flutter_blue_plus 1.11.0

Flutter plugin for connecting and communicationg with Bluetooth Low Energy devices, on Android, iOS, and MacOS.

example/lib/main.dart

// Copyright 2017, Paul DeMarco.
// All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:async';
import 'dart:io';
import 'dart:math';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_blue_plus/flutter_blue_plus.dart';
import 'package:permission_handler/permission_handler.dart';

import 'widgets.dart';

final snackBarKeyA = GlobalKey<ScaffoldMessengerState>();
final snackBarKeyB = GlobalKey<ScaffoldMessengerState>();
final snackBarKeyC = GlobalKey<ScaffoldMessengerState>();

void main() {
  if (Platform.isAndroid) {
    WidgetsFlutterBinding.ensureInitialized();
    [
      Permission.location,
      Permission.storage,
      Permission.bluetooth,
      Permission.bluetoothConnect,
      Permission.bluetoothScan
    ].request().then((status) {
      runApp(const FlutterBlueApp());
    });
  } else {
    runApp(const FlutterBlueApp());
  }
}

class FlutterBlueApp extends StatelessWidget {
  const FlutterBlueApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      color: Colors.lightBlue,
      home: StreamBuilder<BluetoothAdapterState>(
          stream: FlutterBluePlus.adapterState,
          initialData: BluetoothAdapterState.unknown,
          builder: (c, snapshot) {
            final adapterState = snapshot.data;
            if (adapterState == BluetoothAdapterState.on) {
              return const FindDevicesScreen();
            }
            return BluetoothOffScreen(adapterState: adapterState);
          }),
    );
  }
}

class BluetoothOffScreen extends StatelessWidget {
  const BluetoothOffScreen({Key? key, this.adapterState}) : super(key: key);

  final BluetoothAdapterState? adapterState;

  @override
  Widget build(BuildContext context) {
    return ScaffoldMessenger(
      key: snackBarKeyA,
      child: Scaffold(
        backgroundColor: Colors.lightBlue,
        body: Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              const Icon(
                Icons.bluetooth_disabled,
                size: 200.0,
                color: Colors.white54,
              ),
              Text(
                'Bluetooth Adapter is ${adapterState != null ? adapterState.toString().split(".").last : 'not available'}.',
                style: Theme.of(context).primaryTextTheme.titleSmall?.copyWith(color: Colors.white),
              ),
              ElevatedButton(
                child: const Text('TURN ON'),
                onPressed: () async {
                  try {
                    if (Platform.isAndroid) {
                      await FlutterBluePlus.turnOn();
                    }
                  } catch (e) {
                    final snackBar = SnackBar(content: Text(prettyException("Error Turning On:", e)));
                    snackBarKeyA.currentState?.showSnackBar(snackBar);
                  }
                },
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class FindDevicesScreen extends StatelessWidget {
  const FindDevicesScreen({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ScaffoldMessenger(
      key: snackBarKeyB,
      child: Scaffold(
        appBar: AppBar(
          title: const Text('Find Devices'),
          actions: [
            if (Platform.isAndroid)
              ElevatedButton(
                child: const Text('TURN OFF'),
                style: ElevatedButton.styleFrom(
                  backgroundColor: Colors.black,
                  foregroundColor: Colors.white,
                ),
                onPressed: () async {
                  try {
                    if (Platform.isAndroid) {
                      await FlutterBluePlus.turnOff();
                    }
                  } catch (e) {
                    final snackBar = SnackBar(content: Text(prettyException("Error Turning On:", e)));
                    snackBarKeyB.currentState?.showSnackBar(snackBar);
                  }
                },
              ),
          ],
        ),
        body: RefreshIndicator(
          onRefresh: () => FlutterBluePlus.startScan(
              timeout: const Duration(seconds: 15),
              androidUsesFineLocation: false),
          child: SingleChildScrollView(
            child: Column(
              children: <Widget>[
                StreamBuilder<List<BluetoothDevice>>(
                  stream: Stream.periodic(const Duration(seconds: 2))
                      .asyncMap((_) => FlutterBluePlus.connectedSystemDevices),
                  initialData: const [],
                  builder: (c, snapshot) => Column(
                    children: (snapshot.data ?? [])
                        .map((d) => ListTile(
                              title: Text(d.localName),
                              subtitle: Text(d.remoteId.toString()),
                              trailing: StreamBuilder<BluetoothConnectionState>(
                                stream: d.connectionState,
                                initialData: BluetoothConnectionState.disconnected,
                                builder: (c, snapshot) {
                                  if (snapshot.data == BluetoothConnectionState.connected) {
                                    return ElevatedButton(
                                      child: const Text('OPEN'),
                                      onPressed: () => Navigator.of(context)
                                          .push(MaterialPageRoute(builder: (context) => DeviceScreen(device: d))),
                                    );
                                  }
                                  if (snapshot.data == BluetoothConnectionState.disconnected) {
                                    return ElevatedButton(
                                        child: const Text('CONNECT'),
                                        onPressed: () {
                                          Navigator.of(context).push(MaterialPageRoute(builder: (context) {
                                            d.connect().catchError((e) {
                                              final snackBar =
                                                  SnackBar(content: Text(prettyException("Connect Error:", e)));
                                              snackBarKeyB.currentState?.showSnackBar(snackBar);
                                            });
                                            return DeviceScreen(device: d);
                                          }));
                                        });
                                  }
                                  return Text(snapshot.data.toString().toUpperCase().split('.')[1]);
                                },
                              ),
                            ))
                        .toList(),
                  ),
                ),
                StreamBuilder<List<ScanResult>>(
                  stream: FlutterBluePlus.scanResults,
                  initialData: const [],
                  builder: (c, snapshot) => Column(
                    children: (snapshot.data ?? [])
                        .map(
                          (r) => ScanResultTile(
                            result: r,
                            onTap: () => Navigator.of(context).push(MaterialPageRoute(builder: (context) {
                              r.device.connect().catchError((e) {
                                final snackBar = SnackBar(content: Text(prettyException("Connect Error:", e)));
                                snackBarKeyB.currentState?.showSnackBar(snackBar);
                              });
                              return DeviceScreen(device: r.device);
                            })),
                          ),
                        )
                        .toList(),
                  ),
                ),
              ],
            ),
          ),
        ),
        floatingActionButton: StreamBuilder<bool>(
          stream: FlutterBluePlus.isScanning,
          initialData: false,
          builder: (c, snapshot) {
            if (snapshot.data ?? false) {
              return FloatingActionButton(
                child: const Icon(Icons.stop),
                onPressed: () async {
                  try {
                    FlutterBluePlus.stopScan();
                  } catch (e) {
                    final snackBar = SnackBar(content: Text(prettyException("Stop Scan Error:", e)));
                    snackBarKeyB.currentState?.showSnackBar(snackBar);
                  }
                  ;
                },
                backgroundColor: Colors.red,
              );
            } else {
              return FloatingActionButton(
                  child: const Icon(Icons.search),
                  onPressed: () async {
                    try {
                      FlutterBluePlus.startScan(
                          timeout: const Duration(seconds: 15),
                          androidUsesFineLocation: false);
                    } catch (e) {
                      final snackBar = SnackBar(content: Text(prettyException("Start Scan Error:", e)));
                      snackBarKeyB.currentState?.showSnackBar(snackBar);
                    }
                  });
            }
          },
        ),
      ),
    );
  }
}

