[css-animationworklet] Listening to events in Animation Worklet

[Sociopacific]

Can I listen events in animation worklet or transfer data from main thread to running animation worklet?

[majido]

On transferring data from main thread

I think this the need such a mechanism to make animation worklet useful. Since many useful effects running inside animation worklet may need to know about specific values from main thread, e.g., size of window or bounding client rects of various objects.

Since we already allow data to be sent when worklet animation (via options) when it is constructed. The logical extension is to allow options to be updated as well. This is a simple and reasonable extension. I will update the spec to allow this.

See more details on specific proposed change here

On listening to events in animation worklet

Again I think there is a lot of merit to this idea. In fact, one of our goals is to allow worklet animation inside animation worklet context to be able to react to user input (touch, gesture, etc.)

We have been trying to come up with the right abstraction and API to allow this (see: 1, 2, 3), and our recent idea which I am very hopeful about is captured here.

I think once we have the solution for sending data from main thread to worklet, one can build a simple event forwarding on top of it. But we need a better solution to have low-latency event forwarding which the other ideas are trying to address.

[majido]

I filed a separate issue for sending data from main to worklet since I believe the usecases and APIs differ. Lets keep this issue focused on receiving events inside worklet.

[majido]

The proposal for allowing input events to worklets is now published under WICG: https://discourse.wicg.io/t/proposal-exposing-input-events-to-worker-threads/3479

Here is the explainer for it. I am working closely with other folks on this to make sure it addresses Animation Worklet usecases.