Support formats that read ArrayBuffer sources

Drag-and-Drop support for formats that read arraybuffer sources
Add TextDecoder to polyfills
Add custom Drag-and-Drop examples for KMZ and MVT
Add sample download and KML styles option to existing example
Test arraybuffer and constructed formats

doc/tutorials/background.md

@@ -19,7 +19,7 @@ OpenLayers is available as [`ol` npm package](https://npmjs.com/package/ol), whi
 
 By default, OpenLayers uses a performance optimized Canvas renderer.
 
-OpenLayers runs on all modern browsers that support [HTML5](https://html.spec.whatwg.org/multipage/) and [ECMAScript 5](http://www.ecma-international.org/ecma-262/5.1/). This includes Chrome, Firefox, Safari and Edge. For older browsers and platforms like Internet Explorer (down to version 9) and Android 4.x, [polyfills](http://polyfill.io), the application bundle needs to be transpiled (e.g. using [Babel](https://babeljs.io)) and bundled with polyfills for `requestAnimationFrame`, `Element.prototype.classList` and `URL`.
+OpenLayers runs on all modern browsers that support [HTML5](https://html.spec.whatwg.org/multipage/) and [ECMAScript 5](http://www.ecma-international.org/ecma-262/5.1/). This includes Chrome, Firefox, Safari and Edge. For older browsers and platforms like Internet Explorer (down to version 9) and Android 4.x, [polyfills](http://polyfill.io), the application bundle needs to be transpiled (e.g. using [Babel](https://babeljs.io)) and bundled with polyfills for `fetch`, `requestAnimationFrame`, `Element.prototype.classList`, `URL` and `TextDecoder`.
 
 The library is intended for use on both desktop/laptop and mobile devices, and supports pointer and touch interactions.
 

examples/.eslintrc

@@ -11,6 +11,7 @@
     "GyroNorm": false,
     "jsPDF": false,
     "jsts": false,
+    "JSZip": false,
     "mapboxgl": false,
     "saveAs": false,
     "toastr": false,

examples/drag-and-drop-custom-kmz.css

@@ -0,0 +1,9 @@
+#info {
+  width: 100%;
+  height: 24rem;
+  overflow: scroll;
+  display: flex;
+  align-items: baseline;
+  border: 1px solid black;
+  justify-content: flex-start;
+}

examples/drag-and-drop-custom-kmz.html

@@ -0,0 +1,22 @@
+---
+layout: example.html
+title: Custom Drag-and-Drop (KMZ)
+shortdesc: Example of using the drag-and-drop interaction with a custom format to handle KMZ files.
+docs: >
+  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](drag-and-drop.html) example a custom format (subclassing KML) is used to handle KMZ files.
+  KML and icons must be extracted from the KMZ array buffer synchronously.
+  <a href="https://stuk.github.io/jszip/documentation/upgrade_guide.html" target="_blank">JSZip 2.x</a> is used as it has better browser compatibility and is simpler to code than the more recent <a href="https://github.com/ericvergnaud/jszip#readme" target="_blank">JSZip-sync</a>.
+  There is no projection transform support, so this will only work with data in EPSG:4326 and EPSG:3857.
+tags: "drag-and-drop, kml, kmz"
+resources:
+  - https://cdnjs.cloudflare.com/ajax/libs/jszip/2.6.1/jszip.min.js
+---
+<div id="map" class="map"></div>
+<br />
+<div>
+  <a id="download" download></a>
+  <button id="download-kmz">Download sample</button>
+</div>
+<br />
+<div id="info">&nbsp;</div>

