Add supported media type list to feature formats

examples/ogc-vector-tiles.js

@@ -10,7 +10,6 @@ const map = new Map({
     new VectorTileLayer({
       source: new OGCVectorTile({
         url: 'https://maps.ecere.com/ogcapi/collections/NaturalEarth:cultural:ne_10m_admin_0_countries/tiles/WebMercatorQuad',
-        mediaType: 'application/vnd.mapbox-vector-tile',
         format: new MVT(),
       }),
     }),

src/ol/format/Feature.js

@@ -76,6 +76,12 @@ class FeatureFormat {
      * @type {import("../proj/Projection.js").default|undefined}
      */
     this.defaultFeatureProjection = undefined;
+
+    /**
+     * A list media types supported by the format in descending order of preference.
+     * @type {Array<string>}
+     */
+    this.supportedMediaTypes = null;
   }
 
   /**

src/ol/format/GMLBase.js

@@ -132,6 +132,8 @@ class GMLBase extends XMLFeature {
       'featureMember': makeArrayPusher(this.readFeaturesInternal),
       'featureMembers': makeReplacer(this.readFeaturesInternal),
     };
+
+    this.supportedMediaTypes = ['application/gml+xml'];
   }
 
   /**

src/ol/format/GeoJSON.js

@@ -82,6 +82,11 @@ class GeoJSON extends JSONFeature {
      * @private
      */
     this.extractGeometryName_ = options.extractGeometryName;
+
+    this.supportedMediaTypes = [
+      'application/geo+json',
+      'application/vnd.geo+json',
+    ];
   }
 
   /**

src/ol/format/KML.js

@@ -489,6 +489,8 @@ class KML extends XMLFeature {
     this.iconUrlFunction_ = options.iconUrlFunction
       ? options.iconUrlFunction
       : defaultIconUrlFunction;
+
+    this.supportedMediaTypes = ['application/vnd.google-earth.kml+xml'];
   }
 
   /**

src/ol/format/MVT.js

@@ -89,6 +89,11 @@ class MVT extends FeatureFormat {
      * @type {string}
      */
     this.idProperty_ = options.idProperty;
+
+    this.supportedMediaTypes = [
+      'application/vnd.mapbox-vector-tile',
+      'application/x-protobuf',
+    ];
   }
 
   /**

src/ol/source/OGCVectorTile.js

@@ -13,8 +13,7 @@ import {getTileSetInfo} from './ogcTileUtil.js';
  * (zoom level), `{tileRow}`, and `{tileCol}` variables in the URL will always be provided by the source.
  * @property {import("../format/Feature.js").default} format Feature parser for tiles.
  * @property {string} [mediaType] The content type for the tiles (e.g. "application/vnd.mapbox-vector-tile").  If not provided,
- * the source will try to find a link with rel="item" that uses a supported vector type.  The chosen media type
- * must be parseable by the configured format.
+ * the source will try to find a link with rel="item" that uses a vector type supported by the configured format.
  * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
  * @property {boolean} [attributionsCollapsible=true] Attributions are collapsible.
  * @property {number} [cacheSize] Initial tile cache size. Will auto-grow to hold at least twice the number of tiles in the viewport.
@@ -41,6 +40,10 @@ import {getTileSetInfo} from './ogcTileUtil.js';
  * Layer source for map tiles from an [OGC API - Tiles](https://ogcapi.ogc.org/tiles/) service that provides "vector" type tiles.
  * The service must conform to at least the core (http://www.opengis.net/spec/ogcapi-tiles-1/1.0/conf/core)
  * and tileset (http://www.opengis.net/spec/ogcapi-tiles-1/1.0/conf/tileset) conformance classes.
+ *
+ * Vector tile sets may come in a variety of formats (e.g. GeoJSON, MVT).  The `format` option is used to determine
+ * which of the advertised media types is used.  If you need to force the use of a particular media type, you can
+ * provide the `mediaType` option.
  */
 class OGCVectorTile extends VectorTile {
   /**
@@ -65,6 +68,7 @@ class OGCVectorTile extends VectorTile {
       url: options.url,
       projection: this.getProjection(),
       mediaType: options.mediaType,
+      supportedMediaTypes: options.format.supportedMediaTypes,
       context: options.context || null,
     };
 

src/ol/source/ogcTileUtil.js

@@ -93,6 +93,7 @@ const knownVectorMediaTypes = {
  * @typedef {Object} SourceInfo
  * @property {string} url The tile set URL.
  * @property {string} mediaType The preferred tile media type.
+ * @property {Array<string>} [supportedMediaTypes] The supported media types.
  * @property {import("../proj/Projection.js").default} projection The source projection.
  * @property {Object} [context] Optional context for constructing the URL.
  */
@@ -134,13 +135,26 @@ export function getMapTileUrlTemplate(links, mediaType) {
 /**
  * @param {Array<Link>} links Tileset links.
  * @param {string} [mediaType] The preferred media type.
+ * @param {Array<string>} [supportedMediaTypes] The media types supported by the parser.
  * @return {string} The tile URL template.
  */
-export function getVectorTileUrlTemplate(links, mediaType) {
+export function getVectorTileUrlTemplate(
+  links,
+  mediaType,
+  supportedMediaTypes
+) {
   let tileUrlTemplate;
   let fallbackUrlTemplate;
+
+  /**
+   * Lookup of URL by media type.
+   * @type {Object<string, string>}
+   */
+  const hrefLookup = {};
+
   for (let i = 0; i < links.length; ++i) {
     const link = links[i];
+    hrefLookup[link.type] = link.href;
     if (link.rel === 'item') {
       if (link.type === mediaType) {
         tileUrlTemplate = link.href;
@@ -152,6 +166,16 @@ export function getVectorTileUrlTemplate(links, mediaType) {
     }
   }
 
