图层缩放限制

使用 minZoom 和 maxZoom 来控制图层的显示.

图层支持 minZoom 和 maxZoom 选项参数基于视图缩放等级来控制图层的显示。如果设置了最小显示等级或最大显示等级，图层则只会在图层最小等级 minZoom 和最大等级 maxZoom 范围之间才会显示。图层创建完成之后，使用图层的 setMinZoom 和 setMaxZoom 方法也可以设置图层显示限制。本示例在地图等级小于等级 14 级的时候显示 OSM 图层，大于 14 级的时候显示 USGS 图层。

main.js

import Map from 'ol/Map.js';
import OSM from 'ol/source/OSM.js';
import TileJSON from 'ol/source/TileJSON.js';
import TileLayer from 'ol/layer/Tile.js';
import View from 'ol/View.js';
import {fromLonLat} from 'ol/proj.js';

const key = 'Get your own API key at https://www.maptiler.com/cloud/';

const map = new Map({
  target: 'map',
  layers: [
    new TileLayer({
      maxZoom: 14, // visible at zoom levels 14 and below
      source: new OSM(),
    }),
    new TileLayer({
      minZoom: 14, // visible at zoom levels above 14
      source: new TileJSON({
        url: 'https://api.maptiler.com/maps/outdoor/tiles.json?key=' + key,
        tileSize: 512,
      }),
    }),
  ],
  view: new View({
    center: fromLonLat([-112.18688965, 36.057944835]),
    zoom: 15,
    maxZoom: 18,
    constrainOnlyCenter: true,
  }),
});

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Layer Zoom Limits</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>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="./resources/elm-pep.js"></script>
    <script type="module" src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "layer-zoom-limits",
  "dependencies": {
    "ol": "7.3.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}