Location Clustering

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This is an example of enabling and disabling location clustering on the map as well as providing custom cluster tapping behaviour and custom cluster images.

Create the class LocationClusteringFragment that extends Fragment:

public class LocationClusteringFragment extends Fragment {

Add a GoogleMap and a MapControl to the class:

MapControl mMapControl;
GoogleMap mGoogleMap;

Add other needed views for this example:

SupportMapFragment mMapFragment;

The Venue's coordinates:

static final LatLng VENUE_LAT_LNG = new LatLng( 57.05813067, 9.95058065 );

Once the map is ready, move the camera to the venue location and call setupMapsIndoors

OnMapReadyCallback mOnMapReadyCallback = new OnMapReadyCallback() {
public void onMapReady( GoogleMap googleMap )
mGoogleMap = googleMap;
mGoogleMap.moveCamera( CameraUpdateFactory.newLatLngZoom( VENUE_LAT_LNG, 13.0f ) );

Add a locationClusterImageAdapter to customize the cluster marker icons and provide their sizes:

MPLocationClusterImageAdapter locationClusterImageAdapter = new MPLocationClusterImageAdapter() {
public Bitmap getImage( @NonNull String clusterId, @NonNull List<MPLocation> locations, @NonNull ImageSize imageSize )
final int textSize = Convert.getPixels( 15 );
return getCircularImageWithText(
"" + locations.size(),
public ImageSize getImageSize( @NonNull String clusterId, int count )
final int imageSizeInPixels = Convert.getPixels( 25 );
return new ImageSize( imageSizeInPixels, imageSizeInPixels );

Create a method getCircularImageWithText that creates the custom bitmaps for our cluster icons:

public static Bitmap getCircularImageWithText( @NonNull String text, int textSize, int width, int height )
final Paint background = new Paint();
background.setColor( Color.WHITE );
// Now add the icon on the left side of the background rect
final Bitmap result = Bitmap.createBitmap( width, height, Bitmap.Config.ARGB_8888 );
final Canvas canvas = new Canvas( result );
final int radius = width >> 1;
canvas.drawCircle( radius, radius, radius, background );
background.setColor( Color.BLACK );
background.setStyle( Paint.Style.STROKE );
background.setStrokeWidth( 3 );
canvas.drawCircle( radius, radius, radius - 2, background );
final TextPaint tp = new TextPaint();
tp.setTextSize( textSize );
tp.setColor( Color.BLACK );
final Rect bounds = new Rect();
tp.getTextBounds( text, 0, text.length(), bounds );
final int text_height = bounds.height();
final int text_width = bounds.width();
final int textpos_x = (width - text_width) >> 1;
final int textpos_y = (height + text_height) >> 1;
canvas.drawText( text, textpos_x, textpos_y, tp );
return result;

Create a method setupMapsIndoors that:

  • Sets the API key to the desired Solution.
  • Sets the Google API key (required by our routing provider).
  • Instantiates MapControl.
  • Enables clustering.
  • Sets an OnLocationClusterListener so we can handle the cluster markers click events.
  • Sets the LocationClusterImageAdapter.
  • Initializes the MapControl object which will synchronize the data.
  • When the MapControl's initialization is done, it selects a floor and animates the camera to the venue position.
void setupMapsIndoors()
final Activity context = getActivity();
if( (context == null) || (mMapFragment == null) || (mMapFragment.getView() == null) )
if( !MapsIndoors.getAPIKey().equalsIgnoreCase( getString( R.string.mi_api_key ) ) )
MapsIndoors.setAPIKey( getString( R.string.mi_api_key ) );
MapsIndoors.setGoogleAPIKey( getString( R.string.google_maps_key ) );
mMapControl = new MapControl( context );
mMapControl.setGoogleMap( mGoogleMap, mMapFragment.getView() );
// Currently, on Android, we can enable/disable clustering
// - via our CMS
// - by calling MapControl.setLocationClusteringEnabled( true/false ) BEFORE invoking MapControl.init()
// Runtime clustering enable/disable is not currently supported
mMapControl.setLocationClusteringEnabled( true );
// Set the custom cluster image adapter
mMapControl.setLocationClusterImageAdapter( locationClusterImageAdapter );
// When clicking on a cluster marker zoom in to the maximum trying to break the cluster
mMapControl.setOnLocationClusterClickListener( ( marker, locations ) -> {
mGoogleMap.animateCamera( CameraUpdateFactory.newLatLngZoom( marker.getPosition(), 22f ) );
return true;
} );
mMapControl.init( miError -> {
if( miError == null ) {
final Activity _context = getActivity();
if( _context != null ) {
mMapControl.selectFloor( 1 );
mGoogleMap.animateCamera( CameraUpdateFactory.newLatLngZoom( VENUE_LAT_LNG, 20f ) );
} );

