Zoomify

zoomify 1 deepzoom 1 IIP 1 pixel 2 projection 13

Example of a Zoomify source.

Zoomify is a format for deep-zooming into high resolution images. This example shows how to use the Zoomify source with a pixel projection. Internet Imaging Protocol (IIP) with JTL extension is also handled.

main.js

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
});
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
  tilePixelRatio: retinaPixelRatio, // Display retina tiles
  tileSize: 256 / retinaPixelRatio, // from a higher zoom level
});

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
    resolutions: layer.getSource().getTileGrid().getResolutions(),
    // constrain the center: center cannot be set outside this extent
    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);
  }
});

index.html

<!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>

    <script type="module" src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "zoomify",
  "dependencies": {
    "ol": "8.1.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}