Develop Reference

Performance/memory issues on marker clusters in Google Maps

I am using this sample code to add a cluster of markers and infoWindows (and related event listeners) to my map:
function initMap(locations) {
var myLatLng = {lat: 41.69906, lng: 12.39258};
var map = new google.maps.Map(document.getElementById('map'), {
zoom: 5,
center: myLatLng,
mapTypeControl: false,
scaleControl: false
});
var infoWin = new google.maps.InfoWindow();
var markers = locations.map(function(location, i) {
var marker = new google.maps.Marker({
position: location
});
google.maps.event.addListener(marker, 'click', function(evt) {
content = <..some HTML content...>;
infoWin.setContent(content);
infoWin.open(map, marker);
})
return marker;
});
The "locations" variable contains around 1,000 markers with lat/long and name.
The question is: are 1,000 markers too much in terms of performance/memory load? How can I free memory when the application leaves the map to show other data?

Google Map background image is not showing properly in browser

I am implementing a Google Map on my webpage using JavaScript. Here my problem is map is coming with marker but it's background image is not showing at all. The screen shot is given below.
Here is my code:
<div id="dvMap" style="width:1000px; height:1000px;"></div>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<script>
var markers = [{"lat":"20.295728","lng":"85.844990"},{"title":"shilparamam","lat":"20.295728","lng":"85.844990","description":"Mumbai formerly Bombay, is the capital city of the Indian state of Maharashtra."}];
window.onload = function () {
var mapOptions = {
center: new google.maps.LatLng(markers[0].lat, markers[0].lng),
zoom: 10,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById("dvMap"), mapOptions);
var infoWindow = new google.maps.InfoWindow();
var lat_lng = new Array();
var latlngbounds = new google.maps.LatLngBounds();
for (i = 0; i < markers.length; i++) {
var data = markers[i]
var myLatlng = new google.maps.LatLng(data.lat, data.lng);
lat_lng.push(myLatlng);
var marker = new google.maps.Marker({
position: myLatlng,
map: map,
title: data.title
});
latlngbounds.extend(marker.position);
(function (marker, data) {
google.maps.event.addListener(marker, "click", function (e) {
infoWindow.setContent(data.description);
infoWindow.open(map, marker);
});
})(marker, data);
}
map.setCenter(latlngbounds.getCenter());
map.fitBounds(latlngbounds);
}
</script>
Here I need the clear background image for the Google Map.

Why don't you use a simple iframe instead of such a long script? Below link provides you with simple steps to get an iframe code which you just need to embedd in your project or website using html div.
http://www.dummies.com/web-design-development/site-development/how-to-embed-a-google-map-with-iframe/

Google Maps label

I have the following code that creates a marker on Google Maps:
function initializeMap() {
var lat = '-32.089608'; //Set your latitude.
var lon = '115.933216'; //Set your longitude.
var centerLon = lon - 0.0105;
var myOptions = {
scrollwheel: false,
draggable: false,
disableDefaultUI: true,
center: new google.maps.LatLng(lat, centerLon),
zoom: 15,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
//Bind map to elemet with id map-canvas
var map = new google.maps.Map(document.getElementById('map-canvas'), myOptions);
var marker = new google.maps.Marker({
map: map,
position: new google.maps.LatLng(lat, lon),
});
var infowindow = new google.maps.InfoWindow();
google.maps.event.addListener(marker, 'click', function () {
infowindow.open(map, marker);
});
infowindow.open(map, marker);
}
I would like to add custom text to the pointer above the default marker but I cannot work out how to do it. At the moment it displays a small empty box above the default marker. (I am unable to post an example image due to lack of reputation points.
I am not very experienced with coding so any help is appreciated.
Thank you

You only need add content into your infowindow:
var infowindow = new google.maps.InfoWindow({
content: 'abcxyz'
});

I doubt the standard library supports this.
But you can use the google maps utility library:
https://code.google.com/p/google-maps-utility-library-v3/wiki/Libraries#MarkerWithLabel
var myLatlng = new google.maps.LatLng(-25.363882,131.044922);
var myOptions = {
zoom: 8,
center: myLatlng,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
map = new google.maps.Map(document.getElementById('map_canvas'), myOptions);
var marker = new MarkerWithLabel({
position: myLatlng,
map: map,
draggable: true,
raiseOnDrag: true,
labelContent: "A",
labelAnchor: new google.maps.Point(3, 30),
labelClass: "labels", // the CSS class for the label
labelInBackground: false
});
The basics about marker can be found here:
https://developers.google.com/maps/documentation/javascript/overlays#Markers
Google Maps API v3 marker with label

You only need to edit your marker click event function as below.
google.maps.event.addListener(marker, 'click', function () {
infowindow.open(map, marker);
infoWindow.setContent('abcdxyz'); // add this line to your existing code
});
With this you can deal with multiple infoWindow for multiple markers.
Also if you want to display contents on mouseover, then you can use title property of marker like:
var marker = new google.maps.Marker({
position: {lat:lat, lng:lng},
map: map,
title: 'abcXYZ' // this will be displayed on marker mousover
});

