通过指定边界框实现来下载地图

Question

我在高级用户指南中读到，我们可以使用MapDataPrefetcher下载少量地图。我使用Mapfragment在我的应用程序中显示地图，它说MapEngine是通过使用MapFraction自动初始化的。

问题是，我不知道如何应用这些方法，以及在哪里需要初始化下载边界框本身的请求。它在用户指南中并不那么清楚。

如果这里有人能帮我解决这个问题，或者发一个实现的例子，我将非常感激！

这是我对地图和地图片段的init方法

private void initialize() {
setContentView(R.layout.activity_main);
// Search for the map fragment to finish setup by calling init().
//  mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.mapfragment);
mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.mapfragment);
mLocationInfo = (TextView) findViewById(R.id.textViewLocationInfo);
mapFragment.setRetainInstance(false);
// Set up disk cache path for the map service for this application
// It is recommended to use a path under your application folder for storing the disk cache
boolean success = com.here.android.mpa.common.MapSettings.setIsolatedDiskCacheRootPath(
getApplicationContext().getExternalFilesDir(null)+File.separator + ".here-maps",
"com.example.andrey88.MapService"); /* ATTENTION! Do not forget to update {YOUR_INTENT_NAME} */
if (!success) {
Toast.makeText(getApplicationContext(), "Unable to set isolated disk cache path.", Toast.LENGTH_LONG);
} else {
mapFragment.init(new OnEngineInitListener() {
@Override
public void onEngineInitializationCompleted(OnEngineInitListener.Error error) {
if (error == OnEngineInitListener.Error.NONE) {
// retrieve a reference of the map from the map fragment
map = mapFragment.getMap();
// Set the map center to the Ruppin region (no animation)
map.setCenter(new GeoCoordinate(32.343099, 34.911272, 0.0), Map.Animation.NONE);
// Set the zoom level
map.setZoomLevel(17.8);

map.setMapScheme(Map.Scheme.PEDESTRIAN_DAY);
map.setLandmarksVisible(false);
map.setProjectionMode(Map.Projection.MERCATOR);
map.getPedestrianFeaturesVisible();

// position of user
map.addTransformListener(MainActivity.this);
mPositioningManager = PositioningManager.getInstance();
// check source of getting geo location
mHereLocation = LocationDataSourceHERE.getInstance(
new StatusListener() {
@Override
public void onOfflineModeChanged(boolean offline) {
// called when offline mode changes
}
@Override
public void onAirplaneModeEnabled() {
// called when airplane mode is enabled
}
@Override
public void onWifiScansDisabled() {
// called when Wi-Fi scans are disabled
}
@Override
public void onBluetoothDisabled() {
// called when Bluetooth is disabled
}
@Override
public void onCellDisabled() {
// called when Cell radios are switch off
}
@Override
public void onGnssLocationDisabled() {
// called when GPS positioning is disabled
}
@Override
public void onNetworkLocationDisabled() {
// called when network positioning is disabled
}
@Override
public void onServiceError(StatusListener.ServiceError serviceError) {
// called on HERE service error
}
@Override
public void onPositioningError(PositioningError positioningError) {
// called when positioning fails
}
@Override
public void onWifiIndoorPositioningNotAvailable() {
// called when running on Android 9.0 (Pie) or newer
}
});
if (mHereLocation == null) {
Toast.makeText(MainActivity.this, "LocationDataSourceHERE.getInstance(): failed, exiting", Toast.LENGTH_LONG).show();
finish();
}
mPositioningManager.setDataSource(mHereLocation);
mPositioningManager.addListener(new WeakReference<PositioningManager.OnPositionChangedListener>(MainActivity.this));

// Create a custom marker image
com.here.android.mpa.common.Image myImage = new com.here.android.mpa.common.Image();
try {myImage.setImageResource(R.drawable.marker_round);
} catch (IOException e) {
finish();
}
initMarkers(myImage);
createPolygon();
mapFragment.getMapGesture().addOnGestureListener(new MapGesture.OnGestureListener() {
@Override
public void onPanStart() {
}
@Override
public void onPanEnd() {
}
@Override
public void onMultiFingerManipulationStart() {
}
@Override
public void onMultiFingerManipulationEnd() {
}
@Override
public boolean onMapObjectsSelected(List<ViewObject> list) {
return false;
}
@Override
public boolean onTapEvent(PointF pointF) {
return false;
}
@Override
public boolean onDoubleTapEvent(PointF pointF) {
return false;
}
@Override
public void onPinchLocked() {
}
@Override
public boolean onPinchZoomEvent(float v, PointF pointF) {
return false;
}
@Override
public void onRotateLocked() {
}
@Override
public boolean onRotateEvent(float v) {
return false;
}
@Override
public boolean onTiltEvent(float v) {
return false;
}
@Override
public boolean onLongPressEvent(PointF pointF) {
return false;
}
@Override
public void onLongPressRelease() {
}
@Override
public boolean onTwoFingerTapEvent(PointF pointF) {
return false;
}
}, 0, false);
if (mPositioningManager.start(PositioningManager.LocationMethod.GPS_NETWORK_INDOOR)) {
mapFragment.getPositionIndicator().setVisible(true);
} else {
Toast.makeText(MainActivity.this, "PositioningManager.start: failed, exiting", Toast.LENGTH_LONG).show();
finish();
}
}
else {
Log.d("errorTag",error.name());
onDestroy();
}
}
});
}
}

Answer 1

MapEngine必须初始化后才能使用。它应该在主线程中完成。MapEngine是通过使用AndroidXMapFragment为您的应用程序自动初始化的。AndroidXMapFragment是一个片段类，应用程序可以在地图显示活动中用作UI模块。但是，如果您的应用程序不使用AndroidXMapFragment类，那么应用程序应该在使用任何HERE API之前直接初始化MapEngine。您可以通过调用MapEngine.init(ApplicationContext，OnEngineInitListener(来完成此操作，如下所示：

MapEngine mapEngine = MapEngine.getInstance(); ApplicationContext appContext = new ApplicationContext(context); mapEngine.init(appContext, new OnEngineInitListener() {   @Override   public void onEngineInitializationCompleted(Error error) {
if (error == OnEngineInitListener.Error.NONE) {
// Post initialization code goes here
} else {
// handle factory initialization failure
}   } });