itowns/lib/Provider/URLBuilder.js

A JS/WebGL framework for 3D geospatial data visualization

let subDomainsCount = 0;

/**
 * @param {string} url
 * @returns {string}
 */
function subDomains(url) {
  const subDomainsPtrn = /\$\{u:([\w-_.|]+)\}/.exec(url);
  if (!subDomainsPtrn) {
    return url;
  }
  const subDomainsList = subDomainsPtrn[1].split('|');
  return url.replace(subDomainsPtrn[0], subDomainsList[subDomainsCount++ % subDomainsList.length]);
}

/**
 * This module performs basic operations around urls, to replace some elements
 * in it by coordinates or other things.
 *
 * In an url, it is also possible to specify subdomains alternatives using the
 * `${u:a|b|c}` pattern, by separating differents options using `|`. It will go
 * through the following alternative each time (no random). For example
 * `https://${u:xyz.org|yzx.org|zxy.org}/${z}/${x}/${y}.png` or
 * `https://${u:a|b|c}.tile.openstreetmap.org/${z}/${x}/${y}.png`.
 *
 * @module URLBuilder
 */
export default {
  subDomains,
  /**
   * Builds an URL knowing the coordinates and the source to query.
   * <br><br>
   * The source object needs to have an url property, which should have some
   * specific strings that will be replaced by coordinates.
   * <ul>
   * <li>`${x}` or `%COL` will be replaced by `coords.col`</li>
   * <li>`${y}` or `%ROW` will be replaced by `coords.row`</li>
   * <li>`${z}` or `%TILEMATRIX` will be replaced by `coords.zoom`</li>
   * </ul>
   *
   * @example
   * coords = new Extent(CRS.formatToTms('EPSG:4326'), 12, 1410, 2072);
   * source.url = 'http://server.geo/wmts/SERVICE=WMTS&TILEMATRIX=%TILEMATRIX&TILEROW=%ROW&TILECOL=%COL';
   * url = URLBuilder.xyz(coords, source);
   *
   * // The resulting url is:
   * // http://server.geo/wmts/SERVICE=WMTS&TILEMATRIX=12&TILEROW=1410&TILECOL=2072;
   *
   * @example
   * coords = new Extent('TMS', 15, 2142, 3412);
   * source.url = 'http://server.geo/tms/${z}/${y}/${x}.jpg';
   * url = URLBuilder.xyz(coords, source);
   *
   * // The resulting url is:
   * // http://server.geo/tms/15/2142/3412.jpg;
   *
   * @param {Object} coords - tile coordinates
   * @param {number} coords.row - tile row
   * @param {number} coords.col - tile column
   * @param {number} coords.zoom - tile zoom
   * @param {Object} source
   * @param {string} source.url
   * @param {Function} source.tileMatrixCallback
   *
   * @return {string} the formed url
   */
  xyz: function (coords, source) {
    return subDomains(source.url.replace(/(\$\{z\}|%TILEMATRIX)/, source.tileMatrixCallback(coords.zoom)).replace(/(\$\{y\}|%ROW)/, coords.row).replace(/(\$\{x\}|%COL)/, coords.col));
  },
  /**
   * Builds an URL knowing the bounding box and the source to query.
   * <br><br>
   * The source object needs to have an url property, which should have the
   * string `%bbox` in it. This string will be replaced by the four cardinal
   * points composing the bounding box.
   * <br><br>
   * Order of the points can be specified in the `axisOrder` property in
   * source, using the letters `w, s, e, n` respectively for `WEST, SOUTH,
   * EAST, NORTH`. The default order is `wsen`.
   *
   * @example
   * extent = new Extent('EPSG:4326', 12, 14, 35, 46);
   * source.crs = 'EPSG:4326';
   * source.url = 'http://server.geo/wms/BBOX=%bbox&FORMAT=jpg&SERVICE=WMS';
   * url = URLBuilder.bbox(extent, source);
   *
   * // The resulting url is:
   * // http://server.geo/wms/BBOX=12,35,14,46&FORMAT=jpg&SERVICE=WMS
   *
   * @param {Object} bbox - the bounding box
   * @param {number} bbox.west
   * @param {number} bbox.south
   * @param {number} bbox.east
   * @param {number} bbox.north
   * @param {Object} source - the source of data
   * @param {string} source.crs
   * @param {number} source.bboxDigits
   * @param {string} source.url
   * @param {string} source.axisOrder
   *
   * @return {string} the formed url
   */
  bbox: function (bbox, source) {
    let precision = source.crs == 'EPSG:4326' ? 9 : 2;
    if (source.bboxDigits !== undefined) {
      precision = source.bboxDigits;
    }
    const w = bbox.west.toFixed(precision);
    const s = bbox.south.toFixed(precision);
    const e = bbox.east.toFixed(precision);
    const n = bbox.north.toFixed(precision);
    let bboxInUnit = source.axisOrder || 'wsen';
    bboxInUnit = bboxInUnit.replace('w', `${w},`).replace('s', `${s},`).replace('e', `${e},`).replace('n', `${n},`).slice(0, -1);
    return subDomains(source.url.replace('%bbox', bboxInUnit));
  }
};