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High DPI WMTS

Example of a WMTS based HiDPI layer.

The WMTS source has a tilePixelRatio option. A HiDPI capable WMTS could provide tiles with 512x512 pixel tiles, but use them in a 256x256 pixel tile grid. In this case tilePixelRatio needs to be set to 2.

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index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>High DPI WMTS</title>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
      .map {
        background: white;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script src="index.js"></script>
  </body>
</html>
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index.jsimport 'ol/ol.css';
import Map from 'ol/Map';
import View from 'ol/View';
import WMTSCapabilities from 'ol/format/WMTSCapabilities';
import {DEVICE_PIXEL_RATIO} from 'ol/has';
import TileLayer from 'ol/layer/Tile';
import WMTS, {optionsFromCapabilities} from 'ol/source/WMTS';


var capabilitiesUrl = 'https://www.basemap.at/wmts/1.0.0/WMTSCapabilities.xml';

// HiDPI support:
// * Use 'bmaphidpi' layer (pixel ratio 2) for device pixel ratio > 1
// * Use 'geolandbasemap' layer (pixel ratio 1) for device pixel ratio == 1
var hiDPI = DEVICE_PIXEL_RATIO > 1;
var layer = hiDPI ? 'bmaphidpi' : 'geolandbasemap';
var tilePixelRatio = hiDPI ? 2 : 1;

var map = new Map({
  target: 'map',
  view: new View({
    center: [1823849, 6143760],
    zoom: 11
  })
});

fetch(capabilitiesUrl).then(function(response) {
  return response.text();
}).then(function(text) {
  var result = new WMTSCapabilities().read(text);
  var options = optionsFromCapabilities(result, {
    layer: layer,
    matrixSet: 'google3857',
    style: 'normal'
  });
  options.tilePixelRatio = tilePixelRatio;
  map.addLayer(new TileLayer({
    source: new WMTS(options)
  }));
});
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package.json{
  "name": "wmts-hidpi",
  "dependencies": {
    "ol": "6.1.1"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}