Lecture Slides for Location based Services [Android]

Accessing Location-Based services

Software Development for Portable Devices BITS Pilani Goa Campus

Sem I 2011-12

Applications

• Mapping• Directions• Dynamic chat Application• “Geotag” your photos, tweets

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What's common in the above?

• GPS capability of the phone• Technologies to identify your location

– GPS– Cell tower triangulation

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Location based Services (LBS)

• Two elements of LBS:– Location manager : provides hooks to lbs– Location providers : provide current location

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Update location in Emulator

• In DDMS view, you can set the longitude and latitude

• Lets see how.

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Location manager

• You can :– Find available location providers– Obtain your current location– Track movement– Set proximity alerts for detecting movement into

and out of the specified areas

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Location Providers:They know where you are hiding

• Selecting location provider– Explicitly – By specifying the name– Implicitly – By specifying the selection criteria

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Explicit

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User permissions

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Finding yourself

• hasAltitude() and getAltitude() for Altitude• hasSpeed() and getSpeed() for Speed

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On the move

• Why no getMyCurrentLocationNow() ?• Not all location providers are immediately

responsive. • How to get changes in location reflected in

your app?• Register for location updates!

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requestLocationUpdates(String provider, long minTime, float minDistance, LocationListener listener)

• provider : name of location provider• minTime : how long, in milliseconds, before

we might request for a location update• minDistance : how far,…. in meters• Listener : name of object of locationListener

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LocationListener

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These are the functions provided by the location Listeners

STOP!

• When not required use removeUpdates()• If you fail to do this your app will continue

getting location updates even after all activities are closed.

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Are we there yet?

• LocationManager offers addProximityAlert()• Registers a Pending intent• addProximityAlert (double latitude, double

longitude, float radius, long expiration, PendingIntent intent)

• In case the screen goes to sleep, checks for proximity alerts happen only once every 4 minutes.

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parameters

• Radius: the radius of the central point of the alert region, in meters

• Expiration: time for this proximity alert, in milliseconds, or -1 to indicate no expiration

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Thank You!

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References• Location

http://developer.android.com/reference/android/location/Location.html

• Location Manager http://developer.android.com/reference/android/location/LocationManager.html

• Location Provider http://developer.android.com/reference/android/location/LocationProvider.html

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