问题：百度地图绘制圆形，圆形半径可随进度拖动条发生改变

思路：圆形本身是一个覆盖物，可参考百度地图Demo中的OverlayDemo.java这个类进行实现。完成画圆之后，圆形半径如何随着进度条的拖动进行变化？进度条与画圆方法联动，随着进度条的拖动首先清除掉上次绘制的圆形重新绘制。

效果图：

实现代码Activity：

package baidumapsdk.demo.map;

import android.app.Activity;

import android.content.Context;

import android.os.Bundle;

import android.support.annotation.Nullable;

import android.util.Log;

import android.widget.SeekBar;

import android.widget.Toast;

import com.baidu.location.BDLocation;

import com.baidu.location.BDLocationListener;

import com.baidu.location.LocationClient;

import com.baidu.location.LocationClientOption;

import com.baidu.mapapi.map.BaiduMap;

import com.baidu.mapapi.map.CircleOptions;

import com.baidu.mapapi.map.MapStatus;

import com.baidu.mapapi.map.MapStatusUpdate;

import com.baidu.mapapi.map.MapStatusUpdateFactory;

import com.baidu.mapapi.map.MapView;

import com.baidu.mapapi.map.MyLocationData;

import com.baidu.mapapi.map.OverlayOptions;

import com.baidu.mapapi.map.Stroke;

import com.baidu.mapapi.model.LatLng;

import baidumapsdk.demo.R;

/**

* 描述类的功能、用途、现存BUG，以及其它别人可能感兴趣的介绍.

* created by: .

* version: 2017/12/25 14:15.

*/

public class ZTestDemo extends Activity {

private static final String TAG = "ZTestDemo";

private Context mContext;

private MapView mMapView;

public MyLocationListener myListener = new MyLocationListener();

BaiduMap mBaiduMap;

LocationClient mLocClient;

boolean isFirstLoc = true;

boolean isLocationClientStop = false;

private SeekBar seekBar;

private double latitude;//维度

private double longitude;//精度

private int mRadius = 2500;//半径

LatLng ll = null;

@Override

protected void onCreate(@Nullable Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

mContext = this;

setContentView(R.layout.layout_ztestdemo);

seekBar = (SeekBar) findViewById(R.id.seekBar);

mMapView = (MapView) findViewById(R.id.bmapView);

mBaiduMap = mMapView.getMap();

mBaiduMap.setMyLocationEnabled(true);

mLocClient = new LocationClient(mContext);

mLocClient.registerLocationListener(myListener);

LocationClientOption option = new LocationClientOption();

option.setOpenGps(true);

option.setCoorType("bd09ll");//bd09LL

option.setScanSpan(1000);

mLocClient.setLocOption(option);

mLocClient.start();

mBaiduMap.setOnMapStatusChangeListener(new BaiduMap.OnMapStatusChangeListener() {

//地图状态改变前

@Override

public void onMapStatusChangeStart(MapStatus mapStatus) {

Log.i(TAG, "地图状态改变前");

}

//地图状态改变后

@Override

public void onMapStatusChange(MapStatus mapStatus) {

Log.i(TAG, "地图状态改变后");

}

//地图状态改变时

@Override

public void onMapStatusChangeFinish(MapStatus mapStatus) {

Log.i(TAG, "地图状态改变时");

}

});

seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

@Override

public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

Log.e("seekBar", "--" + progress);

mBaiduMap.clear();

//画圆

drawCircle( progress);

}

@Override

public void onStartTrackingTouch(SeekBar seekBar) {

Log.e("seekBar", "开始滑动！");

}

@Override

public void onStopTrackingTouch(SeekBar seekBar) {

Log.e("seekBar", "停止滑动！");

Toast.makeText(mContext, "半径：" + seekBar.getProgress() + "米", Toast.LENGTH_SHORT).show();

}

});

}

public class MyLocationListener implements BDLocationListener {

@Override

public void onReceiveLocation(BDLocation location) {

// TODO Auto-generated method stub

if (location == null || isLocationClientStop)

return;

MyLocationData locData = new MyLocationData.Builder()

.accuracy(location.getRadius())

.direction(100)

.latitude(location.getLatitude())

.longitude(location.getLongitude())

.build();

mBaiduMap.setMyLocationData(locData);

latitude = location.getLatitude();

longitude = location.getLongitude();

if (isFirstLoc) {

isFirstLoc = false;

//定位点坐标

ll = new LatLng(latitude, longitude);

//设置地图中心点和缩放级别

MapStatusUpdate u = MapStatusUpdateFactory.newLatLngZoom(ll, 13);

//以动画方式更新地图状态，动画耗时 300 ms

mBaiduMap.animateMapStatus(u);

//画圆，主要是这里

OverlayOptions ooCircle = new CircleOptions().fillColor(0x384d73b3)

.center(ll).stroke(new Stroke(3, 0x784d73b3))

.radius(mRadius);

mBaiduMap.addOverlay(ooCircle);

}

}

}

private void drawCircle( int mRadius) {

// if (isFirstLoc) {

// isFirstLoc = false;

//画圆，主要是这里

OverlayOptions ooCircle = new CircleOptions().fillColor(0x384d73b3)

.center(ll).stroke(new Stroke(3, 0x784d73b3))

.radius(mRadius);

mBaiduMap.addOverlay(ooCircle);

// }

}

@Override

public void onDestroy() {

// mLocClient.stop();

// mBaiduMap.setMyLocationEnabled(false);

// mMapView = null;

mMapView.onDestroy();

super.onDestroy();

}

@Override

public void onPause() {

super.onPause();

mMapView.onPause();

}

@Override

public void onResume() {

super.onResume();

mMapView.onResume();

}

}

代码实现XML：

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical">

android:layout_width="match_parent"

android:layout_height="match_parent">

android:id="@+id/bmapView"

android:layout_width="match_parent"

android:layout_height="match_parent" />

android:id="@+id/seekBar"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_marginTop="40dp"

android:progress="2500"

android:max="5000" />

提示：代码需要优化，我已优化完成。如果各位看到这边博客的朋友要用的话可以思考一下自己优化的方式。