Develop Reference

Google Maps offline Mode on Android Application

Is there any posibility to show Google Maps if you are offline in your own App?
What about if I download an Area FROM Google Maps application for offline mode, could i visualize the map on the app that i develop if i don't have internet connection?
if not, What options do i have to make this possible? I just want to visualize the map when my app is offline...
The following its the code that this post provided TileProvider using local tiles
#Override
public Tile getTile(int x, int y, int zoom) {
byte[] image = readTileImage(x, y, zoom);
return image == null ? null : new Tile(TILE_WIDTH, TILE_HEIGHT,image);
}
private byte[] readTileImage(int x,int y, int zoom){
InputStream is= null;
ByteArrayOutputStream buffer= null;
try{
is= mAssets.open(getTileFileName(x,y,zoom));
buffer= new ByteArrayOutputStream();
int nRead;
byte[] data= new byte[BUFFER_SIZE];
while ((nRead= is.read(data,0,BUFFER_SIZE)) !=-1){
buffer.write(data,0,nRead);
}
buffer.flush();
return buffer.toByteArray();
}
catch(IOException ex){
Log.e("LINE 60 CustomMap", ex.getMessage());
return null;
}catch(OutOfMemoryError e){
Log.e("LINE 64 CustomMap", e.getMessage());
return null;
}finally{
if(is!=null){
try{
is.close();
} catch (IOException e) {}
}
if(buffer !=null){
try{
buffer.close();
}catch (Exception e){}
}
}
}
private String getTileFileName(int x, int y, int zoom){
return "map/"+ zoom +'/' +x+ '/'+y+".png";
}
I was looking for information, and My questions is, how can i download the tiles?

I was facing the same challenge, and none of the examples I found included a complete implementation of downloading the tiles, writing them to file and reading them from file.
This is my code, which reads the tile from file when it's available locally and downloads/saves the tile when not. This uses the OpenStreetMap.org tile server, but you could use any server you like by changing the URL.
private class OfflineTileProvider implements TileProvider {
private static final String TILES_DIR = "your_tiles_directory/";
private static final int TILE_WIDTH = 256;
private static final int TILE_HEIGHT = 256;
private static final int BUFFER_SIZE_FILE = 16384;
private static final int BUFFER_SIZE_NETWORK = 8192;
private ConnectivityManager connectivityManager;
#Override
public Tile getTile(int x, int y, int z) {
Log.d(TAG, "OfflineTileProvider.getTile(" + x + ", " + y + ", " + z + ")");
try {
byte[] data;
File file = new File(TILES_DIR + z, x + "_" + y + ".png");
if (file.exists()) {
data = readTile(new FileInputStream(file), BUFFER_SIZE_FILE);
} else {
if (connectivityManager == null) {
connectivityManager = (ConnectivityManager) getSystemService(
Context.CONNECTIVITY_SERVICE);
}
NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
if (activeNetworkInfo == null || !activeNetworkInfo.isConnected()) {
Log.w(TAG, "No network");
return NO_TILE;
}
Log.d(TAG, "Downloading tile");
data = readTile(new URL("https://a.tile.openstreetmap.org/" +
z + "/" + x + "/" + y + ".png").openStream(),
BUFFER_SIZE_NETWORK);
try (OutputStream out = new BufferedOutputStream(new FileOutputStream(file))) {
out.write(data);
}
}
return new Tile(TILE_WIDTH, TILE_HEIGHT, data);
} catch (Exception ex) {
Log.e(TAG, "Error loading tile", ex);
return NO_TILE;
}
}
private byte[] readTile(InputStream in, int bufferSize) throws IOException {
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
try {
int i;
byte[] data = new byte[bufferSize];
while ((i = in.read(data, 0, bufferSize)) != -1) {
buffer.write(data, 0, i);
}
buffer.flush();
return buffer.toByteArray();
} finally {
in.close();
buffer.close();
}
}
}
Replace "your_tiles_directory" with the path to the directory where you want to store your tiles.
To use the TileProvider:
map.setMapType(GoogleMap.MAP_TYPE_NONE);
offlineTileOverlay = map.addTileOverlay(new TileOverlayOptions()
.tileProvider(new OfflineTileProvider()));
Edit: You may want to set the max zoom level, the default is 21 but OpenStreetMap for example seems to have a maximum of 19.
map.setMaxZoomPreference(19);

You can download tile image from a tile server and cache on your app. Check some server on this link. Or you can build a tile as this demo, then download tile image from it.
Good luck

