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图层最小/最大分辨率

发布于 2022-11-30 23:36:04 字数 2722 浏览 0 评论 0 收藏 0

根据当前视图分辨率显示/隐藏图层。

放大两次：MapBox 图层应该隐藏，OSM 图层应该显示。

如果继续放大，你将看到 OSM 图层也会消失。

这里使用 minResolution 和 maxResolution 选项参数来控制图层显示影藏的渲染。

main.js

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

const key =
  'Your Mapbox access token from https://mapbox.com/ here';

/**
 * Create the map.
 */
const map = new Map({
  layers: [
    new TileLayer({
      source: new OSM(),
      minResolution: 200,
      maxResolution: 2000,
    }),
    new TileLayer({
      source: new TileJSON({
        url:
          'https://api.tiles.mapbox.com/v4/mapbox.natural-earth-hypso-bathy.json?secure&access_token=' +
          key,
        crossOrigin: 'anonymous',
      }),
      minResolution: 2000,
      maxResolution: 20000,
    }),
  ],
  target: 'map',
  view: new View({
    center: [653600, 5723680],
    zoom: 5,
  }),
});

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Layer Min/Max Resolution</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="https://cdn.polyfill.io/v3/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": "min-max-resolution",
  "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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