Flutter quickstart

import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:neurofit_vitals/neurofit_vitals.dart';

Future<bool> prepareVitals(String licenseKey) async {
  final LicenseStatus status;
  try {
    status = await NeurofitVitals.activate(licenseKey);
  } on PlatformException catch (e) {
    // e.code is a VitalsErrorCode: licenseInvalid, licenseNotValidForApp, licenseUpdatesExpired
    debugPrint('Activation failed: ${e.code} ${e.message}');
    return false;
  }
  for (final w in status.warnings) {
    debugPrint('License warning: $w');
  }

  final DeviceSupport support = await NeurofitVitals.deviceSupport();
  if (!support.isSupported) {
    debugPrint('Vitals not supported: ${support.reason}');
    return false;
  }

  return NeurofitVitals.requestCameraPermission(); // true when granted
}

import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:neurofit_vitals/neurofit_vitals.dart';

class ReadingController {
  VitalsSession? _session;
  StreamSubscription<VitalsEvent>? _events;

  final guidance = ValueNotifier<Guidance?>(null);
  final startProgress = ValueNotifier<double>(0);
  final preview = ValueNotifier<LivePreview?>(null);
  final notice = ValueNotifier<String?>(null);
  final result = Completer<VitalsResult>();

  Future<void> begin() async {
    final sessionId = await NeurofitVitals.createSession(
      const VitalsConfiguration(readingDuration: 60, autoRestartAfterCancel: true, motionBreathing: true),
    );
    final session = VitalsSession(sessionId);
    _session = session;

    _events = session.events.listen((VitalsEvent event) {
      switch (event) {
        case GuidanceEvent(:final guidance, :final startProgress):
          this.guidance.value = guidance;
          this.startProgress.value = startProgress;
        case PreviewEvent(:final preview):
          // preview.rmssdMs is null until about 20 s; preview.breathingRate until about 30 s.
          this.preview.value = preview;
        case CancelledEvent(:final reason):
          notice.value = 'Reading restarted: ${reason.name}'; // the session re-arms by itself
        case ReconfiguringCameraEvent(:final lowPowerMode):
          if (lowPowerMode) notice.value = 'Please turn off Low Power Mode.';
        case CompletedEvent(:final result):
          this.result.complete(result);
        case FailedEvent(:final error):
          this.result.completeError(error); // a VitalsError with code and message
        default:
          break;
      }
    });

    await session.start(); // camera + torch on, then positioning
  }

  Future<void> cancel() async {
    await _session?.cancelReading(reason: 'user_tapped_cancel');
  }

  Future<void> dispose() async {
    await _events?.cancel();
    await _session?.stop(); // idempotent; torch off, handle released
  }
}

void showResult(VitalsResult r) {
  if (r.quality == SignalQuality.withheld) {
    // Metrics may be null. Offer a retry rather than showing numbers.
    return;
  }
  final hr = r.heartRateBpm?.round();
  final rmssd = r.rmssdMs?.round();
  final rr = r.breathingRateBrpm?.toStringAsFixed(1);
  final estimate = (r.breathingRateConfidence ?? 0) < 0.5 ? ' (estimate)' : '';
  debugPrint('HR $hr bpm, HRV (RMSSD) $rmssd ms, breathing $rr brpm$estimate');
}