examples/drag-and-drop-custom-kmz.js

@@ -0,0 +1,155 @@
+import Map from '../src/ol/Map.js';
+import View from '../src/ol/View.js';
+import {
+  DragAndDrop,
+  defaults as defaultInteractions,
+} from '../src/ol/interaction.js';
+import {GPX, GeoJSON, IGC, KML, TopoJSON} from '../src/ol/format.js';
+import {OSM, Vector as VectorSource} from '../src/ol/source.js';
+import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
+
+// Create functions to extract KML and icons from KMZ array buffer,
+// which must be done synchronously.
+
+const zip = new JSZip();
+
+function getKMLData(buffer) {
+  let kmlData;
+  zip.load(buffer);
+  const kmlFile = zip.file(/.kml$/i)[0];
+  if (kmlFile) {
+    kmlData = kmlFile.asText();
+  }
+  return kmlData;
+}
+
+function getKMLImage(href) {
+  let url = href;
+  let path = window.location.href;
+  path = path.slice(0, path.lastIndexOf('/') + 1);
+  if (href.indexOf(path) === 0) {
+    const regexp = new RegExp(href.replace(path, '') + '$', 'i');
+    const kmlFile = zip.file(regexp)[0];
+    if (kmlFile) {
+      url = URL.createObjectURL(new Blob([kmlFile.asArrayBuffer()]));
+    }
+  }
+  return url;
+}
+
+// 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.forEachFeatureAtPixel(pixel, function (feature) {
+    features.push(feature);
+  });
+  if (features.length > 0) {
+    const info = [];
+    let i, ii;
+    for (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);
+      }
+    }
+    document.getElementById('info').innerHTML = info.join('<br/>') || '&nbsp';
+  } else {
+    document.getElementById('info').innerHTML = '&nbsp;';
+  }
+};
+
+map.on('pointermove', function (evt) {
+  if (evt.dragging) {
+    return;
+  }
+  const pixel = map.getEventPixel(evt.originalEvent);
+  displayFeatureInfo(pixel);
+});
+
+map.on('click', function (evt) {
+  displayFeatureInfo(evt.pixel);
+});
+
+// Sample data download
+
+const link = document.getElementById('download');
+
+function download(fullpath, filename) {
+  fetch(fullpath)
+    .then(function (response) {
+      return response.blob();
+    })
+    .then(function (blob) {
+      if (navigator.msSaveBlob) {
+        // link download attribuute does not work on MS browsers
+        navigator.msSaveBlob(blob, filename);
+      } else {
+        link.href = URL.createObjectURL(blob);
+        link.download = filename;
+        link.click();
+      }
+    });
+}
+
+document.getElementById('download-kmz').addEventListener('click', function () {
+  download('data/kmz/iceland.kmz', 'iceland.kmz');
+});

examples/drag-and-drop-custom-mvt.css

@@ -0,0 +1,3 @@
+.tileCoord input {
+  width: 60px;
+}

examples/drag-and-drop-custom-mvt.html

@@ -0,0 +1,23 @@
+---
+layout: example.html
+title: Custom Drag-and-Drop (MVT preview)
+shortdesc: Example of using the drag-and-drop interaction with a custom format to preview MVT tiles.
+docs: >
+  Example of using the drag-and-drop interaction with a custom format to preview MVT tiles.
+  In addition to the formats used in the [Drag-and-Drop](drag-and-drop.html) example individual MVT tiles can be previewed.
+  There is no projection transform support, so this will only work with data in EPSG:4326 and EPSG:3857.
+tags: "drag-and-drop, mvt"
+---
+<div id="map" class="map"></div>
+<br />
+<div class="tileCoord">
+  <a id="download" download></a>
+  <span>Tile coordinate&nbsp;&nbsp;</span>
+  <span>&nbsp;z: <input type="number" id="tileCoordZ" value="6" /></span>
+  <span>&nbsp;x: <input type="number" id="tileCoordX" value="30" /></span>
+  <span>&nbsp;y: <input type="number" id="tileCoordY" value="20" /></span>
+  <span>&nbsp;&nbsp;</span>
+  <button id="download-mvt">Download sample</button>
+</div>
+<br />
+<div id="info">&nbsp;</div>

