Re: [web-animations] Significant changes to Web Animations coming up

>
>
> Unfortunately I was unable to make a shared keyframe list since as was
> discussed at one stage.[3] This is because keyframe lists return their
> computed offsets but for paced keyframe lists, the computed offset may
> depend on their target element in order to resolve percentage values,
> for example. This is problem exists with the API regardless of this
> change so we can address it subsequently (e.g. by making the computed
> keyframe list getter take a target element).
>

I am very concerned by this.

Our implementation demonstrates that parsing of keyframe lists is a major
cost, possibly the largest cost involved in setting up animations. Sharing
keyframe lists where possible would be a major benefit.

Furthermore, keyframe lists should only deal with specified lists - the
problem you're describing doesn't need to exist as accessors on a
KeyframeList should return the unmodified inputs.

It's fine to keep a getFrames method on the KeyframeEffect object for
accessing the computed result (in a place where the target is known) -
although I think this could be deferred to a later level as we don't have
currently have strong use cases for it.

Sincerely,
    -Shane Stephens