update method

void update()

Will be called by the internal timer, or may be called at any time.

Implementation

void update() {
  if (startTime == null) throw Exception('Must call `start()` before calling this.');
  var now = DateTime.now();
  var diff = now.difference(startTime!).inMilliseconds;
  if (diff < 0) throw Exception('Back in Time: Current time is before the start time!');
  frameCount = framerate.realSecondsToFrames(diff / 1000);
}