how to add compass to mapview

问题:

How do I get the compass to be shown on the screen when my mapview is created. What is wrong with this code? any suggestions?

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.map);



        mapView = (MapView) findViewById(R.id.mapview);
        mapView.setBuiltInZoomControls(true);

        mc = mapView.getController();
        myLoc = new MyLocationOverlay(this, mapView);
        myLoc.enableCompass();
        mapView.getOverlays().add(myLoc);


        mapView.postInvalidate();

        locManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

回答1:

Well, I wouldn't call enableCompass() on onCreate() (which is where I assume this code comes from, given the setContentView() call). Enable the compass in onResume() and disable it in onPause(), so you don't keep the sensors alive when your activity is not on-screen. And you should not need postInvalidate().

Otherwise, this seems fine. Bear in mind that it will only work on actual hardware.

Here is a sample project that enables the compass on MyLocationOverlay that definitely works, though you will need to substitute in your own android:apiKey value.