ClusterManager.java

package com.google.maps.android.clustering;

import android.content.Context;
import android.os.AsyncTask;

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.Marker;
import com.google.maps.android.MarkerManager;
import com.google.maps.android.clustering.algo.Algorithm;
import com.google.maps.android.clustering.algo.PreCachingAlgorithmDecorator;
import com.google.maps.android.clustering.algo.NonHierarchicalDistanceBasedAlgorithm;
import com.google.maps.android.clustering.view.ClusterRenderer;
import com.google.maps.android.clustering.view.DefaultClusterRenderer;

import java.util.Collection;
import java.util.Set;

/**
 * Groups many items on a map based on zoom level.
 * <p/>
 * ClusterManager should be added to the map as an:
 * <ul>
 * <li>{@link com.google.android.gms.maps.GoogleMap.OnCameraChangeListener}</li>
 * <li>{@link com.google.android.gms.maps.GoogleMap.OnMarkerClickListener}</li>
 * </ul>
 */
public class ClusterManager<T extends ClusterItem> implements GoogleMap.OnCameraChangeListener, GoogleMap.OnMarkerClickListener {
    private static final String TAG = ClusterManager.class.getName();

    private final MarkerManager mMarkerManager;
    private final MarkerManager.Collection mMarkers;
    private final MarkerManager.Collection mClusterMarkers;

    private Algorithm<T> mAlgorithm;
    private ClusterRenderer<T> mRenderer;

    private GoogleMap mMap;
    private CameraPosition mPreviousCameraPosition;
    private ClusterTask mClusterTask;
    private OnClusterItemClickListener<T> mOnClusterItemClickListener;
    private OnClusterClickListener<T> mOnClusterClickListener;

    public ClusterManager(Context context, GoogleMap map) {
        this(context, map, new MarkerManager(map));
    }

    public ClusterManager(Context context, GoogleMap map, MarkerManager markerManager) {
        mMap = map;
        mMarkerManager = markerManager;
        mClusterMarkers = markerManager.newCollection();
        mMarkers = markerManager.newCollection();
        mRenderer = new DefaultClusterRenderer<T>(context, map, this);
        mAlgorithm = new PreCachingAlgorithmDecorator<T>(new NonHierarchicalDistanceBasedAlgorithm<T>());
        mClusterTask = new ClusterTask();
    }

    public MarkerManager.Collection getMarkerCollection() {
        return mMarkers;
    }

    public MarkerManager.Collection getClusterMarkerCollection() {
        return mClusterMarkers;
    }

    public MarkerManager getMarkerManager() {
        return mMarkerManager;
    }

    public void setRenderer(ClusterRenderer<T> view) {
        view.setOnClusterClickListener(null);
        view.setOnClusterItemClickListener(null);
        mClusterMarkers.clear();
        mMarkers.clear();
        mRenderer.onRemove();
        mRenderer = view;
        mRenderer.onAdd();
        mRenderer.setOnClusterClickListener(mOnClusterClickListener);
        mRenderer.setOnClusterItemClickListener(mOnClusterItemClickListener);
        cluster();
    }

    public void setAlgorithm(Algorithm<T> algorithm) {
        Collection<T> items = null;
        if (mAlgorithm != null) {
            items = mAlgorithm.getItems();
            mAlgorithm.clearItems();
        }

        mAlgorithm = new PreCachingAlgorithmDecorator<T>(algorithm);
        if (items != null) {
            mAlgorithm.addItems(items);
        }
        cluster();
    }

    public void clearItems() {
        mAlgorithm.clearItems();
    }

    public void addItems(Collection<T> items) {
        mAlgorithm.addItems(items);
    }

    public void addItem(T myItem) {
        mAlgorithm.addItem(myItem);
    }

    public void removeItem(T item) {
        mAlgorithm.removeItem(item);
    }

    /**
     * Force a re-cluster. You may want to call this after adding new item(s).
     */
    public void cluster() {
        // Attempt to cancel the in-flight request.
        mClusterTask.cancel(true);
        mClusterTask = new ClusterTask();
        mClusterTask.execute(mMap.getCameraPosition().zoom);
    }

    /**
     * Might re-cluster.
     *
     * @param cameraPosition
     */
    @Override
    public void onCameraChange(CameraPosition cameraPosition) {
        if (mRenderer instanceof GoogleMap.OnCameraChangeListener) {
            ((GoogleMap.OnCameraChangeListener) mRenderer).onCameraChange(cameraPosition);
        }

        // Don't re-compute clusters if the map has just been panned/tilted/rotated.
        CameraPosition position = mMap.getCameraPosition();
        if (mPreviousCameraPosition != null && mPreviousCameraPosition.zoom == position.zoom) {
            return;
        }
        mPreviousCameraPosition = mMap.getCameraPosition();

        cluster();
    }

    @Override
    public boolean onMarkerClick(Marker marker) {
        return getMarkerManager().onMarkerClick(marker);
    }

    /**
     * Runs the clustering algorithm in a background thread, then re-paints when results come
     * back.
     */
    private class ClusterTask extends AsyncTask<Float, Void, Set<? extends Cluster<T>>> {
        @Override
        protected Set<? extends Cluster<T>> doInBackground(Float... zoom) {
            return mAlgorithm.getClusters(zoom[0]);
        }

        @Override
        protected void onPostExecute(Set<? extends Cluster<T>> clusters) {
            mRenderer.onClustersChanged(clusters);
        }
    }

    /**
     * Sets a callback that's invoked when a Cluster is tapped.
     * Note: For this listener to function, the ClusterManager must be added as a click listener to the map.
     */
    public void setOnClusterClickListener(OnClusterClickListener<T> listener) {
        mOnClusterClickListener = listener;
        mRenderer.setOnClusterClickListener(listener);
    }

    /**
     * Sets a callback that's invoked when an individual ClusterItem is tapped.
     * Note: For this listener to function, the ClusterManager must be added as a click listener to the map.
     */
    public void setOnClusterItemClickListener(OnClusterItemClickListener<T> listener) {
        mOnClusterItemClickListener = listener;
        mRenderer.setOnClusterItemClickListener(listener);
    }

    /**
     * Called when a Cluster is clicked.
     */
    public interface OnClusterClickListener<T extends ClusterItem> {
        public boolean onClusterClick(Cluster<T> cluster);
    }

    /**
     * Called when an individual ClusterItem is clicked.
     */
    public interface OnClusterItemClickListener<T extends ClusterItem> {
        public boolean onClusterItemClick(T item);
    }
}