Develop Reference

Plotting coordinates on Route in Gmap (Google Maps Android API)

I'm currently working on one Android application using Google map.
My requirement is to draw a route between source-destination and plot markers at every 500 meters on that route.
I have drawn a route, but not getting how to plot markers at every 500 meters. Is there any Google API available to get coordinates on route, or I have to implement any other logic?

Objectives
The objective is getting a list of LatLng coordinates along the route returned by the Directions API web service at every N meters. Later we can create markers for this list of coordinates.
Solution
The solution has two steps. The first one is getting a list of LatLng that form a route returned by Directions API. You can use a Java Client for Google Maps Services to execute Directions API request and extract a list of LatLng. Have a look at private List<LatLng> getDirectionsPathFromWebService(String origin, String destination) method in my example. This method calls Directions API and loop through legs and steps of the route object to get a complete list of LatLng that form a route.
The second step is implemented in the method private List<LatLng> getMarkersEveryNMeters(List<LatLng> path, double distance). It loops through all LatLng from the first step and creates a list of LatLng at every N meters where N is a distance in meters passed as a second parameter of the method. This method uses internally SphericalUtil class from the Google Maps Android API Utility Library. Have a look at comment to figure out what is happening in this method.
Finally, I create markers from the list that was obtained in second step.
Code snippet
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
private GoogleMap mMap;
private String TAG = "so47784512";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
#Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
String origin = "Avinguda Diagonal, 101, 08005 Barcelona, Spain";
String destination = "Carrer de París, 67, 08029 Barcelona, Spain";
LatLng center = new LatLng(41.391942,2.179413);
//Define list to get all latlng for the route
List<LatLng> path = this.getDirectionsPathFromWebService(origin, destination);
//Draw the polyline
if (path.size() > 0) {
PolylineOptions opts = new PolylineOptions().addAll(path).color(Color.BLUE).width(5);
mMap.addPolyline(opts);
}
List<LatLng> markers = this.getMarkersEveryNMeters(path, 500.0);
if (markers.size() > 0) {
for (LatLng m : markers) {
MarkerOptions mopts = new MarkerOptions().position(m);
mMap.addMarker(mopts);
}
}
mMap.getUiSettings().setZoomControlsEnabled(true);
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(center, 13));
}
private List<LatLng> getDirectionsPathFromWebService(String origin, String destination) {
List<LatLng> path = new ArrayList();
//Execute Directions API request
GeoApiContext context = new GeoApiContext.Builder()
.apiKey("AIzaSyBrPt88vvoPDDn_imh-RzCXl5Ha2F2LYig")
.build();
DirectionsApiRequest req = DirectionsApi.getDirections(context, origin, destination);
try {
DirectionsResult res = req.await();
//Loop through legs and steps to get encoded polylines of each step
if (res.routes != null && res.routes.length > 0) {
DirectionsRoute route = res.routes[0];
if (route.legs !=null) {
for(int i=0; i<route.legs.length; i++) {
DirectionsLeg leg = route.legs[i];
if (leg.steps != null) {
for (int j=0; j<leg.steps.length;j++){
DirectionsStep step = leg.steps[j];
if (step.steps != null && step.steps.length >0) {
for (int k=0; k<step.steps.length;k++){
DirectionsStep step1 = step.steps[k];
EncodedPolyline points1 = step1.polyline;
if (points1 != null) {
//Decode polyline and add points to list of route coordinates
List<com.google.maps.model.LatLng> coords1 = points1.decodePath();
for (com.google.maps.model.LatLng coord1 : coords1) {
path.add(new LatLng(coord1.lat, coord1.lng));
}
}
}
} else {
EncodedPolyline points = step.polyline;
if (points != null) {
//Decode polyline and add points to list of route coordinates
List<com.google.maps.model.LatLng> coords = points.decodePath();
for (com.google.maps.model.LatLng coord : coords) {
path.add(new LatLng(coord.lat, coord.lng));
}
}
}
}
}
}
}
}
} catch(Exception ex) {
Log.e(TAG, ex.getLocalizedMessage());
}
return path;
}
private List<LatLng> getMarkersEveryNMeters(List<LatLng> path, double distance) {
List<LatLng> res = new ArrayList();
LatLng p0 = path.get(0);
res.add(p0);
if (path.size() > 2) {
//Initialize temp variables for sum distance between points and
//and save the previous point
double tmp = 0;
LatLng prev = p0;
for (LatLng p : path) {
//Sum the distance
tmp += SphericalUtil.computeDistanceBetween(prev, p);
if (tmp < distance) {
//If it is less than certain value continue sum
prev = p;
continue;
} else {
//If distance is greater than certain value lets calculate
//how many meters over desired value we have and find position of point
//that will be at exact distance value
double diff = tmp - distance;
double heading = SphericalUtil.computeHeading(prev, p);
LatLng pp = SphericalUtil.computeOffsetOrigin(p, diff, heading);
//Reset sum set calculated origin as last point and add it to list
tmp = 0;
prev = pp;
res.add(pp);
continue;
}
}
//Add the last point of route
LatLng plast = path.get(path.size()-1);
res.add(plast);
}
return res;
}
}
Conclusion
You can see a result of sample code in the following screenshot
The sample project can be found on GitHub:
https://github.com/xomena-so/so47784512
Do not forget to replace an API key with your's.
I hope this helps!

