dynamic Polyline colors with google maps android app

Question

I\'m making an app that uses google maps to show when you deviate from a path previously taken. I can show where the deviations occur with a different color, but I have to initi

Answer 1

There is no direct solution to your problem as you can only control a couple of drawing parameters for the polylines, but I propose a workaround that mixes both of your methods.

That is, addíng points to the existing polyline until it has to change the color, and then start a new polyline. This way you will only see a leap when the color changes.

here is the example code (not tested):

int currentColor = Color.BLACK;

for (HaulEvent event : cycle) { LatLng locToAdd = new LatLng(event.Latitude, event.Longitude);
    if (event.cycle_num < 2) {
        m_aPL.add(mMap.addPolyline(m_PolyLines.geodesic(true)
                .color(Color.BLACK)
                .add(locToAdd)
                .clickable(true)));
        m_aPolyLineList = (ArrayList) m_PolyLines.getPoints();

        currentColor = Color.BLACK;
    } else { //after we've got a base cycle drawn
        if (PolyUtil.isLocationOnPath(locToAdd, m_aBaseRoute, true, tolerance)) {
            if (currentColor == Color.BLACK) {
                m_aPL.add(mMap.addPolyline(m_PolyLines.geodesic(true)
                    .color(Color.BLACK)
                    .add(new LatLng(prevLocation.getLatitude(), prevLocation.getLongitude()), locToAdd)
                    .clickable(true)));
            } else {
                m_aPL.add(mMap.addPolyline(new PolylineOptions().geodesic(true)
                    .color(Color.BLACK)
                    .add(new LatLng(prevLocation.getLatitude(), prevLocation.getLongitude()), locToAdd)
                    .clickable(true)));
            }

            currentColor = Color.BLACK;
        } else {
            if (currentColor == Color.RED) {
                m_aPL.add(mMap.addPolyline(m_PolyLines.geodesic(true)
                    .color(Color.RED)
                    .add(new LatLng(prevLocation.getLatitude(),prevLocation.getLongitude()),locToAdd)
                    .clickable(true)));
            } else {
                m_aPL.add(mMap.addPolyline(new PolylineOptions().geodesic(true)
                    .color(Color.RED)
                    .add(new LatLng(prevLocation.getLatitude(),prevLocation.getLongitude()),locToAdd)
                    .clickable(true)));
            }

            currentColor = Color.RED;
        }
    }
    prevLocation.setLatitude(locToAdd.latitude);
    prevLocation.setLongitude(locToAdd.longitude);
}

Update

Improvement using https://github.com/antoniocarlon/richmaps (I am the owner of the project):

RichLayer richLayer = new RichLayer.Builder(mMap).zIndex(0).build();
RichPolylineOptions polylineOpts = new RichPolylineOptions(null)
    .zIndex(0)
    .strokeWidth(5)
    .strokeColor(Color.BLACK)
    .linearGradient(true);
RichPolyline polyline = polylineOpts.build();
richLayer.addShape(polyline);

// ...

for (HaulEvent event : cycle) { 
    LatLng locToAdd = new LatLng(event.Latitude, event.Longitude);

    if (event.cycle_num < 2) {
        polyline.add(new RichPoint(locToAdd));
    } else { //after we've got a base cycle drawn
        if (PolyUtil.isLocationOnPath(locToAdd, m_aBaseRoute, true, tolerance)) {
            polyline.add(new RichPoint(locToAdd));
        } else {
            polyline.add(new RichPoint(locToAdd).color(Color.RED));
        }
    }
}