在博客《百度地图查询视野范围内的建筑物》当中描述了如何查询视野范围内的建筑物，可以减少地图加载标注物的数量，提升速度。但是当地图的zoom级很小时，会出现标注物重叠的现象，不是很美观，所以下面的文章将介绍地图标注物如何根据zoom的大小聚合显示。
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俗话说站在巨人的肩膀上将事半功倍，在写android的百度地图标注物聚合时，我在网上也进行了大量的查询，发现标注物聚合的算法很早就有人写了，不过他们是js或者是Google地图c#版的。借鉴他们的想法，我写了android的这版代码与大家一起分享。
一、牛人们的想法
下面是我参考的有关的博客，下面将一一列举
1.MarkerCluster之百度地图版 http://hi.baidu.com/liongg/item/d8adece188fbfb11585dd89f
2.Marker Cluster面面观 http://hi.baidu.com/liongg/item/a380cc95bd70c2bdcd80e581
3.GoogleMap标注物聚合解决办法 http://www.svennerberg.com/2009/01/handling-large-amounts-of-markers-in-google-maps/
4.百度地图官网上已经有JS版的标注物聚合实例与原文件，建议看百度地图上的代码，规范且函数注释明确。
百度地图javascript开源库： http://developer.baidu.com/map/library.htm
二、我的思路
1.下面以一个流程图来表述我的想法。
2.下面贴出代码
//cluster聚合器类
package com.zhl.map;
import java.util.ArrayList;
import java.util.List;
import android.graphics.Bitmap;
import android.graphics.Point;
import android.graphics.drawable.BitmapDrawable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.TextView;
import baidumapsdk.demo.R;
import com.baidu.mapapi.cloud.Bounds;
import com.baidu.mapapi.map.MapView;
import com.baidu.mapapi.map.OverlayItem;
import com.baidu.mapapi.utils.DistanceUtil;
import com.baidu.platform.comapi.basestruct.GeoPoint;
import com.zhl.activity.MarkerClusterActivity;
import com.zhl.util.MapUtils;
public class Cluster{
private MarkerClusterActivity mMarkCluster;
private MapView mMapView;
private int mMinClusterSize;
private Boolean isAverageCenter;
private int mGridSize;
private double mDistance;
private List<ClusterMarker> mMarkers;
public Cluster(MarkerClusterActivity markCluster,MapView mapView
,int minClusterSize,Boolean isAverageCenter
,int mGridSize,double mDistance) {
this.mMarkCluster = markCluster;
this.mMapView = mapView;
this.mMinClusterSize = minClusterSize;
this.isAverageCenter = isAverageCenter;
this.mGridSize = mGridSize;
this.mDistance = mDistance;
mMarkers = new ArrayList<ClusterMarker>();
}
public List<OverlayItem> createCluster(List<OverlayItem> markerList){
this.mMarkers.clear();
List<OverlayItem> itemList = new ArrayList<OverlayItem>();
for(int i=0;i<markerList.size();i++){
addCluster(markerList.get(i));
}
for(int i=0;i<mMarkers.size();i++){
ClusterMarker cm = mMarkers.get(i);
setClusterDrawable(cm);
OverlayItem oi = new OverlayItem(cm.getmCenter(),cm.getTitle(),cm.getSnippet());
oi.setMarker(cm.getMarker());
itemList.add(oi);
}
return itemList;
}
private void addCluster(OverlayItem marker){
GeoPoint markGeo = marker.getPoint();
if(mMarkers.size()==0){
ClusterMarker clusterMarker = new ClusterMarker(marker.getPoint(), marker.getTitle(), marker.getSnippet());
clusterMarker.setMarker(marker.getMarker());
clusterMarker.AddMarker(marker, isAverageCenter);
Bounds bound = new Bounds(markGeo.getLatitudeE6(),markGeo.getLongitudeE6(),markGeo.getLatitudeE6(),markGeo.getLongitudeE6());
bound = MapUtils.getExtendedBounds(mMapView, bound, mGridSize);
clusterMarker.setmGridBounds(bound);
mMarkers.add(clusterMarker);
}else{
ClusterMarker clusterContain = null;
double distance = mDistance;
for(int i=0;i<mMarkers.size();i++){
ClusterMarker clusterMarker = mMarkers.get(i);
GeoPoint center = clusterMarker.getmCenter();
double d = DistanceUtil.getDistance(center, marker.getPoint());
if(d<distance){
distance = d;
clusterContain = clusterMarker;
}
}
if(clusterContain == null||!isMarkersInCluster(markGeo, clusterContain.getmGridBounds())){
ClusterMarker clusterMarker = new ClusterMarker(marker.getPoint(), marker.getTitle(), marker.getSnippet());
clusterMarker.AddMarker(marker, isAverageCenter);
clusterMarker.AddMarker(marker, isAverageCenter);
Bounds bound = new Bounds(markGeo.getLatitudeE6(),markGeo.getLongitudeE6(),markGeo.getLatitudeE6(),markGeo.getLongitudeE6()); bound = MapUtils.getExtendedBounds(mMapView, bound, mGridSize);
clusterMarker.setmGridBounds(bound);
mMarkers.add(clusterMarker);
}else{
clusterContain.AddMarker(marker, isAverageCenter);
}
}
}
private void setClusterDrawable(ClusterMarker clusterMarker){
View drawableView = LayoutInflater.from(mMarkCluster).inflate(
R.layout.drawable_mark, null);
TextView text = (TextView) drawableView.findViewById(R.id.drawble_mark);
int markNum = clusterMarker.getmMarkers().size();
if(markNum>=2){
text.setText(markNum+"");
if(markNum<11){
text.setBackgroundResource(R.drawable.m0);
}else if(markNum>10&&markNum<21){
text.setBackgroundResource(R.drawable.m1);
}else if(markNum>20&&markNum<31){
text.setBackgroundResource(R.drawable.m2);
}else if(markNum>30&&markNum<41){
text.setBackgroundResource(R.drawable.m3);
}else{
text.setBackgroundResource(R.drawable.m4);
}
Bitmap bitmap = MapUtils.convertViewToBitmap(drawableView);
clusterMarker.setMarker(new BitmapDrawable(bitmap));
}else{
}
}
private Boolean isMarkersInCluster(GeoPoint markerGeo,Bounds bound){
if(markerGeo.getLatitudeE6()>bound.leftBottom.getLatitudeE6()
&&markerGeo.getLatitudeE6()<bound.rightTop.getLatitudeE6()
&&markerGeo.getLongitudeE6()>bound.rightTop.getLongitudeE6()
&&markerGeo.getLongitudeE6()<bound.leftBottom.getLongitudeE6()){
return true;
}
return false;
}
}3.工程demo代码下载，地图标注物聚合.zip
4.下面是程序的实例图片
作者：fengshuiyue 发表于2013-7-15 9:35:30 原文链接
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