How to prevent buildings from moving on Google Maps Android API

I've set custom overlays on Google Maps to get indoor maps of my building. But when I move the map on the screen, buildings are moving and overlays are fixed. So it gets a bit ugly. You can see how ugly it is on the image below.
ugly indoor map
I'd like to get the map like this : pretty indoor map
How to prevent buildings from moving on Android Google Maps API ?
Below the part of code I use to set overlays on the map :
private GoogleMap mMap;
private MapView mapView;
#Override
public void onMapReady(GoogleMap googleMap) {
this.mMap = googleMap;
refreshGoogleMap();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
mapView = (MapView) findViewById(R.id.mapView);
mapView.onCreate(savedInstanceState);
mapView.getMapAsync(this);
}
private void refreshGoogleMap() {
mMap.clear();
mMap.addTileOverlay(new TileOverlayOptions()
.tileProvider(new AssetsTileProvider())
.zIndex(-1));
}
private class AssetsTileProvider implements TileProvider {
private static final int TILE_WIDTH = 256;
private static final int TILE_HEIGHT = 256;
private static final int BUFFER_SIZE = 16 * 1024;
#Override
public Tile getTile(int x, int y, int zoom) {
byte[] bytes = readFile(x, y, zoom);
return bytes == null ? NO_TILE : new Tile(TILE_WIDTH, TILE_HEIGHT, bytes);
}
private byte[] readFile(int x, int y, int zoom) {
InputStream in = null;
ByteArrayOutputStream buffer = null;
try {
in = getAssets().open(getFilename(x, y, zoom));
buffer = new ByteArrayOutputStream();
int read;
byte[] data = new byte[BUFFER_SIZE];
while ((read = in.read(data, 0, BUFFER_SIZE)) != -1) {
buffer.write(data, 0, read);
}
buffer.flush();
return buffer.toByteArray();
} catch (Exception e) {
// NO OP
} finally {
if (in != null) try { in.close(); } catch (Exception ignored) {}
if (buffer != null) try { buffer.close(); } catch (Exception ignored) {}
}
return null;
}
private String getFilename(int x, int y, int zoom) {
String level = currentLevel == LEVEL_1 ? "level-1" : "level-2";
return level + "/" + zoom + "/" + x + "/" + y + ".png";
}
}

Adding an Authorization header in getTileUrl for Maps Tile Android

I would like to access some Custom Map Tiles when creating a TileOverlay for Google Maps API.
So this is my current code:
TileProvider tileProvider = new UrlTileProvider(256, 256) {
#Override
public URL getTileUrl(int x, int y, int z) {
String url = String.format("https://api.mycustommaps.com/v1/%d/%d/%d.jpg", z, x, y);
if (!checkTileExists(x, y, z)) {
return null;
}
try {
URL tileUrl = new URL(url);
tileUrl.openConnection().addRequestProperty("Authorization", LOGIN_TOKEN);
return tileUrl;
} catch (MalformedURLException e) {
e.printStackTrance();
} catch (IOException e) {
e.printStackTrance();
}
return null;
}
};
Since the connection returns 401 Anauthorized, I can't access the tiles. How could I pass Authorization header to let the url know I am authorized to access those tiles?

you have to implement the "TileProvider" interface, not URLTileProvider (because you have to retrieve the tile on your own, an URL is not enough.
https://developers.google.com/android/reference/com/google/android/gms/maps/model/TileProvider
as you can see, there is a note to keep attention:
Calls to methods in this interface might be made from multiple threads so implementations of this interface must be threadsafe.
and you have to implement a single method:
abstract Tile
getTile(int x, int y, int zoom)
It is now your work download the tile, I've done it for local files, so I'm just writing here some code that might need some more refinement and testing:
#Override
public Tile getTile(int x, int y, int zoom) {
String url = String.format("https://api.mycustommaps.com/v1/%d/%d/%d.jpg", z, x, y);
if (!checkTileExists(x, y, z)) {
return null;
}
try {
URL tileUrl = new URL(url);
//Download the PNG as byte[], I suggest using OkHTTP library or see next code!
final byte[] data = downloadData(tileUrl);
final int height = tileheight;
final int width = tilewidth;
if (data != null) {
if (BuildConfig.DEBUG)Log.d(TAG, "Cache hit for tile " + key);
return new Tile(width, height, data);
}
//In this case error, maybe return a placeholder tile or TileProvider.NO_TILE
} catch (MalformedURLException e) {
e.printStackTrance();
} catch (IOException e) {
e.printStackTrance();
}
}
to download:
byte[] downloadData(URL url){
ByteArrayOutputStream baos = new ByteArrayOutputStream();
InputStream is = null;
try {
tileUrl.openConnection().addRequestProperty("Authorization", LOGIN_TOKEN);
is = url.openStream();
byte[] byteChunk = new byte[4096]; // Or whatever size you want to read in at a time.
int n;
while ( (n = is.read(byteChunk)) > 0 ) {
baos.write(byteChunk, 0, n);
}
}
catch (IOException e) {
System.err.printf ("Failed while reading bytes from %s: %s", url.toExternalForm(), e.getMessage());
e.printStackTrace ();
// Perform any other exception handling that's appropriate.
}
finally {
if (is != null) { is.close(); }
}
return baos.toByteArray():

