Abstracting the map

Abstracting the map Marcel Pintó Biescas Droidcon Berlin | June
26, 2018

© 2017 HERE | HERE Public Abstracting the map |
June 24, 2018 2

How can we avoid it? 1. Single responsibility 2. Immutability
3. Unidirectional data flow © 2017 HERE | HERE Public Abstracting the map | June 24, 2018 3

class MapsActivity : AppCompatActivity(), OnMapReadyCallback, SomeMapView { private lateinit var
mMap: GoogleMap private val presenter = SomeMapPresenter() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_maps) presenter.view = this val mapFragment = supportFragmentManager .findFragmentById(R.id.map) as SupportMapFragment mapFragment.getMapAsync(this) } override fun onMapReady(googleMap: GoogleMap) { mMap = googleMap presenter.onMapReady() } override fun showMarker(marker: MarkerOptions) { mMap.addMarker(marker) } override fun moveCamera(update: CameraUpdate) { mMap.moveCamera(update) } } Simple example © 2017 HERE | HERE Public Abstracting the map | June 24, 2018 4 class MapsActivity : AppCompatActivity(), OnMapReadyCallback { private lateinit var mMap: GoogleMap override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_maps) val mapFragment = supportFragmentManager .findFragmentById(R.id.map) as SupportMapFragment mapFragment.getMapAsync(this) } override fun onMapReady(googleMap: GoogleMap) { mMap = googleMap // Add a marker in Sydney and move the camera val sydney = LatLng(-34.0, 151.0) mMap.addMarker(Marker Options().position(sydney).title("Marker in Sydney")) mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney)) } } interface SomeMapView { fun showMarker(marker: MarkerOptions) fun moveCamera(update: CameraUpdate) } class SomeMapPresenter { var view: SomeMapView? = null fun onMapReady() { val sydney = LatLng(-34.0, 151.0) val marker = MarkerOptions().position(sydney).title("Marker in Sydney") view?.showMarker(marker) view?.moveCamera(CameraUpdateFactory.newLatLng(sydney)) } }

class MapsActivity : AppCompatActivity(), OnMapReadyCallback, SomeMapView { private lateinit var
mMap: GoogleMap private val presenter = SomeMapPresenter() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_maps) presenter.view = this val mapFragment = supportFragmentManager .findFragmentById(R.id.map) as SupportMapFragment mapFragment.getMapAsync(this) } override fun onMapReady(googleMap: GoogleMap) { mMap = googleMap presenter.onMapReady() } override fun showMarker(marker: MarkerOptions) { mMap.addMarker(marker) } override fun moveCamera(update: CameraUpdate) { mMap.moveCamera(update) } } Simple example © 2017 HERE | HERE Public Abstracting the map | June 24, 2018 5 interface SomeMapView { fun showMarker(marker: MarkerOptions) fun moveCamera(update: CameraUpdate) } class SomeMapPresenter { var view: SomeMapView? = null fun onMapReady() { val sydney = LatLng(-34.0, 151.0) val marker = MarkerOptions().position(sydney).title("Marker in Sydney") view?.showMarker(marker) view?.moveCamera(CameraUpdateFactory.newLatLng(sydney)) } }

AnotherActivity AnotherView … and the chaos starts © 2017 HERE
| HERE Public Abstracting the map | June 24, 2018 6 LatLng M arkerOptions M apActivity Som eM apPresenter Som eM apView GoogleM ap Location … SearchRepository PlaceRepository Som eRepository

Single responsibility 1. Map belongs the view layer. 2. Do
NOT spread the Map classes all around, 3. Do NOT contact the Map from different points. 4. Abstract the Map into a class that’s only accessible by a ViewModel. © 2017 HERE | HERE Public Abstracting the map | June 24, 2018 7

