Tuesday, November 10, 2009

AndroidLocation with Zoom Level Control, using SeekBar

Further works on last exercise, MapView to center on the current location from GPS. A SeekBar to change Zoom Level is implemented. Also add valid checking in Start-up Location, skip if invalid; to prevent from Unexpected Stop.



Modify main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
>
<TextView
android:id="@+id/longitude"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Longitude:"
/>
<TextView
android:id="@+id/latitude"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Latitude:"
/>
<SeekBar
android:id="@+id/zoombar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:max="20"
android:progress="0"/>
</LinearLayout>
<com.google.android.maps.MapView
android:id="@+id/mapview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:clickable="false"
android:apiKey="-----Your Own API Key here-------------"
/>
</LinearLayout>


AndroidLocation.java
package com.AndroidLocation;

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

import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.Toast;

public class AndroidLocation extends MapActivity {

private LocationManager myLocationManager;
private LocationListener myLocationListener;
private TextView myLongitude, myLatitude;

private MapView myMapView;
private SeekBar myZoomBar;

private MapController myMapController;

private void CenterLocation(GeoPoint centerGeoPoint)
{
myMapController.animateTo(centerGeoPoint);


myLongitude.setText("Longitude: "+
String.valueOf((float)centerGeoPoint.getLongitudeE6()/1000000)
);
myLatitude.setText("Latitude: "+
String.valueOf((float)centerGeoPoint.getLatitudeE6()/1000000)
);
};

private void SetZoomLevel()
{
int myZoomLevel = myZoomBar.getProgress()+1;
myMapController.setZoom(myZoomLevel);
Toast.makeText(this,
"Zoom Level : " + String.valueOf(myZoomLevel),
Toast.LENGTH_LONG).show();
};

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
myMapView = (MapView)findViewById(R.id.mapview);
myLongitude = (TextView)findViewById(R.id.longitude);
myLatitude = (TextView)findViewById(R.id.latitude);
myZoomBar = (SeekBar)findViewById(R.id.zoombar);

myMapView.setSatellite(true); //Set satellite view
myMapController = myMapView.getController();
SetZoomLevel();

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

myLocationListener = new MyLocationListener();

myLocationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
0,
0,
myLocationListener);

//Get the current location in start-up
//check LastKnownLocation, if not valid, skip it.
Location initLocation=
myLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if(initLocation != null)
{
GeoPoint initGeoPoint = new GeoPoint(
(int)(initLocation.getLatitude()*1000000),
(int)(initLocation.getLongitude()*1000000));
CenterLocation(initGeoPoint);
}
myZoomBar.setOnSeekBarChangeListener(myZoomBarOnSeekBarChangeListener);
}

private SeekBar.OnSeekBarChangeListener myZoomBarOnSeekBarChangeListener =
new SeekBar.OnSeekBarChangeListener(){

public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
// TODO Auto-generated method stub
SetZoomLevel();
}

public void onStartTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub

}

public void onStopTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub

}

};

private class MyLocationListener implements LocationListener{

public void onLocationChanged(Location argLocation) {
// TODO Auto-generated method stub
GeoPoint myGeoPoint = new GeoPoint(
(int)(argLocation.getLatitude()*1000000),
(int)(argLocation.getLongitude()*1000000));

CenterLocation(myGeoPoint);
}

public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}

public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}

public void onStatusChanged(String provider,
int status, Bundle extras) {
// TODO Auto-generated method stub
}
}

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


Download the files.

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