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Revision as of 14:17, 21 June 2011 by hamishwillee (Talk | contribs)

Tracking changes in the current location in Symbian Web Runtime

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Article Metadata
Tested with
Devices(s): Nokia 5800 XpressMusic
Compatibility
Platform(s): S60 5th Edition
S60 5th Edition
Article
Keywords: device.getServiceObject(), Service.Location, Service.Location.Trace()
Created: (17 Nov 2008)
Last edited: hamishwillee (21 Jun 2011)

Overview

This code snippet demonstrates how to track changes in the current location by using the Location Service API of the Web Runtime (WRT).

Source: widget.xhtml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<link rel="StyleSheet" href="style/general.css" type="text/css" />
<script type="text/javascript" src="script/script.js" />
<title>WRT Application</title>
</head>
<body>
<div id="bodyContent" class="bodyContent">
<div id="location">
<table id="locationData">
<tr id="latitude">
<td id="latitudeHeading">Lat.</td>
<td id="latitudeData"></td>
</tr>
<tr id="longitude">
<td id="longitudeHeading">Long.</td>
<td id="longitudeData"></td>
</tr>
</table>
</div>
<input type="button" value="Start tracking"
onclick="startTracking();" />
</div>
</body>
</html>

Source: script.js

var serviceObj = null;
var criteria = null;
 
window.onload = init;
 
// Initializes the widget
function init() {
// Obtain the Location service object
try {
serviceObj = device.getServiceObject("Service.Location", "ILocation");
} catch (ex) {
alert("Service object cannot be found.");
return;
}
 
// Initialize the criteria for the service object
criteria = new Object();
criteria.LocationInformationClass = "BasicLocationInformation";
}
 
// Starts the tracking
function startTracking() {
if (serviceObj == null) {
alert("Service object has not been initialized.");
return;
}
 
try {
// Define the callback function for tracking the location
var result = serviceObj.ILocation.Trace(criteria, locationDataReady);
} catch (ex) {
alert(ex);
}
}
 
// Called when Trace has got data
function locationDataReady(transId, eventCode, result) {
// On error situation, display the error message
if (eventCode == 4) {
alert("Error " + result.ErrorCode + ": " + result.ErrorMessage);
return;
}
 
var latitude = result.ReturnValue.Latitude;
displayData("latitudeData", latitude.toFixed(4) + " \u00B0");
 
var longitude = result.ReturnValue.Longitude;
displayData("longitudeData", longitude.toFixed(4) + " \u00B0");
}
 
// Displays the data in an HTML element
function displayData(elementId, data) {
var element = document.getElementById(elementId);
 
// Remove the first child node, if it's not null
if (element.firstChild != null) {
element.removeChild(element.firstChild);
}
 
element.appendChild(document.createTextNode(data));
}

Postconditions

The changes in current location are displayed.

See also

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