Google Maps API v3 with custom tiles and opacity slider

Posted on 2013-12-26
Last Modified: 2014-01-01
A while back I put together a Google Maps mashup using version 2 of the api.  Now for some reason the opacity slider is not displaying and I can't figure out why....

I decided to update this map to version 3 of the Google Maps api.  I can get the custom tiles on the map with this function...
 var maptiler = new google.maps.ImageMapType({
	getTileUrl: function(coord, zoom) { 
		var proj = map.getProjection();
		var tileSize = 256 / Math.pow(2,zoom);
		var tileBounds = new google.maps.LatLngBounds(
            proj.fromPointToLatLng(new google.maps.Point(coord.x*tileSize, (coord.y+1)*tileSize)),
			proj.fromPointToLatLng(new google.maps.Point((coord.x+1)*tileSize, coord.y*tileSize))
        //if (mapBounds.intersects(tileBounds) && (zoom >= mapMinZoom) && (zoom <= mapMaxZoom))
			// return "" +
			return "datatiles/COGEO/" + zoom + "/x" + coord.x + "_y" + coord.y + ".png" ;
            //return "";
	tileSize: new google.maps.Size(256, 256),
	isPng: true
	//opacity: .5

map.overlayMapTypes.insertAt(0, maptiler);

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I can set the opacity initially with this - maptiler.setOpacity(.5) - but it won't work dynamically with the opacity slider.

I'm using the example at....

When I attempt to use Gavin Harriss' CustomTileOverlay I cannot get it to load my tiles.  My tiles are not all 256 x 256 px - could that be the problem?

Here is my test url....

Question by:Nate_LR
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Expert Comment

ID: 39740873

Accepted Solution

Nate_LR earned 0 total points
ID: 39742513
Here is the solution....

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>

 <style type="text/css"> 
			        html, body { overflow: hidden; padding: 0; height: 100%; width: 100%; font-family: 'Lucida Grande',Geneva,Arial,Verdana,sans-serif; }
			        body { margin: 10px; background: #fff; }
			        #map { height: 95%; border: 1px solid #888; }
<script type="text/javascript" src=""></script>
<script type="text/javascript" src="../js/ExtDraggableObject.js"></script>

<script type="text/javascript">

			     * Constants for given map

				var mapBounds = new google.maps.LatLngBounds (new google.maps.LatLng(32.810613,-94.734029), new google.maps.LatLng(36.627145,-89.526053));
			    var mapMinZoom = 7;
			    var mapMaxZoom = 15;

			    var opacity = 0.75;
			    var map;			    
				var customtiles =[];
			     * Full-screen Window Resize

			    function getWindowHeight() {
			        if (self.innerHeight) return self.innerHeight;
			        if (document.documentElement && document.documentElement.clientHeight)
			            return document.documentElement.clientHeight;
			        if (document.body) return document.body.clientHeight;
			        return 0;

			    function getWindowWidth() {
			        if (self.innerWidth) return self.innerWidth;
			        if (document.documentElement && document.documentElement.clientWidth)
			            return document.documentElement.clientWidth;
			        if (document.body) return document.body.clientWidth;
			        return 0;

			    function resize() { 
			        var map = document.getElementById("map");  
	 = (getWindowHeight()-80) + "px";
	 = (getWindowWidth()-20) + "px";			       

			     * Main load function
			    function load() {
					map = new google.maps.Map(document.getElementById("map") ,{
						zoom : mapMinZoom,
						center: mapBounds.getCenter(),
						zoomControl: true,
						panControl: true,
						rotateControl: true,
						scaleControl: true,
						scrollwheel: true,
						mapTypeControl: true,
						streetViewControl: true,
						mapTypeControlOptions: {
							mapTypeIds: [google.maps.MapTypeId.TERRAIN, google.maps.MapTypeId.SATELLITE, google.maps.MapTypeId.HYBRID],
							style: google.maps.MapTypeControlStyle.HORIZONTAL_BAR
						mapTypeId: google.maps.MapTypeId.TERRAIN


					//the same times with array customtiles
					* create custom type tile
					customtiles[0] =  CustomMapType({
						name		: 'AGS Geology',
						alt			: 'Geologic Map Custom Tile',
						tileSize	: 256,
						BaseUrl		: "",
						minZoom		: 7,
						maxZoom		: 15
					var filterDiv = document.createElement('DIV');
					var mControl = new FilterControl(filterDiv, map);
					filterDiv.index = 1;"position:absolute;right:7px;";
				}//end load()
				* change tile type
				function setTiles(_opacity){	
					for(var i in customtiles){
						map.overlayMapTypes.setAt(i, customtiles[i]);
				* change tile opacity
				function changeMapTileOpacity(_opacity){
					for(var i in customtiles){
				* custom type tile function
				function CustomMapType(args){
					var opts = { 
						  getTileUrl: function(coord, zoom) { 
							if ((zoom < mapMinZoom) || (zoom > mapMaxZoom)) {
			                  return args.BaseUrl + "datatiles/none.png";
							var ymax = 1 << zoom;
							var zFactor=Math.pow(2,zoom);
							var y = ymax - coord.y -1;
							var tileBounds = new google.maps.LatLngBounds(								
								map.getProjection().fromPointToLatLng( new google.maps.Point( (coord.x)*args.tileSize/zFactor, (coord.y+1)*args.tileSize/zFactor ) ),
								map.getProjection().fromPointToLatLng( new google.maps.Point( (coord.x+1)*args.tileSize/zFactor, (coord.y)*args.tileSize/zFactor ) )
							if (mapBounds.intersects(tileBounds)){
								return args.BaseUrl + "datatiles/COGEO/" + zoom + "/x" + coord.x + "_y" + coord.y + ".png" ;
								return args.BaseUrl + "datatiles/none.png";
						tileSize: new google.maps.Size(args.tileSize, args.tileSize),
						isPng: true,
						maxZoom:  args.maxZoom,
						minZoom:  args.minZoom
					var map_type = new google.maps.ImageMapType(opts); =;
					map_type.alt = args.alt;
					return map_type;		
				* tile Opacity slider control
				function FilterControl(controlDiv, map) { = '4px';
					var controlUI = document.createElement('DIV'); = "zoomContainer";"position:absolute;right:7px;width: 70px; height: 21px; z-index: 0; top: 10px;";
					var controlzoom = document.createElement('DIV'); = "zoom";"height: 21px; width: 13px; background-image: url(; left: 22px; top: 0px; position: absolute; cursor: pointer; background-position: -70px 0px;";
					var controlzoomSlider = document.createElement('DIV'); = "zoomSlider";"height:21px; width:70px; background-image: url(";	
					var zoomSlider = new ExtDraggableObject(controlzoom, { restrictY:true, container:controlzoomSlider});
					var dragEndEvent = google.maps.event.addListener(zoomSlider, "dragend", function(e) {
					  var val = zoomSlider.valueX();

<body onload="load()">
	<div id="map"></div>


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Expert Comment

ID: 39742577
Fine with me

Author Closing Comment

ID: 39749625
I found the solution on my own.

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