flutter_google_track_and_trace/example/lib/main.dart

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

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

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

  @override
  State<TrackTraceDemo> createState() => _TrackTraceDemoState();
}

class _TrackTraceDemoState extends State<TrackTraceDemo> {
  TrackTraceController? controller;

  @override
  void initState() {
    Timer.periodic(const Duration(seconds: 5), (_) {
      moveAlongRoute();
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: (controller == null || controller!.route == null)
            ? const Text('TrackTrace example')
            : Text(
                '${controller!.route!.duration} seconds, afstand: '
                '${controller!.route!.distance / 1000} km',
              ),
      ),
      body: GoogleTrackTraceMap(
        startPosition: const Marker(
          markerId: MarkerId('Start locatie'),
          position: LatLng(52.356057, 4.897540),
        ),
        destinationPosition: const Marker(
          markerId: MarkerId('Bestemming Locatie'),
          position: LatLng(52.364709, 4.877157),
        ),
        googleAPIKey: 'AIzaSyDaxZX8TeQeVf5tW-D6A66WLl20arbWV6c',
        travelMode: TravelMode.bicycling,
        mapType: MapType.satellite,
        routeUpdateInterval: 60,
        timerPrecision: TimePrecision.everySecond,
        zoomGesturesEnabled: true,
        line: const Polyline(
          polylineId: PolylineId('test route'),
          color: Colors.purple,
          width: 5,
        ),
        onMapCreated: (ctr) => {
          controller = ctr,
          ctr.addListener(() {
            setState(() {});
          }),
        },
      ),
    );
  }

  void getRandomPointOnMap() {
    // 51.989909, 6.234950 NW
    // 51.939909, 6.314950 SE
    if (controller != null) {
      controller!.start = Marker(
        markerId: const MarkerId('Start Locatie'),
        position: LatLng(
          51.93 + Random().nextDouble() * 0.06,
          6.23 + Random().nextDouble() * 0.08,
        ),
      );
    }
  }

  void moveAlongRoute() {
    if (controller != null &&
        controller!.route != null &&
        controller!.route!.line.length > 1) {
      controller!.start = Marker(
        markerId: const MarkerId('Start Locatie'),
        position: LatLng(
          controller!.route!.line[1].latitude,
          controller!.route!.line[1].longitude,
        ),
      );
    }
  }
}

void main() {
  runApp(const MaterialApp(home: TrackTraceDemo()));
}