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permalink.js
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permalink.js
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import Map from '../src/ol/Map.js';
import OSM from '../src/ol/source/OSM.js';
import TileLayer from '../src/ol/layer/Tile.js';
import View from '../src/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;
});