Navigate Route

In this guide you will learn how to compute a route between a departure point and a destination point, render the route on an interactive map, and then navigate along the route.

Setup

First, get an API key token, see the Getting Started guide.

Prerequisites

Make sure you completed the Environment Setup - Flutter Examples guide before starting this guide.

Build and run

Go to the navigate_route directory, within the flutter examples directory - that is the name of this example project.

Note - the gem_kit directory containing the Maps SDK for Flutter should be in the plugins directory of the example, e.g. example_pathname/plugins/gem_kit - see the environment setup guide above. Replace example_pathname with the actual example path name, such as address_search

Download project dependencies:

flutter upgrade

run the following terminal commands in the project directory, where the pubspec.yaml file is located:

flutter clean

flutter pub get

Run the example:

Android

First, verify that the ANDROID_SDK_ROOT environment variable is set to the root path of your android SDK.

In android/app/src/main/AndroidManifest.xml add the location permissions required for actual navigation, below the top <manifest xmlns:android line, as shown:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />

In android/build.gradle add the maven {} block as shown, within the allprojects {} block, for both debug and release builds, without the line numbers, those are for reference:

allprojects {
    repositories {
        google()
        mavenCentral()
        maven {
           url "${rootDir}/../plugins/gem_kit/android/build"
        }
    }
}

in android/app/build.gradle within the android {} block, in the defaultConfig {} block, the android SDK version minSdk must be set as shown below.

Additionally, for release builds, in android/app/build.gradle, within the android {} block, add the buildTypes {} block as shown:

Replace example_pathname with the actual example pathname, such as center_coordinates

android {
    defaultConfig {
        applicationId "com.magiclane.gem_kit.examples.example_pathname"
        minSdk 21
        targetSdk flutter.targetSdk
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }
    buildTypes {
        release {
            minifyEnabled false
            shrinkResources false

            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

Then run the project:

flutter run --debug

or

flutter run --release

iOS

In the ios/Podfile configuration text file, at the top, set the minimum ios platform to 13 like this:

platform :ios, '13.0'

Also in the ios/Podfile configuration text file, add the location permissions required for actual navigation, at the end of the file, as shown:

post_install do |installer|
  installer.pods_project.targets.each do |target|
    flutter_additional_ios_build_settings(target)

    target.build_configurations.each do |config|
      config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= [
        '$(inherited)',
        ## dart: [PermissionGroup.location, PermissionGroup.locationAlways, PermissionGroup.locationWhenInUse]
         'PERMISSION_LOCATION=1',
      ]
    end
  end
end

In the ios/Runner/Info.plist configuration text file, add the following lines inside the <dict> </dict> block:

<key>NSLocationWhenInUseUsageDescription</key>

<string>Location is needed for map localization and navigation</string>

How it works

import 'package:gem_kit/core.dart';
import 'package:gem_kit/map.dart';
import 'package:gem_kit/navigation.dart';
import 'package:gem_kit/routing.dart';
import 'package:gem_kit/sense.dart';

import 'bottom_navigation_panel.dart';
import 'top_navigation_panel.dart';
import 'utility.dart';

import 'package:permission_handler/permission_handler.dart';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart' hide Route, Animation;

The dart material package is imported, as well as the required gem_kit packages.

The permission handler is to request location (GPS) sensor permission from the user, if it was not previously granted, as this is required for navigation.

void _onMapCreated(GemMapController controller) {
  // Save controller for further usage.
  _mapController = controller;
}

This callback function is called when the interactive map is initialized and ready to use.

void _onBuildRouteButtonPressed(BuildContext context) {
  if (_currentLocation == null) {
    _showSnackBar(context,
        message: 'Current location is needed to compute the route.', duration: const Duration(seconds: 3));
    return;
  }

  // Define the departure
  final departureLandmark = Landmark.withCoordinates(_currentLocation!);

  // Define the destination.
  final destinationLandmark = Landmark.withLatLng(latitude: 52.51614, longitude: 13.37748);

  // Define the route preferences.
  final routePreferences = RoutePreferences();
  _showSnackBar(context, message: 'The route is calculating.');

