Map clustering - max zoom markers still clustered

Question

I'm using android maps utils for clustering the markers on google maps api v2. It worked fine, but when I added 2000+ markers, on max zoom it is still clustered (markers still have numbers):

Here is my method for filling map with markers:

public void getRiverData(String state, String type) {
    URL = getResources().getString(R.string.base_url) + state + "/" + type
            + getResources().getString(R.string.end_url);
    SimpleXmlRequest<XMLData> simpleRequest = new SimpleXmlRequest<XMLData>(
            URL, XMLData.class, new Response.Listener<XMLData>() {

                @Override
                public void onResponse(XMLData response) {

                    // Initialize the manager with the context and the map.
                    // (Activity extends context, so we can pass 'this' in
                    // the constructor.)
                    mClusterManager = new ClusterManager<MarkerItem>(
                            getActivity(), map);

                    mClusterManager.setRenderer(new ClusterRenderer(
                            getActivity(), map, mClusterManager));

                    // response Object
                    waterItemsList = response.getNews();

                    for (News item : waterItemsList) {
                        if (item.getRiver_name() != null
                                && item.getRiver_name() != "") {

                            water_level_value = item.getWater_level_value();

                            if (water_level_value != null
                                    && !water_level_value.equals(0)
                                    && !water_level_value.equals("")) {

                                MarkerItem offsetItem = new MarkerItem(item);
                                mClusterManager.addItem(offsetItem);

                            }

                            map.setOnMarkerClickListener(mClusterManager);

                            map.setInfoWindowAdapter(new InfoWindowAdapter() {

                                @Override
                                public View getInfoWindow(Marker marker) {

                                    return null;
                                }

                                @Override
                                public View getInfoContents(Marker marker) {

                                    try {
                                        View v = getActivity()
                                                .getLayoutInflater()
                                                .inflate(
                                                        R.layout.marker_info,
                                                        null);
                                        TextView title = (TextView) v
                                                .findViewById(R.id.tvMarkerTitle);
                                        TextView info = (TextView) v
                                                .findViewById(R.id.tvMarkerInfo);

                                        title.setText(marker.getTitle()
                                                .toString());
                                        info.setText(marker.getSnippet()
                                                .toString());
                                        return v;
                                    } catch (Exception e) {
                                        // kliknięcie w cluster
                                        return null;

                                    }

                                }
                            });

                        }

                    }

                    map.setOnCameraChangeListener(mClusterManager);

                    map.setOnInfoWindowClickListener(mClusterManager);

                    mClusterManager.cluster();

                }

            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    // error Object
                    error.printStackTrace();
                }
            });

    AppController.getInstance().addToRequestQueue(simpleRequest);
}

Can anyone help me? Why is it not working?

Answer 1

You can extend DefaultClusterRenderer class and set minimum markers to cluster.

public class InfoMarkerRenderer extends DefaultClusterRenderer<MyCustomMarker> {

public InfoMarkerRenderer(Context context, GoogleMap map, ClusterManager<MyCustomMarker> clusterManager) {
    super(context, map, clusterManager);
    //constructor
}

@Override
protected void onBeforeClusterItemRendered(final MyCustomMarker infomarker, MarkerOptions markerOptions) {
      // you can change marker options
}

@Override
protected boolean shouldRenderAsCluster(Cluster cluster) {
    return cluster.getSize() > 5; // if markers <=5 then not clustering
}
}

Answer 2

Via trail and error I found that if the markers are within ~10 feet (equivalent to 0.0000350º difference in lat or long), the markers don't decluster even at the max zoom level.

One way to solve for this problem is to implement a custom Renderer and let the app decide when to cluster. For example, the below code will cluster only when there are more than 1 marker and not at max Zoom. In other words it will decluster all markers at max zoom.

mClusterManager.setRenderer(new DefaultClusterRenderer<MyItem>(mContext, googleMap, mClusterManager) {
    @Override
    protected boolean shouldRenderAsCluster(Cluster cluster) {
        if(cluster.getSize() > 1 && mCurrentZoom < mMaxZoom) {
            return true;
        } else {
            return false;
        }
    }
});

Answer 3

To filter markers that have the same position, you could simply use a hashmasp, whose key is computed from the marker coordinates.

Something like:

Map<String, Marker> uniqueMarkers = new HashMap<String, Marker>();
for (Markers m : allMarkers) {
  // Compute a key to filter duplicates
  // You may need to account for small floating point precision errors by 
  // rounding those coordinates
  String key = m.getLatitude() + "|" + m.getLongitude();

  if (uniqueMarkers.get(key)!=null ) {
    // Skip if we have a marker with the same coordinates
    continue;
  }

  // Add marker and do something with it  
  uniqueMarkers.add(key, m);

  // ...
}