Question

I am using mapview in my android app
using the class com.google.android.maps
I wont lo load markers using background process when the user navigate I want to
send the Viewport coordinate to my server
I can do it in javascript like here

 google.maps.event.addListener(map, 'idle', showMarkers);
  function showMarkers() {
var bounds = map.getBounds();

// Call you server with ajax passing it the bounds

// In the ajax callback delete the current markers and add new markers

}

But how can I do this in java ? Please suggest.

Answer 1

i post this answer and i hope to save some one else time
i found that the best solution for my case is to use custom map view SimpleMapView
first crete the SimpleMapView class in your project and here is the code

import java.util.ArrayList;
import java.util.List;

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

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;




public class SimpleMapView extends MapView {

    private int currentZoomLevel = -1;
    private GeoPoint currentCenter;
    private List<ZoomChangeListener> zoomEvents = new ArrayList<ZoomChangeListener>();
    private List<PanChangeListener> panEvents = new ArrayList<PanChangeListener>();

    public SimpleMapView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public SimpleMapView(Context context, String apiKey) {
        super(context, apiKey);
    }

    public SimpleMapView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    /**
     * 
     * @return
     */
    public int[][] getBounds() {

        GeoPoint center = getMapCenter();
        int latitudeSpan = getLatitudeSpan();
        int longtitudeSpan = getLongitudeSpan();
        int[][] bounds = new int[2][2];

        bounds[0][0] = center.getLatitudeE6() - (latitudeSpan / 2);
        bounds[0][1] = center.getLongitudeE6() - (longtitudeSpan / 2);

        bounds[1][0] = center.getLatitudeE6() + (latitudeSpan / 2);
        bounds[1][1] = center.getLongitudeE6() + (longtitudeSpan / 2);
        return bounds;
    }

    public boolean onTouchEvent(MotionEvent ev) {
        if (ev.getAction() == MotionEvent.ACTION_UP) {
            GeoPoint centerGeoPoint = this.getMapCenter();
            if (currentCenter == null || 
                    (currentCenter.getLatitudeE6() != centerGeoPoint.getLatitudeE6()) ||
                    (currentCenter.getLongitudeE6() != centerGeoPoint.getLongitudeE6()) ) {
                firePanEvent(currentCenter, this.getMapCenter());
            }
            currentCenter = this.getMapCenter();
        }
        return super.onTouchEvent(ev);
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);
        if(getZoomLevel() != currentZoomLevel){
            fireZoomLevel(currentZoomLevel, getZoomLevel());
            currentZoomLevel = getZoomLevel();
        }
    }

    @Override
    public void setSatellite(boolean on){
        super.setSatellite(on);
    }

    @Override
    public MapController getController(){
        return super.getController();
    }

    private void fireZoomLevel(int old, int current){
        for(ZoomChangeListener event : zoomEvents){
            event.onZoom(old, current);
        }
    }

    private void firePanEvent(GeoPoint old, GeoPoint current){
        for(PanChangeListener event : panEvents){
            event.onPan(old, current);
        }
    }

    public void addZoomChangeListener(ZoomChangeListener listener){
        this.zoomEvents.add(listener);
    }

    public void addPanChangeListener(PanChangeListener listener){
        this.panEvents.add(listener);
    }
}

and in your mapactivity just make

 SimpleMapView mapView = (SimpleMapView) findViewById(R.id.mapView);

and then you have

    mapView.addPanChangeListener(new PanChangeListener() {

    @Override
    public void onPan(GeoPoint old, GeoPoint current) {
                  //TODO
              //do your work here 

                }
});

and add the PanChangeListener class here the code

package yourPkageName;

import com.google.android.maps.GeoPoint;

public interface PanChangeListener {
    public void onPan(GeoPoint old, GeoPoint current);
}

and add the ZoomChangeListener class here the code

package yourPkageName;

public interface ZoomChangeListener {
    public void onZoom(int old, int current);
}

and in your xml file add

<?xml version="1.0" encoding="utf-8"?>

<YourPakageName.SimpleMapView   xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mapView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:apiKey="0mAbU5bZyFY2I46PFJ1ysXGcYlAmFM6fYBWSB7Q"
    android:clickable="true" />