Managing the geo-localization and the GPS

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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
Functions available according to the platforms
Summary table

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WEBDEV

WINDEV Mobile

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Managing the geo-localization and the GPS

Overview

WINDEV Mobile and WEBDEV allow you to exploit the geo-localization features and the GPS features found on the telephony devices and on the browsers.

In the phone applications, you have the ability to:

Get information about the last known device position.
Ask to be notified when the device comes near a specific area.
Find out the current device position.
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:

// Is the GPS enabled?
IF GPSStatus() = gpsEnabled THEN
Error("The GPS cannot operate.", ...
"It must be enabled to access this application.")
EndProgram()
END

Be notified when the GPS status changes

To be notified when the GPS status changes, all you have to do is call GPSStatus and specify the name of procedure used to manage the current GPS status.

Example:

GPSStatus(_ChangeOfGPSStatus)

The procedure code is as follows:

PROCEDURE _ChangeOfGPSStatus(Status)

IF CurrentStatus = Status THEN RETURN

CurrentStatus = Status

EndTimerSys(TIMER_RETRIEVAL)

SWITCH Status
CASE gpsEnabled
// The provider was enabled by the user.
STC_Status = "GPS enabled"
CASE gpsDisabled
// The provider was disabled by the user.
STC_Status = "GPS disabled"
CASE gpsOffService
// The provider is off service.
STC_Status = "GPS off service"
CASE gpsUnavailable
// The provider is temporarily unavailable.
STC_Status = "GPS unavailable"
CASE gpsAvailable
// The provider is available.
STC_Status = "GPS available"
// Asks to follow the move with a maximum time between two calls to
// GPSFollowMovement(_GetPosition, 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 move of device, all you have to do is call GPSFollowMovement and specify the name of procedure that will be used to manage the move.

Example:

GPSFollowMovement(_GetPosition, 1000)

The code of the procedure can be as follows:

PROCEDURE _GetPosition(MyPosition)

// Update the information about the position
// Latitude and longitude
STC_Latitude = StringBuild("Latitude: %1", MyPosition..Latitude)
STC_Longitude = StringBuild("Longitude: %1", MyPosition..Longitude)

// Speed
IF MyPosition..SpeedValid = True THEN
STC_Speed = StringBuild("Speed: %1 m/s", MyPosition..Speed)
IMG_SPEED_VALIDITY = IMG_OK
ELSE
STC_Speed = "Speed: N/A"
IMG_SPEED_VALIDITY = IMG_NOTOK
END

// Altitude
IF MyPosition..AltitudeValid = True THEN
STC_Altitude = StringBuild("Altitude: %1 m", MyPosition..Altitude)
IMG_ALTITUDE_VALIDITY = IMG_OK
ELSE
STC_Altitude = "Altitude: N/A"
IMG_ALTITUDE_VALIDITY = IMG_NOTOK
END

// Direction
IF MyPosition.DirectionValid = True THEN
STC_Direction = StringBuild("Direction: %1 ° E", MyPosition..Direction)
IMG_DIRECTION_VALIDITY = IMG_OK
ELSE
STC_Direction = "Direction: N/A"
IMG_DIRECTION_VALIDITY = IMG_NOTOK
END

STC_Last_update = StringBuild("Last update on %1 at %2.", ...
DateToString(MyPosition..MeasurementDate..Date), ...
TimeToString(MyPosition..MeasurementDate..Time))
STC_Last_update..Visible = True

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

Ending the use of GPS functions

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

Functions available according to the platforms

Summary table

The table below presents the different geo-localization and GPS functions as well as the different platforms for which they are currently available (this table can evolve in time):


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 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