GPSGetPosition (Function)

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Help / WLanguage / WLanguage functions / Standard functions / Geolocation functions

Managing locks
Retrieved properties
Operating mode in iPhone/iPad
Required permissions
Browsers allowing the geolocation

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GPSGetPosition (Function)

In french: GPSRécupèrePosition

Retrieves information about the current device position.

Example

MaPosition is geoPosition
MaPosition = GPSGetPosition()
// Vérifie validité de la position avec ErreurDétectée
IF ErrorOccurred THEN RETURN
Info(" Latitude : " + MaPosition.Latitude)  
Info(" Longitude : " + MaPosition.Longitude)

// Géolocalisation depuis WEBDEV, une procédure navigateur est appelée.
// Traitement réalisé depuis un bouton ayant comme action "aucune"
GPSGetPosition(ProcNavigateur, 200)

// Procédure navigateur "ProcNavigateur"
PROCEDURE ProcNavigateur(MaPosition is geoPosition, nMonErreur is int)
SWITCH nMonErreur
	CASE gpsErrorOK
		// Aucune erreur n'a été détectée
		PAGE_Page1.SAI_SansNom1 = MaPosition.Altitude + " " + MaPosition.Longitude
	CASE gpsErrorRights
		PAGE_Page1.SAI_SansNom1 = "Le navigateur n'a pas les droits " + ...
				"pour utiliser la géolocalisation (ou site non HTTPS)."
	CASE gpsErrorPosition
		PAGE_Page1.SAI_SansNom1 = "Impossible de déterminer la position " + ...
				"(erreur interne du fournisseur d'accès par exemple)."
	CASE gpsErrorTimeout
		PAGE_Page1.SAI_SansNom1 = ...
			"La position n'a pas pu être récupérée dans le temps imparti."
	OTHER CASE
		PAGE_Page1.SAI_SansNom1 = "Erreur indéterminée"
END

Syntax

Retrieving information about a device (mobile, ...) Hide the details

<Result> = GPSGetPosition([<Timeout> [, <Message>]])

<Result>: geoPosition variable

geoPosition variable containing information about the device position. If the position is invalid, the ErrorOccurred variable is set to True and the error details are returned by ErrorInfo.
The PositionValid property of the geoPosition type determines if the position is valid.

<Timeout>: Optional integer or optional Duration

Maximum timeout (in hundredths of a second) for updating the device position.
An error occurs if the timeout ends before the position of the device is updated. This error can be detected by the ErrorOccurred variable and the error details can be returned by ErrorInfo.
If this parameter is not specified, the timeout is set to 1 minute.
Note: This parameter can correspond to:
an integer corresponding to the number of hundredths of a second,
a Duration variable,
the duration in a readable format (e.g., 1 s or 10 ms).

<Message>: Optional character string

Message of hourglass displayed when updating the position.
Note This parameter is only taken into account if the call is made in the application's main thread.
This parameter is ignored.

Retrieving the information in browser code Hide the details

GPSGetPosition([<WLanguage procedure> [, <Timeout>]])

<WLanguage procedure>: Procedure name

Name of the WLanguage procedure in browser code ("callback") called when the location is retrieved.
This procedure has the following format:
PROCEDURE <Procedure name>(<Position>,<Error>)
where:
<Position> is a variable of type geoPosition containing information on the position. To determine if a value was assigned to the Speed, Accuracy, Direction or Altitude properties of a geoPosition variable when the location was retrieved, use the SpeedValid, AccuracyValid, DirectionValid and AltitudeValid properties.
<Error> is an Integer constant corresponding to the error code and that can take the following values:
gpsErrorOK No error was detected.
gpsErrorPosition Unable to determine the location (e.g., access provider internal error).
gpsErrorRights
The browser has no sufficient rights to use geolocation.
The browser is recent and the site is not using the HTTPS secure protocol.
gpsErrorTimeout The location could not be retrieved within the timeout.

