Maps Compose Library Tutorial for Android: Getting Began

Google Maps is a contemporary toolkit that gives detailed details about geographical areas. At present, it has greater than a billion customers per day.

Nonetheless, it will get sophisticated whenever you need to use the previous library, Maps SDK for Android, with Jetpack Compose. You could write complicated and infrequently massive View interoperability code blocks to mix Jetpack Compose with the usual map UI element – MapView. This opposes one in every of Jetpack Compose’s main goals of being easy and exact. To unravel this, Google created a brand new and easier method of dealing with Google Maps in Jetpack Compose tasks.

In February 2022, Google launched the Maps Compose library. It’s an open-source set of composable features that simplify Google Maps implementation. Moreover that, the library incorporates particular knowledge sorts associated to Maps SDK for Android suited to Jetpack Compose.

On this tutorial, you’ll construct the GeoMarker app. The app lets you use Maps Compose options like markers, circles and information home windows. Moreover, you’ll additionally be capable to mark factors in your UI and be capable to draw a polygon from chosen factors.

Through the course of, you’ll be taught:

• Organising Google Maps in compose.
• Requesting location permissions.
• Including markers, information home windows and circles in your map.
• Including customized map styling.
• Drawing polygons in your map.
• Testing some map options.

Getting Began

Obtain the starter venture by clicking Obtain Supplies on the high or backside of the tutorial.

Open Android Studio Chipmunk or later and import the starter venture. Construct and run the venture. You’ll see the next screens:

The app exhibits an empty display with a ‘Mark Space’ floating motion button on the backside. You’ll show your map and different map parts on this display. You’ll additionally add the geo-marking performance.

Setting Up

To start out engaged on maps in compose, it’s essential to full the next steps:

1. Organising the dependencies:

  implementation 'com.google.maps.android:maps-compose:2.4.0'
  implementation 'com.google.android.gms:play-services-maps:18.1.0'
  implementation 'com.google.android.gms:play-services-location:20.0.0'

The primary is the Maps Compose library, and the opposite two are the Play Providers maps SDK and site SDKs. Notice that these dependencies exist already within the starter venture, so there’s no must re-add them.

2. Secondly, you want a Google Maps API key for you to have the ability to use any of Google Maps APIs. You’ll find directions on tips on how to get your key right here. After getting your key, proceed so as to add it to your native.properties file as follows:

   MAPS_API_KEY=YOUR_API_KEY
   

Now that you’ve all the things set, time to get your palms soiled with maps in compose. You’ll begin by requesting location permissions in your app.

Requesting Location Permissions

Your app wants location permissions for you to have the ability to present maps. Head over to presentation/screens/MapScreenContent.kt. Change //TODO Add Permissions with:

// 1
val scope = rememberCoroutineScope()
// 2
val context = LocalContext.present
// 3
var showMap by rememberSaveable {
  mutableStateOf(false)
}
// 4
PermissionDialog(
    context = context,
    permission = Manifest.permission.ACCESS_FINE_LOCATION,
    permissionRationale = stringResource(id = R.string.permission_location_rationale),
    snackbarHostState = snackbarHostState) { permissionAction ->
  // 5
  when (permissionAction) {
    is PermissionAction.PermissionDenied -> {
      showMap = false
    }
    is PermissionAction.PermissionGranted -> {
      showMap = true
      scope.launch {
        snackbarHostState.showSnackbar("Location permission granted!")
      }
      fetchLocationUpdates.invoke()
    }
  }
}

To resolve errors, change your imports on the high with:

import android.Manifest
import androidx.compose.material3.SnackbarHostState
import androidx.compose.runtime.*
import androidx.compose.runtime.saveable.rememberSaveable
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.res.stringResource
import com.android.composegeomarker.R
import com.android.composegeomarker.permissions.PermissionAction
import com.android.composegeomarker.permissions.PermissionDialog
import kotlinx.coroutines.launch

Right here’s what the code above does:

1. You create a CoroutineScope variable you’ll use to point out your Snackbar.
2. This can be a variable to get the context of your present composable.
3. You’ve gotten a Boolean variable showMap that represents whether or not the app has needed permissions.
4. Right here, you name PermissionDialog, a customized composable that handles all of the permissions logic.
5. The PermissionDialog has a callback that returns which permission possibility the person has chosen. It could both be PermissionGranted or PermissionDenied. On every of this, you replace the showMap variable. When the person grants the permission, you present a Snackbar with a “Location permission granted!” message and begin the placement updates.

