原文链接及内容

原文链接：https://openlayers.org/en/latest/examples/zoomify.html

运行界面

Zoomify是一种用于深度缩放高分辨率图像的格式。此示例显示如何将Zoomify数据源与像素投影一起使用，还处理了具有JTL扩展的互联网成像协议（IIP，Internet Imaging Protocol）。

main.js代码如下：

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import Map from 'ol/Map.js';
import TileLayer from 'ol/layer/Tile.js';
import View from 'ol/View.js';
import Zoomify from 'ol/source/Zoomify.js';

const imgWidth = 4000;
const imgHeight = 3000;

const zoomifyUrl = 'https://ol-zoomify.surge.sh/zoomify/';

const source = new Zoomify({
  url: zoomifyUrl,
  size: [imgWidth, imgHeight],
  crossOrigin: 'anonymous',
  zDirection: -1, // Ensure we get a tile with the screen resolution or higher
  // 确保我们得到屏幕分辨率或更高的切片
});
const extent = source.getTileGrid().getExtent();

const retinaPixelRatio = 2;
const retinaSource = new Zoomify({
  url: zoomifyUrl,
  size: [imgWidth, imgHeight],
  crossOrigin: 'anonymous',
  zDirection: -1, // Ensure we get a tile with the screen resolution or higher-确保我们得到屏幕分辨率或更高的切片
  // 以下两项配置：Display retina tiles from a higher zoom level-显示可用于Retina显示屏的切片数据
  tilePixelRatio: retinaPixelRatio,
  tileSize: 256 / retinaPixelRatio,
});

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

const map = new Map({
  layers: [layer],
  target: 'map',
  view: new View({
    // adjust zoom levels to those provided by the source
    // 将缩放级别调整为数据源提供的缩放级别
    resolutions: layer.getSource().getTileGrid().getResolutions(),
    // constrain the center: center cannot be set outside this extent
    // 约束中心：不能将中心设置在此范围之外
    extent: extent,
    constrainOnlyCenter: true,
  }),
});
map.getView().fit(extent);

const control = document.getElementById('zoomifyProtocol');
control.addEventListener('change', function (event) {
  const value = event.currentTarget.value;
  if (value === 'zoomify') {
    layer.setSource(source);
  } else if (value === 'zoomifyretina') {
    layer.setSource(retinaSource);
  }
});

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>Zoomify</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>
    <div class="controls">
      <select id="zoomifyProtocol">
        <option value="zoomify">Zoomify</option>
        <option value="zoomifyretina">Zoomify Retina</option>
      </select>
    </div>
    <!-- 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>