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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
900
Users can zoom the map by clicking the zoom controls. They can also zoom and pan by using two-finger movements on the map for touchscreen devices.
You can change the zoom level of the map using simple steps. Step 1 Go to Add or Edit Map page . Step 2 Select 'Default zoom level' in the 'Map Information section'. Step 3 click save map and see the changes.
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.
function initialize() {
map = new google.maps.Map(document.getElementById("map_canvas"), mapOptions);
getMarkers();
google.maps.event.addListener(map,'zoom_changed',function () {
if (map.getZoom() >= 3) showMarkers();
if (map.getZoom() <= 2) eraseMarkers();
});
}
function eraseMarkers() {
for (i = 0; i < locations.length; i++) {
marker[i].setVisible(false);
}
}
function showMarkers() {
for (i = 0; i < locations.length; i++) {
marker[i].setVisible(true);
}
}
function getMarkers() {
for (i = 0; i < locations.length; i++) {
marker[i] = 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}
});
}
eraseMarkers();
}
Looks like thing you are trying to make is called Marker Clustering.
Here you are lots of official google exmamples https://developers.google.com/maps/articles/toomanymarkers written on native javascript
http://gmap3.net/examples/clustering.html - using jQuery library.
I hope this will help you.
40
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