With this, you’re prepared to point out places on a map, and that’s the following step.

Displaying a Place in a Map

Navigate to presentation/composables/MapView.kt. You’ll see two TODOs that you simply’ll work on in a second.

However earlier than that, change your imports with the next:

import android.content material.Context
import androidx.compose.basis.structure.fillMaxSize
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import com.google.android.gms.maps.mannequin.CameraPosition
import com.google.android.gms.maps.mannequin.LatLng
import com.google.maps.android.compose.GoogleMap
import com.google.maps.android.compose.rememberCameraPositionState

Begin by changing // TODO add Digital camera Place State with:

val cameraPositionState = rememberCameraPositionState {
  place = CameraPosition.fromLatLngZoom(location, 16f)
}

Within the code above, you create a CameraPositionState occasion, which holds the configurations in your map. On this case, you set your map’s location and zoom stage.

Second, change // TODO Add Google Map with:

GoogleMap(
    modifier = Modifier.fillMaxSize(),
    cameraPositionState = cameraPositionState
)

GoogleMap is a container for a MapView, to which you go each values, modifier and cameraPositionState. And that’s all it’s essential to present a single location on a map in compose :]

Final, it’s essential to name your customized MapView composable in your MapScreenContent.kt. You go within the context and site as parameters. For an instance, you’ll use a hard and fast location in Singapore. Return to presentation/screens/MapScreenContent.kt and beneath PermissionDialog add:

val currentLocation = LatLng(1.35, 103.87)
if (showMap) {
  MapView(context, currentLocation)
}

Add the next imports to your import statements to resolve the errors.

import com.android.composegeomarker.presentation.composables.MapView
import com.google.android.gms.maps.mannequin.LatLng

Right here, you added the conditional to verify whether or not your map ought to be displayed. As soon as the situation is met, you name MapView passing within the context and present location.

Construct and run the app:

The app now exhibits the placement in Singapore on the map. Within the subsequent part, you’ll add a marker to this location.

Including a Marker on the Map

Inside presentation/composables/MapView.kt, add a pair of curly braces to GoogleMap composable and add the next within the block:

Marker(
    state = MarkerState(place = location),
)

Add any lacking imports by urgent Choice-Return on a Mac or Alt-Enter on a Home windows PC. Your remaining end result will probably be:

GoogleMap(
    modifier = Modifier.fillMaxSize(),
    cameraPositionState = cameraPositionState
) {
  Marker(
      state = MarkerState(place = location),
  )
}

You add a marker in a map by including little one composables to GoogleMap as contents. A Marker requires a MarkerState occasion that observes marker state corresponding to its place and data window.

Go the Singapore location to MarkerState after which construct and run the app.

You may see the pink marker for Singapore on the middle of your map.

Usually, you’ll want to point out info when a person faucets a marker. For that, you’ll have so as to add InfoWindow to your map, which you’ll be taught subsequent.

Displaying Map Data Home windows

Head again to presentation/composables/MapView.kt and add this code beneath the cameraPositionState variable:

val infoWindowState = rememberMarkerState(place = location)

You’ve gotten now created a state variable for the marker properties and handed the placement to this marker.

Subsequent, beneath your Marker composable, add:

MarkerInfoWindow(
    state = infoWindowState,
    title = "My location",
    snippet = "Location customized information window",
    content material = {
      CustomInfoWindow(title = it.title, description = it.snippet)
    }
)

Within the code above, you create your info window utilizing MarkerInfoWindow composable. You may customise your info window to your liking. You go the state, title, snippet and content material as parameters. Contained in the content material lambda, you name your customized composable along with your info window customized view.

Construct and run the app. Faucet the Singapore marker, and you must see:

The knowledge window shows on high of the marker with texts from the title and snippet you handed as parameters.

Drawing Circles on Your Map

Thus far, you’ve seen tips on how to add markers and information home windows to your map. On this part, you’ll add one other form, a Circle.

