Center coordinates

This example demonstrates how to create a Flutter app that centers the map on specific coordinates using GemKit.

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 center_coordinates 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.

Run: flutter pub get

Configure the native parts:

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:

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    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 project pathname

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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
        }
    }
}

iOS

In the ios/Podfile configuration file, at the top, set the minimum ios platform version to 14 like this:

platform :ios, '14.0'

We recommend you to run these commands after you copy the gem_kit into your project: |flutter clean |flutter pub get |and |cd ios |pod install

Then run the project:

flutter run --debug

or

flutter run --release

App entry and initialization

const projectApiToken = String.fromEnvironment('GEM_TOKEN');

void main() {
  runApp(const MyApp());
}

This code initializes the projectApiToken with the required authorization token and launches the app.

How it works

The example app demonstrates the following features:

• Center the map on predefined coordinates.

• Optionally use an animation to smoothly transition the map view.

UI and Map Integration

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Center Coordinates',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late GemMapController _mapController;

  @override
  void dispose() {
    GemKit.release();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.deepPurple[900],
        title: const Text('Center Coordinates',
            style: TextStyle(color: Colors.white)),
        actions: [
          IconButton(
              onPressed: _onCenterCoordinatesButtonPressed,
              icon: const Icon(
                Icons.adjust,
                color: Colors.white,
              ))
        ],
      ),
      body: GemMap(onMapCreated: _onMapCreated, appAuthorization: projectApiToken),
    );
  }

This code sets up the basic structure of the app, including the map and the app bar. It also provides a button in the app bar for centering the map on specific coordinates.

Centering the Map

// The callback for when map is ready to use.
void _onMapCreated(GemMapController controller) async {
  // Save controller for further usage.
  _mapController = controller;
}

void _onCenterCoordinatesButtonPressed() {
  // Predefined coordinates for Rome, Italy.
  final targetCoordinates =
      Coordinates(latitude: 41.902782, longitude: 12.496366);

  // Create an animation (optional).
  final animation = GemAnimation(type: AnimationType.linear);

  // Use the map controller to center on coordinates.
  _mapController.centerOnCoordinates(targetCoordinates, animation: animation);
}

This code handles centering the map on the predefined coordinates for Rome, Italy. The GemMapController is used to perform this action, and an optional animation is provided for a smooth transition.

Flutter Examples

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