Simulate 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 simulate navigation 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 simulate_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/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'

Then run the project:

flutter run --debug

or

flutter run --release

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

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

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

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) {
  // Define the departure.
  final departureLandmark = Landmark.withLatLng(latitude: 45.6517672, longitude: 25.6271132);

  // Define the destination.
  final destinationLandmark = Landmark.withLatLng(latitude: 44.4379187, longitude: 26.0122374);

  // 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) async {
    // If the route calculation is finished, we don't have a progress listener anymore.
    _routingHandler = null;

    ScaffoldMessenger.of(context).clearSnackBars();

    // 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 preset departure position to the preset destination position.

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.

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 _startSimulation() {
  final routes = _mapController.preferences.routes;

  _navigationHandler = NavigationService.startSimulation(routes.mainRoute, (type, instruction) async {
    if (type == NavigationEventType.destinationReached || type == NavigationEventType.error) {
      // If the navigation has ended or if and error occurred while navigating, remove routes.
      setState(() {
        _isSimulationActive = false;
        _cancelRoute();
      });
      return;
    }
    _isSimulationActive = 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 simulated navigation on the selected route.

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();

Flutter Examples

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