class DeviceScreen extends StatelessWidget {
  const DeviceScreen({Key? key, required this.device}) : super(key: key);

  final BluetoothDevice device;

  List<int> _getRandomBytes() {
    final math = Random();
    return [math.nextInt(255), math.nextInt(255), math.nextInt(255), math.nextInt(255)];
  }

  List<Widget> _buildServiceTiles(BuildContext context, List<BluetoothService> services) {
    return services
        .map(
          (s) => ServiceTile(
            service: s,
            characteristicTiles: s.characteristics
                .map(
                  (c) => CharacteristicTile(
                    characteristic: c,
                    onReadPressed: () async {
                      try {
                        await c.read();
                      } catch (e) {
                        final snackBar = SnackBar(content: Text(prettyException("Read Error:", e)));
                        snackBarKeyC.currentState?.showSnackBar(snackBar);
                      }
                    },
                    onWritePressed: () async {
                      try {
                        await c.write(_getRandomBytes(), withoutResponse: true);
                        if (c.properties.read) {
                          await c.read();
                        }
                      } catch (e) {
                        final snackBar = SnackBar(content: Text(prettyException("Write Error:", e)));
                        snackBarKeyC.currentState?.showSnackBar(snackBar);
                      }
                    },
                    onNotificationPressed: () async {
                      try {
                        await c.setNotifyValue(c.isNotifying == false);
                        if (c.properties.read) {
                          await c.read();
                        }
                      } catch (e) {
                        final snackBar = SnackBar(content: Text(prettyException("Subscribe Error:", e)));
                        snackBarKeyC.currentState?.showSnackBar(snackBar);
                      }
                    },
                    descriptorTiles: c.descriptors
                        .map(
                          (d) => DescriptorTile(
                            descriptor: d,
                            onReadPressed: () async {
                              try {
                                await d.read();
                              } catch (e) {
                                final snackBar = SnackBar(content: Text(prettyException("Read Error:", e)));
                                snackBarKeyC.currentState?.showSnackBar(snackBar);
                              }
                            },
                            onWritePressed: () async {
                              try {
                                await d.write(_getRandomBytes());
                              } catch (e) {
                                final snackBar = SnackBar(content: Text(prettyException("Write Error:", e)));
                                snackBarKeyC.currentState?.showSnackBar(snackBar);
                              }
                            },
                          ),
                        )
                        .toList(),
                  ),
                )
                .toList(),
          ),
        )
        .toList();
  }

