Proposed fix to correct Compose UI animations

[geoff-powell]

So animations with offsetMillis didn't work properly in paparazzi. This was due to the Transition apis tracking the startTimeNanos when a transition starts. Since this is set ahead of the transition, the delta to render the frame was always 0. For gif() methods that used start = 0 they render correctly because the starting frame is at 0 nanos.

The best way I could combat this was for cases in Compose where the caller was manually setting the startNanos for Paparazzi.takeSnapshots() I call multiple render calls with time 0 to ensure Transition apis have startTimeNanos = 0

Fixes #627 #678

[BrianGardnerAtl]

I think this looks good. Having to render twice with a 0 start time is a little quirky but the comment explains it well

[harrytmthy]

Hi @geoff-powell, spotted a subtle bug here. hasPendingWork is a computed property backed by synchronized state in Recomposer, so storing its value in a local var like this might introduce an issue if the underlying state changes between reads (which is likely during animation rendering).

Would it make sense to unwrap recomposer once, then query recomposerInstance.hasPendingWork at the moment it's needed, instead of snapshotting into a local var?

That way the logic stays aligned with Recomposer's live state, like:

if (frame == 0 && recomposerInstance.hasPendingWork) {
    withTime(nowNanos) {
        renderForResult()
    }
    if (recomposerInstance.hasPendingWork) {
        logger.warning("...")
    }
}