Update and delete specific marker in Google Map

I am displaying the location of buses in google map where I am getting the location from the bus database table on the server. I am facing problem to delete or to update their locations on google map since a new marker is always being created when the longitude and latitude change in the bus table. How can I delete and update specific Marker in Google Map?
I appreciate any help.
Code:
private void gotoLocation(double lat, double lng, String route_direct) {
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
final float zoom = 11;
LatLng ll = new LatLng(lat, lng);
if (lat != 0 && lng != 0 && !route_direct.isEmpty()) {
MarkerOptions markerOpt = new MarkerOptions().title(route_direct)
.position(ll).visible(true);
Marker marker = map.addMarker(markerOpt);
marker.showInfoWindow();
CameraUpdate update = CameraUpdateFactory.newLatLngZoom(ll, zoom);
map.moveCamera(update);
}
}

I solved in this way. I created HashMap for markers.
Sample,
HashMap<String, Marker> markerlist = new HashMap<>();
markerlist.put(route_direct, yourmarker);//add marker to list
markerlist.get(route_direct);//get marker from list
Then in your update process, try this code
if(markerlist.containsKey(route_direct)){
Marker marker = markerlist.get(route_direct);
//update marker
}else{
//add marker or do anything
}
but to use this flow, you need to have unique data for marker such as marker id.
Hope this will help you. Good luck.

Here we have used on our project in didTap marker delegates, We have created two functions one is Create marker and second one is delete marker code is given below in IOS swift
1.CreateMarker function call when you get Response from APIs
2.DeleteMarker call when you want to delete marker from map
//MARK: CreateMarker
func CreateMarker(TripLocation:[RECDATA])
{
//let path = GMSMutablePath()
for i in 0..<TripLocation.count
{
// Marker icon
var image = UIImage(named: "ic_greenMark")
// Get location coordinate
let locationTujuan = CLLocation(latitude: Double(TripLocation[i].facilityLatitude ?? 0.0) , longitude: Double(TripLocation[i].facilityLongitude ?? 0.0) )
image = UIImage(named: "ic_greenMark")
// create marker
let marker = GMSMarker()
marker.position = CLLocationCoordinate2DMake(locationTujuan.coordinate.latitude, locationTujuan.coordinate.longitude)
// marker.title = titleMarker
marker.icon = image
marker.map = MapView
let camera = GMSCameraPosition.camera(withLatitude:CLLocationDegrees(TripLocation[i].facilityLatitude!), longitude: CLLocationDegrees(TripLocation[i].facilityLongitude ?? 0.0), zoom: 8)
MapView.camera = camera
// append marker into markers array to show all marker in map
markers.append(marker)
}
}
//MARK: DeleteMarker
func DeleteMarker(marker:GMSMarker)
{
// Create Temp Object array
var Tempmarkers = [RECDATA]()
//check marker is exist or not
for obj in arrayRECDATA
{
let lat = Double(obj.facilityLatitude!)
let log = Double(obj.facilityLongitude!)
// remove marker from object array
if marker.position.latitude != lat && marker.position.longitude != log
{
Tempmarkers.append(obj)
}
}
// store temp array into original array
arrayRECDATA = Tempmarkers
// clean all marker and reload
MapView.clear()
CreateMarker(TripLocation: arrayRECDATA)
}
Thank you :)

Define variable for each marker like
Marker m1;
Marker m2;
etc.
And do whatever operation on specific marker using that variable. To delete the specific marker
m1.delete ();
m2.delete ();
Something like this, you can try and let me know if you face any issue.

