementations (which when we began 
this implementation no UA supports this, so it would be good to ensure
 it's in there).

In order to be able to make the use cases work, here is what an 
example implementation would look like:
1.      Apply cascaded values
2.      Detect & Construct animations
3.      Substitute into keyframes
4.      Detect & construct transitions
5.      Apply computed values from transitions and animations
6.      Substitute into the cascaded values

While this will help solve some of the gaps and interop issues we 
found while implementing custom properties, I think we should specify 
these steps normatively in somewhere (possibly the cascading 
specification) so that we can reference them and better understand the
 potential use case and perf impacts with future feature discussions 
(eg: @apply).

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Received on Monday, 23 January 2017 21:58:59 UTC