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Maps Android KTX

Description

This repository contains Kotlin extensions (KTX) for:

1. The Maps SDK for Android
2. The Maps SDK for Android Utility Library

It enables you to write more concise, idiomatic Kotlin. Each set of extensions can be used independently or together.

Requirements

• Kotlin-enabled project
• Kotlin coroutines
• API level 21+
• An API key

Installation

dependencies {

    // KTX for the Maps SDK for Android library
    implementation 'com.google.maps.android:maps-ktx:5.1.1'

    // KTX for the Maps SDK for Android Utility Library
    implementation 'com.google.maps.android:maps-utils-ktx:5.1.1'
}

Example Usage

With this KTX library, you should be able to take advantage of several Kotlin language features such as extension functions, named parameters and default arguments, destructuring declarations, and coroutines.

Demo App

This repository includes a demo app that illustrates the use of this KTX library.

To run the demo app, you'll have to:

1. Get a Maps API key
2. Create a file in the root directory called secrets.properties (this file should NOT be under version control to protect your API key)
3. Add a single line to secrets.properties that looks like MAPS_API_KEY=YOUR_API_KEY, where YOUR_API_KEY is the API key you obtained in the first step
4. Build and run

Maps SDK KTX

Extension functions

Adding a Marker:

Before

GoogleMap googleMap = // ...
LatLng sydney = new LatLng(-33.852, 151.211);
MarkerOptions markerOptions = new MarkerOptions()
    .position(Sydney)
    .title("Marker in Sydney");
Marker marker = googleMap.addMarker(markerOptions);

After

val googleMap = // ...
val sydney = LatLng(-33.852, 151.211)
val marker = googleMap.addMarker {
    position(sydney)
    title("Marker in Sydney")
}

Coroutines

Accessing a GoogleMap instance can be retrieved using coroutines vs. traditional the callback mechanism. The example here demonstrates how you can use this feature alongside with Lifecycle-aware coroutine scopes provided in Android’s Architecture Components. To use this, you'll need to add the following to your build.gradle dependencies: implementation 'androidx.lifecycle:lifecycle-runtime-ktx:<latest-version>'

Before

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    SupportMapFragment mapFragment = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map));

    mapFragment.getMapAsync(new OnMapReadyCallback {
        @Override
        public void onMapReady(GoogleMap googleMap) {
            // Access GoogleMap instance here
        }
    });
}

After

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val mapFragment = supportFragmentManager.findFragmentById(R.id.map) as? SupportMapFragment

    lifecycle.coroutineScope.launchWhenCreated {
        val googleMap = mapFragment?.awaitMap()
    }
}

Flow

Listing to camera events can be collected via Kotlin Flow.

Before

val googleMap = //...
googleMap.setOnCameraIdleListener = { //... }
googleMap.setOnCameraMoveCanceledListener { //... }
googleMap.setOnCameraMoveListener { //... }
googleMap.setOnCameraMoveStartedListener { //... }

After

// To be invoked within a coroutine scope
googleMap.cameraIdleEvents().collect { //... }
googleMap.cameraMoveCanceledEvents().collect { //... }
googleMap.cameraMoveEvents().collect { //... }
googleMap.cameraMoveStartedEvents().collect { //... }

Maps SDK for Android Utilities KTX

Extension functions

Checking if a LatLng is contained within a Polygon:

Before

Polygon polygon = // some polygon
LatLng latlng = // some latlng
boolean result = PolygonUtil.containsLocation(latlng, polygon.getPoints(), true);

After

val polygon: Polygon = // some polygon
val latlng: LatLng = // some latlng
val result: Boolean = polygon.contains(latLng)

Named parameters and default arguments

Creating a GeoJsonLayer object:

Before

GeoJsonLayer layer = new GeoJsonLayer(
    map, 
    geoJsonFile, 
    null, 
    polygonManager, 
    null, 
    groundOverlayManager
);

After

val layer = geoJsonLayer(
    map = map,
    geoJsonFile = geoJsonFile,
    polygonManager = polygonManager,
    groundOverlayManager = groundOverlayManager
)

Destructuring Declarations

Destructuring properties of a Point:

Before

Point point = new Point(1.0, 2.0);
double x = point.x;
double y = point.y;

After

val point = Point(1.0, 2.0)
val (x, y) = point

Documentation

You can learn more about all the extensions provided by this library by reading the reference documents.

Support

Encounter an issue while using this library?

If you find a bug or have a feature request, please file an issue. Or, if you'd like to contribute, send us a pull request and refer to our code of conduct.

You can also reach us on our Discord channel.

For more information, check out the detailed guide on the Google Developers site.