examples/drag-and-drop-custom-mvt.js

@@ -0,0 +1,133 @@
+import Feature from '../src/ol/Feature.js';
+import Map from '../src/ol/Map.js';
+import View from '../src/ol/View.js';
+import {
+  DragAndDrop,
+  defaults as defaultInteractions,
+} from '../src/ol/interaction.js';
+import {GPX, GeoJSON, IGC, KML, MVT, TopoJSON} from '../src/ol/format.js';
+import {OSM, Vector as VectorSource} from '../src/ol/source.js';
+import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
+import {createXYZ} from '../src/ol/tilegrid.js';
+
+// Define a custom MVT format as ol/format/MVT requires an extent
+
+const tileCoordZ = document.getElementById('tileCoordZ');
+const tileCoordX = document.getElementById('tileCoordX');
+const tileCoordY = document.getElementById('tileCoordY');
+
+class customMVT extends MVT {
+  constructor() {
+    super({featureClass: Feature});
+  }
+  readFeatures(source, options) {
+    options.extent = createXYZ().getTileCoordExtent([
+      parseInt(tileCoordZ.value),
+      parseInt(tileCoordX.value),
+      parseInt(tileCoordY.value),
+    ]);
+    return super.readFeatures(source, options);
+  }
+}
+
+// Set up map with Drag and Drop interaction
+
+const dragAndDropInteraction = new DragAndDrop({
+  formatConstructors: [customMVT, 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.forEachFeatureAtPixel(pixel, function (feature) {
+    features.push(feature);
+  });
+  if (features.length > 0) {
+    const info = [];
+    let i, ii;
+    for (i = 0, ii = features.length; i < ii; ++i) {
+      const description =
+        features[i].get('name') ||
+        features[i].get('_name') ||
+        features[i].get('layer');
+      if (description) {
+        info.push(description);
+      }
+    }
+    document.getElementById('info').innerHTML = info.join(', ') || '&nbsp';
+  } else {
+    document.getElementById('info').innerHTML = '&nbsp;';
+  }
+};
+
+map.on('pointermove', function (evt) {
+  if (evt.dragging) {
+    return;
+  }
+  const pixel = map.getEventPixel(evt.originalEvent);
+  displayFeatureInfo(pixel);
+});
+
+map.on('click', function (evt) {
+  displayFeatureInfo(evt.pixel);
+});
+
+// Sample data download
+
+const link = document.getElementById('download');
+
+function download(fullpath, filename) {
+  fetch(fullpath)
+    .then(function (response) {
+      return response.blob();
+    })
+    .then(function (blob) {
+      if (navigator.msSaveBlob) {
+        // link download attribuute does not work on MS browsers
+        navigator.msSaveBlob(blob, filename);
+      } else {
+        link.href = URL.createObjectURL(blob);
+        link.download = filename;
+        link.click();
+      }
+    });
+}
+
+document.getElementById('download-mvt').addEventListener('click', function () {
+  const fullpath =
+    'https://basemaps.arcgis.com/v1/arcgis/rest/services/World_Basemap/VectorTileServer/tile/' +
+    tileCoordZ.value +
+    '/' +
+    tileCoordY.value +
+    '/' +
+    tileCoordX.value +
+    '.pbf';
+  const filename =
+    tileCoordZ.value + '-' + tileCoordX.value + '-' + tileCoordY.value + '.mvt';
+  download(fullpath, filename);
+});

examples/drag-and-drop.html

@@ -10,4 +10,20 @@ cloak:
     value: Get your own API key at https://www.maptiler.com/cloud/
 ---
 <div id="map" class="map"></div>
+<div><input type="checkbox" id="extractstyles" checked /> Extract styles from KML</div>
+<br />
+<div>
+  <a id="download" download></a>
+  Download samples:&nbsp;&nbsp;
+  <button id="download-gpx">GPX</button>
+  &nbsp;
+  <button id="download-geojson">GeoJSON</button>
+  &nbsp;
+  <button id="download-igc">IGC</button>
+  &nbsp;
+  <button id="download-kml">KML</button>
+  &nbsp;
+  <button id="download-topojson">TopoJSON</button>
+</div>
+<br />
 <div id="info">&nbsp;</div>

examples/drag-and-drop.js

@@ -1,24 +1,16 @@
+import DragAndDrop from '../src/ol/interaction/DragAndDrop.js';
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import {
-  DragAndDrop,
-  defaults as defaultInteractions,
-} from '../src/ol/interaction.js';
 import {GPX, GeoJSON, IGC, KML, TopoJSON} from '../src/ol/format.js';
 import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
 import {Vector as VectorSource, XYZ} from '../src/ol/source.js';
 
-const dragAndDropInteraction = new DragAndDrop({
-  formatConstructors: [GPX, GeoJSON, IGC, KML, TopoJSON],
-});
-
 const key = 'get_your_own_D6rA4zTHduk6KOKTXzGB';
 const attributions =
   '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ' +
   '<a href="https://www.openstreetmap.org/copyright" target="_blank">&copy; OpenStreetMap contributors</a>';
 
 const map = new Map({
-  interactions: defaultInteractions().extend([dragAndDropInteraction]),
   layers: [
     new TileLayer({
       source: new XYZ({
@@ -36,7 +28,24 @@ const map = new Map({
   }),
 });
 
