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google maps – update polyline according to the user moving android googleMaps v2

Posted by: admin June 15, 2020 Leave a comment

Questions:

I have googleMap (v2) with polyline that presents a route between the user current location and the destination point.
Now, I want to update the polyline according to the user moving.

I tried to redrawing the whole polyline when location is changed but the polyline is flickering.

I didn’t find any appropriate function in the PolylineOptions class
(the function add() is only to add a vertex but not to update or remove)

do you have any idea how to update the polyline ???
thank you for giving your time.

How to&Answers:

The only way as of version 3.1.36:

List<LatLng> points = polyline.getPoints();
points.add(newPoint);
polyline.setPoints(points);

Hopefully the API will be enhanced in later versions.

Answer:

*I have already done working on updating polyline path without removing the polyline. We can do this by changing the points of that polyline. Check below code.

This is the logic of setting new points to polyline.

/*Here the routes contain the points(latitude and longitude)*/
for (int i = 0; i < routes.size(); i++) {
            Route route = routes.get(i);
            if(polyline_path != null){
                polyline_path.setPoints(route.points);
            }
        }

Detail Explanation:

private GoogleMap map_object;
private Marker marker_driver;
private Marker marker_drop_off;
private Polyline polyline_path;
private PolylineOptions polylineOptions_path;

...
...
...

/*HelperDirectionFinder is a class that I create to call google API and I used this 
  class to get directions routes*/

/*I have created Service, and I'm calling this lines below after 5 sec. to get the 
  updated routes from google API.*/

HelperDirectionFinder directionFinder = new HelperDirectionFinder(
            JobEndScreen.this, source, destinations);
    try {
        directionFinder.showDirection();
    } catch (UnsupportedEncodingException e) {
        HelperProgressDialog.closeDialog();
    }

...
...
...

@Override
public void onDirectionFinderStart() {
    if(polylineOptions_path == null){
        HelperProgressDialog.showDialog(getActivity(), "", getString(R.string.text_loading));
    }
}


/*This interface method is called after getting routes from google API.*/
/*Here the routes contains the list of path or routes returned by Google Api*/
@Override
public void onDirectionFinderSuccess(List<Route> routes) {
    HelperProgressDialog.closeDialog();


    /*When polylineOptions_path is null it means the polyline is not drawn.*/
    /*If the polylineOptions_path is not null it means the polyline is drawn on map*/
    if(polylineOptions_path == null){
        for (Route route : routes) {
            polylineOptions_path = new PolylineOptions().
                    geodesic(true).
                    color(ContextCompat.getColor(getActivity(), R.color.color_bg_gray_dark)).
                    width(10);

            for (int i = 0; i < route.points.size(); i++)
                polylineOptions_path.add(route.points.get(i));

            polyline_path = map_object.addPolyline(polylineOptions_path);
        }
    }
    else {
        for (int i = 0; i < routes.size(); i++) {
            Route route = routes.get(i);
            if(polyline_path != null){
                polyline_path.setPoints(route.points);
            }
        }
    }
}

Answer:

//Declare on global
PolylineOptions polyOptions, polyOptions2;
Polyline polyline2;
List<LatLng> ltln;
private Double lat_decimal = 0.0,lng_decimal=0.0;



//initialize
ltln = new ArrayList<>();

//if you are using routing library

compile 'com.github.jd-alexander:library:1.0.7'

 @Override
    public void onRoutingSuccess(ArrayList<Route> arrayList, int i) {

    //Add this code snippet on onRoutingSuccess  to store latlan list
        ltln = new ArrayList<>();
        System.out.println("-----arrayList------" + arrayList.get(0).getPoints());
        ltln = arrayList.get(0).getPoints();



        //  NOTE here already we draw polyLine 1

       }


 //below mentioned how to update polyline

   private void UpdatePoliline(){
    System.out.println("-------runnablePolyline-------"+ltln.size());
    try {
        if (ltln.size() > 0) {
            for (int i = 0; i < ltln.size(); i++) {
                ltln.remove(i);
                if (CalculationByDistance(ltln.get(i), new LatLng(lat_decimal, lng_decimal)) >= 10) {
                    break;
                }

            }
            polyOptions2 = new PolylineOptions();
            polyOptions2.color(getResources().getColor(R.color.app_color));
            polyOptions2.width(7);
            polyOptions2.addAll(ltln);


            if (polyline2 == null) {
                polyline2 = googleMap.addPolyline(polyOptions2);
                if (polyLines.size() > 0) {
                    for (Polyline poly : polyLines) {
                        poly.remove();
                    }
                }
                polyLines.add(polyline2);
                if (polyline != null) {
                    polyline.remove();
                    polyline = null;
                }
            } else {
                polyline = googleMap.addPolyline(polyOptions2);
                if (polyLines.size() > 0) {
                    for (Polyline poly : polyLines) {
                        poly.remove();
                    }
                }
                polyLines.add(polyline);
                if (polyline2 != null) {
                    polyline2.remove();
                    polyline2 = null;
                }
            }
            System.out.println("=====waypoints new===" + ltln);
        }
    } catch (IndexOutOfBoundsException e) {
        e.printStackTrace();
    }
}

// Calculating distance between 2 points

 public float CalculationByDistance(LatLng StartP, LatLng EndP) {


    Location locationA = new Location("Source");
    locationA.setLatitude(StartP.latitude);
    locationA.setLongitude(StartP.longitude);

    Location locationB = new Location("Destination");
    locationB.setLatitude(EndP.latitude);
    locationB.setLongitude(EndP.longitude);



    float distance = locationA.distanceTo(locationB);


    return distance;
}

//Redraw Polyline vehicle is not in current polyline with particular distance

    if (ltln.size() > 0) {

        if (PolyUtil.isLocationOnPath(new LatLng(currentlat, currentLon), ltln, false, 60.0f) ){
            System.out.println("===tolarance===" + true);
        } else {
           //Redraw Polyline
        }
    }

   UpdatePoliline();