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permalink2 openstreetmap22 history1

Example on how to create permalinks.

In this example the HTML 5 History API is used to update the browser URL with the current zoom-level, center and rotation when the map is moved.

main.js
import Map from 'ol/Map.js';
import OSM from 'ol/source/OSM.js';
import TileLayer from 'ol/layer/Tile.js';
import View from 'ol/View.js';

// default zoom, center and rotation
let zoom = 2;
let center = [0, 0];
let rotation = 0;

if (window.location.hash !== '') {
  // try to restore center, zoom-level and rotation from the URL
  const hash = window.location.hash.replace('#map=', '');
  const parts = hash.split('/');
  if (parts.length === 4) {
    zoom = parseFloat(parts[0]);
    center = [parseFloat(parts[1]), parseFloat(parts[2])];
    rotation = parseFloat(parts[3]);
  }
}

const map = new Map({
  layers: [
    new TileLayer({
      source: new OSM(),
    }),
  ],
  target: 'map',
  view: new View({
    center: center,
    zoom: zoom,
    rotation: rotation,
  }),
});

let shouldUpdate = true;
const view = map.getView();
const updatePermalink = function () {
  if (!shouldUpdate) {
    // do not update the URL when the view was changed in the 'popstate' handler
    shouldUpdate = true;
    return;
  }

  const center = view.getCenter();
  const hash =
    '#map=' +
    view.getZoom().toFixed(2) +
    '/' +
    center[0].toFixed(2) +
    '/' +
    center[1].toFixed(2) +
    '/' +
    view.getRotation();
  const state = {
    zoom: view.getZoom(),
    center: view.getCenter(),
    rotation: view.getRotation(),
  };
  window.history.pushState(state, 'map', hash);
};

map.on('moveend', updatePermalink);

// restore the view state when navigating through the history, see
// https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onpopstate
window.addEventListener('popstate', function (event) {
  if (event.state === null) {
    return;
  }
  map.getView().setCenter(event.state.center);
  map.getView().setZoom(event.state.zoom);
  map.getView().setRotation(event.state.rotation);
  shouldUpdate = false;
});
index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Permalink</title>
    <link rel="stylesheet" href="node_modules/ol/ol.css">
    <style>
      .map {
        width: 100%;
        height: 400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>

    <script type="module" src="main.js"></script>
  </body>
</html>
package.json
{
  "name": "permalink",
  "dependencies": {
    "ol": "9.1.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}