-dragAndDropInteraction.on('addfeatures', function (event) {
+const extractStyles = document.getElementById('extractstyles');
+let dragAndDropInteraction;
+
+function setInteraction() {
+  if (dragAndDropInteraction) {
+    map.removeInteraction(dragAndDropInteraction);
+  }
+  dragAndDropInteraction = new DragAndDrop({
+    formatConstructors: [
+      GPX,
+      GeoJSON,
+      IGC,
+      // use constructed format to set options
+      new KML({extractStyles: extractStyles.checked}),
+      TopoJSON,
+    ],
+  });
+  dragAndDropInteraction.on('addfeatures', function (event) {
     const vectorSource = new VectorSource({
       features: event.features,
     });
@@ -46,7 +55,12 @@ dragAndDropInteraction.on('addfeatures', function (event) {
       })
     );
     map.getView().fit(vectorSource.getExtent());
-});
+  });
+  map.addInteraction(dragAndDropInteraction);
+}
+setInteraction();
+
+extractStyles.addEventListener('change', setInteraction);
 
 const displayFeatureInfo = function (pixel) {
   const features = [];
@@ -76,3 +90,48 @@ map.on('pointermove', function (evt) {
 map.on('click', function (evt) {
   displayFeatureInfo(evt.pixel);
 });
+
+// Sample data downloads
+
+const link = document.getElementById('download');
+
+function download(fullpath, filename) {
+  fetch(fullpath)
+    .then(function (response) {
+      return response.blob();
+    })
+    .then(function (blob) {
+      if (navigator.msSaveBlob) {
+        // link download attribuute does not work on MS browsers
+        navigator.msSaveBlob(blob, filename);
+      } else {
+        link.href = URL.createObjectURL(blob);
+        link.download = filename;
+        link.click();
+      }
+    });
+}
+
+document.getElementById('download-gpx').addEventListener('click', function () {
+  download('data/gpx/fells_loop.gpx', 'fells_loop.gpx');
+});
+
+document
+  .getElementById('download-geojson')
+  .addEventListener('click', function () {
+    download('data/geojson/roads-seoul.geojson', 'roads-seoul.geojson');
+  });
+
+document.getElementById('download-igc').addEventListener('click', function () {
+  download('data/igc/Ulrich-Prinz.igc', 'Ulrich-Prinz.igc');
+});
+
+document.getElementById('download-kml').addEventListener('click', function () {
+  download('data/kml/states.kml', 'states.kml');
+});
+
+document
+  .getElementById('download-topojson')
+  .addEventListener('click', function () {
+    download('data/topojson/fr-departments.json', 'fr-departments.json');
+  });

examples/resources/common.js

@@ -9,7 +9,7 @@
 
   function fetchResource(resource) {
     return new Promise(function (resolve, reject) {
-      const isImage = /\.(png|jpe?g|gif|tiff|svg)$/.test(resource);
+      const isImage = /\.(png|jpe?g|gif|tiff|svg|kmz)$/.test(resource);
       if (isImage) {
         resolve ({
           isBinary: true,

examples/templates/example.html

@@ -68,7 +68,7 @@
     <link rel="stylesheet" href="./css/ol.css" type="text/css">
     <link rel="stylesheet" href="./resources/layout.css" type="text/css">
     <script src="https://unpkg.com/elm-pep"></script>
-    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL"></script>
+    <script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder"></script>
     {{{ extraHead.local }}}
     {{{ css.tag }}}
     <title>{{ title }}</title>
@@ -194,7 +194,7 @@
     &lt;!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer --&gt;
     &lt;script src="https://unpkg.com/elm-pep"&gt;&lt;/script&gt;{{#if extraHead.remote}}
     &lt;!-- The line below is only needed for old environments like Internet Explorer and Android 4.x --&gt;
-    &lt;script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL"&gt;&lt;/script&gt;
+    &lt;script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder"&gt;&lt;/script&gt;
 {{ indent extraHead.remote spaces=4 }}{{/if}}
     &lt;style&gt;
       .map {

src/ol/interaction/DragAndDrop.js

@@ -5,6 +5,7 @@
 
 import Event from '../events/Event.js';
 import EventType from '../events/EventType.js';
+import FormatType from '../format/FormatType.js';
 import Interaction from './Interaction.js';
 import {TRUE} from '../functions.js';
 import {get as getProjection} from '../proj.js';
@@ -12,7 +13,8 @@ import {listen, unlistenByKey} from '../events.js';
 
