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MapServer WMS GetFeatureInfo (local MS4W layer)

 

Using an image WMS source with GetFeatureInfo requests

This example shows how to trigger WMS GetFeatureInfo requests on click for a MapServer WMS layer. The local mapfile used is /ms4w/apps/openlayers/examples/map/wms-server.map (data is in Spatialite format). Additionally map.forEachLayerAtPixel is used to change the mouse pointer when hovering a non-transparent pixel on the map.

index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>MapServer WMS GetFeatureInfo (local MS4W layer)</title>
    <!-- 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>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div id="info">&nbsp;</div>
    <script src="index.js"></script>
  </body>
</html>
index.jsimport 'ol/ol.css';
import Map from 'ol/Map';
import View from 'ol/View';
import ImageLayer from 'ol/layer/Image';
import ImageWMS from 'ol/source/ImageWMS';


var wmsSource = new ImageWMS({
  url: 'https://ms4w.dev/cgi-bin/mapserv.exe?MAP=/ms4w/apps/openlayers-6.1.1/examples/map/wms-server.map',
  params: {'LAYERS': 'countries'},
  serverType: 'mapserver',
  crossOrigin: 'anonymous'
});

var wmsLayer = new ImageLayer({
  source: wmsSource
});

var view = new View({
  center: [0, 0],
  zoom: 1
});

var map = new Map({
  layers: [wmsLayer],
  target: 'map',
  view: view
});

map.on('singleclick', function(evt) {
  document.getElementById('info').innerHTML = '';
  var viewResolution = /** @type {number} */ (view.getResolution());
  var url = wmsSource.getFeatureInfoUrl(
    evt.coordinate, viewResolution, 'EPSG:3857',
    {'INFO_FORMAT': 'text/html'});
  if (url) {
    fetch(url)
      .then(function (response) { return response.text(); })
      .then(function (html) {
        document.getElementById('info').innerHTML = html;
      });
  }
});

map.on('pointermove', function(evt) {
  if (evt.dragging) {
    return;
  }
  var pixel = map.getEventPixel(evt.originalEvent);
  var hit = map.forEachLayerAtPixel(pixel, function() {
    return true;
  });
  map.getTargetElement().style.cursor = hit ? 'pointer' : '';
});
package.json{
  "name": "getfeatureinfo-image",
  "dependencies": {
    "ol": "6.1.1"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}