Delay animations until attached

[kurkle]

Played around a bit with animation delaying, for issue #7290

Pen: https://codepen.io/kurkle/pen/MWaowYj

Update: added container attachment detection and also delayed initial update to happen after atteched.

[benmccann]

I didn't look super closely, but the overall idea seems reasonable to me.

canvas needs to be detached, initial parent detachment is not detected

Is that something that would be hard to implement?

canvas is going to be 300x150 and the animation starts from there.

This part seemed unexpected to me. I'd expect that the bars in the codepen should be handled just like the normal initial animation reset case instead of a resize

[etimberg]

Is this a breaking API change that we need to document now?

[kurkle]

I don't think a new return value is breaking, but it could be documented for sure.
Its not something you'd expect addEventListener to return though, that's why I didn't bother to document it.

Maybe the logic should be moved to core from platform:

if (platform.isAttached(me)) {
  platform.addEventListener(me, 'resize', ...)
  platform.addEventListener(me, 'detach', ...)
} else {
  platrofm.addEventListener(me, 'attach', ...)
}

[etimberg]

I think this would be a good strategy. It would allow for alternate implementations without returning from addEventListener

[etimberg]

Docstring needs an update