stop method

void stop ({bool canceled: false })

Stops calling this Ticker's callback.

If called with the canceled argument set to false (the default), causes the future returned by start to resolve. If called with the canceled argument set to true, the future does not resolve, and the future obtained from TickerFuture.orCancel, if any, resolves with a TickerCanceled error.

Calling this sets isActive to false.

This method does nothing if called when the ticker is inactive.

By convention, this method is used by the object that receives the ticks (as opposed to the TickerProvider which created the ticker).

Implementation 

void stop({ bool canceled = false }) {
  if (!isActive)
    return;

  // We take the _future into a local variable so that isTicking is false
  // when we actually complete the future (isTicking uses _future to
  // determine its state).
  final TickerFuture localFuture = _future;
  _future = null;
  _startTime = null;
  assert(!isActive);

  unscheduleTick();
  if (canceled) {
    localFuture._cancel(this);
  } else {
    localFuture._complete();
  }
}