Android Open Source - clusterkraf Clusters Builder

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License

The source code is released under:
Apache License
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Java Source Code

package com.twotoasters.clusterkraf;
// w  w  w .  j a  va 2  s  .  com
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.HashSet;

import com.google.android.gms.maps.Projection;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.LatLngBounds;
import com.google.android.gms.maps.model.VisibleRegion;

class ClustersBuilder {

  private final Options options;

  private final ArrayList<InputPoint> relevantInputPointsList = new ArrayList<InputPoint>();
  private final HashSet<InputPoint> releventInputPointsSet = new HashSet<InputPoint>();

  private final WeakReference<Projection> projectionRef;
  private final WeakReference<VisibleRegion> visibleRegionRef;

  ClustersBuilder(Projection projection, Options options, ArrayList<ClusterPoint> initialClusteredPoints) {
    this.options = options;

    this.projectionRef = new WeakReference<Projection>(projection);
    this.visibleRegionRef = new WeakReference<VisibleRegion>(projection.getVisibleRegion());

    if (initialClusteredPoints != null) {
      addRelevantInitialInputPoints(initialClusteredPoints);
    }
  }

  private void addRelevantInitialInputPoints(ArrayList<ClusterPoint> initialClusteredPoints) {
    for (ClusterPoint clusterPoint : initialClusteredPoints) {
      clusterPoint.clearScreenPosition();
      addAll(clusterPoint.getPointsInCluster());
    }
  }

  private Projection getProjection() {
    return projectionRef.get();
  }

  private VisibleRegion getVisibleRegion() {
    return visibleRegionRef.get();
  }

  void addAll(ArrayList<InputPoint> points) {
    if (points != null) {
      Projection projection = getProjection();
      VisibleRegion visibleRegion = getVisibleRegion();
      if (projection != null && visibleRegion != null) {
        LatLngBounds bounds = getExpandedBounds(visibleRegion.latLngBounds);
        for (InputPoint point : points) {
          addIfNecessary(point, projection, bounds);
        }
      }
    }
  }

  private LatLngBounds getExpandedBounds(LatLngBounds bounds) {
    if (bounds != null && options != null) {
      double expandBoundsFactor = options.getExpandBoundsFactor();

      boolean spans180Meridian = bounds.northeast.longitude < bounds.southwest.longitude;

      double distanceFromNorthToSouth = bounds.northeast.latitude - bounds.southwest.latitude;
      double distanceFromEastToWest;
      if (spans180Meridian == false) {
        distanceFromEastToWest = bounds.northeast.longitude - bounds.southwest.longitude;
      } else {
        distanceFromEastToWest = (180 + bounds.northeast.longitude) + (180 - bounds.southwest.longitude);
      }

      double expandLatitude = distanceFromNorthToSouth * expandBoundsFactor;
      double expandLongitude = distanceFromEastToWest * expandBoundsFactor;

      LatLng newNortheast = new LatLng(bounds.northeast.latitude + expandLatitude, bounds.northeast.longitude + expandLongitude);
      LatLng newSouthwest = new LatLng(bounds.southwest.latitude - expandLatitude, bounds.southwest.longitude - expandLongitude);

      return new LatLngBounds(newSouthwest, newNortheast);
    }
    return null;
  }

  private void addIfNecessary(InputPoint point, Projection projection, LatLngBounds bounds) {
    if (bounds != null && bounds.contains(point.getMapPosition()) && !releventInputPointsSet.contains(point)) {
      point.buildScreenPosition(projection);
      relevantInputPointsList.add(point);
      releventInputPointsSet.add(point);
    }
  }

  ArrayList<ClusterPoint> build() {
    Projection projection = getProjection();
    ArrayList<ClusterPoint> clusteredPoints = null;
    if (projection != null) {
      clusteredPoints = new ArrayList<ClusterPoint>(relevantInputPointsList.size());
      for (InputPoint point : relevantInputPointsList) {
        boolean addedToExistingCluster = false;
        for (ClusterPoint clusterPoint : clusteredPoints) {
          if (clusterPoint.getPixelDistanceFrom(point) <= options.getPixelDistanceToJoinCluster()) {
            clusterPoint.add(point);
            addedToExistingCluster = true;
            break;
          }
        }
        if (addedToExistingCluster == false) {
          clusteredPoints.add(new ClusterPoint(point, projection, false));
        }
      }
    }
    return clusteredPoints;
  }

}
Java Source Code List