See the sample in LocationClusteringFragment.java

  1. Developing on the new Arm-based Apple Silicon (M1) Macs requires building and running on a physical iOS device or using an iOS simulator running iOS 13.7, e.g. iPhone 11. This is a temporary limitation in Google Maps SDK for iOS, and as such also a limitation in MapsIndoors, due to the dependency to Google Maps.
  2. Note: Due to a bug in CocoaPods it is necessary to include the post_install hook in your Podfile described in the PodFile post_install wiki.

This is an example of enabling and disabling location grouping on the map as well as providing custom cluster tapping behavior and custom cluster images.

Start by creating a UIViewController class that conforms to the MPMapControlDelegate protocol

class ClusteringController: UIViewController, MPMapControlDelegate {

Add a GMSMapView and a MPMapControl to the class Also define a clustering enabling/disabling button and a dictionary to store the clustering images for reuse

var map: GMSMapView? = nil
var mapControl: MPMapControl? = nil
let clusteringButton = UIButton.init()
var clusteringImageDictionary = Dictionary<String, UIImage>()

Setup map so that it shows the demo venue and initialise mapControl

self.map = GMSMapView.init(frame: CGRect.zero)
self.map?.camera = .camera(withLatitude: 57.057964, longitude: 9.9504112, zoom: 20)
self.mapControl = MPMapControl.init(map: self.map!)
self.mapControl?.delegate = self

Setup a button that enables/disables the location grouping / clustering mechanism

clusteringButton.setTitle("Clustering disabled", for: .normal)
clusteringButton.setTitle("Clustering enabled", for: .selected)
clusteringButton.addTarget(self, action: #selector(toggleClustering), for: .touchUpInside)
clusteringButton.backgroundColor = UIColor.blue

Arrange the map view and the button in a stackview

let stackView = UIStackView.init(arrangedSubviews: [map!, clusteringButton])
stackView.axis = .vertical
view = stackView

Define an objective-c method toggleClustering that will receive events from your button, and toggle the clustering flag:

  • Check current state
  • Swap state
  • Make button reflect the state
@objc func toggleClustering() {
if MPMapControl.locationClusteringEnabled {
MPMapControl.locationClusteringEnabled = false
} else {
MPMapControl.locationClusteringEnabled = true
clusteringButton.isSelected = MPMapControl.locationClusteringEnabled

Define the delegate method didTap that will receive tap events from a cluster marker

  • Check if zoom is possible and increment map zoom
  • Return true to indicate that you handle the event and do not want default behavior to happen
func didTap(_ marker: GMSMarker, forPoiGroup locations: [MPLocation]?, moreZoomPossible: Bool) -> Bool {
if moreZoomPossible {
self.map?.animate(toZoom: self.map!.camera.zoom + 1)
return true

Define the delegate method getImageSizeForPoiGroup that provides the size of the potential cluster

  • Check if zoom is possible and increment map zoom
  • Return true to indicate that you handle the event and do not want default behavior to happen
func getImageSizeForPoiGroup(withCount count: UInt, clusterId: String) -> CGSize {
let width = 48 * (Int(log10(Double(count))) + 1)
let height = 48
return CGSize.init(width: width, height: height)

Define the delegate method getImageForPoiGroup that asynchronously provides the image of the potential cluster

func getImageForPoiGroup(_ poiGroup: [MPLocation], imageSize: CGSize, clusterId: String, completion: @escaping (UIImage?) -> Void) -> Bool {

In getImageForPoiGroup create a string hash for the image

let imgHash = "img\(poiGroup.count)\(clusterId)"

In getImageForPoiGroup check if image already exists. If image does not exist, go in a background thread to get a dummy image and call the completion handler. Return true to indicate that you handle the clustering image.

var img = clusteringImageDictionary[imgHash]
if img == nil {
DispatchQueue.global().async {
let imgUrlString = "https://placem.at/people?txt=\(poiGroup.count)&random=\(Int.random(in: 0 ..< 10))&w=\(imageSize.width*2)&h=\(imageSize.height*2)"
let imgUrl = URL(string: imgUrlString)
do {
let imgData = try Data.init(contentsOf: imgUrl!)
img = UIImage(data: imgData, scale: 2)
self.clusteringImageDictionary[imgHash] = img
} catch {
} else {
return true

See the sample in ClusteringController.swift