Android MapActivity 和 ItemizedOverlay 在 TouchEvent 上改变当前位置

Question

我有一个应用程序，其中一个 Activity 显示 map ，另一个类用于在 map 上放置标记或任何叠加项。它工作得很好，但现在当用户触摸 map 时，它会显示一 strip 有新位置的消息(此代码在 AddItemizedOverlay 的 ontouche 事件上实现)。

我想改为更改 map 上新位置的图钉(主要 Activity 中的代码)。如何将新位置数据从 AddItemizedOverlay 类传递到主要 Activity ？如何绘制新用户位置？谢谢!!!

myMapactivity.java

public class myMapactivity extends MapActivity 
{

private MapView mapView;
private MapController mapCtrl;
List<Overlay> mapOverlays;
GeoPoint mePoint;

AddItemizedOverlay itemizedOverlay;
OverlayItem overlayitem;

    public void onCreate(Bundle savedInstanceState)
    {
        ...

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

   mapOverlays = mapView.getOverlays();
   mapOverlays.clear();
   mapCtrl = mapView.getController();

       drawCurrentUserLocation();
     }

     private void drawCurrentUserLocation()
{

   // Drawable marker icon
   Drawable drawable_user = this.getResources()
            .getDrawable(R.drawable.mark_red);

   itemizedOverlay = new AddItemizedOverlay(drawable_user, this);

   overlayitem = new OverlayItem(mePoint, "Your Location","That is you!");

   itemizedOverlay.addOverlay(overlayitem);

   mapOverlays.add(itemizedOverlay);
   itemizedOverlay.populateNow();
   mapCtrl.animateTo(mePoint);
   mapCtrl.setZoom(17);
}
}

AddItemizedOverlay.java

   public class AddItemizedOverlay extends ItemizedOverlay<OverlayItem> {

   private ArrayList<OverlayItem> mapOverlays = new ArrayList<OverlayItem>();

   private Context context;

   public AddItemizedOverlay(Drawable defaultMarker) {
        super(boundCenterBottom(defaultMarker));
   }

   public AddItemizedOverlay(Drawable defaultMarker, Context context) {
        this(defaultMarker);
        this.context = context;
   }

   @Override
   public boolean onTouchEvent(MotionEvent event, MapView mapView)
   {   

       if (event.getAction() == 1) {
           GeoPoint geopoint = mapView.getProjection().fromPixels(
               (int) event.getX(),
               (int) event.getY());
           // latitude
           double lat = geopoint.getLatitudeE6() / 1E6;
           // longitude
           double lon = geopoint.getLongitudeE6() / 1E6;

           Geocoder geocoder = new Geocoder(context, Locale.getDefault());   
           String result = null;
           try {
               List<Address> list = geocoder.getFromLocation(lat, lon, 1);
               if (list != null && list.size() > 0) {
                   Address address = list.get(0);
                   // sending back first address line and locality
                   result = address.getAddressLine(0) + ", " + address.getLocality();
                   Toast.makeText(context, result, Toast.LENGTH_SHORT).show();
               }
           } catch (IOException e) {
               Log.e("Error", "Impossible to connect to Geocoder", e);
           } 

       }
       return false;
   } 

Answer 1

由于 myMapactivity 是 AddItemizedOverlay 的上下文，您可以使用:

((myMapactivity)context).setMarker(event) 在 AddItemizedOverlay 中；这将调用应在 myMapactivity 中实现的公共(public)方法 setMarker(MotionEvent event)。