positionFlow
Observes the playhead as a cold flow.
Emits at most once per tick of media time, snapped to that grid. Pass Duration.ZERO for every UI frame, which is only worth it for a smooth scrubber thumb, and even then prefer drawing over recomposing.
Return
a cold flow of playhead positions.
Parameters
tick
The grid to snap emissions to, or Duration.ZERO for every update.