attach method

Stream<int> attach(Stream<List<int>> dataResponse)

Attach this RxTap to the Frame's dataResponse characteristic stream.

Implementation

Stream<int> attach(Stream<List<int>> dataResponse) {
  // TODO check for illegal state - attach() already called on this RxTap etc?
  // might be possible though after a clean close(), do I want to prevent it?

  // the subscription to the underlying data stream
  StreamSubscription<List<int>>? dataResponseSubs;

  // Our stream controller that transforms/accumulates the raw tap events into multi-taps
  _controller = StreamController();

  // track state of multi-taps
  int lastTapTime = 0;
  int taps = 0;
  Timer? t;

  _controller!.onListen = () {
    dataResponseSubs = dataResponse
      .where((data) => data[0] == tapFlag)
      .listen((data) {
        int tapTime = DateTime.now().millisecondsSinceEpoch;
        // debounce taps that occur too close to the prior tap
        if (tapTime - lastTapTime < 40) {
          _log.finer('tap ignored - debouncing');
          lastTapTime = tapTime;
        }
        else {
          _log.finer('tap detected');
          lastTapTime = tapTime;

          taps++;
          t?.cancel();
          t = Timer(threshold, () {
            _controller!.add(taps);
            taps = 0;
          });
        }

    }, onDone: _controller!.close, onError: _controller!.addError);
    _log.fine('TapDataResponse stream subscribed');
  };

  _controller!.onCancel = () {
    _log.fine('TapDataResponse stream unsubscribed');
    dataResponseSubs?.cancel();
    _controller!.close();
  };

  return _controller!.stream;
}