在 Android Studio 上的 Kotlin 中使用 Mapbox 实现 Geojson 点以映射和定位我

Question

My question is about Mapbox. In this period I am working on an ANDROID application based on mapbox, using Kotlin and Fragments and my problem concerns the visualization of points on the map itself. That is my need is to be able to show points on the map through a GEOJSON file, for now I have been able to see the map in full in the application, but I cannot find a way to show the points taken from a GeoJson file and locate myself in the map via a button. I should implement both functions in the fragment, so my problem is precisely that of not being able to show the points of a geojson file and find a way to locate myself in the map itself. I await help if there is someone able to help me with this problem, I also leave the code of the fragment class in kotlin. Thanks everyone in advance !!

FRAGMENT HOME

class HomeFragment : Fragment() {

        private var mapView: MapView? = null

        @Nullable
        override fun onCreateView(
            inflater: LayoutInflater,
            @Nullable container: ViewGroup?,
            @Nullable savedInstanceState: Bundle?
        ): View? {
            Mapbox.getInstance(
                context!!.applicationContext,
                "MIO CODICE MAPBOX"
            )
            val view: View = inflater.inflate(R.layout.fragment_home, container, false)
            mapView = view.findViewById<View>(R.id.mapView) as MapView
            mapView!!.onCreate(savedInstanceState)
            return view
        }

        override fun onResume() {
            super.onResume()
            mapView!!.onResume()
        }

        override fun onPause() {
            super.onPause()
            mapView!!.onPause()
        }

        override fun onSaveInstanceState(outState: Bundle) {
            super.onSaveInstanceState(outState)
            mapView!!.onSaveInstanceState(outState)
        }

        override fun onLowMemory() {
            super.onLowMemory()
            mapView!!.onLowMemory()
        }

        override fun onDestroyView() {
            super.onDestroyView()
            mapView!!.onDestroy()
        }
    }

HOST ACTIVITY :

class HostActivity : AppCompatActivity() {
    lateinit var googleSignInClient: GoogleSignInClient
    private lateinit var navController: NavController
    private val mAuth: FirebaseAuth = FirebaseAuth.getInstance()
    private val db: FirebaseFirestore = FirebaseFirestore.getInstance()
    private lateinit var drawerLayout: DrawerLayout
    private lateinit var navViewBinding: DrawerHeaderLayoutBinding
    override fun onCreate(savedInstanceState: Bundle?) {
        setTheme(R.style.AppTheme)
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_host)
        val toolbar = customToolbar
        setSupportActionBar(toolbar)

        val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.default_web_client_id))
            .requestEmail()
            .build()
        googleSignInClient = GoogleSignIn.getClient(this, gso)

        drawerLayout = drawer_layout
        navViewBinding = DrawerHeaderLayoutBinding.inflate(layoutInflater, navView, true)
        val navHost =
            supportFragmentManager.findFragmentById(R.id.navHostFragment) as NavHostFragment
        navController = navHost.navController

        val navInflater = navController.navInflater

        val graph = navInflater.inflate(R.navigation.main_graph)

        navController.addOnDestinationChangedListener { _, destination, _ ->
            if (destination.id == R.id.onBoarding ||
                destination.id == R.id.authFragment ||
                destination.id == R.id.loginFragment ||
                destination.id == R.id.signUpFragment
            ) {
                toolbar.visibility = View.GONE
                drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED)
            } else {
                toolbar.visibility = View.VISIBLE
                drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED)
            }
        }
        if (!Prefs.getInstance(this)!!.hasCompletedWalkthrough!!) {
            if (mAuth.currentUser == null) {
                graph.startDestination = R.id.authFragment
            } else {
                getUserData()
                graph.startDestination = R.id.homeFragment
            }
        } else {
            graph.startDestination = R.id.onBoarding

        }
        navController.graph = graph

        NavigationUI.setupActionBarWithNavController(this, navController, drawerLayout)
        navView.setupWithNavController(navController)
        navView.setNavigationItemSelectedListener {
            it.isChecked
            drawerLayout.closeDrawers()
            when (it.itemId) {
                R.id.action_logout -> {
                    MyApplication.currentUser!!.active = false
                    FirestoreUtil.updateUser(MyApplication.currentUser!!) {
                        mAuth.signOut()
                    }
                    googleSignInClient.signOut()
                    MyApplication.currentUser = null
                    navController.navigate(R.id.action_logout)
                }
            }
            true
        }
    }

    private fun getUserData() {

        val ref = db.collection("users").document(mAuth.currentUser!!.uid)

        ref.get().addOnSuccessListener {
            val userInfo = it.toObject(UserModel::class.java)
            navViewBinding.user = userInfo
            MyApplication.currentUser = userInfo
            MyApplication.currentUser!!.active = true
            FirestoreUtil.updateUser(MyApplication.currentUser!!) {
            }
        }.addOnFailureListener {
            val intent = Intent(this, MyApplication::class.java)
            startActivity(intent)
            finish()
        }
    }

    override fun onSupportNavigateUp(): Boolean {
        return NavigationUI.navigateUp(navController, drawerLayout)
    }

}

Answer 1

You'll need to use a GeoJsonSource . https://github.com/mapbox/mapbox-android-demo/search?q=GeoJsonSource shows how the demo app uses the source.

https://github.com/mapbox/mapbox-android-demo/blob/master/MapboxAndroidDemo/src/main/java/com/mapbox/mapboxandroiddemo/examples/basics/KotlinSupportMapFragmentActivity.kt ( Its XML layout file )

Putting icons on the map. https://docs.mapbox.com/android/maps/examples/marker-symbol-layer/ . Do all of the icon setup inside of the fragment's onStyleLoaded() callback as seen at https://github.com/mapbox/mapbox-android-demo/blob/master/MapboxAndroidDemo/src/main/java/com/mapbox/mapboxandroiddemo/examples/basics/KotlinSupportMapFragmentActivity.kt#L51-L55

https://github.com/mapbox/mapbox-android-demo/search?q=loadGeojson shows how the demo app loads from a GeoJson file. You could use coroutines instead of building out the AsyncTask.

Although it's in Java, https://docs.mapbox.com/android/maps/examples/show-a-users-location-on-a-fragment/ shows how to combine the Maps SDK's LocationComponent with a fragment.

Regarding moving the camera to the device's last known location when a button is clicked, see my answer at https://stackoverflow.com/a/64159178/6358488