public class MainActivity extends AppCompatActivity {

    private static final int REQUEST_CODE_ASK_PERMISSIONS = 0x01;
    private Map m_map;
    private MapView m_mapView;
    private MapMarker marker;
    private Route route;
    private boolean updateMap = false;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        m_mapView = findViewById(R.id.map);
        requestPermissions();
    }

    private void requestPermissions() {
        final int result = ContextCompat.checkSelfPermission(this,
                Manifest.permission.WRITE_EXTERNAL_STORAGE);

        if (result != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this,
                    new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE},
                    REQUEST_CODE_ASK_PERMISSIONS);
        } else {
            initMap();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                           @NonNull int[] grantResults) {
        final boolean permissionGranted = grantResults.length > 0
                && (requestCode == REQUEST_CODE_ASK_PERMISSIONS
                && grantResults[0] == PackageManager.PERMISSION_GRANTED);

        if (permissionGranted) {
            initMap();
        } else {
            requestPermissions();
        }
    }

    /**
     * Initialize m_map engine.
     * After initialization set m_map object for {@link MapView}.
     * Also in callback check if initialization completed successfully
     */
    private void initMap() {
        MapEngine.getInstance().init(new ApplicationContext(getApplicationContext()),
                new OnEngineInitListener() {
                    @Override
                    public void onEngineInitializationCompleted(Error error) {
                        if (error == Error.NONE) {
                            /* get the map object */
                            m_map = new Map();
                            m_mapView.setMap(m_map);
                            startRoute();
                        } else {
                            Toast.makeText(getApplicationContext(), error.name(),
                                    Toast.LENGTH_SHORT).show();
                        }
                    }
                });
    }

    @Override
    protected void onResume() {
        super.onResume();
        m_mapView.onResume();

        if (updateMap) {
            m_map.zoomTo(route.getBoundingBox(), Map.Animation.NONE, 10f);
            m_map.setZoomLevel(12.0);
            updateMap = false;
        }
    }

    @Override
    protected void onUserLeaveHint() {
        super.onUserLeaveHint();
        if (!isInPictureInPictureMode()) {
            final PictureInPictureParams.Builder builder = new PictureInPictureParams.Builder();
            builder.setAspectRatio(new Rational(2, 3));
            enterPictureInPictureMode(builder.build());
        }
    }

    @Override
    public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode, Configuration newConfig) {
        super.onPictureInPictureModeChanged(isInPictureInPictureMode, newConfig);
        if (isInPictureInPictureMode) {
            m_map.setCenter(marker.getCoordinate(), Map.Animation.NONE);
            m_map.setZoomLevel(23.0);
        } else {
            updateMap = true;
        }
    }

    private void startRoute() {
        final GeoCoordinate start = new GeoCoordinate(52.52816, 13.39210);
        final GeoCoordinate end = new GeoCoordinate(52.51178, 13.49416);
        final RoutePlan plan = new RoutePlan();
        final RouteOptions routeOptions = new RouteOptions();
        routeOptions.setRouteCount(1);

        plan.addWaypoint(new RouteWaypoint(start));
        plan.addWaypoint(new RouteWaypoint(end));
        plan.setRouteOptions(routeOptions);

        final CoreRouter coreRouter = new CoreRouter();
        coreRouter.calculateRoute(plan, new Router.Listener<List<RouteResult>, RoutingError>() {
            @Override
            public void onProgress(int i) { }

            @Override
            public void onCalculateRouteFinished(List<RouteResult> routeResults, RoutingError routingError) {
                if (routingError == RoutingError.NONE) {
                    route = routeResults.get(0).getRoute();
                    m_map.addMapObject(new MapRoute(route));
                    m_map.zoomTo(route.getBoundingBox(), Map.Animation.NONE, 10f);
                    final Image image = new Image();

                    try {
                        image.setImageResource(R.drawable.arrow);
                        marker = new MapMarker(start, image);
                        m_map.addMapObject(marker);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

            }
        });
    }
}