+  if (!tileUrlTemplate && supportedMediaTypes) {
+    for (let i = 0; i < supportedMediaTypes.length; ++i) {
+      const supportedMediaType = supportedMediaTypes[i];
+      if (hrefLookup[supportedMediaType]) {
+        tileUrlTemplate = hrefLookup[supportedMediaType];
+        break;
+      }
+    }
+  }
+
   if (!tileUrlTemplate) {
     if (fallbackUrlTemplate) {
       tileUrlTemplate = fallbackUrlTemplate;
@@ -333,7 +357,8 @@ function parseTileSetMetadata(sourceInfo, tileSet) {
   } else if (tileSet.dataType === 'vector') {
     tileUrlTemplate = getVectorTileUrlTemplate(
       tileSet.links,
-      sourceInfo.mediaType
+      sourceInfo.mediaType,
+      sourceInfo.supportedMediaTypes
     );
   } else {
     throw new Error('Expected tileset data type to be "map" or "vector"');

test/node/ol/source/ogcTileUtil.test.js

@@ -143,6 +143,48 @@ describe('ol/source/ogcTileUtil.js', () => {
         'https://maps.ecere.com/ogcapi/collections/NaturalEarth:cultural:ne_10m_admin_0_countries/tiles/WebMercatorQuad/3/1/2.mvt'
       );
     });
+
+    it('uses supported media types if available', async () => {
+      baseUrl = 'https://maps.ecere.com/';
+      const sourceInfo = {
+        url: 'https://maps.ecere.com/ogcapi/collections/ne_10m_admin_0_countries/tiles/WebMercatorQuad',
+        supportedMediaTypes: [
+          'bogus-media-type',
+          'application/vnd.mapbox-vector-tile',
+          'application/geo+json', // should not be used
+        ],
+      };
+      const tileInfo = await getTileSetInfo(sourceInfo);
+      expect(tileInfo).to.be.an(Object);
+      expect(tileInfo.urlTemplate).to.be(
+        '/ogcapi/collections/NaturalEarth:cultural:ne_10m_admin_0_countries/tiles/WebMercatorQuad/{tileMatrix}/{tileRow}/{tileCol}.mvt'
+      );
+      expect(tileInfo.urlFunction).to.be.a(Function);
+      expect(tileInfo.urlFunction([3, 2, 1])).to.be(
+        'https://maps.ecere.com/ogcapi/collections/NaturalEarth:cultural:ne_10m_admin_0_countries/tiles/WebMercatorQuad/3/1/2.mvt'
+      );
+    });
+
+    it('treats supported media types in descending order of priority', async () => {
+      baseUrl = 'https://maps.ecere.com/';
+      const sourceInfo = {
+        url: 'https://maps.ecere.com/ogcapi/collections/ne_10m_admin_0_countries/tiles/WebMercatorQuad',
+        supportedMediaTypes: [
+          'bogus-media-type',
+          'application/geo+json', // should be preferred
+          'application/vnd.mapbox-vector-tile',
+        ],
+      };
+      const tileInfo = await getTileSetInfo(sourceInfo);
+      expect(tileInfo).to.be.an(Object);
+      expect(tileInfo.urlTemplate).to.be(
+        '/ogcapi/collections/NaturalEarth:cultural:ne_10m_admin_0_countries/tiles/WebMercatorQuad/{tileMatrix}/{tileRow}/{tileCol}.json'
+      );
+      expect(tileInfo.urlFunction).to.be.a(Function);
+      expect(tileInfo.urlFunction([3, 2, 1])).to.be(
+        'https://maps.ecere.com/ogcapi/collections/NaturalEarth:cultural:ne_10m_admin_0_countries/tiles/WebMercatorQuad/3/1/2.json'
+      );
+    });
   });
 
   describe('getVectorTileUrlTemplate()', () => {
@@ -173,6 +215,15 @@ describe('ol/source/ogcTileUtil.js', () => {
       );
     });
 
+    it('uses supported media types is preferred media type is not given', () => {
+      const urlTemplate = getVectorTileUrlTemplate(links, undefined, [
+        'application/vnd.mapbox-vector-tile',
+      ]);
+      expect(urlTemplate).to.be(
+        '/ogcapi/collections/NaturalEarth:cultural:ne_10m_admin_0_countries/tiles/WebMercatorQuad/{tileMatrix}/{tileRow}/{tileCol}.mvt'
+      );
+    });
+
     it('throws if it cannot find preferred media type or a known fallback', () => {
       function call() {
         getVectorTileUrlTemplate([], 'application/vnd.mapbox-vector-tile');