I was wondering if it is possible that Google has a feature to view different markers on different zoom levels.
For example, on zoom level 1, I want one marker over China with the label saying “5”. And as the user zooms in, lets say on zoom level 4, I want the previous marker and label to disappear. And I want to have 5 new markers/labels, each on a different city in China all saying “1”. Thus China will say a number and all the cities in China will say numbers adding up to China’s number.
The key concept I am trying to figure out here is how to hide markers and labels based on zoom levels. A constraint for me is that I am living in China currently where google is censored, so a lot of online documents are censored for me, including many of google’s documentations.
Here is my code thus far
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<title>TM China</title>
<style type="text/css">
html, body, #map_canvas { margin: 0; padding: 0; height: 100% }
.labels {
color: red;
background-color: white;
font-family: "Lucida Grande", "Arial", sans-serif;
font-size: 10px;
font-weight: bold;
text-align: center;
width: 60px;
border: 2px solid black;
white-space: nowrap;
}
</style>
<script type="text/javascript"
src="http://maps.googleapis.com/maps/api/js?key=AIzaSyDV0lcdK7C2GHbQAmdkBID70Uppuf-D030&sensor=true">
</script>
<script type="text/javascript">
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var map;
var mapOptions = { center: new google.maps.LatLng(35, 105), zoom: 3,
mapTypeId: google.maps.MapTypeId.ROADMAP };
var locations = [
['Hong Kong', 22.39, 114.10, 1885],
['Shanghai', 31.232, 121.47, 5885],
['Beijing', 39.88, 116.40, 6426],
['Guangzhou', 23.129, 113.264, 4067],
['Shenzhen', 22.54, 114.05, 3089],
['Hangzhou', 30.27, 120.15, 954]
];
var infowindow = new google.maps.InfoWindow();
var i;
/*
for (i = 0; i < locations.length; i++) {
marker = new google.maps.Marker({
position: new google.maps.LatLng(locations[i][1], locations[i][2]),
map: map
});
google.maps.event.addListener(marker, 'click', (function(marker, i) {
return function() {
infowindow.setContent(locations[i][0]);
infowindow.open(map, marker);
}
})(marker, i));
} */
function myMarker(options) {
if(!options.labelAnchor) {
options.labelAnchor = new google.maps.Point(30, 50);
}
if(!options.labelClass) {
options.labelClass = "labels";
}
options.map = map;
return new MarkerWithLabel(options);
}
function initialize() {
map = new google.maps.Map(document.getElementById("map_canvas"), mapOptions);
for (i = 0; i < locations.length; i++) {
var marker = new MarkerWithLabel({
position: new google.maps.LatLng(locations[i][1], locations[i][2]),
draggable: false,
map: map,
labelContent: locations[i][3],
labelAnchor: new google.maps.Point(30, 0),
labelClass: "labels", // the CSS class for the label
labelStyle: {opacity: 0.75}
});
}
/*
var marker2 = new myMarker({
position: new google.maps.LatLng(20,20),
draggable: true,
labelContent: "second"
});
*/
}
google.maps.event.addDomListener(window, 'load', initialize);
</script>
</head>
<body onload="initialize()">
<div id="map_canvas" style="width:85%; height:85%"></div>
<script type="text/javascript">
</script>
</body>
</html>
EDIT
I have been trying to experiment with the MarkerManager, but I can’t get the markers to create successfully on different zoom levels.
First, I changed my default zoom level to 1, and then I changed my code to what is shown below.
function initialize() {
map = new google.maps.Map(document.getElementById("map_canvas"), mapOptions);
/* for (i = 0; i < locations.length; i++) {
var marker = new MarkerWithLabel({
position: new google.maps.LatLng(locations[i][1], locations[i][2]),
draggable: false,
map: map,
labelContent: locations[i][3],
labelAnchor: new google.maps.Point(30, 0),
labelClass: "labels", // the CSS class for the label
labelStyle: {opacity: 0.75}
});
} */
var listener = google.maps.event.addListener(map, 'bounds_changed', function(){
setupMarkers();
google.maps.event.removeListener(listener);
});
}
function createCityMarkers() {
for (i = 0; i < locations.length; i++) {
var marker = new MarkerWithLabel({
position: new google.maps.LatLng(locations[i][1], locations[i][2]),
draggable: false,
map: map,
labelContent: locations[i][3],
labelAnchor: new google.maps.Point(30, 0),
labelClass: "labels", // the CSS class for the label
labelStyle: {opacity: 0.75}
});
}
}
function setupMarkers() {
mgr = new MarkerManager(map);
google.maps.event.addListener(mgr, 'loaded', function(){
mgr.addMarkers(createCityMarkers(), 4);
mgr.refresh();
});
}
I have also tried applying the source code of this link as well, but nothing is working out. And when I copy the source code directly to my computer and replace all the icons with markers, the markers still don’t appear. I can’t seem to figure how to make markers appear using the marker Manager.
http://google-maps-utility-library-v3.googlecode.com/svn/tags/markermanager/1.0/examples/weather_map.html
The real reason why my program was failing was because of the Marker Manager, which doesn’t work with my Markers with Labels.
There was actually a much simpler approach, however, to fulfill my needs.