Flutter Background Geolocation hello_world.dart https://shop.transistorsoft.com/blogs/news

flutter_background_geolocation_helloworld.dart

/**
* flutter_background_geolocation Hello World
* https://github.com/transistorsoft/flutter_background_geolocation
*/

import 'package:flutter/material.dart';
import 'package:flutter_background_geolocation/flutter_background_geolocation.dart' as bg;

////
// For pretty-printing location JSON.  Not a requirement of flutter_background_geolocation
//
import 'dart:convert';
JsonEncoder encoder = new JsonEncoder.withIndent("     ");
//
////

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'BackgroundGeolocation Demo',
      theme: new ThemeData(
        primarySwatch: Colors.amber,
      ),
      home: new MyHomePage(title: 'BackgroundGeolocation Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  bool _isMoving;
  bool _enabled;
  String _motionActivity;
  String _odometer;
  String _content;

  @override
  void initState() {
    _isMoving = false;
    _enabled = false;
    _content = '';
    _motionActivity = 'UNKNOWN';
    _odometer = '0';

    // 1.  Listen to events (See docs for all 12 available events).
    bg.BackgroundGeolocation.onLocation(_onLocation);
    bg.BackgroundGeolocation.onMotionChange(_onMotionChange);
    bg.BackgroundGeolocation.onActivityChange(_onActivityChange);
    bg.BackgroundGeolocation.onProviderChange(_onProviderChange);
    bg.BackgroundGeolocation.onConnectivityChange(_onConnectivityChange);

    // 2.  Configure the plugin
    bg.BackgroundGeolocation.ready(bg.Config(
        desiredAccuracy: bg.Config.DESIRED_ACCURACY_HIGH,
        distanceFilter: 10.0,
        stopOnTerminate: false,
        startOnBoot: true,
        debug: true,
        logLevel: bg.Config.LOG_LEVEL_VERBOSE,
        reset: true
    )).then((bg.State state) {
      setState(() {
        _enabled = state.enabled;
        _isMoving = state.isMoving;
      });
    });
  }

  void _onClickEnable(enabled) {
    if (enabled) {
      bg.BackgroundGeolocation.start().then((bg.State state) {
        print('[start] success $state');
        setState(() {
          _enabled = state.enabled;
          _isMoving = state.isMoving;
        });
      });
    } else {
      bg.BackgroundGeolocation.stop().then((bg.State state) {
        print('[stop] success: $state');
        // Reset odometer.
        bg.BackgroundGeolocation.setOdometer(0.0);

        setState(() {
          _odometer = '0.0';
          _enabled = state.enabled;
          _isMoving = state.isMoving;
        });
      });
    }
  }

  // Manually toggle the tracking state:  moving vs stationary
  void _onClickChangePace() {
    setState(() {
      _isMoving = !_isMoving;
    });
    print("[onClickChangePace] -> $_isMoving");

    bg.BackgroundGeolocation.changePace(_isMoving).then((bool isMoving) {
      print('[changePace] success $isMoving');
    }).catchError((e) {
      print('[changePace] ERROR: ' + e.code.toString());
    });
  }

  // Manually fetch the current position.
  void _onClickGetCurrentPosition() {
    bg.BackgroundGeolocation.getCurrentPosition(
        persist: false,     // <-- do not persist this location
        desiredAccuracy: 0, // <-- desire best possible accuracy
        timeout: 30000,     // <-- wait 30s before giving up.
        samples: 3          // <-- sample 3 location before selecting best.
    ).then((bg.Location location) {
      print('[getCurrentPosition] - $location');
    }).catchError((error) {
      print('[getCurrentPosition] ERROR: $error');
    });
  }

  ////
  // Event handlers
  //

  void _onLocation(bg.Location location) {
    print('[location] - $location');

    String odometerKM = (location.odometer / 1000.0).toStringAsFixed(1);

    setState(() {
      _content = encoder.convert(location.toMap());
      _odometer = odometerKM;
    });
  }

  void _onMotionChange(bg.Location location) {
    print('[motionchange] - $location');
  }

  void _onActivityChange(bg.ActivityChangeEvent event) {
    print('[activitychange] - $event');
    setState(() {
      _motionActivity = event.activity;
    });
  }

  void _onProviderChange(bg.ProviderChangeEvent event) {
    print('$event');

    setState(() {
      _content = encoder.convert(event.toMap());
    });
  }

  void _onConnectivityChange(bg.ConnectivityChangeEvent event) {
    print('$event');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Background Geolocation'),
        actions: <Widget>[
          Switch(
            value: _enabled,
            onChanged: _onClickEnable
          ),
        ]
      ),
      body: SingleChildScrollView(
          child: Text('$_content')
      ),
      bottomNavigationBar: BottomAppBar(
        child: Container(
          padding: const EdgeInsets.only(left: 5.0, right: 5.0),
          child: Row(
            mainAxisSize: MainAxisSize.max,
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              IconButton(
                icon: Icon(Icons.gps_fixed),
                onPressed: _onClickGetCurrentPosition,
              ),
              Text('$_motionActivity · $_odometer km'),
              MaterialButton(
                minWidth: 50.0,
                child: Icon((_isMoving) ? Icons.pause : Icons.play_arrow, color: Colors.white),
                color: (_isMoving) ? Colors.red : Colors.green,
                onPressed: _onClickChangePace
              )
            ]
          )
        )
      ),
    );
  }
}