How to support custom tiled map format in Runtime v100 ?

[PatrickBolduc]

Hi,

We are trying to migrate one of our applicatoin from v10.2.9 to v100.1. We need to support map formats that are currently unsupported in the new runtime (i.e. : MBTiles). In our case, the system is always offline and the map are stored locally on the Android device.

It was easy to do that in the previous version (Creating a custom TileServiceLayer in ArcGIS Android | ArcGIS Blog ), but I had no success so for on the new v100.1.

I tried to extend the ImageTiledLayer, but I get an exception when I try to create a TileInfo using the following code :

public static ImageTiledLayer createMBTilesLayer(final Uri databaseUri)
{
    final SQLiteDatabase database = SQLiteDatabase.openDatabase(databaseUri.getPath(), null, SQLiteDatabase.OPEN_READONLY, new ErrorHandler());
    final int maxLevel = retrieveMaxLevel(database);

    final List<LevelOfDetail> levelOfDetails = new ArrayList<>();
    for(int i = 0; i < maxLevel; i++)
        levelOfDetails.add(new LevelOfDetail(i, 156543.032 / Math.pow(2, i), 554678932 / Math.pow(2, i)));

    final TileInfo tileInfo = new TileInfo(96, TileInfo.ImageFormat.JPG, levelOfDetails, new Point(0, 0), SpatialReferences.getWebMercator(), 256, 256);

    return new MBTilesLayer(tileInfo, new Envelope(-180.0, -85.0, 180, 85, SpatialReferences.getWebMercator()), database);
}
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java.lang.RuntimeException: Unable to start activity ComponentInfo{}: com.esri.arcgisruntime.ArcGISRuntimeException: Invalid argument
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2456)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2539)
at android.app.ActivityThread.access$900(ActivityThread.java:159)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1384)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5507)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Caused by: com.esri.arcgisruntime.ArcGISRuntimeException: Invalid argument
at com.esri.arcgisruntime.internal.jni.CoreTileInfo.nativeCreateWith(Native Method)
at com.esri.arcgisruntime.internal.jni.CoreTileInfo.<init>(SourceFile:72)
at com.esri.arcgisruntime.arcgisservices.TileInfo.<init>(SourceFile:121)

...

Is it the right approach to support other tiled format ? Is it some obvious error in the code snippet above that I do not see ?

Regards,

[AlexanderNohe1 · Accepted solution]

I took some time today and converted the 10.2.x sample to runtime 100:

This is the MBTilesLayer.java class:

package com.arcgis.apps.mbtiles;

import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

import com.esri.arcgisruntime.arcgisservices.LevelOfDetail;
import com.esri.arcgisruntime.arcgisservices.TileInfo;
import com.esri.arcgisruntime.data.TileKey;
import com.esri.arcgisruntime.geometry.Envelope;
import com.esri.arcgisruntime.geometry.GeometryEngine;
import com.esri.arcgisruntime.geometry.Point;
import com.esri.arcgisruntime.geometry.SpatialReferences;
import com.esri.arcgisruntime.layers.ImageTiledLayer;

import java.util.ArrayList;
import java.util.List;


/**
 * The MBTilesLayer class allows you to work with a MBTiles stored in a SQLite
 * database.
 * 
 */
public class MBTilesLayer extends ImageTiledLayer {

  private SQLiteDatabase mapDb;
  private int mLevels = 0;

  /**
   * The constructor to instantiate MBTiles from a path on device
   * 
   * @param path
   *          path is expected to be of the form /sdcard/path/package.mbtiles
   */
  public static MBTilesLayer init(String path) {
    SQLiteDatabase mapDb;
    int mLevels = 0;
    try {
      mapDb = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READONLY);
    } catch (SQLException ex) {
      Log.e("MBTiles", ex.getMessage());
      throw (ex);
    }

    // Default TMS bounds = bounds of Web Mercator projection
    Envelope envWGS = new Envelope(-180.0, -85.0511, 180.0, 85.0511, SpatialReferences.getWgs84());

