How to add text above polyline in google maps?

Question

I have 2 markers, I would like to draw a line between them, and have a text showing the distance above the line, just like in the web version of google maps.

I've already found this sample about drawing a line between 2 markers, but how do I add text above the line?

Answer 1

One idea would be to calculate the midpoint between the two markers using their lat and long coordinates and then put an infowindow with whatever information you want to show. Or something like the following could help: Link

Answer 2

I had a situation to show the distance between two markers above the polyline.

Below is what was my requirement:

I managed to do it in some other way and it is quite interesting way, this way you can customize it to achieve anything.

Steps:

1. Calculate the distance between the markers by using Location.distanceBetween() method.
2. Create a new Layout XML file and create whatever type of UI you want to show for your text. In my case it contained only one TextView.
3. Set the calculated distance in the TextView.
4. Convert the XML Layout to Bitmap.
5. Create a BitmapDescriptor from that Bitmap object.
6. Find out the midpoint between the desired markers and add a custom marker by using the BitmapDescriptor created in last step and you are done.

Code:

To calculate distance between two markers

float[] distance1 = new float[1];
Location.distanceBetween(userMarker.getPosition().latitude, userMarker.getPosition().longitude, positionMarker.getPosition().latitude, positionMarker.getPosition().longitude, distance1);

Create Bitmap from XML Layout file

LinearLayout distanceMarkerLayout = (LinearLayout) getLayoutInflater().inflate(R.layout.distance_marker_layout, null);

distanceMarkerLayout.setDrawingCacheEnabled(true);
distanceMarkerLayout.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
distanceMarkerLayout.layout(0, 0, distanceMarkerLayout.getMeasuredWidth(), distanceMarkerLayout.getMeasuredHeight()); 
distanceMarkerLayout.buildDrawingCache(true);

TextView positionDistance = (TextView) distanceMarkerLayout.findViewById(R.id.positionDistance);

positionDistance.setText(distance1[0]+" meters");           

Bitmap flagBitmap = Bitmap.createBitmap(distanceMarkerLayout.getDrawingCache());
                distanceMarkerLayout.setDrawingCacheEnabled(false);
                BitmapDescriptor flagBitmapDescriptor = BitmapDescriptorFactory.fromBitmap(flagBitmap);

To find out mid point between two markers do something like the following:

double dLon = Math.toRadians(flagMarker.getPosition().longitude - positionMarker.getPosition().longitude);

double lat1 = Math.toRadians(positionMarker.getPosition().latitude);
double lat2 = Math.toRadians(flagMarker.getPosition().latitude);
double lon1 = Math.toRadians(positionMarker.getPosition().longitude);

double Bx = Math.cos(lat2) * Math.cos(dLon);
double By = Math.cos(lat2) * Math.sin(dLon);
double lat3 = Math.atan2(Math.sin(lat1) + Math.sin(lat2), Math.sqrt((Math.cos(lat1) + Bx) * (Math.cos(lat1) + Bx) + By * By));
double lon3 = lon1 + Math.atan2(By, Math.cos(lat1) + Bx);

lat3 = Math.toDegrees(lat3);
lon3 = Math.toDegrees(lon3);

Add a new cutom marker by using the bitmap descriptor created by us in previous steps

Marker centerOneMarker = mMap.addMarker(new MarkerOptions()
                .position(new LatLng(lat3, lon3))
                .icon(flagBitmapDescriptor));

Hope it helps you.