【Flutter】ビーコン信号の受信を行う方法ご紹介。

今回の記事はFlutterでビーコンの信号の送受信を行う方法に関してご紹介します。

基本的に公式のドキュメントに従ったものになりますのでかなり簡単なものになっております。公式版を日本語にして初心者用に改変したというかんじだと思っていただければ幸いです。

ではメインの記事に進んでいきます。

ビーコン信号を受信するためのライブラリご紹介
Flutterでビーコン取得を行うコード

ビーコン信号を受信するためのライブラリご紹介

ビーコン信号を受信するためのプラグインは「flutter_beacon」というものです。「pubspec.yaml」に下記を追加してください。

dependencies:
  flutter_beacon: ^0.3.0

「pub get」してプラグインの設定は完了です。

Flutterでビーコン取得を行うコード

下記が公式のサンプルになります。基本的に自身の使用するビーコンのUUIDを下記の「使用するビーコンのUUID」の箇所に記載するのみです。実際にbuildすると検出した際に画面に受信したものの状態が表示されます。

import 'dart:io';

import 'package:flutter/material.dart';
import 'dart:async';

import 'package:flutter/services.dart';
import 'package:flutter_beacon/flutter_beacon.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> with WidgetsBindingObserver {
  final StreamController<BluetoothState> streamController = StreamController();
  StreamSubscription<BluetoothState> _streamBluetooth;
  StreamSubscription<RangingResult> _streamRanging;
  final _regionBeacons = <Region, List<Beacon>>{};
  final _beacons = <Beacon>[];
  bool authorizationStatusOk = false;
  bool locationServiceEnabled = false;
  bool bluetoothEnabled = false;

  @override
  void initState() {
    WidgetsBinding.instance.addObserver(this);

    super.initState();

    listeningState();
  }

  listeningState() async {
    print('Listening to bluetooth state');
    _streamBluetooth = flutterBeacon
        .bluetoothStateChanged()
        .listen((BluetoothState state) async {
      print('BluetoothState = $state');
      streamController.add(state);

      switch (state) {
        case BluetoothState.stateOn:
          initScanBeacon();
          break;
        case BluetoothState.stateOff:
          await pauseScanBeacon();
          await checkAllRequirements();
          break;
      }
    });
  }

  checkAllRequirements() async {
    final bluetoothState = await flutterBeacon.bluetoothState;
    final bluetoothEnabled = bluetoothState == BluetoothState.stateOn;
    final authorizationStatus = await flutterBeacon.authorizationStatus;
    final authorizationStatusOk =
        authorizationStatus == AuthorizationStatus.allowed ||
            authorizationStatus == AuthorizationStatus.always;
    final locationServiceEnabled =
        await flutterBeacon.checkLocationServicesIfEnabled;

    setState(() {
      this.authorizationStatusOk = authorizationStatusOk;
      this.locationServiceEnabled = locationServiceEnabled;
      this.bluetoothEnabled = bluetoothEnabled;
    });
  }

  initScanBeacon() async {
    await flutterBeacon.initializeScanning;
    await checkAllRequirements();
    if (!authorizationStatusOk ||
        !locationServiceEnabled ||
        !bluetoothEnabled) {
      print('RETURNED, authorizationStatusOk=$authorizationStatusOk, '
          'locationServiceEnabled=$locationServiceEnabled, '
          'bluetoothEnabled=$bluetoothEnabled');
      return;
    }
    final regions = <Region>[
      Region(
        identifier: 'Cubeacon',
        proximityUUID: '[使用するビーコンのUUID]',
      ),
    ];

    if (_streamRanging != null) {
      if (_streamRanging.isPaused) {
        _streamRanging.resume();
        return;
      }
    }

