Single Image WMS with Proj4js

This example uses OpenLayers v4.0.1. The latest is v.

#### Single Image WMS with Proj4js

Example of integrating Proj4js for coordinate transforms.

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

Related API documentation:

- ol.Map
,
- ol.View
,
- ol.control
,
- ol.control.ScaleLine
,
- ol.layer.Image
,
- ol.proj
,
- ol.proj.Projection
,
- ol.source.ImageWMS

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Single Image WMS with Proj4js Example of integrating Proj4js for coordinate transforms. // 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 https://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: 'https://wms.geo.admin.ch/', crossOrigin: 'anonymous', attributions: '© <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.WMSServerType} */ ('mapserver') }) }), new ol.layer.Image({ extent: extent, source: new ol.source.ImageWMS({ url: 'https://wms.geo.admin.ch/', crossOrigin: 'anonymous', attributions: '© <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.WMSServerType} */ ('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 }) }); <div id="map" class="map"></div>

    <!DOCTYPE html>
    <html>
      <head>
        <title>Single Image WMS with Proj4js</title>
        <link rel="stylesheet" href="https://openlayers.org/en/v4.0.1/css/ol.css" type="text/css">
        <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
        <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
        <script src="https://openlayers.org/en/v4.0.1/build/ol.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/proj4js/2.3.15/proj4.js"></script>
        <script src="https://epsg.io/21781-1753.js"></script>
      </head>
      <body>
        <div id="map" class="map"></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 https://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: 'https://wms.geo.admin.ch/',
                crossOrigin: 'anonymous',
                attributions: '© <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.WMSServerType} */ ('mapserver')
              })
            }),
            new ol.layer.Image({
              extent: extent,
              source: new ol.source.ImageWMS({
                url: 'https://wms.geo.admin.ch/',
                crossOrigin: 'anonymous',
                attributions: '© <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.WMSServerType} */ ('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>