Single responsibility © 2017 HERE | HERE Public Abstracting the
map | June 24, 2018 8 class MapViewModel: ViewModel() { private val _mapItems = MediatorLiveData<List<MapItem>>() private val searchRepository = SearchRepository() private val placeRepository = PlaceRepository() init { // Add sources to the _mapItems mediator _mapItems.addSource(searchRepository.searchItems) { updateItems() } _mapItems.addSource(placeRepository.placeItems) { updateItems() } } fun getMapItems(): LiveData<List<MapItem>> = _mapItems private fun updateItems() { val searchItems = searchRepository.searchItems.value?.map { MapItem.Point.Marker.Search(it.id, it.position) }.orEmpty() val placeItems = placeRepository.placeItems.value?.map { MapItem.Point.Marker.Place(it.id, it.position) }.orEmpty() // Apply some logic to decide which ones to show or filter... _mapItems.postValue(searchItems.plus(placeItems)) } }

override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) viewModel
= ViewModelProviders.of(this).get(MapViewModel::class.java) mapView.getMapAsync { googleMap = it viewModel.getMapItems().observe(this, Observer { googleMap.clear() it?.forEach { val marker = when (it) { is MapItem.Path.Route -> TODO() is MapItem.Point.Marker.Search -> { val icon = BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE) MarkerOptions().position(LatLng(it.latitude, it.longitude)).icon(icon) } is MapItem.Point.Marker.Place -> { val icon = BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE) MarkerOptions().position(LatLng(it.latitude, it.longitude)).icon(icon) } } googleMap.addMarker(marker) } }) } } Single responsibility © 2017 HERE | HERE Public Abstracting the map | June 24, 2018 12

Immutability • Map provider objects might be mutable, letting your
app with an unexpected/invalid state. • Immutable objects avoid possible concurrency issues and ensure consistency between your model an views. • Easy to test. © 2017 HERE | HERE Public Abstracting the map | June 24, 2018 15

Immutability © 2017 HERE | HERE Public Abstracting the map
| June 24, 2018 16 data class GeoCoordinate(val latitude: Double, val longitude: Double) sealed class MapItem { abstract val id: String sealed class Path : MapItem() { data class Route(override val id: String, val path: List<Point>) : Path() } sealed class Point : MapItem() { abstract val coordinate: GeoCoordinate sealed class Marker(override val id: String, override val coordinate: GeoCoordinate) : Point() { data class Search(override val id: String, override val coordinate: GeoCoordinate) : Marker(id, coordinate) data class Place(override val id: String, override val coordinate: GeoCoordinate) : Marker(id, coordinate) } } }

| June 24, 2018 17 data class GeoCoordinate(val latitude: Double, val longitude: Double) sealed class MapItem { abstract val id: String sealed class Path : MapItem() { data class Route(override val id: String, val path: List<Point>) : Path() } sealed class Point : MapItem() { abstract val coordinate: GeoCoordinate sealed class Marker(override val id: String, override val coordinate: GeoCoordinate) : Point() { data class Search(override val id: String, override val coordinate: GeoCoordinate) : Marker(id, coordinate) data class Place(override val id: String, override val coordinate: GeoCoordinate) : Marker(id, coordinate) } } }

| June 24, 2018 18 fun getMapItems(): LiveData<List<MapItem>> = _mapItems private fun updateItems() { val searchItems = searchRepository.searchItems.value?.map { MapItem.Point.Marker.Search(it.id, it.position) }.orEmpty() val placeItems = placeRepository.placeItems.value?.map { MapItem.Point.Marker.Place(it.id, it.position) }.orEmpty() // Apply some logic to decide which ones to show or filter... _mapItems.postValue(searchItems.plus(placeItems)) }

| June 24, 2018 19 fun getMapItems(): LiveData<List<MapItem>> = _mapItems private fun updateItems() { val searchItems = searchRepository.searchItems.value?.map { MapItem.Point.Marker.Search(it.id, it.position) }.orEmpty() val placeItems = placeRepository.placeItems.value?.map { MapItem.Point.Marker.Place(it.id, it.position) }.orEmpty() // Apply some logic to decide which ones to show or filter... _mapItems.postValue(searchItems.plus(placeItems)) } Immutable LiveData

| June 24, 2018 20 fun getMapItems(): LiveData<List<MapItem>> = _mapItems private fun updateItems() { val searchItems = searchRepository.searchItems.value?.map { MapItem.Point.Marker.Search(it.id, it.position) }.orEmpty() val placeItems = placeRepository.placeItems.value?.map { MapItem.Point.Marker.Place(it.id, it.position) }.orEmpty() // Apply some logic to decide which ones to show or filter... _mapItems.postValue(searchItems.plus(placeItems)) } Immutable LiveData New Immutable Object

| June 24, 2018 21 fun getMapItems(): LiveData<List<MapItem>> = _mapItems private fun updateItems() { val searchItems = searchRepository.searchItems.value?.map { MapItem.Point.Marker.Search(it.id, it.position) }.orEmpty() val placeItems = placeRepository.placeItems.value?.map { MapItem.Point.Marker.Place(it.id, it.position) }.orEmpty() // Apply some logic to decide which ones to show or filter... _mapItems.postValue(searchItems.plus(placeItems)) } New Immutable list Immutable LiveData New Immutable Object

