Le code suivant fait essentiellement ce que vous voulez. Il calcule la distance et le relèvement depuis votre position actuelle (par GPS) jusqu'à une position de destination et utilise la boussole pour déterminer votre cap actuel. La différence entre votre cap actuel et le cap vers la destination est l'angle de votre flèche.
Le code des actifs et compilé Android APK peut être téléchargé ici: http://ge.tt/4Kb2oQv/v/0
Voici le code, espère que ça aide!
<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Compass test</title>
<script type="text/javascript" src="phonegap.js"></script>
<script type="text/javascript" src ="jquery-1.7.1.min.js">//</script> <!--http://code.jquery.com/jquery-1.7.1.min.js -->
<script type="text/javascript" src ="latlon.js">//</script> <!-- based on http://www.movable-type.co.uk/scripts/latlong.html -->
<style type="text/css">
#error, #results{
display: none;
}
#arrow{
position: absolute;
width: 30px;
height: 30px;
background: 50% 50% no-repeat;
background-size: 30px 30px;
background-image: url('arrow.png');
top: 0;
left: 50%;
margin: 30px 0 0 -15px;
}
#results .text{
margin-top: 100px;
}
</style>
<script type="text/javascript" >
var destinationPosition;
var destinationBearing;
var positionTimerId;
var currentPosition;
var prevPosition;
var prevPositionError;
var compassTimerId;
var currentHeading;
var prevHeading;
var prevCompassErrorCode;
$(document).on("deviceready", function() {
minPositionAccuracy = 50; // Minimum accuracy in metres to accept as a reliable position
minUpdateDistance = 1; // Minimum number of metres to move before updating distance to destination
$targetLat = $('#target-lat');
$targetLon = $('#target-lon');
$error = $('#error');
$results = $('#results');
$distance = $('#distance');
$bearing = $('#bearing');
$heading = $('#heading');
$difference = $('#difference');
$arrow = $('#arrow');
watchPosition();
watchCompass();
// Set destination
$targetLat.change(updateDestination);
$targetLon.change(updateDestination);
updateDestination();
});
function watchPosition(){
if(positionTimerId) navigator.geolocation.clearWatch(positionTimerId);
positionTimerId = navigator.geolocation.watchPosition(onPositionUpdate, onPositionError, {
enableHighAccuracy: true,
timeout: 1000,
maxiumumAge: 0
});
}
function watchCompass(){
if(compassTimerId) navigator.compass.clearWatch(compassTimerId);
compassTimerId = navigator.compass.watchHeading(onCompassUpdate, onCompassError, {
frequency: 100 // Update interval in ms
});
}
function onPositionUpdate(position){
if(position.coords.accuracy > minPositionAccuracy) return;
prevPosition = currentPosition;
currentPosition = new LatLon(position.coords.latitude, position.coords.longitude);
if(prevPosition && prevPosition.distanceTo(currentPosition)*1000 < minUpdateDistance) return;
updatePositions();
}
function onPositionError(error){
watchPosition();
if(prevPositionError && prevPositionError.code == error.code && prevPositionError.message == error.message) return;
$error.html("Error while retrieving current position. <br/>Error code: " + error.code + "<br/>Message: " + error.message);
if(!$error.is(":visible")){
$error.show();
$results.hide();
}
prevPositionError = {
code: error.code,
message: error.message
};
}
function onCompassUpdate(heading){
prevHeading = currentHeading;
currentHeading = heading.trueHeading >= 0 ? Math.round(heading.trueHeading) : Math.round(heading.magneticHeading);
if(currentHeading == prevHeading) return;
updateHeading();
}
function onCompassError(error){
watchCompass();
if(prevCompassErrorCode && prevCompassErrorCode == error.code) return;
var errorType;
switch(error.code){
case 1:
errorType = "Compass not supported";
break;
case 2:
errorType = "Compass internal error";
break;
default:
errorType = "Unknown compass error";
}
$error.html("Error while retrieving compass heading: "+errorType);
if(!$error.is(":visible")){
$error.show();
$results.hide();
}
prevCompassErrorCode = error.code;
}
function updateDestination(){
destinationPosition = new LatLon($targetLat.val(), $targetLon.val());
updatePositions();
}
function updatePositions(){
if(!currentPosition) return;
if(!$results.is(":visible")){
$results.show();
$error.hide();
}
destinationBearing = Math.round(currentPosition.bearingTo(destinationPosition));
$distance.html(Math.round(currentPosition.distanceTo(destinationPosition)*1000));
$bearing.html(destinationBearing);
updateDifference();
}
function updateHeading(){
$heading.html(currentHeading);
updateDifference();
}
function updateDifference(){
var diff = destinationBearing - currentHeading;
$difference.html(diff);
$arrow.css("-webkit-transform", "rotate("+diff+"deg)");
}
</script>
</head>
<body>
<div id="results">
<div id="arrow"></div>
<div class="text">
<p>Distance to destination: <span id="distance"></span> metres</p>
<p>Bearing to destination: <span id="bearing"></span> degrees</p>
<p>Current heading: <span id="heading"></span> degrees</p>
<p>Difference in heading and bearing: <span id="difference"></span> degrees</p>
</div>
</div>
<p id="error"></p>
<h2>Destination</h2>
<div>
<label for="target-lat">Latitude: </label>
<input id="target-lat" value="50.623966949462" />
</div>
<div>
<label for="target-lon">Longitude: </label>
<input id="target-lon" value="-4.7256830197787" />
</div>
</body>
</html>
Pouvez-vous fournir un nouveau lien vers les fichiers dans un dossier dropbox, je pouvais vraiment l'utiliser dans un projet, je travaille sur Thx à l'avance –
j'ai téléchargé le projet ge.tt et mis à jour lien pour pointer à ceci :-) – DaveAlden