  // Calling the calculateRoute SDK method.
  // (err, results) - is a callback function that gets called when the route computing is finished.
  // err is an error enum, results is a list of routes.
  _routingHandler =
      RoutingService.calculateRoute([departureLandmark, destinationLandmark], routePreferences, (err, routes) {
    // If the route calculation is finished, we don't have a progress listener anymore.
    _routingHandler = null;

    ScaffoldMessenger.of(context).clearSnackBars();

    if (err == GemError.routeTooLong) {
      print('The destination is too far from your current location. Change the coordinates of the destination.');
      return;
    }

    // If there aren't any errors, we display the routes.
    if (err == GemError.success) {
      // Get the routes collection from map preferences.
      final routesMap = _mapController.preferences.routes;

      // Display the routes on map.
      for (final route in routes!) {
        routesMap.add(route, route == routes.first, label: route.getMapLabel());
      }

      // Center the camera on routes.
      _mapController.centerOnRoutes(routes);
      setState(() {
        _areRoutesBuilt = true;
      });
    }
  });
}

When the route button in the upper right corner is pressed, a route is computed from the current position to a preset location in Europe.

A route must have at least 2 waypoints, one for the departure, and one for the destination. Optionally, 0 or more intermediate waypoints may be specified, through which the route will pass, in order from departure to destination.

Each waypoint is a Landmark and has latitude and longitude coordinates.

In this case, the current location is obtained and set in the departure landmark waypoint:

final departureLandmark = Landmark.withCoordinates(_currentLocation!);

and the destination is set to preset coordinates:

final destinationLandmark = Landmark.withLatLng(latitude: 52.51614, longitude: 13.37748);

then the route is calculated:

RoutingService.calculateRoute()

If there are no errors, the list of resulting routes (as there may be a few alternatives), is added to the map:

routesMap.add()

the first resulting route is autoselected as the main route, and then the map is centered on the resulting routes, such that they fit in the viewport:

_mapController.centerOnRoutes(routes);

void _startNavigation() {
  final routes = _mapController.preferences.routes;

  _navigationHandler = NavigationService.startNavigation(routes.mainRoute, (type, instruction) async {
    if (type == NavigationEventType.destinationReached || type == NavigationEventType.error) {
      // If the navigation has ended or if and error occured while navigating, remove routes.
      setState(() {
        _isNavigationActive = false;
        _cancelRoute();
      });
      return;
    }
    _isNavigationActive = true;

    if (instruction != null) {
      setState(() => currentInstruction = instruction);
    }
  });

  // Set the camera to follow position.
  _mapController.startFollowingPosition();
}

Once a route is computed, tapping the play button in the upper right starts navigation on the selected route.

void _onFollowPositionButtonPressed() async {
  if (kIsWeb) {
    // On web platform permission are handled differently than other platforms.
    // The SDK handles the request of permission for location.
    _locationPermissionStatus = PermissionStatus.granted;
  } else {
    // For Android & iOS platforms, permission_handler package is used to ask for permissions.
    _locationPermissionStatus = await Permission.locationWhenInUse.request();
  }

  if (_locationPermissionStatus == PermissionStatus.granted) {
    // After the permission was granted, we can set the live data source (in most cases the GPS).
    // The data source should be set only once, otherwise we'll get -5 error.
    if (!_hasLiveDataSource) {
      PositionService.instance.setLiveDataSource();
      _getCurrentLocation();
      _hasLiveDataSource = true;
    }

    // After data source is set, startFollowingPosition can be safely called.
    // Optionally, we can set an animation
    final animation = GemAnimation(type: AnimationType.linear);

    // Calling the start following position SDK method.
    _mapController.startFollowingPosition(animation: animation);
  }
  setState(() {});
}

Follow position means the camera tracks the position of the phone/device, indicated by an arrow moving along the route on the map.

_mapController.startFollowingPosition();

Note that if location (GPS sensor) permission was not previously granted, the app will ask for location permission from the user, as this is required for navigation.

_locationPermissionStatus = await Permission.locationWhenInUse.request();

Once permission is granted by the user, it is possible to set the location (GPS sensor) as the data source for the phone/device position on the map:

PositionService.instance.setLiveDataSource();

If the user pans the map away from the route, clicking the Re-center button starts following position again.

Flutter Examples

Maps SDK for Flutter Examples can be downloaded or cloned with Git