In MapView.kt, add the next beneath MarkerInfoWindow within the GoogleMap composable:

Circle(
    middle = location,
    fillColor = MaterialTheme.colorScheme.secondaryContainer,
    strokeColor = MaterialTheme.colorScheme.secondaryContainer,
    radius = 300.00
)

Resolve the MaterialTheme lacking imports by urgent Choice-Return on a Mac or Alt-Enter on a PC.

Circle is one more map little one composable and has a number of parameters. For this tutorial, you solely must assign values to:

• middle – the LatLng that represents the middle of this circle.
• fillColor – fill colour of the circle.
• strokeColor – colour of the outer circle or stroke.
• radius – circle radius.

Construct and run the app.

Now you can see a blue circle on the middle of your map. Its middle is the Singapore location that you simply handed.

Thus far, you’ve drawn a number of shapes in your map. Within the subsequent part, you’ll discover ways to customise your map’s look by including a customized JSON map fashion.

Customizing the Look of Your Map

There are two map styling choices obtainable with maps:

1. Cloud-based styling: This lets you create and edit map kinds with out requiring any modifications in your app. You make all of the modifications within the cloud console, that are mirrored in your apps after getting a map ID.
2. JSON primarily based styling: Right here, you create a map fashion on the outdated fashion wizard . When you full the customization, you’ll be able to obtain the JSON file and add it to your map.

On this tutorial, you’ll be utilizing JSON styling. You’ll create your customized fashion so as to add to the map within the subsequent part.

Making a Customized JSON Map Styling

Open your most popular browser and head to the outdated fashion wizard. You need to see:

On the left, you might have customization choices corresponding to altering the density of the options and altering the theme of your map.

Begin by choosing the Silver theme as proven beneath:

On the best aspect, you’ll be able to see the map colour modifications to mirror the chosen theme. Subsequent, click on MORE OPTIONS as proven above.

This exhibits a listing of options you’ll be able to customise and visualize on the map. For this tutorial, you’ll customise the Highway function.

Comply with these steps:

• Click on the Highway function, which is able to open up the aspect sort part on the best.
• The weather sort part has a listing of parts you’ll be able to customise, which on this case are labels and geometry.
• Click on the Geometry possibility and alter the colour as per your choice. You may see the colour is instantly mirrored on the map.

That’s all for now. You may add as many customization choices as you would like. Click on FINISH, and also you’ll see the Export Model dialog as proven:

Click on COPY JSON possibility. This copies the JSON fashion in your clipboard. You’re now a couple of steps away from making use of the customized fashion to your compose map.

Navigate again to Android Studio. Proper-click the res listing, select New ▸ Android Useful resource Listing and choose uncooked. Within the new uncooked listing, create a file named map_style.json and paste the copied fashion right here.

Now, you might have the fashion prepared to be used. Subsequent, it’s essential to apply it to your map.

Making use of Customized Model to Your Map

Head over to presentation/composables/MapView.kt. Under your infoWindowState variable add:

val mapProperties by bear in mind {
  mutableStateOf(
      MapProperties(
          mapStyleOptions = MapStyleOptions.loadRawResourceStyle(context, R.uncooked.map_style)
      )
  )
}

Add any lacking imports by urgent Choice-Return on a Mac or Alt-Enter on a PC. As seen above, you create a brand new state variable of sort MapProperties. This variable holds properties you’ll be able to change on the map. You go the customized fashion to the mapStyleOptions, which masses the fashion from the uncooked listing.

Subsequent, add this variable mapProperties as properties parameter to your GoogleMap. Your remaining end result ought to be:

GoogleMap(
    modifier = Modifier.fillMaxSize(),
    cameraPositionState = cameraPositionState,
    properties = mapProperties
) {
  // Baby Composables
}

Construct and run the app.

You may see your map now applies the fashion out of your JSON file.

Requesting Location Updates

Notice: This part is elective. You may skip forward to Marking Polygon Positions if you wish to begin including your geo marking performance. Nonetheless, should you’d like to grasp tips on how to do location updates, you’re in the best place! The performance is already within the starter venture.