 /**
  * @typedef {Object} Options
- * @property {Array<typeof import("../format/Feature.js").default>} [formatConstructors] Format constructors.
+ * @property {Array<typeof import("../format/Feature.js").default|import("../format/Feature.js").default>} [formatConstructors] Format constructors
+ * (and/or formats pre-constructed with options).
  * @property {import("../source/Vector.js").default} [source] Optional vector source where features will be added.  If a source is provided
  * all existing features will be removed and new features will be added when
  * they are dropped on the target.  If you want to add features to a vector
@@ -75,6 +77,11 @@ export class DragAndDropEvent extends Event {
 /**
  * @classdesc
  * Handles input of vector data by drag and drop.
+ *
+ * Note that the DragAndDrop interaction uses the TextDecoder() constructor if the supplied
+ * combinnation of formats read both text string and ArrayBuffer sources. Older browsers such
+ * as IE which do not support this will need a TextDecoder polyfill to be loaded before use.
+ *
  * @api
  *
  * @fires DragAndDropEvent
@@ -92,11 +99,27 @@ class DragAndDrop extends Interaction {
 
     /**
      * @private
-     * @type {Array<typeof import("../format/Feature.js").default>}
+     * @type {boolean}
      */
-    this.formatConstructors_ = options.formatConstructors
+    this.readAsBuffer_ = false;
+
+    /**
+     * @private
+     * @type {Array<import("../format/Feature.js").default>}
+     */
+    this.formats_ = [];
+    const formatConstructors = options.formatConstructors
       ? options.formatConstructors
       : [];
+    for (let i = 0, ii = formatConstructors.length; i < ii; ++i) {
+      let format = formatConstructors[i];
+      if (typeof format === 'function') {
+        format = new format();
+      }
+      this.formats_.push(format);
+      this.readAsBuffer_ =
+        this.readAsBuffer_ || format.getType() === FormatType.ARRAY_BUFFER;
+    }
 
     /**
      * @private
@@ -139,10 +162,18 @@ class DragAndDrop extends Interaction {
       projection = view.getProjection();
     }
 
-    const formatConstructors = this.formatConstructors_;
-    for (let i = 0, ii = formatConstructors.length; i < ii; ++i) {
-      const format = new formatConstructors[i]();
-      const features = this.tryReadFeatures_(format, result, {
+    let text;
+    const formats = this.formats_;
+    for (let i = 0, ii = formats.length; i < ii; ++i) {
+      const format = formats[i];
+      let input = result;
+      if (this.readAsBuffer_ && format.getType() !== FormatType.ARRAY_BUFFER) {
+        if (text === undefined) {
+          text = new TextDecoder().decode(result);
+        }
+        input = text;
+      }
+      const features = this.tryReadFeatures_(format, input, {
         featureProjection: projection,
       });
       if (features && features.length > 0) {
@@ -249,9 +280,13 @@ class DragAndDrop extends Interaction {
         EventType.LOAD,
         this.handleResult_.bind(this, file)
       );
+      if (this.readAsBuffer_) {
+        reader.readAsArrayBuffer(file);
+      } else {
         reader.readAsText(file);
       }
     }
+  }
 
   /**
    * @param {DragEvent} event Event.

test/spec/ol/interaction/draganddrop.test.js

@@ -2,6 +2,7 @@ import DragAndDrop from '../../../../src/ol/interaction/DragAndDrop.js';
 import Event from '../../../../src/ol/events/Event.js';
 import EventTarget from '../../../../src/ol/events/Target.js';
 import GeoJSON from '../../../../src/ol/format/GeoJSON.js';
+import MVT from '../../../../src/ol/format/MVT.js';
 import VectorSource from '../../../../src/ol/source/Vector.js';
 import View from '../../../../src/ol/View.js';
 
@@ -29,8 +30,8 @@ where('FileReader').describe('ol.interaction.DragAndDrop', function () {
       expect(interaction).to.be.an(DragAndDrop);
     });
 
-    it('sets formatConstructors on the instance', function () {
-      expect(interaction.formatConstructors_).to.have.length(1);
+    it('sets formats on the instance', function () {
+      expect(interaction.formats_).to.have.length(1);
     });
 
     it('accepts a source option', function () {
@@ -88,18 +89,28 @@ where('FileReader').describe('ol.interaction.DragAndDrop', function () {
 
   describe('#handleDrop_', function () {
     let OrigFileReader;
+    let mockReadAsText;
+    let mockReadAsArrayBuffer;
 
     beforeEach(function () {
       OrigFileReader = FileReader;
+      mockReadAsText = false;
+      mockReadAsArrayBuffer = false;
 
       class MockFileReader extends EventTarget {
         constructor() {
           super(...arguments);
         }
         readAsText(file) {
+          mockReadAsText = true;
           this.result = file;
           this.dispatchEvent('load');
         }
+        readAsArrayBuffer(file) {
+          mockReadAsArrayBuffer = true;
+          this.result = new TextEncoder().encode(file).buffer;
+          this.dispatchEvent('load');
+        }
       }
       FileReader = MockFileReader;
     });
@@ -108,9 +119,11 @@ where('FileReader').describe('ol.interaction.DragAndDrop', function () {
       FileReader = OrigFileReader;
     });
 
