Overlaying an Image Map Type

by tea4two

HTML

<div id="map"></div>
<!-- Replace the value of the key parameter with your own API key. -->
<script async defer
src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&callback=initMap">
</script>

CSS

/* Always set the map height explicitly to define the size of the div
 * element that contains the map. */
#map {
  height: 100%;
}
/* Optional: Makes the sample page fill the window. */
html, body {
  height: 100%;
  margin: 0;
  padding: 0;
}

JavaScript

function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 18,
    center: {lat: 37.783, lng: -122.403}
  });

  var bounds = {
    17: [[20969, 20970], [50657, 50658]],
    18: [[41939, 41940], [101315, 101317]],
    19: [[83878, 83881], [202631, 202634]],
    20: [[167757, 167763], [405263, 405269]]
  };

  var imageMapType = new google.maps.ImageMapType({
    getTileUrl: function(coord, zoom) {
      if (zoom < 17 || zoom > 20 ||
          bounds[zoom][0][0] > coord.x || coord.x > bounds[zoom][0][1] ||
          bounds[zoom][1][0] > coord.y || coord.y > bounds[zoom][1][1]) {
        return null;
      }

      return ['//www.gstatic.com/io2010maps/tiles/5/L2_',
          zoom, '_', coord.x, '_', coord.y, '.png'].join('');
    },
    tileSize: new google.maps.Size(256, 256 )
  });

  map.overlayMapTypes.push(imageMapType);
}