jquery-ui-map load json and update markers - json

Question

I've searched all over the web and SO, but I couldn't figure this out.
Here's the problem:
I'm using the below demo from jquery-ui-map site to load a JSON file:
http://jquery-ui-map.googlecode.com/svn/trunk/demos/jquery-google-maps-json.html
It works fine to load my markers, but I need to refresh its content every 30 seconds and grab new markers.
At first I thought I would just call the function again, but that left the markers there. After some research I found out I needed to clear the markers (not so easy on V3, but I was able to to do) but the issue is that I can't get the markers to show again.
If I use the destroy function, then I'm able to reload new markers and remove the old ones, but that causes the map to blink. When I try to clear markers then no new markers are shown.
Any help is greatly appreciated.
Below is my code:
<script type="text/javascript">
function mapTest() {
$('#map_canvas').gmap('destroy');
//clearMap();
demo.add(function() {
$('#map_canvas').gmap({'disableDefaultUI':true, 'callback': function() {
var self = this;
$.getJSON( 'json/demo.json?'+ new Date().getTime(), function(data) {
$.each( data.markers, function(i, marker) {
self.addMarker({ 'position': new google.maps.LatLng(marker.latitude, marker.longitude), 'bounds':true } ).click(function() {
self.openInfoWindow({ 'content': marker.content }, this);
});
});
});
}});
}).load();
}
function clearMap(){
$('#map_canvas').gmap('clear', 'markers');
}
mapTest();
setInterval(mapTest, 30000 );
</script>
Cheers.

Answer 1

Your map initialization function is inside the mapTest() function - which you call over an over again every 30 seconds with setInterval.
That is wrong, because you are essentially reloading the map( you destroy it and then recreate it again every 30 seconds ), and that is why it blinks.
Place the map initialization outside the mapTest(), but clear and retrieve new markers from within the mapTest()
Update:
var mapOptions = {
disableDefaultUI: true
// add more options if you wish.
};
function mapTest() {
$('#map_canvas').gmap('clear', 'markers'); // clear old markers
$.getJSON( 'json/demo.json?'+ new Date().getTime(), function(data) {
$.each( data.markers, function(i, marker) {
var self = this;
self.addMarker({ 'position': new google.maps.LatLng(marker.latitude, marker.longitude), 'bounds':true } ).click(function() {
self.openInfoWindow({ 'content': marker.content }, this);
});
});
});
}
$(function(){
$('#map_canvas').gmap(mapOptions, function(){
$.getJSON( 'json/demo.json?'+ new Date().getTime(), function(data) {
$.each( data.markers, function(i, marker) {
var self = this;
self.addMarker({ 'position': new google.maps.LatLng(marker.latitude, marker.longitude), 'bounds':true } ).click(function() {
self.openInfoWindow({ 'content': marker.content }, this);
});
});
});
});
setInterval(mapTest, 30000 );
});

Answer 2

I found a Solution to update markers without reloading the map. Try this code...
$(document).ready(function() {
var $map = $('#map_canvas');
App.drawMap($map);
setInterval(function() {
$('#map_canvas').gmap('clear', 'markers');
App.drawMap($map);
},10000);
});
var App = {
drawMap: function($divMap) {
Http.doAjaxGetJson('../../js/testjson.json', function(data) {
for (var k in data.gpsData) {
$divMap.gmap({ 'center': new google.maps.LatLng(data.gpsData[k].latitude,data.gpsData[k].longitude),'zoom':15, 'callback': function() {}});
$divMap.gmap('addMarker', {
'title':data.obj.name,
'position': new google.maps.LatLng(data.gpsData[k].latitude, data.gpsData[k].longitude),
'bounds': false,
}).click(function() {
var $_obj = $(this);
});
}
});
}
};
By this code markers will update in every 10 seconds..