Unidirectional data flow © 2017 HERE | HERE Public Abstracting
the map | June 24, 2018 22 Som eFragm ent Som eViewM odel M apFragm ent M apViewM odel SearchRepository PlaceRepository M ainInteractor

Result © 2017 HERE | HERE Public Abstracting the map
| June 24, 2018 23 LatLng M arkerOptions GoogleM ap Cam eraUpdate … Som eFragm ent Som eViewM odel M apFragm ent M apViewM odel SearchRepository PlaceRepository M ainInteractor

Improvements © 2017 HERE | HERE Public Abstracting the map
| June 24, 2018 24 override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) viewModel = ViewModelProviders.of(this).get(MapViewModel::class.java) mapView.getMapAsync { googleMap = it viewModel.getMapItems().observe(this, Observer { googleMap.clear() it?.forEach { val marker = when (it) { is MapItem.Path.Route -> TODO() is MapItem.Point.Marker.Search -> { val icon = BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE) MarkerOptions().position(LatLng(it.latitude, it.longitude)).icon(icon) } is MapItem.Point.Marker.Place -> { val icon = BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE) MarkerOptions().position(LatLng(it.latitude, it.longitude)).icon(icon) } } googleMap.addMarker(marker) } }) } }

| June 24, 2018 25 override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) viewModel = ViewModelProviders.of(this).get(MapViewModel::class.java) mapView.getMapAsync { googleMap = it viewModel.getMapItems().observe(this, Observer { googleMap.clear() it?.forEach { val marker = when (it) { is MapItem.Path.Route -> TODO() is MapItem.Point.Marker.Search -> { val icon = BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE) MarkerOptions().position(LatLng(it.latitude, it.longitude)).icon(icon) } is MapItem.Point.Marker.Place -> { val icon = BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE) MarkerOptions().position(LatLng(it.latitude, it.longitude)).icon(icon) } } googleMap.addMarker(marker) } }) } }

| June 24, 2018 26 override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) viewModel = ViewModelProviders.of(this).get(MapViewModel::class.java) adapter = MapsAdapter(requireContext()) mapView.getMapAsync { googleMap = it adapter.attach(view, googleMap) viewModel.getMapItems().observe(this, adapter) } } Adapter Pattern https://github.com/TradeMe/MapMe

| June 24, 2018 27 class MapsAdapter(context: Context) : GoogleMapMeAdapter(context), Observer<List<MapItem>> { private var markers: List<MapItem.Point> = emptyList() override fun onChanged(items: List<MapItem>?) { // Since we don't support Path yet just cast it val newMarkers = items.orEmpty().map { it as MapItem.Point } val diff = DiffUtil.calculateDiff(MarkersDiffCallback(markers, newMarkers)) markers = newMarkers diff.dispatchUpdatesTo(this) } override fun getItemCount(): Int = markers.size override fun onCreateAnnotation(factory: AnnotationFactory<GoogleMap>, position: Int, annotationType: Int): MapAnnotation { val item = this.markers[position] return factory.createMarker(item.toLatLng(), getIcon(item), item.id) } override fun onBindAnnotation(annotation: MapAnnotation, position: Int, payload: Any?) { if (annotation is MarkerAnnotation) { val item = this.markers[position] annotation.latLng = item.toLatLng() annotation.icon = getIcon(item) } } } Adapter Pattern https://github.com/TradeMe/MapMe

Showcase https://github.com/skimarxall/AbstractingTheMap

Next steps • Handle Camera State • Map gestures •
Path, routes and other object types • Complex interactions © 2017 HERE | HERE Public Abstracting the map | June 24, 2018 34

Thank you Contact M arcel Pintó Biescas @ m arxallski
https://m edium .com /@ m arxallski https://github.com /skim arxall

Abstracting the map

Abstracting the map

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