Android Open Source - android-gmaps-addons Map Box Offline Tile Provider

• Back to Map/API  ↑

From Project

Back to project page android-gmaps-addons.

License

The source code is released under:

Copyright (c) 2014 Jonathan Baker Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Sof...

Java Source Code

package com.cocoahero.android.gmaps.addons.mapbox;
/*from www .  j  a  va  2 s.  c  o m*/
import java.io.Closeable;
import java.io.File;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.LatLngBounds;
import com.google.android.gms.maps.model.Tile;
import com.google.android.gms.maps.model.TileProvider;

public class MapBoxOfflineTileProvider implements TileProvider, Closeable {

    // ------------------------------------------------------------------------
    // Instance Variables
    // ------------------------------------------------------------------------

    private int mMinimumZoom = Integer.MIN_VALUE;

    private int mMaximumZoom = Integer.MAX_VALUE;

    private LatLngBounds mBounds;

    private SQLiteDatabase mDatabase;

    // ------------------------------------------------------------------------
    // Constructors
    // ------------------------------------------------------------------------

    public MapBoxOfflineTileProvider(File file) {
        this(file.getAbsolutePath());
    }

    public MapBoxOfflineTileProvider(String pathToFile) {
        int flags = SQLiteDatabase.OPEN_READONLY | SQLiteDatabase.NO_LOCALIZED_COLLATORS;
        this.mDatabase = SQLiteDatabase.openDatabase(pathToFile, null, flags);
        this.calculateZoomConstraints();
        this.calculateBounds();
    }

    // ------------------------------------------------------------------------
    // TileProvider Interface
    // ------------------------------------------------------------------------

    @Override
    public Tile getTile(int x, int y, int z) {
        Tile tile = NO_TILE;
        if (this.isZoomLevelAvailable(z) && this.isDatabaseAvailable()) {
            String[] projection = {
                "tile_data"
            };
            int row = ((int) (Math.pow(2, z) - y) - 1);
            String predicate = "tile_row = ? AND tile_column = ? AND zoom_level = ?";
            String[] values = {
                    String.valueOf(row), String.valueOf(x), String.valueOf(z)
            };
            Cursor c = this.mDatabase.query("tiles", projection, predicate, values, null, null, null);
            if (c != null) {
                c.moveToFirst();
                if (!c.isAfterLast()) {
                    tile = new Tile(256, 256, c.getBlob(0));
                }
                c.close();
            }
        }
        return tile;
    }

    // ------------------------------------------------------------------------
    // Closeable Interface
    // ------------------------------------------------------------------------

    /**
     * Closes the provider, cleaning up any background resources.
     * 
     * <p>
     * You must call {@link #close()} when you are finished using an instance of
     * this provider. Failing to do so may leak resources, such as the backing
     * SQLiteDatabase.
     * </p>
     */
    @Override
    public void close() {
        if (this.mDatabase != null) {
            this.mDatabase.close();
            this.mDatabase = null;
        }
    }

    // ------------------------------------------------------------------------
    // Public Methods
    // ------------------------------------------------------------------------

    /**
     * The minimum zoom level supported by this provider.
     * 
     * @return the minimum zoom level supported or {@link Integer.MIN_VALUE} if
     *         it could not be determined.
     */
    public int getMinimumZoom() {
        return this.mMinimumZoom;
    }

    /**
     * The maximum zoom level supported by this provider.
     * 
     * @return the maximum zoom level supported or {@link Integer.MAX_VALUE} if
     *         it could not be determined.
     */
    public int getMaximumZoom() {
        return this.mMaximumZoom;
    }

    /**
     * The geographic bounds available from this provider.
     * 
     * @return the geographic bounds available or {@link null} if it could not
     *         be determined.
     */
    public LatLngBounds getBounds() {
        return this.mBounds;
    }

    /**
     * Determines if the requested zoom level is supported by this provider.
     * 
     * @param zoom The requested zoom level.
     * @return {@code true} if the requested zoom level is supported by this
     *         provider.
     */
    public boolean isZoomLevelAvailable(int zoom) {
        return (zoom >= this.mMinimumZoom) && (zoom <= this.mMaximumZoom);
    }

    // ------------------------------------------------------------------------
    // Private Methods
    // ------------------------------------------------------------------------

    private void calculateZoomConstraints() {
        if (this.isDatabaseAvailable()) {
            String[] projection = new String[] {
                "value"
            };

            String[] minArgs = new String[] {
                "minzoom"
            };

            String[] maxArgs = new String[] {
                "maxzoom"
            };

            Cursor c;

            c = this.mDatabase.query("metadata", projection, "name = ?", minArgs, null, null, null);

            c.moveToFirst();
            if (!c.isAfterLast()) {
                this.mMinimumZoom = c.getInt(0);
            }
            c.close();

            c = this.mDatabase.query("metadata", projection, "name = ?", maxArgs, null, null, null);

            c.moveToFirst();
            if (!c.isAfterLast()) {
                this.mMaximumZoom = c.getInt(0);
            }
            c.close();
        }
    }

    private void calculateBounds() {
        if (this.isDatabaseAvailable()) {
            String[] projection = new String[] {
                "value"
            };

            String[] subArgs = new String[] {
                "bounds"
            };

            Cursor c = this.mDatabase.query("metadata", projection, "name = ?", subArgs, null, null, null);

            c.moveToFirst();
            if (!c.isAfterLast()) {
                String[] parts = c.getString(0).split(",\\s*");

                double w = Double.parseDouble(parts[0]);
                double s = Double.parseDouble(parts[1]);
                double e = Double.parseDouble(parts[2]);
                double n = Double.parseDouble(parts[3]);

                LatLng ne = new LatLng(n, e);
                LatLng sw = new LatLng(s, w);

                this.mBounds = new LatLngBounds(sw, ne);
            }
            c.close();
        }
    }

    private boolean isDatabaseAvailable() {
        return (this.mDatabase != null) && (this.mDatabase.isOpen());
    }

}

Java Source Code List

• Back to Map/API  ↑