location based services - code app, level up - [dec. 2012]

Viktor StojanovskiAndroid Developer @ Seavus

12.12.2012

Location-Based Services

Agenda

Location API

Android permissions for Location

Location Providers

Obtain device location

Location tips

Demo code

Things to do with Location

Q&A Session

Android Location API

Location

A class representing a geographic location.

LocationManager

Provides access to system location services.

LocationListener

Interface used for receiveing notifications from the LocationManager when location is changed.

Android permissions for Location

ACCESS_COARSE_LOCATION (NETWORK_PROVIDER)

ACCESS_FINE_LOCATION (GPS_PROVIDER)

NETWORK_PROVIDER vs GPS_PROVIDER

You need to declare the ACCESS_COARSE_LOCATION permission if your application uses a network-based location provider only.

The more accurate GPS requires the ACCESS_FINE_LOCATION permission.

Note that declaring the ACCESS_FINE_LOCATION permission implies ACCESS_COARSE_LOCATION already.

Challenges in Determining User Location

Multitude of location sources

GPS, Cell-ID, Wi-Fi

Time

Getting user information should be fast.

Re-Estimate user location

User is moving around

Varying accuracy

Different sources for location, choose the best accuracy

Battery

Don’t kill the battery, the user needs it.

How to obtain device location?

1. Add permissions to AndroidManifest.xml

2. Get a Reference to LocationManager.

3. Define a listener (LocationListener) that responds to location updates.

4. Register the LocationListener with LocationManager to receive location updates.

5. Don’t forget to unregister the listener.

How to obtain device location?

How to obtain device location?

type of location provider

minimum time interval between location updates, in milliseconds

minimum distance between location updates, in meters

setting both to zero requests location notifications as frequently as possible

Location Criteria

Fresh location information

How to reduce the latency for getting your first location?

Use getLastKnownLocation(provider) from LocationManager.

Is it enough? Which provider should be used for this? No. All providers.

Fresh location informationIterate through each location provider on the device:

Find the most timely and accurate last known location

Verify the Location Provider is Enabled

Get device location Flow

Criteria Provider Location Manager Location Listener

- Power- Accuracy

Best provider by criteria- Last Known Location- onLocationChanged

Update user data

Demo Code - MyLocation

Once you got Location, what’s next?

1. Draw maps (Google Maps, Open Street Maps, …)

2. Use third party API’s to get data (example: Google Places, Foursqare, …)

3. Get content from some server (your server) based on device’s location, maybe you are building RSS reader that displays news based on current location.

Google Maps API

Two ways for showing device’s location Open Intent with latitude and longitude for Google

MapsStandard VIEW Intent

Embed MapActivity in your applicationGenerate API Key for your device (generate another

API Key for production)Implement everything you need with maps

Google Maps API

The API automatically handles: Access to Google Maps servers Data downloading Displaying maps Touch gestures Adding markers, polygons, overlays Change view of map: (Satellite, Terrain, Traffic,

Latitude)

Someone has already done it. Use it!

https://developers.google.com/places/

https://developer.foursquare.com/

Google Places API – Nearby Search

Place Searches

Nearby Search Requests

Text Search Requests

Place Details

Place Actions

Places Autocomplete

Output: either JSON or XML

Foursqaure API

Search for venues

Addresses

Popularity

Tips

Photos

Access recommendations

Example: https://github.com/jomartigcal/lbs-android-sample

Read more …

Chapter 13 Chapter 22