bluetooth_low_energy/example/lib/main.dart

import 'dart:async';
import 'dart:convert';

import 'package:bluetooth_low_energy/bluetooth_low_energy.dart';
import 'package:convert/convert.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() {
  final app = MaterialApp(
    theme: ThemeData(
      fontFamily: 'IBM Plex Mono',
    ),
    home: HomeView(),
    routes: {
      'gatt': (context) => GattView(),
    },
  );
  runApp(app);
}

class HomeView extends StatefulWidget {
  const HomeView({Key? key}) : super(key: key);

  @override
  _HomeViewState createState() => _HomeViewState();
}

class _HomeViewState extends State<HomeView> with WidgetsBindingObserver {
  final ValueNotifier<bool> state;
  final ValueNotifier<bool> discovering;
  final ValueNotifier<Map<UUID, Discovery>> discoveries;
  late StreamSubscription<BluetoothState> stateSubscription;
  late StreamSubscription<Discovery> discoverySubscription;

  _HomeViewState()
      : state = ValueNotifier(false),
        discovering = ValueNotifier(false),
        discoveries = ValueNotifier({});

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance!.addObserver(this);
    setup();
  }

  void setup() async {
    final state = await central.state;
    this.state.value = state == BluetoothState.poweredOn;
    stateSubscription = central.stateChanged.listen(
      (state) {
        this.state.value = state == BluetoothState.poweredOn;
        final invisible = !ModalRoute.of(context)!.isCurrent;
        if (invisible) return;
        if (this.state.value) {
          startDiscovery();
        } else {
          discovering.value = false;
        }
      },
    );
    discoverySubscription = central.discovered.listen(
      (discovery) {
        discoveries.value[discovery.uuid] = discovery;
        discoveries.value = {...discoveries.value};
      },
    );
    if (this.state.value) {
      startDiscovery();
    }
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    super.didChangeAppLifecycleState(state);
  }

  @override
  void dispose() {
    stopDiscovery();
    stateSubscription.cancel();
    discoverySubscription.cancel();
    discoveries.dispose();
    discovering.dispose();
    WidgetsBinding.instance!.removeObserver(this);
    print('dispose');
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home'),
      ),
      body: bodyView,
    );
  }

  void startDiscovery() async {
    if (discovering.value || !state.value) return;
    await central.startDiscovery();
    discovering.value = true;
  }

  void stopDiscovery() async {
    if (!discovering.value || !state.value) return;
    await central.stopDiscovery();
    discoveries.value = {};
    discovering.value = false;
  }

  void showAdvertisements(Discovery discovery) {
    showModalBottomSheet(
      context: context,
      backgroundColor: Colors.transparent,
      elevation: 0.0,
      builder: (context) => buildAdvertisementsView(discovery),
    );
  }

  void showGattView(Discovery discovery) async {
    stopDiscovery();
    await Navigator.of(context).pushNamed(
      'gatt',
      arguments: discovery.uuid,
    );
    startDiscovery();
  }
}

extension on _HomeViewState {
  Widget get bodyView {
    return ValueListenableBuilder(
      valueListenable: state,
      builder: (context, bool state, child) =>
          state ? discoveriesView : closedView,
    );
  }

  Widget get closedView {
    return Center(
      child: Text('蓝牙未开启'),
    );
  }

