How can I code in Dart / Flutter to enable my debug mode when a region is touched 5 times in 10 seconds

Question

I am using Flutter and the Bloc Pattern with rxdart and would like to have a debug mode in my app similar like you enable the developer mode in Android the user should touch 5 times a logo in the UI. The UI part is pretty simple with:

Column _renderLogo(BuildContext context) => new Column(
        children: <Widget>[
          GestureDetector(
            onTap: () => BlocProvider.of(context).debugEnabledSink.add(true), 
            child: Container( ...more logo rendering...

With that in mind, I am looking for an easy elegant way to enable the detection of 5 events in 10 seconds. The whole detection should reset when not enough events are detected in any 10 second time window.

Answer 1

You can use a pseudo-timer to achieve this:

const maxDebugTimerSeconds = 10;
const maxTapCount = 5;

DateTime firstTap;
int tapCount;

void doGestureOnTap() {
  final now = DateTime.now();
  if (firstTap != null && now.difference(firstTap).inSeconds < maxDebugTimerSeconds) {
    tapCount++;
    if (tapCount >= maxTapCount) {
      BlocProvider.of(context).debugEnabledSink.add(true);
    }
  } else {
    firstTap = now;
    tapCount = 0;
  }
}

...

GestureDetector(
  onTap: doGestureOnTap,
  ...
),

Answer 2

This answer is based on the comment of @pskink above. I just post it here because it seems like a very elegant way of solving my problem. Thank you @pskink

DebugSwitcher might not be the best class Name it's more TimeWindowEventDetector but you get the idea.

class DebugSwitcher {
  final Duration window;
  final int cnt;
  bool value = false;
  var timeStamps = [];

  DebugSwitcher({this.window = const Duration(seconds: 10), this.cnt = 5});

  call(data, sink) {
    var now = DateTime.now();
    timeStamps.removeWhere((ts) => now.difference(ts) >= window);
    timeStamps.add(now);
    if (timeStamps.length >= cnt) {
      timeStamps = [];
      sink.add(value = !value);
    }
  }
}

Than u listen to the Sink Events this way:

 _debugEnabledController.stream
        .transform(StreamTransformer.fromHandlers(handleData: DebugSwitcher()))
        .listen(
      (_) {
        _isDebugModeOn.value = true;
        infoInternal.value = 'Enabled Debug Mode';
      },
    );

The Sink is defined like this:

  final StreamController<bool> _debugEnabledController =
      StreamController<bool>();

  Sink<bool> get debugEnabledSink => _debugEnabledController.sink;

In the UI the code looks like this:

 Column _renderLogo(BuildContext context) => new Column(
        children: <Widget>[
          GestureDetector(
            onTap: () => BlocProvider.of(context).debugEnabledSink.add(true),
            child: Container(
              margin: const EdgeInsets.only(top: 10.0, right: 10.0),
              height: 80.0,
              child: Theme.of(context).primaryColorBrightness ==
                      Brightness.light
                  ? new Image.asset('assets/app_icon_light.png', fit: BoxFit.contain)
                  : new Image.asset('assets/app_icon.png', fit: BoxFit.contain),
            ),
          ),
        ],
      );