Google Maps API Android - Tile provider's tiles resolution

I'm using custom TileProviders in my Android app to display offline maps and OpenStreetMap maps. It works, but there is a problem with the tiles resolution, which is quite bad. The files have a size of 256x256, and setting the width/height of my TileProvider to 128 doesn't change anything.
Here is some piece of code :
public class GenericUrlTileProvider extends UrlTileProvider {
// ---------------------------------------------------------------------------------------
// Private attributes :
private String _baseUrl;
// ---------------------------------------------------------------------------------------
// ---------------------------------------------------------------------------------------
// Constructor :
public GenericUrlTileProvider(int width, int height, String url) {
super(width, height);
this._baseUrl = url;
}
#Override
public URL getTileUrl(int x, int y, int zoom) {
try {
return new URL(_baseUrl.replace("{z}", "" + zoom).replace("{x}", "" + x).replace("{y}", "" + y));
}
catch (MalformedURLException e) { e.printStackTrace(); }
return null;
}
// ---------------------------------------------------------------------------------------
}
Does anyone know how to fix this to support high resolution devices ?
Thanks

On #grub request, here is what I did for getting the 4 tiles of the next zoom level :
public Tile getTileFromNextZoomLevel(int x, int y, int zoom) {
final String topLeftTileUrl = _source.getUrlSchema().replace("{z}", "" + (zoom + 1)).replace("{x}", "" + (x * 2)).replace("{y}", "" + (y * 2));
final String topRightTileUrl = _source.getUrlSchema().replace("{z}", "" + (zoom + 1)).replace("{x}", "" + (x * 2 + 1)).replace("{y}", "" + (y * 2));
final String bottomLeftTileUrl = _source.getUrlSchema().replace("{z}", "" + (zoom + 1)).replace("{x}", "" + (x * 2)).replace("{y}", "" + (y * 2 + 1));
final String bottomRightTileUrl = _source.getUrlSchema().replace("{z}", "" + (zoom + 1)).replace("{x}", "" + (x * 2 + 1)).replace("{y}", "" + (y * 2 + 1));
final Bitmap[] tiles = new Bitmap[4];
Thread t1 = new Thread() {
#Override
public void run() { tiles[0] = Utils.getBitmapFromURL(topLeftTileUrl); }
};
t1.start();
Thread t2 = new Thread() {
#Override
public void run() { tiles[1] = Utils.getBitmapFromURL(topRightTileUrl); }
};
t2.start();
Thread t3 = new Thread() {
#Override
public void run() { tiles[2] = Utils.getBitmapFromURL(bottomLeftTileUrl); }
};
t3.start();
Thread t4 = new Thread() {
#Override
public void run() { tiles[3] = Utils.getBitmapFromURL(bottomRightTileUrl); }
};
t4.start();
try {
t1.join();
t2.join();
t3.join();
t4.join();
}
catch (InterruptedException e) { e.printStackTrace(); }
byte[] tile = Utils.mergeBitmaps(tiles, Bitmap.CompressFormat.JPEG); // PNG is a lot slower, use it only if you really need to
return tile == null ? TileProvider.NO_TILE : new Tile( (int) _source.getTileSize().getWidth(), (int) _source.getTileSize().getHeight(), tile);
}
And the Utils methods :
public static byte[] mergeBitmaps(Bitmap[] parts, Bitmap.CompressFormat format) {
// Check if all the bitmap are null (if so return null) :
boolean allNulls = true;
for (int i = 0; i < parts.length; i++) {
if(parts[i] != null) {
allNulls = false;
break;
}
}
if(allNulls) return null;
Bitmap tileBitmap = Bitmap.createBitmap(512, 512, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(tileBitmap);
Paint paint = new Paint();
for (int i = 0; i < parts.length; i++) {
if(parts[i] == null) {
parts[i] = Bitmap.createBitmap(256, 256, Bitmap.Config.ARGB_8888);
}
canvas.drawBitmap(parts[i], parts[i].getWidth() * (i % 2), parts[i].getHeight() * (i / 2), paint);
}
ByteArrayOutputStream stream = new ByteArrayOutputStream();
tileBitmap.compress(format, 100, stream);
byte[] bytes = stream.toByteArray();
return bytes;
}
public static Bitmap getBitmapFromURL(String urlString) {
try {
// Ensure the file exists :
if(Utils.getResponseCode(urlString) != 200) return null;
URL url = new URL(urlString);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
Bitmap bitmap = BitmapFactory.decodeStream(connection.getInputStream());
return bitmap;
}
catch (IOException e) { return null; }
}
You may have to adapt it for your needs. Please note that my app is still under development, and this code may need some tests / improvements.

