Android google map自定义的折现图层的实现

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实现结果如下：

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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     */@Overrideprotected boolean isRouteDisplayed() {return true;}}

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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 */@Overridepublic 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;}}}}}}

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