Android google map自定义的折现图层的实现

实现结果如下：

代码如下： 

    package com.easyway.polyline;

import java.util.ArrayList;
import java.util.List;

import android.os.Bundle;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
/**
 * 自定义的折现图层的实现
 *  在特定情况下，可能需要我们开发人员绘制特定的图层在google map上面显示
 *  
 *  
 * 
 * @author longgangbai
 *
 */
public class GooglePolylineActivity extends MapActivity {
	private MapView mapView;
	
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mapView =(MapView)findViewById(R.id.mapView);
        
        //存储连接的点的信息
        List<GeoPoint> points = new ArrayList<GeoPoint>();
        points.add(new GeoPoint(39907794,116356694));
        points.add(new GeoPoint(39950181,116415059));
        points.add(new GeoPoint(39909637,116435315));
        points.add(new GeoPoint(39902526,116398236));
        
        //添加自定义的图层
        PolyLine polyline = new PolyLine(points);
        
        mapView.getOverlays().add(polyline); //map是MapView类型
        
        mapView.invalidate();
        mapView.setBuiltInZoomControls(true);
        
        MapController mapcontroller=mapView.getController();
        GeoPoint  point=new GeoPoint(39950181,116415059);
        mapcontroller.setCenter(point);
        mapcontroller.setZoom(7);
    }

    /**
     * 是否显示路线显示
     */
	@Override
	protected boolean isRouteDisplayed() {
		return true;
	}
	
	
}
  

    package com.easyway.polyline;


import java.util.List;

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.Projection;

/**
 * Goolge地图之Polyline实现Overlay 以图层形式存在.
 * MyLocationOverlay:定位当前位置的图层
 * ItemizedOverlay:图层的基类
 * OverlayItem:图层的项
 * 
 * 
 * @author longgangbai
 */
public class PolyLine extends Overlay {
	List<GeoPoint> points;
	Paint paint;

	/**
	 * 构造函数，使用GeoPoint List构造Polyline
	 * 
	 * @param points
	 *            GeoPoint点List
	 */
	public PolyLine(List<GeoPoint> points) {
		this.points = points;
		paint = new Paint();
		paint.setColor(Color.BLUE);
		paint.setAlpha(150);
		paint.setAntiAlias(true);
		paint.setStyle(Paint.Style.FILL_AND_STROKE);
		paint.setStrokeWidth(4);
	}

	/**
	 * 使用GeoPoint点List和Paint对象来构造Polyline
	 * 
	 * @param points
	 *            GeoPoint点List，所有的拐点
	 * @param paint
	 *            Paint对象，用来控制划线样式
	 */
	public PolyLine(List<GeoPoint> points, Paint paint) {
		this.points = points;
		this.paint = paint;
	}


	/**
	 * 真正将线绘制出来 只需将线绘制到canvas上即可，主要是要转换经纬度到屏幕坐标
	 */
	@Override
	public void draw(Canvas canvas, MapView mapView, boolean shadow) {
		if (!shadow) {// 不是绘制shadow层
			Projection projection = mapView.getProjection();
			if (points != null) {
				if (points.size() >= 2) {
					Point start = projection.toPixels(points.get(0), null);// 需要转换坐标
					for (int i = 1; i < points.size(); i++) {
						Point end = projection.toPixels(points.get(i), null);
						canvas.drawLine(start.x, start.y, end.x, end.y, paint);// 绘制到canvas上即可
						start = end;
					}
				}
			}
		}
	}
}
  

Android google map自定义的折现图层的实现