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Preload Tiles

发布于 2022-11-30 23:36:05 字数 2765 浏览 0 评论 0 收藏 0

Example of tile preloading.

The map on the top preloads low resolution tiles. The map on the bottom does not use any preloading. Try zooming out and panning to see the difference.

main.js

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

const view = new View({
  center: [-4808600, -2620936],
  zoom: 8,
});

const map1 = new Map({
  layers: [
    new TileLayer({
      preload: Infinity,
      source: new BingMaps({
        key: 'Your Bing Maps Key from https://www.bingmapsportal.com/ here',
        imagerySet: 'Aerial',
      }),
    }),
  ],
  target: 'map1',
  view: view,
});

const map2 = new Map({
  layers: [
    new TileLayer({
      preload: 0, // default value
      source: new BingMaps({
        key: 'Your Bing Maps Key from https://www.bingmapsportal.com/ here',
        imagerySet: 'AerialWithLabelsOnDemand',
      }),
    }),
  ],
  target: 'map2',
  view: view,
});

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Preload Tiles</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="map1" class="map"></div>
    <div id="map2" class="map"></div>
    <script src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "preload",
  "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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