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Permalink

发布于 2022-11-30 23:36:05 字数 4265 浏览 0 评论 0 收藏 0

本示例演示创建 permalinks.

本示例中，当移动操作地图的时候，使用 HTML 5 History API 基于地图当前缩放级别、中心点、旋转等更新浏览器的地址注意，并不是所有浏览器都支持 History API，可以使用 polyfill.

其实就是在地址栏记录地图的缩放、中心点等状态，点击回退按钮的时候，可以返回地图状态。

main.js

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

// 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>
    <!-- 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="./resources/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>
    <script src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "permalink",
  "dependencies": {
    "ol": "7.1.0"
  },
  "devDependencies": {
    "parcel": "^2.0.0-beta.1"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}

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