This example uses OpenLayers v10.9.0. The latest is v.
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#### Custom Drag-and-Drop (KMZ)

drag-and-drop 3 kml 9 kmz 1

#####

Example of using the drag-and-drop interaction with a custom format to handle KMZ files.

Example of using the drag-and-drop interaction with a custom format to handle KMZ files. In addition to the formats used in the Drag-and-Drop example a custom format (subclassing KML) is used to handle KMZ files. KML and icons must be extracted from the KMZ array buffer synchronously. There is no projection transform support, so this will only work with data in EPSG:4326 and EPSG:3857.

##### main.js

    import {unzipSync} from 'fflate';
    import Map from 'ol/Map.js';
    import View from 'ol/View.js';
    import GPX from 'ol/format/GPX.js';
    import GeoJSON from 'ol/format/GeoJSON.js';
    import IGC from 'ol/format/IGC.js';
    import KML from 'ol/format/KML.js';
    import TopoJSON from 'ol/format/TopoJSON.js';
    import DragAndDrop from 'ol/interaction/DragAndDrop.js';
    import {defaults as defaultInteractions} from 'ol/interaction/defaults.js';
    import TileLayer from 'ol/layer/Tile.js';
    import VectorLayer from 'ol/layer/Vector.js';
    import OSM from 'ol/source/OSM.js';
    import VectorSource from 'ol/source/Vector.js';

    // Create functions to extract KML and icons from KMZ array buffer,
    // which must be done synchronously.

    let zip;

    function getKMLData(buffer) {
      zip = unzipSync(new Uint8Array(buffer));
      const kml = Object.keys(zip).find((key) => /\.kml$/i.test(key));
      if (!(kml in zip)) {
        return null;
      }
      return new TextDecoder().decode(zip[kml]);
    }

    function getKMLImage(href) {
      const index = window.location.href.lastIndexOf('/');
      if (index === -1) {
        return href;
      }
      const image = href.slice(index + 1);
      if (!(image in zip)) {
        return href;
      }
      return URL.createObjectURL(new Blob([zip[image]]));
    }

    // Define a KMZ format class by subclassing ol/format/KML

    class KMZ extends KML {
      constructor(opt_options) {
        const options = opt_options || {};
        options.iconUrlFunction = getKMLImage;
        super(options);
      }

      getType() {
        return 'arraybuffer';
      }

      readFeature(source, options) {
        const kmlData = getKMLData(source);
        return super.readFeature(kmlData, options);
      }

      readFeatures(source, options) {
        const kmlData = getKMLData(source);
        return super.readFeatures(kmlData, options);
      }
    }

    // Set up map with Drag and Drop interaction

    const dragAndDropInteraction = new DragAndDrop({
      formatConstructors: [KMZ, GPX, GeoJSON, IGC, KML, TopoJSON],
    });

    const map = new Map({
      interactions: defaultInteractions().extend([dragAndDropInteraction]),
      layers: [
        new TileLayer({
          source: new OSM(),
        }),
      ],
      target: 'map',
      view: new View({
        center: [0, 0],
        zoom: 2,
      }),
    });

    dragAndDropInteraction.on('addfeatures', function (event) {
      const vectorSource = new VectorSource({
        features: event.features,
      });
      map.addLayer(
        new VectorLayer({
          source: vectorSource,
        }),
      );
      map.getView().fit(vectorSource.getExtent());
    });

    const displayFeatureInfo = function (pixel) {
      const features = map.getFeaturesAtPixel(pixel);
      let html;
      if (features.length > 0) {
        const info = [];
        for (let i = 0, ii = features.length; i < ii; ++i) {
          const description =
            features[i].get('description') ||
            features[i].get('name') ||
            features[i].get('_name') ||
            features[i].get('layer');
          if (description) {
            info.push(description);
          }
        }
        html = info.join('<br/>');
      }
      document.getElementById('info').innerHTML = html ?? '';
    };

    map.on('pointermove', function (evt) {
      if (evt.dragging) {
        return;
      }
      displayFeatureInfo(evt.pixel);
    });

    map.on('click', function (evt) {
      displayFeatureInfo(evt.pixel);
    });

    // Sample data download

    const link = document.getElementById('download');

    function download(fullpath, filename) {
      fetch(fullpath)
        .then((response) => response.blob())
        .then(function (blob) {
          link.href = URL.createObjectURL(blob);
          link.download = filename;
          link.click();
        });
    }

    document.getElementById('download-kmz').addEventListener('click', function () {
      download('data/kmz/iceland.kmz', 'iceland.kmz');
    });

##### index.html

    <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="UTF-8">
        <title>Custom Drag-and-Drop (KMZ)</title>
        <link rel="stylesheet" href="node_modules/ol/ol.css">
        <style>
          .map {
            width: 100%;
            height: 400px;
          }
          #info {
            width: 100%;
            height: 24rem;
            margin-top: 10px;
            overflow: scroll;
            display: flex;
            align-items: baseline;
            border: 1px solid black;
            justify-content: flex-start;
          }
        </style>
      </head>
      <body>
        <div id="map" class="map"></div>
        <div>
          <a id="download" download></a>
          <button id="download-kmz">Download sample</button>
        </div>
        <div id="info"></div>

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

##### package.json

    {
      "name": "drag-and-drop-custom-kmz",
      "dependencies": {
        "ol": "10.9.0",
        "fflate": "^0.8.2"
      },
      "devDependencies": {
        "vite": "^3.2.3"
      },
      "scripts": {
        "start": "vite",
        "build": "vite build"
      }
    }