Android Open Source - WiseRadar G P S Helper

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From Project

Back to project page WiseRadar.

License

The source code is released under:

Apache License

Java Source Code

package wiseguys.radar.conn;
/*from   ww  w  .  j  a v a2s  .c  o m*/
import wiseguys.radar.R;
import wiseguys.radar.helpers.RadarHelper;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.Toast;

public class GPSHelper {
  
  private Context context;
  
  private Location lastKnownLocation;
  private boolean GPSSetup;
  private LocationManager locationManager;
  private LocationListener locationListener;

    public static double lastGoodLat;
    public static double lastGoodLong;
    public static double cityLat;
    public static double cityLong;

  
  public GPSHelper(Context c) {
    context = c;
    lastKnownLocation = null;
        GPSSetup = false;
  }
  
  public Location getLastLocation() {
    return lastKnownLocation;
  }
  
  /**
     * Warn if they have a disabled GPS
     */
    private void alert() {
          final AlertDialog.Builder builder = new AlertDialog.Builder(context);
          builder.setMessage("Your GPS seems to be disabled, do you want to enable it?")
                 .setCancelable(false)
                 .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                     public void onClick(final DialogInterface dialog, final int id) {
                         context.startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
                         setup();
                     }
                 })
                 .setNegativeButton("No", new DialogInterface.OnClickListener() {
                     public void onClick(final DialogInterface dialog, final int id) {
                          dialog.cancel();
                     }
                 });
          final AlertDialog alert = builder.create();
          alert.show();
  }
    
    public void setup() {
    // Acquire a reference to the system Location Manager
    locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);

    if (!locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER) &&
        !locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
      //No providers enabled
      alert();
    }

    // Define a listener that responds to location updates
    locationListener = new LocationListener() {

        public void onLocationChanged(Location location) {
          if (newLocationIsBetter(location)) {
            lastKnownLocation = location;
                    RadarHelper.latestLocation = location;
          }
        }

      public void onStatusChanged(String provider, int status, Bundle extras) {

      }

        public void onProviderEnabled(String provider) {
          if (!locationManager.getProviders(true).contains(provider)) {
            locationManager.requestLocationUpdates(provider, 0, 0, this);
          }
          GPSSetup = true;
        }

        public void onProviderDisabled(String provider) {
          if (provider.equals(LocationManager.NETWORK_PROVIDER)) {
            GPSSetup = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
          } else if (provider.equals(LocationManager.GPS_PROVIDER)) {
            GPSSetup = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
          }
        }
    };

    // Register the listeners with the Location Manager to receive location updates
    if (locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
      locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, RadarHelper.TEN_MINUTES, 2000, locationListener);
    }

    if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
      locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, RadarHelper.TEN_MINUTES, 2000, locationListener);
    }

    //Setup our last known good location
    lastKnownLocation = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

        lastGoodLat = lastKnownLocation.getLatitude();
        lastGoodLong = lastKnownLocation.getLongitude();
    
    GPSSetup = !locationManager.getProviders(true).isEmpty();
    }

    /**
     * Compare new GPS location to old and update if necessary
     * @param location new location we compare our old to
     * @return true if we need an update
     */
  public boolean newLocationIsBetter(Location location) {
    //Always update a null
    if (lastKnownLocation == null) {
      return true;
    }

      //Check times
      long timeDelta = location.getTime() - lastKnownLocation.getTime();
      boolean isSignificantlyNewer = timeDelta > RadarHelper.TEN_MINUTES;
      boolean isSignificantlyOlder = timeDelta < -RadarHelper.TEN_MINUTES;
      boolean isNewer = timeDelta > 0;

      // If it's been more than two minutes since the current location, use the new location
      // because the user has likely moved
      if (isSignificantlyNewer) {
          return true;
      // If the new location is more than two minutes older, it must be worse
      } else if (isSignificantlyOlder) {
          return false;
      }

      // Check whether the new location fix is more or less accurate
      int accuracyDelta = (int) (location.getAccuracy() - lastKnownLocation.getAccuracy());
      boolean isLessAccurate = accuracyDelta > 0;
      boolean isMoreAccurate = accuracyDelta < 0;
      boolean isSignificantlyLessAccurate = accuracyDelta > 2000; //2KM Difference

      // Check if the old and new location are from the same provider
      boolean isFromSameProvider = location.getProvider().equals( lastKnownLocation.getProvider() );

      // Determine location quality using a combination of timeliness and accuracy
      if (isMoreAccurate) {
          return true;
      } else if (isNewer && !isLessAccurate) {
          return true;
      } else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
          return true;
      }
      return false;
  }

  public void disable() {
     locationManager.removeUpdates(locationListener);
     GPSSetup = false;
  }
  
  public boolean ready() {
    if (!GPSSetup) {
      setup();
    }
    return GPSSetup;
  }

  public String findClosestCity(Location lastKnownLocation) {  
    if (lastKnownLocation == null) {
      return null;
    }
    
    String[] radarLats = context.getResources().getStringArray(R.array.city_lat_vals);
    String[] radarLongs = context.getResources().getStringArray(R.array.city_long_vals);
    String[] radarCodes = context.getResources().getStringArray(R.array.radar_codes);
    String[] radarNames = context.getResources().getStringArray(R.array.radar_cities);
    
    String closest = null;
    String closestName = null;
    float closestDist = Float.MAX_VALUE;
    
    for (int i = 0; i < radarLats.length; i++) {
      try {
        double lat = Double.parseDouble(radarLats[i]);
        double lon = Double.parseDouble(radarLongs[i]);
        
        Location currCityLoc = new Location("WiseRadar");
        currCityLoc.setLatitude(lat);
        currCityLoc.setLongitude(lon);
        
        float currDist = lastKnownLocation.distanceTo(currCityLoc);
        if (currDist < closestDist) {
          closestDist = currDist;
          closestName = radarNames[i];
          closest = radarCodes[i];
                    cityLat = lat;
                    cityLong = lon;
        }        
      } catch (NumberFormatException e) {
        return null;
      }
    }
    
    Toast.makeText(context, "GPS has selected '" + closestName + "'", Toast.LENGTH_LONG).show();
    
    return closest;
  }
}

Java Source Code List

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