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GeoCoordinateWatcher Class

Supplies location data that is based on latitude and longitude coordinates.

System.Object
  System.Device.Location.GeoCoordinateWatcher

Namespace:  System.Device.Location
Assembly:  System.Device (in System.Device.dll)

public class GeoCoordinateWatcher : IDisposable, 
	INotifyPropertyChanged, IGeoPositionWatcher<GeoCoordinate>

The GeoCoordinateWatcher type exposes the following members.

  NameDescription
Public methodGeoCoordinateWatcher()Initializes a new instance of GeoCoordinateWatcher with default accuracy settings.
Public methodGeoCoordinateWatcher(GeoPositionAccuracy)Initializes a new instance of GeoCoordinateWatcher, given an accuracy level.
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  NameDescription
Public propertyDesiredAccuracyThe requested accuracy level for the location data that is provided by the GeoCoordinateWatcher.
Public propertyMovementThresholdThe distance that must be moved, in meters, relative to the coordinate from the last PositionChanged event, before the location provider raises another PositionChanged event.
Public propertyPermissionIndicates whether permission to access location data from location providers has been granted or denied.
Public propertyPositionGets the GeoCoordinate which indicates the current location.
Public propertyStatusGets the current status of the GeoCoordinateWatcher.
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  NameDescription
Public methodDispose()Releases all resources that are used by the current instance of the GeoCoordinateWatcher class.
Protected methodDispose(Boolean)Releases all resources used by the current instance of the GeoCoordinateWatcher class.
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeFrees resources and performs other cleanup operations before the GeoCoordinateWatcher is reclaimed by garbage collection. (Overrides Object.Finalize().)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodOnPositionChangedCalled when a PositionChanged event occurs.
Protected methodOnPositionStatusChangedCalled when a StatusChanged event occurs.
Protected methodOnPropertyChangedCalled when a property of the GeoCoordinateWatcher changes.
Public methodStart()Initiate the acquisition of data from the current location provider. This method enables PositionChanged events and allows access to the Position property.
Public methodStart(Boolean)Initiate the acquisition of data from the current location provider. This method enables PositionChanged events and allows access to the Position property.
Public methodStopStops the GeoCoordinateWatcher from providing location data and events.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodTryStartInitiates the acquisition of data from the current location provider. This method returns synchronously.
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  NameDescription
Public eventPositionChangedIndicates that the latitude or longitude of the location data has changed.
Public eventStatusChangedIndicates that the status of the GeoCoordinateWatcher object has changed.
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  NameDescription
Explicit interface implemetationPrivate eventIGeoPositionWatcher<GeoCoordinate>.PositionChangedIndicates that the location data has changed.
Explicit interface implemetationPrivate eventIGeoPositionWatcher<GeoCoordinate>.StatusChangedIndicates that the status of the location provider has changed.
Explicit interface implemetationPrivate eventINotifyPropertyChanged.PropertyChangedIndicates that the Status property, the Position property, or the Permission property has changed.
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The GeoCoordinateWatcher class supplies coordinate-based location data from the current location provider. The current location provider is prioritized as the highest on the computer, based on a number of factors, such as the age and accuracy of the data from all providers, the accuracy requested by location applications, and the power consumption and performance impact associated with the location provider. The current location provider might change over time, for instance, when a GPS device loses its satellite signal indoors and a Wi-Fi triangulation provider becomes the most accurate provider on the computer.

To begin accessing location data, create a GeoCoordinateWatcher and call Start or TryStart to initiate the acquisition of data from the current location provider.

The Status property can be checked to determine if data is available. If data is available, you can get the location one time from the Position property, or receive continuous location updates by handling the PositionChanged event.

The Permission, Status, and Position properties support INotifyPropertyChanged, so that an application can data-bind to these properties.

In Windows 7, all the System.Device.Location classes are fully functional if a location provider is installed and able to resolve the computer's location.

NoteNote

On Windows 7 Starter Edition, the only supported location provider is the Default Location Provider in Control Panel, and an add-in must be installed to specify latitude and longitude.

Note   In versions of Windows prior to Windows 7, the following conditions apply:

The following program shows how to create a GeoCoordinateWatcher and start acquiring data by using an initialization timeout. The code then prints the coordinates of the location, if known.

using System;
using System.Device.Location;

namespace GetLocationProperty
{
    class Program
    {
        static void Main(string[] args)
        {
            GetLocationProperty();
        }

        static void GetLocationProperty()
        {
            GeoCoordinateWatcher watcher = new GeoCoordinateWatcher();

            // Do not suppress prompt, and wait 1000 milliseconds to start.
            watcher.TryStart(false, TimeSpan.FromMilliseconds(1000));

            GeoCoordinate coord = watcher.Position.Location;

            if (coord.IsUnknown != true)
            {
                Console.WriteLine("Lat: {0}, Long: {1}",
                    coord.Latitude,
                    coord.Longitude);
            }
            else
            {
                Console.WriteLine("Unknown latitude and longitude.");
            }
        }
    }
}

The following program shows how to receive continuous location updates by subscribing to PositionChanged events.

using System;
using System.Device.Location;

namespace GetLocationEvent
{
    class Program
    {
        static void Main(string[] args)
        {
            CLocation myLocation = new CLocation();
            myLocation.GetLocationEvent();
            Console.WriteLine("Enter any key to quit.");
            Console.ReadLine();            
        }
        class CLocation
        {
            GeoCoordinateWatcher watcher;

            public void GetLocationEvent()
            {
                this.watcher = new GeoCoordinateWatcher();
                this.watcher.PositionChanged += new EventHandler<GeoPositionChangedEventArgs<GeoCoordinate>>(watcher_PositionChanged);
                bool started = this.watcher.TryStart(false, TimeSpan.FromMilliseconds(2000));
                if (!started)
                {
                    Console.WriteLine("GeoCoordinateWatcher timed out on start.");
                }
            }

            void watcher_PositionChanged(object sender, GeoPositionChangedEventArgs<GeoCoordinate> e)
            {
                PrintPosition(e.Position.Location.Latitude, e.Position.Location.Longitude);
            }

            void PrintPosition(double Latitude, double Longitude)
            {
                Console.WriteLine("Latitude: {0}, Longitude {1}", Latitude, Longitude);
            }
        }
    }
}

.NET Framework

Supported in: 4.5, 4

.NET Framework Client Profile

Supported in: 4

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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