Managing geolocation and GPS

ONLINE HELP
WINDEV, WEBDEV AND WINDEV MOBILE

Version:

Home | Sign in | English

This content has been translated automatically. Click here to view the French version.

Overview
Implementing the GPS management
Checking whether the GPS is enabled
Be notified when the GPS status changes
Following the move
Ending the use of GPS functions
When to use each function?
Functions available according to the platforms
Summary table

WINDEV

WEBDEV

WINDEV Mobile

Others

See also

Managing geolocation and GPS

Overview

WINDEV Mobile and WEBDEV allow you to exploit geolocation and GPS features found on mobile devices and browsers.

In the phone applications, you have the ability to:

Get information about the last known location of the device.
Ask to be notified when the device comes near a specific area.
Find out the current location of the device.
Retrieve an address.
...

Implementing the GPS management

Checking whether the GPS is enabled

To check whether the GPS is enabled, all you have to do is use GPSStatus.

Example:

// Est-ce-que le GPS est actif?
IF GPSStatus() <> gpsEnabled THEN
Error("Le GPS n'est pas en état de fonctionner.", ...
"Veuillez l'activer pour avoir accès à cette application.")
EndProgram()
END

Be notified when the GPS status changes

To be notified when the report of the GPS changes, you just have to use the GPSStatus function by specifying the name of the Procedure that will manage the current report of the GPS.

Example:

GPSStatus(_ChangementEtatGPS)

The procedure code is as follows:

PROCÉDURE _ChangementEtatGPS(Etat)

IF EtatActuel = Etat THEN RETURN

EtatActuel = Etat

EndTimerSys(TIMER_RECUPERATION)

SWITCH Etat
CASE gpsEnabled
// Le fournisseur a été activé par l'utilisateur.
LIB_Etat = "GPS activé"
CASE gpsDisabled
// Le fournisseur a été désactivé par l'utilisateur.
LIB_Etat = "GPS désactivé"
CASE gpsOffService
// Le fournisseur est hors-service.
LIB_Etat = "GPS hors-service"
CASE gpsUnavailable
// Le fournisseur est temporairement indisponible.
LIB_Etat = "GPS indisponible"
CASE gpsAvailable
// Le fournisseur est disponible.
LIB_Etat = "GPS disponible"
// Demande à suivre le déplacement avec un temps maximum entre deux appels de
// GPSSuitDéplacement(_RécupèrePosition, 1000)
OTHER CASE
END

In this procedure, if the GPS is enabled, a specific procedure is used to follow the movement.

Following the move

To follow the movement of the device, it is enough to use the GPSFollowMovement function by specifying the name of the Procedure which will manage the movement.

Example:

GPSFollowMovement(_RécupèrePosition, 1000)

The code of the procedure can be as follows:

PROCÉDURE _RécupèrePosition(MaPosition)

// Mise à jour des informations sur la position
// Latitude et longitude
LIB_Latitude = StringBuild("Latitude: %1", MaPosition.Latitude)
LIB_Longitude = StringBuild("Longitude: %1", MaPosition.Longitude)

// Vitesse
IF MaPosition.VitesseValide = True THEN
LIB_Vitesse = StringBuild("Vitesse: %1 m/s", MaPosition.Vitesse)
IMG_VALIDITE_VITESSE = IMG_OK
ELSE
LIB_Vitesse = "Vitesse: N/A"
IMG_VALIDITE_VITESSE = IMG_PASOK
END

// Altitude
IF MaPosition.AltitudeValide = True THEN
LIB_Altitude = StringBuild("Altitude: %1 m", MaPosition.Altitude)
IMG_VALIDITE_ALTITUDE = IMG_OK
ELSE
LIB_Altitude = "Altitude: N/A"
IMG_VALIDITE_ALTITUDE = IMG_PASOK
END

// Direction
IF MaPosition.DirectionValide = True THEN
LIB_Direction = StringBuild("Direction: %1 ° E", MaPosition.Direction)
IMG_VALIDITE_DIRECTION = IMG_OK
ELSE
LIB_Direction = "Direction: N/A"
IMG_VALIDITE_DIRECTION = IMG_PASOK
END

LIB_Dernière_mise_à_jour = StringBuild("Dernière mise à jour le %1 à %2.", ...
DateToString(MaPosition.Datemesure.PartieDate), ...
TimeToString(MaPosition.Datemesure.PartieHeure))
LIB_Dernière_mise_à_jour.Visible = True

In this code, MyPosition is an Variable of type geoPosition. The properties of this type of variable are used to find out the location characteristics.

Ending the use of GPS functions

Depending on the selected settings and on the call frequency, geolocation functions can consume a lot of resources on the device (battery, bandwidth, etc.). GPSEnd must be called when the location functions are no longer used by the application.

When to use each function?

Function	When to use it?	Accuracy	Energy consumption

geoTrackingXXX	Permanent tracking of location changes, even when the application is in the background.	High accuracy, but the frequency of notifications is low and varies depending on the system.	Low
GPSFollowMovement	Permanent tracking of location changes when the application is in the foreground.	Accuracy according to GPSInitParameter.	Consumption according to GPSInitParameter.
GPSDetectPosition	Notification of the proximity of a given location when the application is in the foreground.	Accuracy according to GPSInitParameter.	Consumption according to GPSInitParameter.
GPSGetPosition	Get current location at a specific moment when the application is in the foreground. It may take long, depending on the surroundings (inside a building, cloudy day, etc.).	Accuracy according to GPSInitParameter.	Depends on the number of calls.
GPSLastPosition	Immediately get the last known location of the device.	Low consumption, since it depends on when the last location was actually retrieved. Also depends on GPSInitParameter.	Low consumption.

Functions available according to the platforms

Summary table

The table below presents the different geolocation/GPS functions and the different platforms for which they are currently available (this table can evolve with each version):


Functions			Universal Windows App
geoAzimuth	X	X
geoDistance	X	X	X
Versions 17 and later geoRunApp New in version 17 geoRunApp geoRunApp	X	X
Versions 17 and later geoGetAddress New in version 17 geoGetAddress geoGetAddress	X	X
Versions 26 and later geoGetArea New in version 26 geoGetArea geoGetArea	X	X		X
Versions 21 and later geoTrackingEnable New in version 21 geoTrackingEnable geoTrackingEnable	X	X
Versions 21 and later geoTrackingDisable New in version 21 geoTrackingDisable geoTrackingDisable	X	X
Versions 21 and later geoTrackingStatus New in version 21 geoTrackingStatus geoTrackingStatus	X	X
Versions 21 and later geoTrackingProcedure New in version 21 geoTrackingProcedure geoTrackingProcedure	X	X
GPSStopDetection	X		X
GPSLastPosition	X	X	X	X
GPSDetectPosition	X		X
GPSStatus	X	X	X	X
GPSInfo	X		X
GPSInitParameter	X	X	X
GPSGetPosition	X	X	X	X
GPSFollowMovement	X	X	X	X
GPSEnd	X	X	X

Related Examples:

Cross-platform examples (WINDEV Mobile): WM Geolocation

[ + ] This example explains how to perform proximity searches with geolocation :
- search around me
- search in a city, at a given address, or close to a specific address.
The results are displayed in a looper and in a map with markers.