# GMaps.js — Overlay Map Types

You can define many overlay map types this way:

    var getTile = function(coord, zoom, ownerDocument) {
      var div = ownerDocument.createElement('div');
      div.innerHTML = coord;
      div.style.width = this.tileSize.width + 'px';
      div.style.height = this.tileSize.height + 'px';
      div.style.background = 'rgba(250, 250, 250, 0.55)';
      div.style.fontFamily = 'Monaco, Andale Mono, Courier New, monospace';
      div.style.fontSize = '10';
      div.style.fontWeight = 'bolder';
      div.style.border = 'dotted 1px #aaa';
      div.style.textAlign = 'center';
      div.style.lineHeight = this.tileSize.height + 'px';
      return div;
    };

    map.addOverlayMapType({
      index: 0,
      tileSize: new google.maps.Size(256, 256),
      getTile: getTile
    });

You must define a function called `getTile`, which returns a HTML element used to fill the map overlay. Also, you have to set an overlay `index`, which place the overlay on top of the base map, according this index.

NOTE: You can remove an overlay map type using `removeOverlayMapType(overlay_index)`.