Base map objects

Everything drawn by MapKit itself — POIs, buildings, toponyms, roads — is a base map object. You do not create them; you react to taps on them and read their metadata.

Reacting to a tap

GeoObjectTapListener fires before the map's InputListener. Returning true consumes the event, false lets it fall through to onMapTap.

class GeoObjectController(private val map: Map) {

    private val tapListener = GeoObjectTapListener { event ->
        val geoObject = event.geoObject
        println("${geoObject.name}: ${geoObject.descriptionText}")
        false
    }

    init {
        map.addTapListener(tapListener.asWeakRef())
    }
}

event.isValid tells whether the event is still usable — it is invalidated once the callback returns, so nothing about it should be kept beyond the call.

Selecting an object

MapKit can highlight the tapped object with its own selection style, which is what the map application does when you tap a POI. It needs the object's GeoObjectSelectionMetadata:

private val tapListener = GeoObjectTapListener { event ->
    val metadata = event.geoObject.selectionMetadata ?: return@GeoObjectTapListener false
    map.selectGeoObject(metadata)
    true
}

map.deselectGeoObject() clears it.

Returning true here matters: if the event keeps propagating, the tap also reaches onMapTap and whatever it does.

Reading the metadata

MapKit keeps object metadata in a dictionary keyed by native classes, which has no common representation. The wrapper exposes the entries the lite SDK attaches, each as a nullable property:

Property	Type	What it carries
selectionMetadata	GeoObjectSelectionMetadata	objectId, dataSourceName, layerId, groupId — what selectGeoObject needs
inspectionMetadata	GeoObjectInspectionMetadata	layerId and the ObjectType — POINT, POLYLINE, POLYGON, CIRCLE
tags	GeoObjectTags	the object's tag list, e.g. what kind of POI it is
uriMetadata	UriObjectMetadata	Uris that identify the object elsewhere in Yandex services
personalizedPoiMetadata	PersonalizedPoiExtraMetadata	key/value entries of a personalized POI

private val tapListener = GeoObjectTapListener { event ->
    val geoObject = event.geoObject

    val kind = geoObject.tags?.tags?.firstOrNull()
    val uri = geoObject.uriMetadata?.uris?.firstOrNull()?.value
    val type = geoObject.inspectionMetadata?.objectType

    println("$kind $type $uri")
    false
}

The object itself

Property	Type
name	String?
descriptionText	String?
geometry	List<Geometry>
boundingBox	BoundingBox?
aref	List<String>
attributionMap	Map<String, Attribution>

geometry is a list because one object can consist of several shapes. Each Geometry holds exactly one of point, polyline, polygon, multiPolygon, boundingBox or circle.

val point = geoObject.geometry.firstNotNullOfOrNull { it.point }

if (point != null) {
    map.move(
        CameraPosition(point, zoom = 17f, azimuth = 0f, tilt = 0f),
        Animation(Animation.Type.SMOOTH, 300.milliseconds),
    )
}

attributionMap maps an attribution id to an Attribution with its author, link and avatarImage — what has to be shown next to third-party data.

Zooming to what was tapped

private val tapListener = GeoObjectTapListener { event ->
    val box = event.geoObject.boundingBox ?: return@GeoObjectTapListener false
    map.move(
        map.cameraPosition(box.toGeometry()),
        Animation(Animation.Type.SMOOTH, 300.milliseconds),
    )
    true
}

In Compose

MapListeners wires the same listener up for as long as it is in the composition:

YandexMap(modifier = Modifier.fillMaxSize()) {
    MapListeners(
        onGeoObjectTap = { event ->
            val metadata = event.geoObject.selectionMetadata ?: return@MapListeners false
            selection = metadata
            true
        },
    )
    MapEffect(selection) { map ->
        val metadata = selection
        if (metadata != null) map.selectGeoObject(metadata) else map.deselectGeoObject()
    }
}

Layer ids

layerId in the metadata is one of the ids MapKit uses for its own layers, listed in LayerIds:

LayerIds.mapLayerId
LayerIds.jamsLayerId
LayerIds.buildingsLayerId
LayerIds.transportLayerId
LayerIds.mapObjectsLayerId
LayerIds.userLocationLayerId

They are also what you compare against when adding a layer of your own — see Layers and tiles.