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Geographic Coordinates

geographic4

Using geographic coordinates for the map view.

Calling the useGeographic function in the 'ol/proj' module makes it so the map view uses geographic coordinates (even if the view projection is not geographic).

main.js
import {Feature, Map, Overlay, View} from 'ol/index.js';
import {OSM, Vector as VectorSource} from 'ol/source.js';
import {Point} from 'ol/geom.js';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer.js';
import {useGeographic} from 'ol/proj.js';

useGeographic();

const place = [-110, 45];

const point = new Point(place);

const map = new Map({
  target: 'map',
  view: new View({
    center: place,
    zoom: 8,
  }),
  layers: [
    new TileLayer({
      source: new OSM(),
    }),
    new VectorLayer({
      source: new VectorSource({
        features: [new Feature(point)],
      }),
      style: {
        'circle-radius': 9,
        'circle-fill-color': 'red',
      },
    }),
  ],
});

const element = document.getElementById('popup');

const popup = new Overlay({
  element: element,
  stopEvent: false,
});
map.addOverlay(popup);

function formatCoordinate(coordinate) {
  return `
    <table>
      <tbody>
        <tr><th>lon</th><td>${coordinate[0].toFixed(2)}</td></tr>
        <tr><th>lat</th><td>${coordinate[1].toFixed(2)}</td></tr>
      </tbody>
    </table>`;
}

const info = document.getElementById('info');
map.on('moveend', function () {
  const view = map.getView();
  const center = view.getCenter();
  info.innerHTML = formatCoordinate(center);
});

let popover;
map.on('click', function (event) {
  if (popover) {
    popover.dispose();
    popover = undefined;
  }
  const feature = map.getFeaturesAtPixel(event.pixel)[0];
  if (!feature) {
    return;
  }
  const coordinate = feature.getGeometry().getCoordinates();
  popup.setPosition([
    coordinate[0] + Math.round(event.coordinate[0] / 360) * 360,
    coordinate[1],
  ]);

  popover = new bootstrap.Popover(element, {
    container: element.parentElement,
    content: formatCoordinate(coordinate),
    html: true,
    offset: [0, 20],
    placement: 'top',
    sanitize: false,
  });
  popover.show();
});

map.on('pointermove', function (event) {
  const type = map.hasFeatureAtPixel(event.pixel) ? 'pointer' : 'inherit';
  map.getViewport().style.cursor = type;
});
index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Geographic Coordinates</title>
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css">
    <link rel="stylesheet" href="node_modules/ol/ol.css">
    <style>
      .map {
        width: 100%;
        height: 400px;
      }
      td {
        padding: 0 0.5em;
        text-align: right;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map">
      <div id="popup"></div>
    </div>
    <div id="info"></div>


    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js"></script>
    <script type="module" src="main.js"></script>
  </body>
</html>
package.json
{
  "name": "geographic",
  "dependencies": {
    "ol": "8.2.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}