  Widget get discoveriesView {
    return RefreshIndicator(
      onRefresh: () async => discoveries.value = {},
      child: ValueListenableBuilder(
        valueListenable: discoveries,
        builder: (context, Map<UUID, Discovery> discoveries, child) {
          return ListView.builder(
            padding: EdgeInsets.all(6.0),
            itemCount: discoveries.length,
            itemBuilder: (context, i) {
              final discovery = discoveries.values.elementAt(i);
              return Card(
                color: discovery.connectable ? Colors.amber : Colors.grey,
                clipBehavior: Clip.antiAlias,
                shape: BeveledRectangleBorder(
                  borderRadius: BorderRadius.only(
                      topRight: Radius.circular(12.0),
                      bottomLeft: Radius.circular(12.0)),
                ),
                margin: EdgeInsets.all(6.0),
                key: Key(discovery.uuid.name),
                child: InkWell(
                  splashColor: Colors.purple,
                  onTap: discovery.connectable
                      ? () => showGattView(discovery)
                      : null,
                  onLongPress: () => showAdvertisements(discovery),
                  child: Container(
                    height: 100.0,
                    padding: EdgeInsets.all(12.0),
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.spaceAround,
                      children: [
                        Expanded(
                          flex: 3,
                          child: Column(
                            mainAxisAlignment: MainAxisAlignment.center,
                            children: [
                              Text(discovery.name ?? 'NaN'),
                              Text(
                                discovery.uuid.name,
                                softWrap: true,
                              ),
                            ],
                          ),
                        ),
                        Expanded(
                          flex: 1,
                          child: Text(
                            discovery.rssi.toString(),
                            textAlign: TextAlign.center,
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
              );
            },
          );
        },
      ),
    );
  }

  Widget buildAdvertisementsView(Discovery discovery) {
    final widgets = <Widget>[
      Row(
        children: [
          Text('Type'),
          Expanded(
            child: Center(
              child: Text('Value'),
            ),
          ),
        ],
      ),
      Divider(),
    ];
    for (final entry in discovery.advertisements.entries) {
      final key = entry.key.toRadixString(16).padLeft(2, '0');
      final value = hex.encode(entry.value);
      final widget = Row(
        children: [
          Text('0x$key'),
          Container(width: 12.0),
          Expanded(
            child: Text(
              '$value',
              softWrap: true,
            ),
          ),
        ],
      );
      widgets.add(widget);
      if (entry.key != discovery.advertisements.entries.last.key) {
        final divider = Divider();
        widgets.add(divider);
      }
    }
    return Container(
      margin: const EdgeInsets.all(12.0),
      child: Material(
        elevation: 1.0,
        shape: BeveledRectangleBorder(
          borderRadius: BorderRadius.only(
            topLeft: Radius.circular(12.0),
            bottomRight: Radius.circular(12.0),
          ),
        ),
        clipBehavior: Clip.antiAlias,
        child: Padding(
          padding: const EdgeInsets.all(12.0),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: widgets,
          ),
        ),
      ),
    );
  }
}

class GattView extends StatefulWidget {
  const GattView({Key? key}) : super(key: key);

  @override
  _GattViewState createState() => _GattViewState();
}

class _GattViewState extends State<GattView> {
  final ValueNotifier<ConnectionState> state;
  GATT? gatt;
  StreamSubscription? connectionLostSubscription;
  final ValueNotifier<GattService?> service;
  final ValueNotifier<GattCharacteristic?> characteristic;
  final TextEditingController writeController;
  final ValueNotifier<Map<GattCharacteristic, StreamSubscription>> notifies;
  final ValueNotifier<List<String>> logs;

  late UUID uuid;

  _GattViewState()
      : state = ValueNotifier(ConnectionState.disconnected),
        service = ValueNotifier(null),
        characteristic = ValueNotifier(null),
        writeController = TextEditingController(),
        notifies = ValueNotifier({}),
        logs = ValueNotifier([]);

  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    uuid = ModalRoute.of(context)!.settings.arguments as UUID;
    return Scaffold(
      appBar: AppBar(
        title: Text(uuid.name),
        actions: [
          changeStateView,
        ],
      ),
      body: bodyView,
    );
  }

  void Function()? disposeListener;

