@geoext/geoext/src/data/serializer/XYZ.js

GeoExt is Open Source and enables building desktop-like GIS applications through the web. It is a JavaScript framework that combines the GIS functionality of OpenLayers with the user interface savvy of the ExtJS library provided by Sencha.

/* Copyright (c) 2015-present The Open Source Geospatial Foundation
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/**
 * A serializer for layers that have an `ol.source.XYZ` source.
 * Sources with an tileUrlFunction are currently not supported.
 *
 * @class GeoExt.data.serializer.XYZ
 */
Ext.define(
  'GeoExt.data.serializer.XYZ',
  {
    extend: 'GeoExt.data.serializer.Base',
    mixins: ['GeoExt.mixin.SymbolCheck'],

    symbols: [
      'ol.layer.Base#getOpacity',
      'ol.size.toSize',
      'ol.source.XYZ',
      'ol.source.XYZ#getTileGrid',
      'ol.source.XYZ#getUrls',
      'ol.tilegrid.TileGrid#getResolutions',
      'ol.tilegrid.TileGrid#getTileSize',
    ],

    inheritableStatics: {
      /**
       *
       */
      allowedImageExtensions: ['png', 'jpg', 'gif'],

      /**
       * @inheritdoc
       */
      sourceCls: ol.source.XYZ,

      /**
       * @inheritdoc
       */
      validateSource: function (source) {
        if (!(source instanceof this.sourceCls)) {
          Ext.raise('Cannot serialize this source with this serializer');
        }
        if (source.getUrls() === null) {
          Ext.raise(
            'Cannot serialize this source without an URL. ' +
              'Usage of tileUrlFunction is not yet supported',
          );
        }
      },

      /**
       * @inheritdoc
       */
      serialize: function (layer, source) {
        this.validateSource(source);
        const tileGrid = source.getTileGrid();
        const serialized = {
          baseURL: source.getUrls()[0],
          opacity: layer.getOpacity(),
          imageExtension: this.getImageExtensionFromSource(source) || 'png',
          resolutions: tileGrid.getResolutions(),
          tileSize: ol.size.toSize(tileGrid.getTileSize()),
          type: 'OSM',
        };
        return serialized;
      },

      /**
       * Returns the file extension from the url and compares it to whitelist.
       * Sources with an tileUrlFunction are currently not supported.
       *
       * @private
       * @param {ol.source.XYZ} source An ol.source.XYZ.
       * @return {string} The fileExtension or `false` if none is found.
       */
      getImageExtensionFromSource: function (source) {
        const urls = source.getUrls();
        const url = urls ? urls[0] : '';
        const extension = url.substr(url.length - 3);

        if (
          Ext.isDefined(url) &&
          Ext.Array.contains(this.allowedImageExtensions, extension)
        ) {
          return extension;
        }
        Ext.raise('No url(s) supplied for ', source);
        return false;
      },
    },
  },
  function (cls) {
    // Register this serializer via the inherited method `register`.
    cls.register(cls);
  },
);