onSignal abstract method

void Function() onSignal(
  1. void listener(
    1. PresentationSignal signal
    )
)

Subscribes to this presentation's signals.

DisplayedSignal arrives first and at most once; nothing arrives after outcome. A ClickedSignal may arrive after holdReleased — that window is the non-blocking case. Returns an unsubscribe function; calling it twice is safe.

Implementation

void Function() onSignal(void Function(PresentationSignal signal) listener);