Google Maps API Marker not displaying

I ahve just started using the Goggle Maps API and I have followed all of the instructions but for some reason the Map shows but the Marker to show the specific location is not displaying.
Below is the code I'm using:
function initialize() {
var map_canvas = document.getElementById('map_canvas');
var myLatIng = new google.maps.LatLng(-1.288902, 36.806304);
var map_options = {
center: myLatIng,
zoom: 19
}
var map = new google.maps.Map(map_canvas, map_options);
var contentString = '<h2>Capacity Development Institute</h2><p>NAS Apartments, Milimani Road,<br>P.O.Box 33411 - 00600, Nairobi, Kenya</p>';
var infowindow = new google.maps.InfoWindow({
content: contentString
});
var marker = new google.maps.Marker({
position: myLatlng,
map: map,
title: 'Capacity Development Institute'
});
google.maps.event.addListener(marker, 'click', function() {
infowindow.open(map,marker);
});
}
google.maps.event.addDomListener(window, 'load', initialize);
What exactly am I doing wrong?
Thanks

If you check console log you will see a message:
Uncaught ReferenceError: myLatlng is not defined
You have a typo:
var myLatIng = new google.maps.LatLng(-1.288902, 36.806304);
It should be
var myLatlng= new google.maps.LatLng(-1.288902, 36.806304);
So you have to change it in map_options and marker definition to be the same.

How to make buttons to hide and show markers?

In Google maps, I want to have buttons that will hide and show map markers, but I need to have multiple buttons, each with their own set of markers. For example, button 1 would show and hide markers 1 and 3, while button 2 would show and hide markers 2 and 4.
It's kinda hard for me cause I'm new in api v3.
Here is my code.
function initialize() {
var mapDiv = document.getElementById('map-canvas');
var map = new google.maps.Map(mapDiv, {
center: new google.maps.LatLng(-8.762472, -63.887951),
zoom: 13,
mapTypeId: google.maps.MapTypeId.ROADMAP });
var marker = new google.maps.Marker({
map: map,
position: new google.maps.LatLng(-8.759662,-63.906489),
icon: predio});
var infowindow = new google.maps.InfoWindow({
content:contentimage})
google.maps.event.addListener(marker,'click',function(){
infowindow.open(map,marker); });
var marker1 = new google.maps.Marker({
map: map,
position: new google.maps.LatLng(-8.766159,-63.889567),
icon: yellow});
var infowindow1 = new google.maps.InfoWindow({
content:contentimage1})
google.maps.event.addListener(marker1,'click',function(){
infowindow1.open(map,marker1); });
}

You may like this
A Working Example Here.
function init()
{
// Icon urls for 4 icons
var bell="http://image1.png", cam="http://image2.png",
black="http://image3.png", green="http://image4.png";
// Image urls for 4 images
conimg1="http://contentImage1.jpg", conimg2="http://contentImage2.jpg",
conimg3="http://contentImage3.jpg", conimg4="http://contentImage4.jpg",
var map,
locations = [
[42.82846160000000000000, -76.53560419999997000000, bell, conimg1],
[43.65162010000000000000, -77.73558579999997000000, black, conimg2],
[44.75846240000000000000, -78.22252100000003000000, cam, conimg3],
[41.71773540000000000000, -75.74897190000002000000, green, conimg4]
],
myOptions = {
zoom: 6,
center: new google.maps.LatLng(locations[0][0], locations[0][1]),
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var mapDiv = document.getElementById('map');
map = new google.maps.Map(mapDiv, myOptions);
var infowindow = new google.maps.InfoWindow(), marker, i, markers=[];
for (i = 0; i < locations.length; i++) {
marker = new google.maps.Marker({
position: new google.maps.LatLng(locations[i][0], locations[i][1]),
map: map,
icon: locations[i][2],
visible:true
});
markers.push(marker)
google.maps.event.addListener(marker, 'click',(function(marker, i){
return function() {
var img="<img class='contentImage' src='"+locations[i][3]+"' />";
infowindow.setContent(img);
infowindow.open(map, marker);
}
})(marker, i));
}
var btn1=document.getElementById('btn1');
google.maps.event.addDomListener(btn1, 'click', function(){
if(markers[0].visible)
{
this.innerHTML="Show Icons (1 and 2)";
this.className="btn";
markers[0].setVisible(false);
markers[1].setVisible(false);
}
else
{
this.innerHTML="Hide Icons (1 and 2)";
this.className="btn btn-primary";
markers[0].setVisible(true);
markers[1].setVisible(true);
}
});
var btn2=document.getElementById('btn2');
google.maps.event.addDomListener(btn2, 'click', function(){
if(markers[2].visible)
{
this.innerHTML="Show Icons (3 and 4)";
this.className="btn";
markers[2].setVisible(false);
markers[3].setVisible(false);
}
else
{
this.innerHTML="Hide Icons (3 and 4)";
this.className="btn btn-primary";
markers[2].setVisible(true);
markers[3].setVisible(true);
}
});
}