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<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
<meta name="apple-mobile-web-app-capable" content="yes">
<title>OpenLayers Grayscale OSM Example</title>
<link rel="stylesheet" href="../theme/default/style.css" type="text/css">
<link rel="stylesheet" href="style.css" type="text/css">
<script src="../lib/OpenLayers.js"></script>
<script type="text/javascript">
var map, layer;
function init() {
if (!OpenLayers.CANVAS_SUPPORTED) {
var unsupported = OpenLayers.Util.getElement('unsupported');
unsupported.innerHTML = 'Your browser does not support canvas, nothing to see here !';
}
layer = new OpenLayers.Layer.OSM('Simple OSM Map', null, {
eventListeners: {
tileloaded: function(evt) {
var ctx = evt.tile.getCanvasContext();
if (ctx) {
var imgd = ctx.getImageData(0, 0, evt.tile.size.w, evt.tile.size.h);
var pix = imgd.data;
for (var i = 0, n = pix.length; i < n; i += 4) {
pix[i] = pix[i + 1] = pix[i + 2] = (3 * pix[i] + 4 * pix[i + 1] + pix[i + 2]) / 8;
}
ctx.putImageData(imgd, 0, 0);
evt.tile.imgDiv.removeAttribute("crossorigin");
evt.tile.imgDiv.src = ctx.canvas.toDataURL();
}
}
}
});
// If you get a security error because the tile are not
// from the same domain as this page, a simple Apache
// proxy can be created to workaround this issue:
//
// <Proxy *>
// Order deny,allow
// Allow from localhost
// </Proxy>
// ProxyPass /osm http://tile.openstreetmap.org/
//
// Then, in the layer definition above, replace null with '/osm/${z}/${x}/${y}.png'
map = new OpenLayers.Map('map', {
layers: [layer],
zoom: 3,
center: [-1081125, 6212801]
});
}
</script>
</head>
<body onload="init()">
<h1 id="title">Grayscale OSM Example</h1>
<div id="tags">
openstreetmap canvas grayscale light
</div>
<div id="shortdesc">Show an OSM Map in grayscale</div>
<div id="map" class="smallmap"></div>
<div id="docs">
<p>This example shows an OSM layer where the tiles were
converted to grayscale
with <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html">canvas</a>.</p>
<p style="color:red;" id="unsupported"></p>
</div>
</body>
</html>
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