How get a string from asset to double for latlng google maps v2 android

i am new to android programming and i try to draw a polyline on google maps v2 android. the coordinates (more than 100) are stored in two txt-files (one txt for lat and one for lng) in asstes directory. i tryed to load the content of the files in a string but now i don't how to convert these to double for the polyline feature.
Double.parseDouble(contentdlat); won't work!
the coordinates in the txt's ar seperatet with a "," and looks like:
dlat.txt = 42.4630,42.4539
dlng.txt = -75.0572,-73.9737
UPDATE: now i use only one file instead of two.
coord_short.txt = 42.4630,-75.0572,42.4539,-73.9737
the old code is shown below:
//Add Polyline
ArrayList<LatLng> all=new ArrayList<LatLng>();
ArrayList<Double> lat1=new ArrayList<Double>();
ArrayList<Double> lon=new ArrayList<Double>();
AssetManager assetManager = getAssets();
// To load dlat text file
InputStream inputdlat;
try {
inputdlat = assetManager.open("dlat.txt");
int sizedlat = inputdlat.available();
byte[] bufferdlat = new byte[sizedlat];
inputdlat.read(bufferdlat);
inputdlat.close();
// byte buffer into a string
String contentdlat = new String(bufferdlat);
Toast.makeText(this, contentdlat, Toast.LENGTH_SHORT).show();
//String[] splitdlat = contentdlat.split(",");
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// To load dlng text file
InputStream inputdlng;
try {
inputdlng = assetManager.open("dlng.txt");
int sizedlng = inputdlng.available();
byte[] bufferdlng = new byte[sizedlng];
inputdlng.read(bufferdlng);
inputdlng.close();
// byte buffer into a string
String contentdlng = new String(bufferdlng);
Toast.makeText(this, contentdlng, Toast.LENGTH_SHORT).show();
//String[] splitdlng = contentdlng.split(",");
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
double dlat = Double.parseDouble(contentdlat);
double dlat = Double.parseDouble(contentdlng);
//double[] dlat = {42.4630,42.4539};
//double[] dlon = new double[]{-75.0572,-73.9737};
for(double n : dlat){
lat1.add(n);
}
for(double n : dlon){
lon.add(n);
}
for(int a=0;a<lat1.size();a++)
{
LatLng allLatLng= new LatLng(lat1.get(a),lon.get(a));
all.add(allLatLng);
}
Polyline polyline = map.addPolyline(new PolylineOptions()
.addAll(all)
.width(8)
.color(Color.GREEN));
It will be great if anybody can help me.
Ok with Piyush Gupta's help i changed the code to:
AssetManager assetManager = getAssets();
// To load coordinate text with hundreds of coordinates file like
InputStream input;
try {
input = assetManager.open("coord_short.txt");
int size = input.available();
byte[] buffer = new byte[size];
input.read(buffer);
input.close();
// byte buffer into a string
String content = new String(buffer);
String[] separated = content.split(",");
String latString = separated[0];
String longString = separated[1];
double coordlat = Double.parseDouble(latString);
double coordlon = Double.parseDouble(longString);
LatLng coordlocation = new LatLng(coordlat, coordlon);
Polyline polyline = map.addPolyline(new PolylineOptions()
.add(coordlocation)
.width(8)
.color(Color.GREEN));
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
But now my Polyline is not drawn on the map.
whats now wrong?

InputStream is = getAssets().open("test.txt");
int size = is.available();
byte[] buffer = new byte[size]; //declare the size of the byte array with size of the file
is.read(buffer); //read file
is.close(); //close file
// Store text file data in the string variable
String str_data = new String(buffer);