[csswg-drafts] [web-animations-1] Propose moving iterationComposite to web-animations-2 (#4300)

stephenmcgruer has just created a new issue for https://github.com/w3c/csswg-drafts:

== [web-animations-1] Propose moving iterationComposite to web-animations-2 ==
This is a proposal to move the [iteration composite operation](https://drafts.csswg.org/web-animations-1/#iteration-composite-operation) concept to the level 2 version of the spec. If adopted, [section 5.5](https://drafts.csswg.org/web-animations-1/#iteration-composite-operation) would be removed, as well as all references to the iteration composite operation.

### Motivation

This proposal is primarily motivated by the difficulty of implementing iterationComposite in Chromium (as our interpolation stack would have to change significantly to support it), backed by the claim that we would not lose too much utility in moving it to level 2. The goal is to clear the path for all web browsers to ship web-animations-1 in an interoperable way.

It is hard to judge what iterationComposite brings to the spec. It is not covered in the listed [use-cases](https://drafts.csswg.org/web-animations-1/#use-cases) for web-animations-1. I was unable to find any JavaScript animation libraries offering a similar property in a quick search, but they may exist. If there are use-cases, I would be interested to hear them.

Based on the [WPT tests](https://wpt.fyi/results/web-animations/animation-model/keyframe-effects/effect-value-iteration-composite-operation.html?label=master&label=experimental&aligned), only Firefox implements iteration composite operations today.

### Implications

Although less ergonomic, I believe web developers should be able to mimic the behavior of iterationComposite by setting the correct keyframes on the animation. (Please correct me if this is not the case.) So the main implication is a loss of ergnomics, if the web developer wants to do something iterationComposite-like.


Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/4300 using your GitHub account

Received on Thursday, 12 September 2019 17:26:10 UTC