GIS的学习（三十五）osmdroid 地图触摸图层的实现

   源代码源自osmdbonusPack的代码，具体实现如下：

package com.etrip.osmdroid;

import org.osmdroid.api.IGeoPoint;
import org.osmdroid.views.MapView;
import org.osmdroid.views.MapView.Projection;
import org.osmdroid.views.overlay.Overlay;

import android.content.Context;
import android.graphics.Canvas;
import android.view.MotionEvent;

/**
 * Empty overlay than can be used to detect events on the map, 
 * and to throw them to a MapEventsReceiver. 
 * @see MapEventsReceiver
 * @author M.Kergall
 */
public class MapEventsOverlay extends Overlay {
	
	private Context context;
	private MapEventsReceiver mReceiver;
	private int x;
	private int y;
	
	/**
	 * @param ctx the context
	 * @param receiver the object that will receive/handle the events. 
	 * It must implement MapEventsReceiver interface. 
	 */
	public MapEventsOverlay(Context ctx, int x, int y,MapEventsReceiver receiver) {
        super(ctx);
        this.context = ctx;
        this.x = x;
        this.y = y;
		mReceiver = receiver;
    }

	@Override 
	protected void draw(Canvas c, MapView osmv, boolean shadow) {
		
	}
	
	@Override public boolean onSingleTapUp(MotionEvent e, MapView mapView){
		Projection proj = mapView.getProjection();
		IGeoPoint p = proj.fromPixels(e.getX(), e.getY());
		
		


		mapView.getController().animateTo(p);
		
		return mReceiver.singleTapUpHelper(p);
	}
	
	@Override public boolean onLongPress(MotionEvent e, MapView mapView) {
		Projection proj = mapView.getProjection();
		IGeoPoint p = proj.fromPixels(e.getX(), e.getY());
		//throw event to the receiver:
		return mReceiver.longPressHelper(p);
    }

}

package com.etrip.osmdroid;

import org.osmdroid.api.IGeoPoint;

/**
 * Interface for objects that need to handle map events thrown by a MapEventsOverlay. 
 * @see MapEventsOverlay
 * @author M.Kergall
 */
public interface MapEventsReceiver {

	/**
	 * @param p the position where the event occurred. 
	 * @return true if the event has been "consumed" and should not be handled by other objects. 
	 */
	boolean singleTapUpHelper(IGeoPoint p);
	
	/**
	 * @param p the position where the event occurred. 
	 * @return true if the event has been "consumed" and should not be handled by other objects. 
	 */
	boolean longPressHelper(IGeoPoint p);	
}

具体的使用如下：

package com.etrip.osmdroid;
import org.osmdroid.api.IGeoPoint;
import org.osmdroid.tileprovider.tilesource.TileSourceFactory;
import org.osmdroid.util.GeoPoint;
import org.osmdroid.views.MapController;
import org.osmdroid.views.MapView;

import android.app.Activity;
import android.os.Bundle;
import android.widget.Toast;

/**
 * 
 * @Title: 
 * @Description: 实现TODO
 * @Copyright:Copyright (c) 2011
 * @Company:
 * @Date:2012-7-31
 * @author  longgangbai
 * @version 1.0
 */
public class GeoServersmdroidActivity extends Activity {
	private MapController mapController;
	
	private MapView mapView;
	
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		mapView = (MapView) findViewById(R.id.map);

		mapView.setTileSource(TileSourceFactory.MAPNIK);

		mapView.setBuiltInZoomControls(true);

		mapController = mapView.getController();

		mapController.setZoom(15);

		GeoPoint geopoint=new GeoPoint(39.92605, 116.42616); 

		mapController.setCenter(geopoint);
		
		MapEventsOverlay mapEventOverlay=new MapEventsOverlay(this,100,100,new MapEventsReceiver() {
			
			@Override
			public boolean singleTapUpHelper(IGeoPoint p) {
		        Toast.makeText(GeoServersmdroidActivity.this, "test touch event ", Toast.LENGTH_LONG).show();
				return true;
			}
			
			@Override
			public boolean longPressHelper(IGeoPoint p) {
				return false;
			}
		});
		mapView.getOverlays().add(mapEventOverlay);
		mapView.invalidate();
	}
}