    // See if the MBTiles DB defines their own Bounds in the metadata table
    Cursor bounds = mapDb.rawQuery("SELECT value FROM metadata WHERE name = 'bounds'", null);
    if (bounds.moveToFirst()) {
      String bs = bounds.getString(0);
      String[] ba = bs.split(",", 4);
      if (ba.length == 4) {
        double leftLon = Double.parseDouble(ba[0]);
        double topLat = Double.parseDouble(ba[3]);
        double rightLon = Double.parseDouble(ba[2]);
        double bottomLat = Double.parseDouble(ba[1]);

        envWGS = new Envelope(leftLon, bottomLat, rightLon, topLat, SpatialReferences.getWgs84());
      }
    }

    Envelope envWeb = (Envelope) GeometryEngine.project(envWGS,
        SpatialReferences.getWebMercator());

    Point origin = new Point(envWeb.getXMin(), envWeb.getYMax(), envWeb.getSpatialReference());

    Cursor maxLevelCur = mapDb.rawQuery("SELECT MAX(zoom_level) AS max_zoom FROM tiles", null);
    if (maxLevelCur.moveToFirst()) {
      mLevels = maxLevelCur.getInt(0);
    }

    Log.i("TAG", "Max levels = " + Integer.toString(mLevels));

    double[] resolution = new double[mLevels];
    double[] scale = new double[mLevels];
    List<LevelOfDetail> lod = new ArrayList<>(mLevels);
    for (int i = 0; i < mLevels; i++) {
      // see the TMS spec for derivation of the level 0 scale and resolution
      // For each level the resolution (in meters per pixel) doubles
      resolution[i] = 156543.032 / Math.pow(2, i);
      // Level 0 scale is 1:554,678,932. Each level doubles this.
      scale[i] = 554678932 / Math.pow(2, i);
      lod.add(new LevelOfDetail(i, resolution[i], scale[i]));
    }

    /*
     * Note, the constructor must set the following values or we won't send the
     * status change events to listeners and the tiles will not be fetched
     * 
     * Origin is Top Left (web Mercator) , the rest are defined by the TMS
     * Global-mercator spec (scales, resolution, 96dpi 256x256 pixel tiles) See:
     * http://wiki.osgeo.org/wiki/Tile_Map_Service_Specification#global-mercator
     */
    TileInfo ti = new TileInfo(96, TileInfo.ImageFormat.PNG, lod, origin, origin.getSpatialReference(), 256, 256);

    return new MBTilesLayer(ti, envWeb, mapDb, mLevels);

  }

  private MBTilesLayer(TileInfo tileInfo, Envelope fullExtent, SQLiteDatabase mapDb, int mLevels) {
    super(tileInfo, fullExtent);
    this.mapDb = mapDb;
    this.mLevels = mLevels;
  }


  @Override
  protected byte[] getTile(TileKey tileKey) {
    // need to flip origin
    int nRows = (1 << tileKey.getLevel()); // Num rows = 2^level
    int tmsRow = nRows - 1 - tileKey.getRow();

    Cursor imageCur = mapDb.rawQuery("SELECT tile_data FROM tiles WHERE zoom_level = " + Integer.toString(tileKey.getLevel())
            + " AND tile_column = " + Integer.toString(tileKey.getColumn()) + " AND tile_row = " + Integer.toString(tmsRow), null);
    if (imageCur.moveToFirst()) {
      return imageCur.getBlob(0);
    }
    return null; // Alternatively we might return a "no data" tile
  }
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

And here is how I called it:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mapView = (MapView) findViewById(R.id.mapView);

    MBTilesLayer mbTilesLayer = MBTilesLayer.init(Environment.getExternalStorageDirectory().getPath() 
         + "/ArcGIS/mmpks/world_countries.mbtiles");

    ArcGISMap arcGISMap = new ArcGISMap(new Basemap(mbTilesLayer));


    mapView.setMap(arcGISMap);
}

There are some things I am avoiding (like runtime permissions) but this should be a good start for you to implement this in your applications.

I hope this helps!

[PatrickBolduc]

Hi Alexander,

I changed the envelope creation code with what you provided in your reply and it fixed my issue and it works fine.

Thanks for the quick reply !

[AlexanderNohe1]

No problem!

If it helped resolve your problem, could you kindly mark the answer as correct.