A standard function of maps on gadgets is the power for them to replace in actual time. To do this right here, You’ll use a callbackFlow to request for location updates. Inside utils package deal you’ll discover LocationUtils.kt file. The placement callbackFlow is as follows:

@SuppressLint("MissingPermission")
enjoyable FusedLocationProviderClient.locationFlow() = callbackFlow {
  val callback = object : LocationCallback() {
    override enjoyable onLocationResult(end result: LocationResult) {
      attempt {
        trySend(end result.lastLocation)
      } catch (e: Exception) {
        Log.e("Error", e.message.toString())
      }
    }
  }
  requestLocationUpdates(createLocationRequest(), callback, Looper.getMainLooper())
      .addOnFailureListener { e ->
        shut(e)
      }

  awaitClose {
    removeLocationUpdates(callback)
  }
}

Right here, you wrap your LocationCallback in a callbackFlow. Within the callbackFlow, callback is known as at any time when you might have location updates from requestLocationUpdates. And at last, you clear up assets when your callback is eliminated inside awaitClose.

Open up MainActivity.kt, and take a look at fetchLocationUpdates() to see the way it fetches location updates:

personal enjoyable fetchLocationUpdates() {
  lifecycleScope.launch {
    lifecycle.repeatOnLifecycle(Lifecycle.State.STARTED) {
      fusedLocationClient.locationFlow().acquire {
        it?.let { location ->
          geoMarkerViewModel.setCurrentLatLng(LatLng(location.latitude, location.longitude))
        }
      }
    }
  }
}

This makes use of repeatOnLifecycle() to gather safely out of your Movement within the UI. You additionally go the placement to your viewmodel to share the newest worth along with your composable.

Within the subsequent part, you’ll see how to attract polygons in your map and end the geo marking a part of the app.

Marking Polygon Positions

There are two choices obtainable to create your geo marker:

• Drawing polylines: You employ the placement replace function to attract polylines as a person walks in a sure space. You draw polylines after a person updates their location at set intervals.
• Draw polygons: You draw polygons from a listing of LatLng coordinates. For this tutorial, you’ll be utilizing this feature.

Head over to presentation/screens/GeoMarkerScreen.kt and also you’ll see:

On this file, you might have a GeoMarkerScreen composable that has a number of map state variables outlined. It has a Scaffold inside the place you might have your GoogleMap composable. You’ve gotten three TODOs you’ll tackle in a second.

Construct and run the app. Faucet Mark Space.

You may see the map and a button on the backside of the map. You’ll be including performance for including geo factors by clicking any three factors on the map.

To start with, change // TODO Add click on listener with:

if (!drawPolygon) {
  showSavePoint = true
  clickedLocation = it
}

Right here, you do a conditional verify to verify whether or not the polygon is already drawn. When the situation isn’t glad, you replace the showSavePoint, which is a Boolean that determines whether or not to point out the UI to save lots of the clicked level. Clicking a map additionally returns a LatLng of the clicked level. You assign this worth to the clickedLocation variable.

Subsequent, change // TODO Save Level UI with:

if (showSavePoint) {
  SaveGeoPoint(latLng = clickedLocation) {
    showSavePoint = it.hideSavePointUi
    areaPoints.add(it.level)
  }
} else {
  if (areaPoints.isEmpty()) {
    Textual content(
        modifier = Modifier
            .fillMaxWidth(),
        colour = Colour.Blue,
        textual content = "Click on any level on the map to mark it.",
        textAlign = TextAlign.Middle,
        fontWeight = FontWeight.Daring
    )
  }
}

Add any lacking imports by urgent Choice-Return on a Mac or Alt-Enter on a PC. You add one other conditional verify.

When showSavePoint is true, you present the SaveGeoPoint composable. SaveGeoPoint is a customized composable with UI for saving the clicked level. You go the clickedLocation from the map click on listener. When the situation evaluates to false, you present a textual content with directions on tips on how to mark factors on the map.

Construct and run the app. Navigate to the Geo Marker Display screen as soon as extra. You’ll see:

Faucet any level on the map.

You may see the UI to save lots of the purpose in your map. It shows the LatLng and the Save Level motion which saves your level.

You’ll discover whenever you save three factors that the Full button on the backside turns into energetic. Faucet Full. Nothing occurs on the map; it solely exhibits a reset button. Like me, you have been anticipating to see a polygon. Don’t fear. You’ll repair this conduct in a second.

