原文链接及内容

原文链接：https://openlayers.org/en/latest/examples/layer-opacity.html

运行界面

可以调用layer.setopacity()方法来调整图层的透明度。

main.js代码如下：

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import Map from 'ol/Map.js';
import OSM from 'ol/source/OSM.js';
import TileLayer from 'ol/layer/WebGLTile.js';
import View from 'ol/View.js';
import XYZ from 'ol/source/XYZ.js';

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

const imagery = new TileLayer({
  className: 'ol-layer-imagery',
  source: new XYZ({
    attributions:
      '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ',
    url: 'https://api.maptiler.com/tiles/satellite/{z}/{x}/{y}.jpg?key=' + key,
    maxZoom: 20,
    crossOrigin: '',
  }),
});

const osm = new TileLayer({
  source: new OSM(),
});

const map = new Map({
  layers: [imagery, osm],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 2,
  }),
});

const opacityInput = document.getElementById('opacity-input');
const opacityOutput = document.getElementById('opacity-output');
function update() {
  const opacity = parseFloat(opacityInput.value);
  osm.setOpacity(opacity);
  opacityOutput.innerText = opacity.toFixed(2);
}
opacityInput.addEventListener('input', update);
update();

界面布局文件index.html代码如下：

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Layer Opacity</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>
    <label>
      Layer opacity
      <input id="opacity-input" type="range" min="0" max="1" step="0.01" value="1" />
      <span id="opacity-output"></span>
    </label>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://cdn.jsdelivr.net/npm/elm-pep@1.0.6/dist/elm-pep.js"></script>
    <script type="module" src="main.js"></script>
  </body>
</html>