zoom_changed listener doesn't work to me

Asked by At

I'm trying to use a zoom listene event in a google maps so that I can resize some axis I have in it. As a beginning, I'm trying to use an alert so that I can see whether if the listener detects a change in the zoom level or not, but I'm not able to get any alert at all. My code is the following:

<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
<title>Google Maps - pygmaps </title>
<script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?libraries=visualization&sensor=true_or_false"></script>
<script type="text/javascript">
    var map;
    function initialize() {
        var centerlatlng = new google.maps.LatLng(49.801674, 11.188139);
        var myOptions = {
            zoom: 18,
            center: centerlatlng,
            scaleControl:true,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };

        map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);

* plotting stuff *

google.maps.event.addDomListener(window, 'load',initialize);
google.maps.event.addDomListener(maps,'zoom_changed', function()
{
    alert("changed");
});

</script>
</head>
<body>

    <div style="text-align:center;">
        <button onclick="draw_axis()">Enable/Disable Axis</button> <br><br>    <div id="log"></div>  
    </div>
    <div id="map_canvas" style="width: 100%; height: 90%;"></div>
    </body>
    </html>

Does anyone see the problem? Thanks in advance

2 Answers

2
geocodezip On Best Solutions

The map variable isn't defined when you create the zoom_changed listener, it is created later, when the initialize function runs (also the variable is map, not maps).

code snippet:

var map;

function initialize() {
  var centerlatlng = new google.maps.LatLng(49.801674, 11.188139);
  var myOptions = {
    zoom: 18,
    center: centerlatlng,
    scaleControl: true,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  };

  map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);
  google.maps.event.addDomListener(map, 'zoom_changed', function() {
    alert("changed");
  });

}
google.maps.event.addDomListener(window, 'load', initialize);
html,
body,
#map_canvas {
  height: 100%;
  width: 100%;
  margin: 0px;
  padding: 0px
}
<script src="https://maps.googleapis.com/maps/api/js"></script>
<div style="text-align:center;">
  <div id="log"></div>
</div>
<div id="map_canvas" style="width: 100%; height: 90%;"></div>

1
martin On

You need to set zoom_changed event on the instance of google.maps.Map inside your initialize() function.

map.addListener('zoom_changed', function() {
    alert("changed");
});