Starting with Windows Phone 8 Location Services

Today I looked at the location services for Windows Phone 8.

In this blog post we will look at these three things:
1. Get decice location
2. Get street/city or whatever by coordinates (Geocode)
3. Get coordinates by street or city (ReverseGeocode)

Full sourcecode is also hosted on pastebin http://pastebin.com/MhTyG4AJ.

1.
To get the device location, the app needs the “ID_CAP_LOCATION” capability.
Here is the code for getting the device location.

         /// <summary>
        /// Get actual Position from GPS/Wifi/gsm
        /// </summary>
        /// <returns></returns>
        private async Task<Geoposition> getLocation(int maxAgeInMinutes = 5, int timeOutinSeconds = 10)
        {
            Geolocator geolocator = new Geolocator();

            Geoposition geoposition = null;

            if (geolocator.LocationStatus != PositionStatus.Disabled) // Check if we can access the LocationService
            {
                geoposition = await geolocator.GetGeopositionAsync(
                maximumAge: TimeSpan.FromMinutes(maxAgeInMinutes),
                timeout: TimeSpan.FromSeconds(timeOutinSeconds)
                );
            }

            return geoposition;
        }

As result you will get something like this:
image

2.
A simple thing is to get the full address of a location described trough latitude/longitude.
In Windows Phone 7.x the developer had to create a bing maps developer access token. With this token you can query the bing maps rest service and get the result.
I am glad that with Windows Phone 8, there is a build in library for most of the Geocode tasks (I think internally this library is doing the same thing I described above Smile).

         /// <summary>
        /// Get Location name by lat and long
        /// </summary>
        private async void getLocationName()
        {
            Geoposition geoposition = await getLocation(1);

            List<MapLocation> locations;
            ReverseGeocodeQuery query = new ReverseGeocodeQuery();
            query.GeoCoordinate = new GeoCoordinate(geoposition.Coordinate.Latitude, geoposition.Coordinate.Longitude);
            query.QueryCompleted += (s, e) =>
            {
                if (e.Error == null && e.Result.Count > 0)
                {
                    locations = e.Result as List<MapLocation>;

                    Model.LocationName = locations[0].Information.Address.Street;
                    // Do whatever you want with returned locations. 
                    // e.g. MapAddress address = locations[0].Information.Address;
                }
            };
            query.QueryAsync();
        }

3.
The next thing I looked at is called ReverseGeocode. You have the name of a street or a city and you need the longitude and the latide for this location. For example for showing it on a map.
You can achieve this, with this code:

/// <summary>
        /// Get Coordinates from adress
        /// </summary>
        /// <param name="searchTerm"></param>
        private async void getLocationCoordsfromAdress(string searchTerm)
        {
            GeocodeQuery a = new GeocodeQuery();

            Geoposition geoposition = await getLocation();

            if (geoposition != null)
                a.GeoCoordinate = new GeoCoordinate(geoposition.Coordinate.Latitude, geoposition.Coordinate.Longitude);
            else
                a.GeoCoordinate = new GeoCoordinate();
            a.SearchTerm = searchTerm; // mock search, replace with search value

            a.QueryCompleted += (s, e) =>
            {
                if (e.Error == null && e.Result.Count > 0)
                {
                    // DO SOMETHING SERIOUS
                }
            };

            a.QueryAsync();
        }

 

With this three operations you have good start in the world of Windows Phone 8 location services.


Posted Jan 19 2015, 05:16 PM by Holger Vetter
Filed under:

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