使用MapBox Android SDK进行离线磁贴缓存

Question

I have a working iOS prototype using the iOS tile-caching technique as shown below (Objective-C code):

RMTileCache  * tileCache = [[RMTileCache alloc] initWithExpiryPeriod:0]; 
[tileCache setBackgroundCacheDelegate:self]; 
RMMapboxSource * tileSource = [[RMMapboxSource alloc] initWithMapID:mapID]; 
[tileCache beginBackgroundCacheForTileSource:tileSource southWest:southWest northEast:northEasth minZoom:minZoom maxZoom:maxZoom];

What this basically does is download the map, cache the tiles permanently and make it possible for the app to run offline in the future. Since we're going through the official payed API, this is of course not violating any of the legal restrictions.

Now I'd like to achieve the same on Android. I have the SDK running in Android Studio and a working project with a remote map using the Map ID, basically this (Android Eclipse layout XML):

<com.mapbox.mapboxsdk.views.MapView
    android:id="@+id/mapview"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    mapid=“my_map_id" />

This works fine, but the solution has to be completely offline once the caching is done. My question is: is there a Java equivalent of the iOS source code above in the MapBox SDK? I attempted to look in the API, but could not find a solid reference to the tile caching system. And after some painful time trying to get it running based on the method names and code documentation, I gave up.

I'm running the latest GitHub distribution of MapBox along with the latest Android Studio, everything's up and running fine, but can't find the code to accomplish this. I don't necessarily need an API reference, a few lines of code showing how it's done would be enough.

Answer 1

Offline Tile Caching support is now available in the Mapbox Android SDK as of version 0.5.1. It was released on 20-December-2014. Here's a basic example of how to get started:

OfflineMapDownloader offlineMapDownloader = OfflineMapDownloader.getOfflineMapDownloader(getActivity());
BoundingBox boundingBox = mapView.getBoundingBox();
CoordinateSpan span = new CoordinateSpan(boundingBox.getLatitudeSpan(), boundingBox.getLongitudeSpan());
CoordinateRegion coordinateRegion = new CoordinateRegion(mapView.getCenter(), span);
offlineMapDownloader.beginDownloadingMapID("MapboxMapID", coordinateRegion, (int) mapView.getZoomLevel(), (int) mapView.getZoomLevel());

To load a previously saved map:

ArrayList<OfflineMapDatabase> offlineMapDatabases = offlineMapDownloader.getMutableOfflineMapDatabases();
OfflineMapDatabase db = offlineMapDatabases.get(0);
OfflineMapTileProvider tp = new OfflineMapTileProvider(getActivity(), db);
offlineMapOverlay = new TilesOverlay(tp);
mapView.addOverlay(offlineMapOverlay);

Answer 2

I asked this question to the support team, here's the answer:

"We don't currently have a release date for the Android SDK or for this feature, because both are in very early stages of development.

-- Tom MacWright support@mapbox.com"

It's a very good product, I hope we can use it soon in Android.

Answer 3

In your layout file there must be:

<com.mapbox.mapboxsdk.views.MapView
        android:id="@+id/yourMapViewId"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />

In code where you want to initialize MapView :

File file = new File("your full path to tiles db");
MBTilesLayer mbTilesLayer = new MBTilesLayer(file);
MapView mapView = (MapView) findViewById(R.id.yourMapViewId);
mapView.setTileSource(mbTilesLayer);