AnimationWorklet should have access to the full AnimationEffect functionality in the worklet context but it currently has only a very limited subset (i.e., setting local time).

Here is the currently exposed interface:
interface EffectProxy {
  attribute unrestricted double? localTime;
};

The interface that we eventually want is KeyframeEffect [2]. One tricky part it to figure out the best way to plumb keyframe values to the worklet for the composited animations.


As a first step we can probably start by exposing AnimationEffect interface which only include timing related properties which are available both on blink and cc.

interface AnimationEffect {
    EffectTiming getTiming();
    ComputedEffectTiming getComputedTiming();
    [RaisesException] void updateTiming(optional OptionalEffectTiming timing);

    [exposed=AnimationWorklet]
    attribute unrestricted double? localTime;
};
                                                                                


[1] https://cs.chromium.org/chromium/src/third_party/blink/renderer/modules/animationworklet/effect_proxy.idl

[2] https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/animation/keyframe_effect.idl