  @override
  void dispose() {
    super.dispose();

    if (state.value != ConnectionState.disconnected) {
      disposeListener ??= () => disposeGATT();
      state.addListener(disposeListener!);
      if (state.value == ConnectionState.connected) {
        disconnect();
      }
    } else {
      state.dispose();
      service.dispose();
      characteristic.dispose();
      notifies.dispose();
      logs.dispose();
    }
  }

  void disposeGATT() {
    switch (state.value) {
      case ConnectionState.connected:
        disconnect();
        break;
      case ConnectionState.disconnected:
        state.removeListener(disposeListener!);
        state.dispose();
        service.dispose();
        characteristic.dispose();
        notifies.dispose();
        logs.dispose();
        break;
      default:
        break;
    }
  }

  void connect() async {
    try {
      state.value = ConnectionState.connecting;
      gatt = await central.connect(uuid);
      state.value = ConnectionState.connected;
      connectionLostSubscription = gatt!.connectionLost.listen(
        (errorCode) async {
          for (var subscription in notifies.value.values) {
            await subscription.cancel();
          }
          await connectionLostSubscription!.cancel();
          gatt = null;
          connectionLostSubscription = null;
          service.value = null;
          characteristic.value = null;
          notifies.value.clear();
          logs.value.clear();
          state.value = ConnectionState.disconnected;
        },
      );
    } on PlatformException {
      state.value = ConnectionState.disconnected;
    }
  }

  void disconnect() async {
    try {
      state.value = ConnectionState.disconnecting;
      await gatt!.disconnect();
      for (var subscription in notifies.value.values) {
        await subscription.cancel();
      }
      await connectionLostSubscription!.cancel();
      gatt = null;
      connectionLostSubscription = null;
      service.value = null;
      characteristic.value = null;
      notifies.value.clear();
      logs.value.clear();
      state.value = ConnectionState.disconnected;
    } on PlatformException {
      state.value = ConnectionState.connected;
    }
  }
}

extension on _GattViewState {
  Widget get changeStateView {
    return ValueListenableBuilder(
      valueListenable: state,
      builder: (context, ConnectionState stateValue, child) {
        void Function()? onPressed;
        String data;
        switch (stateValue) {
          case ConnectionState.disconnected:
            onPressed = connect;
            data = '连接';
            break;
          case ConnectionState.connecting:
            data = '连接';
            break;
          case ConnectionState.connected:
            onPressed = disconnect;
            data = '断开';
            break;
          case ConnectionState.disconnecting:
            data = '断开';
            break;
          default:
            data = '';
            break;
        }
        return TextButton(
          onPressed: onPressed,
          style: TextButton.styleFrom(
            primary: Colors.white,
          ),
          child: Text(data),
        );
      },
    );
  }

  Widget get bodyView {
    return ValueListenableBuilder(
      valueListenable: state,
      builder: (context, ConnectionState stateValue, child) {
        switch (stateValue) {
          case ConnectionState.disconnected:
            return disconnectedView;
          case ConnectionState.connecting:
            return connectingView;
          case ConnectionState.connected:
            return connectedView;
          case ConnectionState.disconnecting:
            return disconnectingView;
          default:
            throw UnimplementedError();
        }
      },
    );
  }

  Widget get disconnectedView {
    return Center(
      child: Text('未连接'),
    );
  }

  Widget get connectingView {
    return Center(
      child: Text('正在建立连接'),
    );
  }

