In order to add a label to the map you need to create a custom overlay. The sample at http://blog.mridey.com/2009/09/label-overlay-example-for-google-maps.html uses a custom class, Layer, that inherits from OverlayView (which inherits from MVCObject) from the Google Maps API. He has a revised version (adds support for visibility, zIndex and a click event) which can be found here: http://blog.mridey.com/2011/05/label-overlay-example-for-google-maps.html
The following code is taken directly from Marc Ridey's Blog (the revised link above).
Layer class
// Define the overlay, derived from google.maps.OverlayView
function Label(opt_options) {
// Initialization
this.setValues(opt_options);
// Label specific
var span = this.span_ = document.createElement('span');
span.style.cssText = 'position: relative; left: -50%; top: -8px; ' +
'white-space: nowrap; border: 1px solid blue; ' +
'padding: 2px; background-color: white';
var div = this.div_ = document.createElement('div');
div.appendChild(span);
div.style.cssText = 'position: absolute; display: none';
};
Label.prototype = new google.maps.OverlayView;
// Implement onAdd
Label.prototype.onAdd = function() {
var pane = this.getPanes().overlayImage;
pane.appendChild(this.div_);
// Ensures the label is redrawn if the text or position is changed.
var me = this;
this.listeners_ = [
google.maps.event.addListener(this, 'position_changed', function() { me.draw(); }),
google.maps.event.addListener(this, 'visible_changed', function() { me.draw(); }),
google.maps.event.addListener(this, 'clickable_changed', function() { me.draw(); }),
google.maps.event.addListener(this, 'text_changed', function() { me.draw(); }),
google.maps.event.addListener(this, 'zindex_changed', function() { me.draw(); }),
google.maps.event.addDomListener(this.div_, 'click', function() {
if (me.get('clickable')) {
google.maps.event.trigger(me, 'click');
}
})
];
};
// Implement onRemove
Label.prototype.onRemove = function() {
this.div_.parentNode.removeChild(this.div_);
// Label is removed from the map, stop updating its position/text.
for (var i = 0, I = this.listeners_.length; i < I; ++i) {
google.maps.event.removeListener(this.listeners_[i]);
}
};
// Implement draw
Label.prototype.draw = function() {
var projection = this.getProjection();
var position = projection.fromLatLngToDivPixel(this.get('position'));
var div = this.div_;
div.style.left = position.x + 'px';
div.style.top = position.y + 'px';
div.style.display = 'block';
this.span_.innerHTML = this.get('text').toString();
};
Usage
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>
Label Overlay Example
</title>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<script type="text/javascript" src="label.js"></script>
<script type="text/javascript">
var marker;
function initialize() {
var latLng = new google.maps.LatLng(40, -100);
var map = new google.maps.Map(document.getElementById('map_canvas'), {
zoom: 5,
center: latLng,
mapTypeId: google.maps.MapTypeId.ROADMAP
});
marker = new google.maps.Marker({
position: latLng,
draggable: true,
zIndex: 1,
map: map,
optimized: false
});
var label = new Label({
map: map
});
label.bindTo('position', marker);
label.bindTo('text', marker, 'position');
label.bindTo('visible', marker);
label.bindTo('clickable', marker);
label.bindTo('zIndex', marker);
google.maps.event.addListener(marker, 'click', function() { alert('Marker has been clicked'); })
google.maps.event.addListener(label, 'click', function() { alert('Label has been clicked'); })
}
function showHideMarker() {
marker.setVisible(!marker.getVisible());
}
function pinUnpinMarker() {
var draggable = marker.getDraggable();
marker.setDraggable(!draggable);
marker.setClickable(!draggable);
}
</script>
</head>
<body onload="initialize()">
<div id="map_canvas" style="height: 200px; width: 200px"></div>
<button type="button" onclick="showHideMarker();">Show/Hide Marker</button>
<button type="button" onclick="pinUnpinMarker();">Pin/Unpin Marker</button>
</body>
</html>