<Timeout>: Optional integer or optional Duration

Maximum timeout (in hundredths of a second) for updating the device position.
If this timeout ends before the device position is updated, gpsErrorTimeOut is returned in the <Error> parameter of the WLanguage procedure.
If this parameter is not specified, the timeout is set to 1 minute.
Note: This parameter can correspond to:
an integer corresponding to the number of hundredths of a second,
a Duration variable,
the duration in a readable format (e.g., 1 s or 10 ms).

Remarks

Managing locks

GPSGetPosition blocks execution until the current device location is retrieved or until the timeout defined by the <Timeout> parameter expires.

If the function is called in the main thread of the application, an hourglass will be displayed during the function execution. The message displayed by the hourglass can be specified via the <Message> parameter.
Otherwise, the execution of secondary thread will be locked during the function execution and no hourglass will be displayed.

This function is not locking.

Note: To find out the last known position of the device without delay, use the GPSLastPosition function.. Caution, the positioning information that was retrieved may not correspond to the current device position if the device was moved while the GPS signal was not valid for example. You can use the MeasurementDate property of the geoPosition variable to determine the date and time at which the position was calculated.

Retrieved properties

To determine if a value was assigned to the Speed, Accuracy, Direction or Altitude properties of a geoPosition variable when the location was retrieved, use the SpeedValid, AccuracyValid, DirectionValid and AltitudeValid properties.
To reinitialize a geoPosition variable, use VariableReset.
It is recommended to reset the parameters of the location provider with GPSInitParameter before retrieving a location.
The positioning information retrieved corresponds to the device's last known position: it may therefore not correspond to the device's current position if, for example, the device has been moved while the GPS signal was invalid. You can use the MeasurementDate property of the geoPosition variable to determine the date and time at which the position was calculated.
Speed, Accuracy, Direction and Altitude will be specified only if the location provider allows it (otherwise, these properties will take their default value).
The location provider can be configured with GPSInitParameter.

Operating mode in iPhone/iPad

When a GPS function is first run, the system requests geolocation permission from the user. If the user refuses, all the GPS functions used in the rest of the application will fail (fatal error).

To re-allow the use of GPS for this application, the system configuration of the application must be modified.

Required permissions

This function changes the permissions required by the application.
Permission required: ACCESS_FINE_LOCATION.

Android 11 specific case: This function requires the ACCESS_BACKGROUND_LOCATION permission to access the device's location.
This permission allows using the function when the application is in the background.

If the application needs to use background location:

Manually add the "ACCESS_BACKGROUND_LOCATION" permission in the Android application generation wizard.

Explicitly request background location permission with PermissionRequest. For example:

PermissionRequest(permBackgroundLocation, Callback)
INTERNAL PROCEDURE Callback(p is Permission)
	IF p.Accordé THEN
		// Utilisation possible des fonctions nécessitant la localisation en arrière-plan
	END
END

A window allows users to:

allow access to the device location while the application is in the background,
allow access to the location only while the application is in use,
deny access to the location. The user can also change these permissions at any time in the Android settings.

Remarks:

Follow Google's guidelines for applications that require background location access. For more details, see https://support.google.com/googleplay/android-developer/answer/9799150. If these conditions are not met (especially user information requirements), applications may not be accepted for publication on Google Play.
The background location permission should only be requested if the location permission has been granted. Otherwise, PermissionRequest will fail.
If the option chosen by the user for the background location access request is more restrictive than the option chosen for the location access request, the application will be automatically restarted.
On devices running Android 10 or earlier, if location permission has been granted to the application, the background location permission will be granted without displaying a window.

Browsers allowing the geolocation

During the call to a geolocation function, the browser requests a location authorization.Note: As of Chrome 50 (including Android), the function GPSGetPosition function can only be used on secure sites (via an SSL certificate, for example). If the site is not secured, the function returns a result that cannot be used. During the test in local (localhost), the function operates properly.

Business / UI classification: Business Logic

Component: wd300java.dll