Single image WMS with Proj4js projection example

Example of integrating Proj4js for coordinate transforms.

With transparent Proj4js integration, OpenLayers can transform coordinates between arbitrary projections.

wms, single image, proj4js, projection
<!DOCTYPE html>
<html>
<head>
<title>Single image WMS with Proj4js projection example</title>
<script src="https://code.jquery.com/jquery-1.11.2.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="http://openlayers.org/en/v3.9.0/css/ol.css" type="text/css">
<script src="http://openlayers.org/en/v3.9.0/build/ol.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/proj4js/2.3.6/proj4.js"></script>
<script src="http://epsg.io/21781-1753.js"></script>
</head>
<body>
<div class="container-fluid">

<div class="row-fluid">
  <div class="span12">
    <div id="map" class="map"></div>
  </div>
</div>

</div>
<script>
// Transparent Proj4js support:
//
// EPSG:21781 is known to Proj4js because its definition was loaded in the html.
// Now when we create an ol.proj.Projection instance with the 'EPSG:21781' code,
// OpenLayers will pick up parameters like units and transform functions from
// Proj4js.
//
// Note that we are setting the projection's extent here, which is used to
// determine the view resolution for zoom level 0. Recommended values for a
// projection's validity extent can be found at http://epsg.io/.
//
// If you use Proj4js only to transform coordinates, you don't even need to
// create an ol.proj.Projection instance. ol.proj.get() will take care of it
// internally.

var projection = new ol.proj.Projection({
  code: 'EPSG:21781',
  extent: [485869.5728, 76443.1884, 837076.5648, 299941.7864]
});

var extent = [420000, 30000, 900000, 350000];
var layers = [
  new ol.layer.Image({
    extent: extent,
    source: new ol.source.ImageWMS({
      url: 'http://wms.geo.admin.ch/',
      crossOrigin: 'anonymous',
      attributions: [new ol.Attribution({
        html: '&copy; ' +
            '<a href="http://www.geo.admin.ch/internet/geoportal/' +
            'en/home.html">' +
            'Pixelmap 1:1000000 / geo.admin.ch</a>'
      })],
      params: {
        'LAYERS': 'ch.swisstopo.pixelkarte-farbe-pk1000.noscale',
        'FORMAT': 'image/jpeg'
      },
      serverType: /** @type {ol.source.wms.ServerType} */ ('mapserver')
    })
  }),
  new ol.layer.Image({
    extent: extent,
    source: new ol.source.ImageWMS({
      url: 'http://wms.geo.admin.ch/',
      crossOrigin: 'anonymous',
      attributions: [new ol.Attribution({
        html: '&copy; ' +
            '<a href="http://www.geo.admin.ch/internet/geoportal/' +
            'en/home.html">' +
            'National parks / geo.admin.ch</a>'
      })],
      params: {'LAYERS': 'ch.bafu.schutzgebiete-paerke_nationaler_bedeutung'},
      serverType: /** @type {ol.source.wms.ServerType} */ ('mapserver')
    })
  })
];

var map = new ol.Map({
  controls: ol.control.defaults().extend([
    new ol.control.ScaleLine()
  ]),
  layers: layers,
  target: 'map',
  view: new ol.View({
    projection: projection,
    center: ol.proj.fromLonLat([8.23, 46.86], projection),
    extent: extent,
    zoom: 2
  })
});

</script>
</body>
</html>