android - 如何在 Google map Android 上绘制一条叠加层

Question

我想在我的 map 项目上画一条线，但无法绘制。我在哪里以及如何声明叠加层？我尝试了各种方法，但无法正常工作。即，代码仅在 Eclipse 中显示错误。我不想做的是画一条从 A 到 B 的路线，而是在我移动时画出路线。

// Creating a MapView
public class Gpstrack extends MapActivity {
    private MapView map;
    private MapController controller;
    private Projection projection;
    ArrayList<GeoPoint> geoPointsArray = new ArrayList<GeoPoint>();

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        initMapView();
        initMyLocation();


        TabHost.TabSpec spec;

        TabHost th = (TabHost)findViewById(R.id.tabhost);
        th.setup();

        spec = th.newTabSpec("tag1");
        spec.setContent(R.id.map_Tab);
        spec.setIndicator("Map");
        th.addTab(spec);

        spec = th.newTabSpec("tag2");
        spec.setContent(R.id.log_Tab);
        spec.setIndicator("Log");
        th.addTab(spec);

        spec = th.newTabSpec("tag3");
        spec.setContent(R.id.details_Tab);
        spec.setIndicator("Details");
        th.addTab(spec);

        spec = th.newTabSpec("tag4");
        spec.setContent(R.id.student_Tab);
        spec.setIndicator("Student Info");
        th.addTab(spec);

    }

    @Override
    protected boolean isRouteDisplayed() {
        // TODO Auto-generated method stub
        return false;
    }

    //Map and Controls
    private void initMapView() {
        map = (MapView) findViewById(R.id.mvMain);
        controller = map.getController();
        map.setSatellite(true);
        //map.setStreetView(true);
        map.setBuiltInZoomControls(true);
    }


    //Creates an Overlay that marks current position
    private void initMyLocation() {
        final MyLocationOverlay overlay = new MyLocationOverlay(this, map);

        overlay.enableMyLocation();
        overlay.enableCompass();
        overlay.runOnFirstFix(new Runnable() {
            public void run() {
                controller.setZoom(17);
                controller.animateTo(overlay.getMyLocation());
                map.getOverlays().add(overlay);



            }

        });

    }


    //Experiment
    class MyOverlay extends Overlay {
        public void draw(Canvas canvas, MapView mapv, boolean shadow) {
            super.draw(canvas, mapv, shadow);
            Projection projection = mapv.getProjection();
            Path p = new Path();



            for (int i = 0; i < geoPointsArray.size(); i++) {
                if (i == geoPointsArray.size() -1) {
                    break;
                }
                Point from = new Point();
                Point to = new Point();
                projection.toPixels(geoPointsArray.get(i), from);
                projection.toPixels(geoPointsArray.get(i + 1), to);
                p.moveTo(from.x, from.y);
                p.lineTo(to.x, to.y);
                }

            Paint mPaint = new Paint();
            mPaint.setStyle(Style.STROKE);
            mPaint.setColor(Color.GREEN);
            mPaint.setAntiAlias(true);
            mPaint.setStrokeWidth(5);
            canvas.drawPath(p, mPaint);
            mapv.invalidate();
            super.draw(canvas, mapv, shadow);


        }
    }       
}

Answer 1

你试过用这个演示来实现Google Map Overlay吗？ ？