LocationHelper.java

package com.papagiannis.tuberun;

import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;

public final class LocationHelper {
	public static final String FAKE_PROVIDER = "FAKE";
	protected static final int TWO_MINUTES = 1000 * 60 * 2;

	/**
	 * Determines whether one Location reading is better than the current
	 * Location fix
	 * 
	 * @param location
	 *            The new Location that you want to evaluate
	 * @param currentBestLocation
	 *            The current Location fix, to which you want to compare the new
	 *            one
	 */
	public static boolean isBetterLocation(Location location,
			Location currentBestLocation) {
		if (currentBestLocation == null) {
			// A new location is always better than no location
			return true;
		}

		// Check whether the new location fix is newer or older
		long timeDelta = location.getTime() - currentBestLocation.getTime();
		boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
		boolean isSignificantlyOlder = timeDelta < -TWO_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() - currentBestLocation
				.getAccuracy());
		boolean isLessAccurate = accuracyDelta > 0;
		boolean isMoreAccurate = accuracyDelta < 0;
		boolean isSignificantlyLessAccurate = accuracyDelta > 200;

		// Check if the old and new location are from the same provider
		boolean isFromSameProvider = isSameProvider(location.getProvider(),
				currentBestLocation.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;
	}

	/** Checks whether two providers are the same */
	private static boolean isSameProvider(String provider1, String provider2) {
		if (provider1 == null) {
			return provider2 == null;
		}
		return provider1.equals(provider2);
	}

	public static final void requestLocationUpdates(
			LocationManager locationManager, LocationListener locationListener) {
		if (locationManager != null) {
			locationManager.requestLocationUpdates(
					LocationManager.NETWORK_PROVIDER, 2 * 1000, 5,
					locationListener);
			locationManager
					.requestLocationUpdates(LocationManager.GPS_PROVIDER,
							3 * 1000, 5, locationListener);
		}
	}

	public static Location getLastKnownLocation(LocationManager locationManager) {
		Location result = new Location(FAKE_PROVIDER);
		if (locationManager==null) return result;
		Location lastKnownLocation = locationManager
				.getLastKnownLocation(LocationManager.GPS_PROVIDER);
		if (lastKnownLocation == null)
			lastKnownLocation = locationManager
					.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
		if (lastKnownLocation != null) {
			// never trust old accuracies
			if (lastKnownLocation.getAccuracy() < 50) {
				lastKnownLocation.setAccuracy(1000);
			}
			result = lastKnownLocation;
		}
		return result;
	}

}