-    it('reads dropped files', function (done) {
+    it('reads dropped files as text', function (done) {
       interaction.on('addfeatures', function (evt) {
         expect(evt.features.length).to.be(1);
+        expect(mockReadAsText).to.be(true);
+        expect(mockReadAsArrayBuffer).to.be(false);
         done();
       });
       interaction.setMap(map);
@@ -135,6 +148,121 @@ where('FileReader').describe('ol.interaction.DragAndDrop', function () {
       expect(event.propagationStopped).to.be(true);
     });
 
+    it('reads dropped files as arraybuffer', function (done) {
+      const drop = new DragAndDrop({
+        formatConstructors: [GeoJSON, MVT],
+      });
+      drop.setMap(map);
+
+      drop.on('addfeatures', function (evt) {
+        expect(evt.features.length).to.be(1);
+        expect(mockReadAsText).to.be(false);
+        expect(mockReadAsArrayBuffer).to.be(true);
+        done();
+      });
+
+      const event = new Event();
+      event.dataTransfer = {};
+      event.type = 'dragenter';
+      viewport.dispatchEvent(event);
+      event.type = 'dragover';
+      viewport.dispatchEvent(event);
+      event.type = 'drop';
+      event.dataTransfer.files = {
+        length: 1,
+        item: function () {
+          return JSON.stringify({
+            type: 'FeatureCollection',
+            features: [{type: 'Feature', id: '1'}],
+          });
+        },
+      };
+      viewport.dispatchEvent(event);
+      expect(event.dataTransfer.dropEffect).to.be('copy');
+      expect(event.propagationStopped).to.be(true);
+    });
+
+    it('reads using constructed formats', function (done) {
+      const drop = new DragAndDrop({
+        formatConstructors: [new GeoJSON()],
+      });
+      drop.setMap(map);
+
+      drop.on('addfeatures', function (evt) {
+        expect(evt.features.length).to.be(1);
+        expect(mockReadAsText).to.be(true);
+        expect(mockReadAsArrayBuffer).to.be(false);
+        done();
+      });
+
+      const event = new Event();
+      event.dataTransfer = {};
+      event.type = 'dragenter';
+      viewport.dispatchEvent(event);
+      event.type = 'dragover';
+      viewport.dispatchEvent(event);
+      event.type = 'drop';
+      event.dataTransfer.files = {
+        length: 1,
+        item: function () {
+          return JSON.stringify({
+            type: 'FeatureCollection',
+            features: [{type: 'Feature', id: '1'}],
+          });
+        },
+      };
+      viewport.dispatchEvent(event);
+      expect(event.dataTransfer.dropEffect).to.be('copy');
+      expect(event.propagationStopped).to.be(true);
+    });
+
+    it('reads using arraybuffer formats', function (done) {
+      class binaryGeoJSON extends GeoJSON {
+        constructor(options) {
+          super(options);
+        }
+        getType() {
+          return 'arraybuffer';
+        }
+        readFeatures(source, options) {
+          const data = new TextDecoder().decode(source);
+          return super.readFeatures(data, options);
+        }
+      }
+
+      const drop = new DragAndDrop({
+        formatConstructors: [binaryGeoJSON],
+      });
+      drop.setMap(map);
+
+      drop.on('addfeatures', function (evt) {
+        expect(evt.features.length).to.be(1);
+        expect(mockReadAsText).to.be(false);
+        expect(mockReadAsArrayBuffer).to.be(true);
+        done();
+      });
+
+      const event = new Event();
+      event.dataTransfer = {};
+      event.type = 'dragenter';
+      viewport.dispatchEvent(event);
+      event.type = 'dragover';
+      viewport.dispatchEvent(event);
+      event.type = 'drop';
+      event.dataTransfer.files = {
+        length: 1,
+        item: function () {
+          return JSON.stringify({
+            type: 'FeatureCollection',
+            features: [{type: 'Feature', id: '1'}],
+          });
+        },
+      };
+      viewport.dispatchEvent(event);
+      expect(event.dataTransfer.dropEffect).to.be('copy');
+      expect(event.propagationStopped).to.be(true);
+    });
+
     it('adds dropped features to a source', function (done) {
       const source = new VectorSource();
       const drop = new DragAndDrop({