  @override
  Widget build(BuildContext context) {
    return ScaffoldMessenger(
      key: snackBarKeyC,
      child: Scaffold(
        appBar: AppBar(
          title: Text(device.localName),
          actions: <Widget>[
            StreamBuilder<BluetoothConnectionState>(
              stream: device.connectionState,
              initialData: BluetoothConnectionState.connecting,
              builder: (c, snapshot) {
                VoidCallback? onPressed;
                String text;
                switch (snapshot.data) {
                  case BluetoothConnectionState.connected:
                    onPressed = () async {
                      try {
                        await device.disconnect();
                      } catch (e) {
                        final snackBar = SnackBar(content: Text(prettyException("Disconnect Error:", e)));
                        snackBarKeyC.currentState?.showSnackBar(snackBar);
                      }
                    };
                    text = 'DISCONNECT';
                    break;
                  case BluetoothConnectionState.disconnected:
                    onPressed = () async {
                      try {
                        await device.connect();
                      } catch (e) {
                        final snackBar = SnackBar(content: Text(prettyException("Connect Error:", e)));
                        snackBarKeyC.currentState?.showSnackBar(snackBar);
                      }
                    };
                    text = 'CONNECT';
                    break;
                  default:
                    onPressed = null;
                    text = snapshot.data.toString().split(".").last.toUpperCase();
                    break;
                }
                return TextButton(
                    onPressed: onPressed,
                    child: Text(
                      text,
                      style: Theme.of(context).primaryTextTheme.labelLarge?.copyWith(color: Colors.white),
                    ));
              },
            )
          ],
        ),
        body: SingleChildScrollView(
          child: Column(
            children: <Widget>[
              StreamBuilder<BluetoothConnectionState>(
                stream: device.connectionState,
                initialData: BluetoothConnectionState.connecting,
                builder: (c, snapshot) => ListTile(
                  leading: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      snapshot.data == BluetoothConnectionState.connected
                          ? const Icon(Icons.bluetooth_connected)
                          : const Icon(Icons.bluetooth_disabled),
                      snapshot.data == BluetoothConnectionState.connected
                          ? StreamBuilder<int>(
                              stream: rssiStream(),
                              builder: (context, snapshot) {
                                return Text(snapshot.hasData ? '${snapshot.data}dBm' : '',
                                    style: Theme.of(context).textTheme.bodySmall);
                              })
                          : Text('', style: Theme.of(context).textTheme.bodySmall),
                    ],
                  ),
                  title: Text('Device is ${snapshot.data.toString().split('.')[1]}.'),
                  subtitle: Text('${device.remoteId}'),
                  trailing: StreamBuilder<bool>(
                    stream: device.isDiscoveringServices,
                    initialData: false,
                    builder: (c, snapshot) => IndexedStack(
                      index: (snapshot.data ?? false) ? 1 : 0,
                      children: <Widget>[
                        TextButton(
                          child: const Text("Discover Services"),
                          onPressed: () async {
                            try {
                              await device.discoverServices();
                            } catch (e) {
                              final snackBar = SnackBar(content: Text(prettyException("Discover Services Error:", e)));
                              snackBarKeyC.currentState?.showSnackBar(snackBar);
                            }
                          },
                        ),
                        const IconButton(
                          icon: SizedBox(
                            child: CircularProgressIndicator(
                              valueColor: AlwaysStoppedAnimation(Colors.grey),
                            ),
                            width: 18.0,
                            height: 18.0,
                          ),
                          onPressed: null,
                        )
                      ],
                    ),
                  ),
                ),
              ),
              StreamBuilder<int>(
                stream: device.mtu,
                initialData: 0,
                builder: (c, snapshot) => ListTile(
                  title: const Text('MTU Size'),
                  subtitle: Text('${snapshot.data} bytes'),
                  trailing: IconButton(
                      icon: const Icon(Icons.edit),
                      onPressed: () async {
                        try {
                          await device.requestMtu(223);
                        } catch (e) {
                          final snackBar = SnackBar(content: Text(prettyException("Change Mtu Error:", e)));
                          snackBarKeyC.currentState?.showSnackBar(snackBar);
                        }
                      }),
                ),
              ),
              StreamBuilder<List<BluetoothService>>(
                stream: device.servicesStream,
                initialData: const [],
                builder: (c, snapshot) {
                  return Column(
                    children: _buildServiceTiles(context, snapshot.data ?? []),
                  );
                },
              ),
            ],
          ),
        ),
      ),
    );
  }

  Stream<int> rssiStream({Duration frequency = const Duration(seconds: 1)}) async* {
    var isConnected = true;
    final subscription = device.connectionState.listen((v) {
      isConnected = v == BluetoothConnectionState.connected;
    });
    while (isConnected) {
      try {
        yield await device.readRssi();
      } catch (e) {
        print("Error reading RSSI: $e");
        break;
      }
      await Future.delayed(frequency);
    }
    // Device disconnected, stopping RSSI stream
    subscription.cancel();
  }
}

String prettyException(String prefix, dynamic e) {
  if (e is FlutterBluePlusException) {
    return "$prefix ${e.errorString}";
  } else if (e is PlatformException) {
    return "$prefix ${e.message}";
  }
  return e.toString();
}