Change // TODO Add Polygon with:

// 1
if (drawPolygon && areaPoints.isNotEmpty()) {
  // 2
  areaPoints.forEach {
    Marker(state = MarkerState(place = it))
  }
  
  // 3
  Polygon(
      factors = areaPoints,
      fillColor = Colour.Blue,
      strokeColor = Colour.Blue
  )
}
// 4
if (showSavePoint) {
  Marker(state = MarkerState(place = clickedLocation))
}

Add any lacking imports by urgent Choice-Return on a Mac or Alt-Enter on a PC.

Right here’s what the code above does:

1. This can be a conditional verify to verify whether or not the polygon is drawn. You additionally verify if the areaPoints has values since you want a listing of LatLng to attract a polygon.
2. Right here, for every merchandise within the areaPoints checklist, you add a marker in your map.
3. You employ Polygon composable, to attract your polygon. You go within the factors to attract and the colours in your polygon.
4. This can be a marker for every level you click on on the map.

Construct and run the app, then faucet the marker space button and add three markers. Lastly, faucet the entire button.

Congratulations! You’ve been in a position to create a geo marker with a polygon. You may reset the map and draw as many polygons as you need.

Writing Map UI Assessments

Assessments are often vital in any piece of software program. Google Map Compose library was not left behind when it comes to writing exams in your map logic. To make it extra fascinating, it’s simpler so that you can write the UI exams in your map composables.

Head over to your androidTest listing and open GoogleMapTest.kt. The take a look at class GoogleMapTest solely has a useful setup methodology that runs earlier than your exams run. It initializes a CameraPositionState with a location and a zoom stage.

Earlier than writing your exams, it’s essential to arrange your map. Add the next methodology beneath the setup methodology:

personal enjoyable loadMap() {
  val countDownLatch = CountDownLatch(1)
  composeTestRule.setContent {
    GoogleMap(
        modifier = Modifier.fillMaxSize(),
        cameraPositionState = cameraPositionState,
        onMapLoaded = {
          countDownLatch.countDown()
        }
    )
  }
  val mapLoaded = countDownLatch.await(30, TimeUnit.SECONDS)
  assertTrue("Map loaded", mapLoaded)
}

Change your imports on the high with:

import androidx.compose.basis.structure.fillMaxSize
import androidx.compose.ui.Modifier
import androidx.compose.ui.take a look at.junit4.createComposeRule
import com.google.android.gms.maps.mannequin.CameraPosition
import com.google.android.gms.maps.mannequin.LatLng
import com.google.maps.android.compose.CameraPositionState
import com.google.maps.android.compose.GoogleMap
import junit.framework.Assert.assertTrue
import org.junit.Earlier than
import org.junit.Rule
import java.util.concurrent.CountDownLatch
import java.util.concurrent.TimeUnit

You’ve gotten a CountDownLatch to permit ready for the map to load earlier than doing any operation on the map. You set the content material of your display with the composeTestRule. Within the setContent lambda, you add the GoogleMap composable. You additionally go the cameraPositionState modifier, and inside your onMapLoaded, you begin your countdown.

Lastly, you carry out an assertion after ready 30 seconds to verify whether or not the map was loaded. You’ll use this methodology to initialize your map in consecutive exams.

You’ll now add exams to point out the digicam place and map zoom stage are set to the right values.

Add the next exams:

@Check
enjoyable testCameraPosition() {
  loadMap()
  assertEquals(singapore, cameraPositionState.place.goal)
}
@Check
enjoyable testZoomLevel() {
  loadMap()
  assertEquals(cameraZoom, cameraPositionState.place.zoom)
}

Within the code above, you might have two exams: one for testing the digicam place and the opposite for testing the zoom stage of your map. In every of those exams, you name loadMap() after which assert that the place and zoom stage on the map is just like your preliminary location. Run the take a look at.

You may see all of your exams run efficiently!

The place to Go From Right here?

Obtain the ultimate venture by clicking Obtain Supplies on the high or backside of the tutorial.

You may discover the drawing polyline choice to display somebody strolling by way of a area. You may maybe add extra exams to check your map-related functionalities.

Take a look at the official Google Maps Compose documentation to be taught extra about maps in Compose. To be taught extra about testing your compose layouts, checkout the official testing documentation.

Hopefully, you loved this tutorial. If in case you have any questions or feedback, please be a part of the discussion board dialogue beneath!