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WMS GetFeatureInfo (Image Layer)

getfeatureinfo2 forEachLayerAtPixel2

 

Using an image WMS source with GetFeatureInfo requests

This example shows how to trigger WMS GetFeatureInfo requests on click for a WMS image layer. Additionally map.forEachLayerAtPixel is used to change the mouse pointer when hovering a non-transparent pixel on the map.

main.js
import 'ol/ol.css';
import ImageLayer from 'ol/layer/Image';
import ImageWMS from 'ol/source/ImageWMS';
import Map from 'ol/Map';
import View from 'ol/View';

const wmsSource = new ImageWMS({
  url: 'https://ahocevar.com/geoserver/wms',
  params: {'LAYERS': 'ne:ne'},
  serverType: 'geoserver',
  crossOrigin: 'anonymous',
});

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

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

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

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

map.on('pointermove', function (evt) {
  if (evt.dragging) {
    return;
  }
  const pixel = map.getEventPixel(evt.originalEvent);
  const hit = map.forEachLayerAtPixel(pixel, function () {
    return true;
  });
  map.getTargetElement().style.cursor = hit ? 'pointer' : '';
});
index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>WMS GetFeatureInfo (Image Layer)</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep"></script>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder,Number.isInteger"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div id="info">&nbsp;</div>
    <script src="main.js"></script>
  </body>
</html>
package.json
{
  "name": "getfeatureinfo-image",
  "dependencies": {
    "ol": "6.9.0"
  },
  "devDependencies": {
    "parcel": "^2.0.0-beta.1"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}