Re: [csswg-drafts] [web-animations-1] Alternative to FillAnimation: replace events (#3689)

> Disadvantages:
> 
> * It introduces _two_ new concepts for authors to understand: "replacing" and `FillAnimation`s. That said, many authors will never need to deal with either.
> * It suffers the same problems as `FillAnimation` with regards to it being difficult to compact additive content. It will always be an incomplete solution.

If we can switch the composition and interpolation order as proposed in #2204 I believe this will be a complete solution as we can always replace with the equivalent transform matrix.

> * It has the same compatibility uncertainly as the proposal in this issue.

I think the compatibility risk is reduced over this proposal. The only time existing sites would break is if they tried to use completed animations, whereas in this proposal animations will silently be dropped and change output value.

> * It's a bit more magical than the proposal in this issue.

I disagree, I think that this proposal describes a hard to predict set of circumstances for dropping animations where an always replace model has very predictable behavior. We could however make it only replace at the point in time where there was more than one filling animation.

> Personally, my main concern is that I'm still not sure that this alternative offers a net reduction in complexity. Although it reduces complexity surrounding existing `Animation` objects, it still includes many of the harder parts of the `FillAnimation` proposal (e.g. generating a sensible result from `getKeyframes()` for some internal representation of an additive stack) and adds to it the complexity of the replacing functionality.

I believe that resolving #2204 would mean that the keyframes of a replaced animation could simply have the transform matrix which greatly reduces the complexity.
> 
> If it turns out that this proposal is comparable to the `FillAnimation` one in terms of implementation complexity, then I would lean towards the original `FillAnimation` proposal for its conceptual simplicity.

Agreed

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Received on Monday, 1 April 2019 14:41:32 UTC