Show my realtime position on googlemap with phonegap, working but really slow in updating

Question

Basically I want to set a marker in my position (retrieved with navigator.geolocation) and update his position as I move to make it show my real position. This is my code.

  var map;
  var marker;
  var newLatlng;
  var i = 0;

  //here i create a map centered on 0,0
  function initialize() {
    directionsDisplay = new google.maps.DirectionsRenderer();
    var chicago = new google.maps.LatLng(0,0);
    var mapOptions = {
      zoom: 6,
      mapTypeId: google.maps.MapTypeId.ROADMAP,
      center: chicago
    }
    map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
    directionsDisplay.setMap(map);

    updatePos();

  }


//here I set my marker (if i==0 -> first run)
function updatePos(){

var options = {
    timeout: 500000, enableHighAccuracy: true
};
var myUpdatedPos = navigator.geolocation.watchPosition(onSuccess, onError, options);

function onSuccess(position) {

    if (i==0){
        marker = new google.maps.Marker({
                        position: new google.maps.LatLng(position.coords.latitude, position.coords.longitude),
                        map: map,
                        animation: google.maps.Animation.DROP
                    });
    }
    i++;

    //here I update the position
    newLatlng = new google.maps.LatLng(position.coords.latitude, position.coords.longitude);
    marker.setPosition(newLatlng);
}

// onError Callback receives a PositionError object
//
    function onError(error) {
        alert('code: '    + error.code    + '\n' +
        'message: ' + error.message + '\n');
    }
}

This code is working, but is a bit slow in updating my position, i think because of the:

new google.maps.LatLng(position.coords.latitude, position.coords.longitude);

that is called everytime my position change. But I'm not sure of what this construct really do. Does it make a call to a server and have to wait for the answer?

Anyone have any good advide for speed up this code?

Thank you in advance!

Answer 1

Using watchPosition, you can specify the duration of the cached position. Try to use something that is not too short and not too long.

Simple example that will update the position :

navigator.geolocation.getCurrentPosition(onSuccess, onError, { maximumAge: 3000, timeout: 5000, enableHighAccuracy: true });

Reference:

http://docs.phonegap.com/en/2.5.0/cordova_geolocation_geolocation.md.html#geolocationOptions