  Widget get connectedView {
    return ValueListenableBuilder(
      valueListenable: service,
      builder: (context, GattService? serviceValue, child) {
        final services = gatt!.services.values
            .map((service) => DropdownMenuItem<GattService>(
                  value: service,
                  child: Text(
                    service.uuid.name,
                    softWrap: false,
                  ),
                ))
            .toList();
        final serviceView = DropdownButton<GattService>(
          isExpanded: true,
          hint: Text('选择服务'),
          value: serviceValue,
          items: services,
          onChanged: (value) {
            service.value = value;
            characteristic.value = null;
          },
        );
        final views = <Widget>[serviceView];
        if (serviceValue != null) {
          final characteristics = serviceValue.characteristics.values
              .map((characteristic) => DropdownMenuItem(
                    value: characteristic,
                    child: Text(
                      characteristic.uuid.name,
                      softWrap: false,
                    ),
                  ))
              .toList();
          final characteristicView = ValueListenableBuilder(
            valueListenable: characteristic,
            builder: (context, GattCharacteristic? characteristicValue, child) {
              final canWrite = characteristicValue != null &&
                  (characteristicValue.canWrite ||
                      characteristicValue.canWriteWithoutResponse);
              final canRead =
                  characteristicValue != null && characteristicValue.canRead;
              final canNotify =
                  characteristicValue != null && characteristicValue.canNotify;
              final readAndNotifyView = Row(
                mainAxisAlignment: MainAxisAlignment.end,
                children: [
                  IconButton(
                    onPressed: canRead
                        ? () async {
                            final value = await characteristicValue!.read();
                            final time = DateTime.now().display;
                            final log = '[$time][READ] ${hex.encode(value)}';
                            logs.value = [...logs.value, log];
                          }
                        : null,
                    icon: Icon(Icons.archive),
                  ),
                  ValueListenableBuilder(
                      valueListenable: notifies,
                      builder: (context,
                          Map<GattCharacteristic, StreamSubscription>
                              notifiesValue,
                          child) {
                        final notifying =
                            notifiesValue.containsKey(characteristicValue);
                        return IconButton(
                          onPressed: canNotify
                              ? () async {
                                  if (notifying) {
                                    await characteristicValue!.notify(false);
                                    await notifiesValue
                                        .remove(characteristicValue)!
                                        .cancel();
                                  } else {
                                    await characteristicValue!.notify(true);
                                    notifiesValue[characteristicValue] =
                                        characteristicValue.valueChanged
                                            .listen((value) {
                                      final time = DateTime.now().display;
                                      final log =
                                          '[$time][NOTIFY] ${hex.encode(value)}';
                                      logs.value = [...logs.value, log];
                                    });
                                  }
                                  notifies.value = {...notifiesValue};
                                }
                              : null,
                          icon: Icon(
                            Icons.notifications,
                            color: notifying ? Colors.blue : null,
                          ),
                        );
                      }),
                ],
              );
              final controllerView = TextField(
                controller: writeController,
                decoration: InputDecoration(
                  hintText: 'MTU: ${gatt!.maximumWriteLength}',
                  suffixIcon: IconButton(
                    onPressed: canWrite
                        ? () {
                            final value = utf8.encode(writeController.text);
                            final withoutResponse =
                                !characteristicValue!.canWrite;
                            characteristicValue.write(value,
                                withoutResponse: withoutResponse);
                          }
                        : null,
                    icon: Icon(Icons.send),
                  ),
                ),
              );
              return Column(
                children: [
                  DropdownButton<GattCharacteristic>(
                    isExpanded: true,
                    hint: Text('选择特征值'),
                    value: characteristicValue,
                    items: characteristics,
                    onChanged: (value) => characteristic.value = value,
                  ),
                  readAndNotifyView,
                  controllerView,
                ],
              );
            },
          );
          views.add(characteristicView);
        }
        final loggerView = Expanded(
          child: Padding(
            padding: const EdgeInsets.symmetric(vertical: 12.0),
            child: ValueListenableBuilder(
                valueListenable: logs,
                builder: (context, List<String> logsValue, child) {
                  return ListView.builder(
                    itemCount: logsValue.length,
                    itemBuilder: (context, i) {
                      final log = logsValue[i];
                      return Text(log);
                    },
                  );
                }),
          ),
        );
        views.add(loggerView);
        return Container(
          padding: EdgeInsets.symmetric(horizontal: 12.0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: views,
          ),
        );
      },
    );
  }

  Widget get disconnectingView {
    return Center(
      child: Text('正在断开连接'),
    );
  }
}

extension on DateTime {
  String get display {
    final hh = hour.toString().padLeft(2, '0');
    final mm = minute.toString().padLeft(2, '0');
    final ss = second.toString().padLeft(2, '0');
    return '$hh:$mm:$ss';
  }
}

enum ConnectionState {
  disconnected,
  connecting,
  connected,
  disconnecting,
}