Draw polyline snap to road Android google maps app

I'm currently developing an android google maps app help to get direction between 2 points on the map. I'm able to get the response from google maps service (Direction API) and draw polyline (Google Maps Android SDK) base on list of steps but the line is not snap to the road (curved line stick to road on the map), it's just straight line.
How can I draw polyline snap to road in Android app? I'm using Android Studio.
Here is my code to draw polyline.
void updateMapDirection() {
Polyline newPolyline;
PolylineOptions options = new PolylineOptions().width(3).color(Color.BLUE).geodesic(true);
LatLng latLng = new LatLng(mLegs.get(0).getmStartLocation().getmLatitude(),
mLegs.get(0).getmStartLocation().getmLongitude());
options.add(latLng);
for (WNStep i : mLegs.get(0).getmSteps()) {
latLng = new LatLng(i.getmEndLocation().getmLatitude(), i.getmEndLocation().getmLongitude());
options.add(latLng);
}
newPolyline = map.addPolyline(options);
}
Thanks for your help.

This is how you can do it:
Once you have your JSON object as "result". Parse it, Also decode the polyline in form of a List.
final JSONObject json = new JSONObject(result);
JSONArray routeArray = json.getJSONArray("routes");
JSONObject routes = routeArray.getJSONObject(0);
JSONObject overviewPolylines = routes
.getJSONObject("overview_polyline");
String encodedString = overviewPolylines.getString("points");
List<LatLng> list = decodePoly(encodedString);
Finally add Polyline Option by looping over the list and setting the properties of your polyline corresponding to the road you want to show as retrieved from Direction API on Google Maps.
PolylineOptions options = new PolylineOptions().width(5).color(Color.BLUE).geodesic(true);
for (int z = 0; z < list.size(); z++) {
LatLng point = list.get(z);
options.add(point);
}
line = myMap.addPolyline(options);

Android put marker on start and end of polyline

Hi I am using Async task to grab longitude and latitude in an JSONArray. I am able to draw polyline but I cannot figure out how to draw put in the start and the end of the polyline.
// Initialization
ArrayList<LatLng> polylines = new ArrayList<LatLng>();
JSONArray lines = null;
JSONObject jsonPolyline;
LatLng polyline;
And here is what I have on the onPostExecute of my AsyncTask
lines = json.getJSONArray("track");
for (int i = 0; i < lines.length(); i++) {
jsonPolyline = lines.getJSONObject(i);
polyline = new LatLng(Double.valueOf(jsonPolyline.getString("lat")),
Double.valueOf(jsonPolyline.getString("lon")));
polylines.add(polyline);
}
/*call the polyline */
myMap.addPolyline(new PolylineOptions().addAll(polylines).width(2.0f).color(Color.GREEN));
I tried using , ListIterator but since my Arraylist is <latlng> , I cannot get the first and last element on the arraylist.
How can I get the first and last element on my arraylist so that I can draw marker on the start and end position.

Every Java List<> implements get() and size() methods:
first = polylines.get(0);
last = polylines.get(polyline.size() -1);

Break out multiple coordinates into multiple latlng googlemap v2

I have a huge list in an XML tag like so:
<coor> -123.3858,41.34119,0
-123.3856,41.34109,0
-123.3852,41.34121,0
-123.3848,41.34139,0</coor>
and need it like this:
new LatLng(-123.3858,41.34119),
new LatLng(-123.3856,41.34109),
new LatLng(-123.3852,41.34121),
new LatLng(-123.3848,41.34139),
to work with google maps v2 android.
I've done a string replace on the coordinates and am getting the correct results like so:
String ll = "),new LatLng(";
coor = coor.replaceAll(",0", ll);
replacing the ,0 for the new LatLng(... I am not figuring out how to change the large string of latlng text into latlng locations to put into my polygon:
PolygonOptions perimeteres = new PolygonOptions().add(coor);
Is there way to do this? Or do I need to separate each out and make them individual latlng?
EDIT::::
String[] splitData = coor.split(",0");
for (String eachSplit : splitData) {
if (!eachSplit.endsWith(",0")) {
//Log.e("EACH",eachSplit);
Log.v("e","new LatLon("+eachSplit+");");
}
}
This is getting me a little closer...

You are going completely in the wrong direction, this
String ll = "),new LatLng(";
coor = coor.replaceAll(",0", ll);
is not the same as
new LatLng(-123.3858,41.34119)
the first gives you a string which does nothing for you, the second is an object which is what you need.
Edit
you need to remove the 0 from the coordinates then you do a string split on the , so you have an array of latitudes and longitudes.
then create a List<LatLng> which is what you need to create a polygon of points
and loop through your points
for(int j=0;j<locationAry.length;j++){
if(j%2 == 0){
lon = Float.parseFloat(locationAry[j+1]);
lat = Float.parseFloat(locationAry[j]);
}
}