start method

void start(dynamic callback(Duration), [ int updateInterval = 100 ])

Implementation

void start(Function(Duration) callback, [int updateInterval = 100]) {
  if (_isRunning) {
    _timer.cancel();
  }

  _startTime = DateTime.now();
  _isRunning = true;
  _timer = Timer.periodic(Duration(milliseconds: updateInterval), (Timer timer) {
    final DateTime now = DateTime.now();
    final Duration elapsed = now.difference(_startTime);
    callback(elapsed);
  });
}