基本的な例

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:tracelet/tracelet.dart';
 
// 1. The Headless Task must be a top-level function.
// It will run when the app is completely terminated and a location event occurs.
@pragma('vm:entry-point')
void headlessTask(HeadlessEvent event) {
  print('[Headless] Received event: ${event.name}');
  
  if (event is LocationEvent) {
    print('[Headless] Location: ${event.location.coords.latitude}, ${event.location.coords.longitude}');
  }
}
 
void main() async {
  WidgetsFlutterBinding.ensureInitialized();
 
  // 2. Register the Headless Task early
  Tracelet.registerHeadlessTask(headlessTask);
 
  runApp(const MyApp());
}
 
class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);
 
  @override
  State<MyApp> createState() => _MyAppState();
}
 
class _MyAppState extends State<MyApp> {
  String _locationStatus = "Unknown";
  
  @override
  void initState() {
    super.initState();
    _initTracelet();
  }
 
  Future<void> _initTracelet() async {
    // 3. Request permissions required natively via Tracelet
    if (Platform.isAndroid) {
      await Tracelet.requestNotificationAuthorization();
      await Tracelet.requestMotionAuthorization();
    }
    
    final authStatus = await Tracelet.requestLocationAuthorization();
    if (authStatus == AuthorizationStatus.deniedForever) {
      setState(() => _locationStatus = "Permissions Denied");
      return;
    }
 
    // 4. Subscribe to Location Events in the UI
    Tracelet.onLocation((location) {
      setState(() {
        _locationStatus = "${location.coords.latitude}, ${location.coords.longitude}";
      });
    });
 
    // 5. Configure and Start Tracelet
    await Tracelet.ready(Config.balanced(
      stopOnTerminate: false,
      startOnBoot: true,
      android: AndroidConfig(
        foregroundService: ForegroundServiceConfig(
          contentTitle: "Tracelet Active",
          contentText: "Tracking location in the background",
          notificationIcon: "mipmap/ic_launcher",
        ),
      ),
    ));
 
    await Tracelet.start();
  }
 
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: const Text('Tracelet Basic Example')),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              const Text("Latest Location:", style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold)),
              const SizedBox(height: 10),
              Text(_locationStatus, style: const TextStyle(fontSize: 16)),
            ],
          ),
        ),
      ),
    );
  }
}