    _streamRanging =
        flutterBeacon.ranging(regions).listen((RangingResult result) {
      print(result);
      if (result != null && mounted) {
        setState(() {
          _regionBeacons[result.region] = result.beacons;
          _beacons.clear();
          _regionBeacons.values.forEach((list) {
            _beacons.addAll(list);
          });
          _beacons.sort(_compareParameters);
        });
      }
    });
  }

  pauseScanBeacon() async {
    _streamRanging?.pause();
    if (_beacons.isNotEmpty) {
      setState(() {
        _beacons.clear();
      });
    }
  }

  int _compareParameters(Beacon a, Beacon b) {
    int compare = a.proximityUUID.compareTo(b.proximityUUID);

    if (compare == 0) {
      compare = a.major.compareTo(b.major);
    }

    if (compare == 0) {
      compare = a.minor.compareTo(b.minor);
    }

    return compare;
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) async {
    print('AppLifecycleState = $state');
    if (state == AppLifecycleState.resumed) {
      if (_streamBluetooth != null && _streamBluetooth.isPaused) {
        _streamBluetooth.resume();
      }
      await checkAllRequirements();
      if (authorizationStatusOk && locationServiceEnabled && bluetoothEnabled) {
        await initScanBeacon();
      } else {
        await pauseScanBeacon();
        await checkAllRequirements();
      }
    } else if (state == AppLifecycleState.paused) {
      _streamBluetooth?.pause();
    }
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    streamController?.close();
    _streamRanging?.cancel();
    _streamBluetooth?.cancel();
    flutterBeacon.close;

    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        brightness: Brightness.light,
        primaryColor: Colors.white,
      ),
      darkTheme: ThemeData(
        brightness: Brightness.dark,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Flutter Beacon'),
          centerTitle: false,
          actions: <Widget>[
            if (!authorizationStatusOk)
              IconButton(
                  icon: Icon(Icons.portable_wifi_off),
                  color: Colors.red,
                  onPressed: () async {
                    await flutterBeacon.requestAuthorization;
                  }),
            if (!locationServiceEnabled)
              IconButton(
                  icon: Icon(Icons.location_off),
                  color: Colors.red,
                  onPressed: () async {
                    if (Platform.isAndroid) {
                      await flutterBeacon.openLocationSettings;
                    } else if (Platform.isIOS) {

                    }
                  }),
            StreamBuilder<BluetoothState>(
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  final state = snapshot.data;

                  if (state == BluetoothState.stateOn) {
                    return IconButton(
                      icon: Icon(Icons.bluetooth_connected),
                      onPressed: () {},
                      color: Colors.lightBlueAccent,
                    );
                  }

                  if (state == BluetoothState.stateOff) {
                    return IconButton(
                      icon: Icon(Icons.bluetooth),
                      onPressed: () async {
                        if (Platform.isAndroid) {
                          try {
                            await flutterBeacon.openBluetoothSettings;
                          } on PlatformException catch (e) {
                            print(e);
                          }
                        } else if (Platform.isIOS) {

                        }
                      },
                      color: Colors.red,
                    );
                  }

                  return IconButton(
                    icon: Icon(Icons.bluetooth_disabled),
                    onPressed: () {},
                    color: Colors.grey,
                  );
                }

                return SizedBox.shrink();
              },
              stream: streamController.stream,
              initialData: BluetoothState.stateUnknown,
            ),
          ],
        ),
        body: _beacons == null || _beacons.isEmpty
            ? Center(child: CircularProgressIndicator())
            : ListView(
                children: ListTile.divideTiles(
                    context: context,
                    tiles: _beacons.map((beacon) {
                      return ListTile(
                        title: Text(beacon.proximityUUID),
                        subtitle: new Row(
                          mainAxisSize: MainAxisSize.max,
                          children: <Widget>[
                            Flexible(
                                child: Text(
                                    'Major: ${beacon.major}\nMinor: ${beacon.minor}',
                                    style: TextStyle(fontSize: 13.0)),
                                flex: 1,
                                fit: FlexFit.tight),
                            Flexible(
                                child: Text(
                                    'Accuracy: ${beacon.accuracy}m\nRSSI: ${beacon.rssi}',
                                    style: TextStyle(fontSize: 13.0)),
                                flex: 2,
                                fit: FlexFit.tight)
                          ],
                        ),
                      );
                    })).toList(),
              ),
      ),
    );
  }
}