heli-agri/lib/source/Source.js

HeliAgri is a high-performance, feature-packed library for creating interactive maps on the web. It can display map tiles, vector data and markers loaded from any source on any web page. OpenLayers has been developed to further the use of geographic infor

/**
 * @module ol/source/Source
 */
import BaseObject from '../Object.js';
import {get as getProjection} from '../proj.js';

/**
 * @typedef {'undefined' | 'loading' | 'ready' | 'error'} State
 * State of the source, one of 'undefined', 'loading', 'ready' or 'error'.
 */

/**
 * A function that takes a {@link import("../View.js").ViewStateLayerStateExtent} and returns a string or
 * an array of strings representing source attributions.
 *
 * @typedef {function(import("../View.js").ViewStateLayerStateExtent): (string|Array<string>)} Attribution
 */

/**
 * A type that can be used to provide attribution information for data sources.
 *
 * It represents either
 * * a simple string (e.g. `'© Acme Inc.'`)
 * * an array of simple strings (e.g. `['© Acme Inc.', '© Bacme Inc.']`)
 * * a function that returns a string or array of strings ({@link module:ol/source/Source~Attribution})
 *
 * @typedef {string|Array<string>|Attribution} AttributionLike
 */

/**
 * @typedef {Object} Options
 * @property {AttributionLike} [attributions] Attributions.
 * @property {boolean} [attributionsCollapsible=true] Attributions are collapsible.
 * @property {import("../proj.js").ProjectionLike} [projection] Projection. Default is the view projection.
 * @property {import("./Source.js").State} [state='ready'] State.
 * @property {boolean} [wrapX=false] WrapX.
 * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
 * the nearest neighbor is used when resampling.
 */

/**
 * @classdesc
 * Abstract base class; normally only used for creating subclasses and not
 * instantiated in apps.
 * Base class for {@link module:ol/layer/Layer~Layer} sources.
 *
 * A generic `change` event is triggered when the state of the source changes.
 * @abstract
 * @api
 */
class Source extends BaseObject {
  /**
   * @param {Options} options Source options.
   */
  constructor(options) {
    super();

    /**
     * @protected
     * @type {import("../proj/Projection.js").default|null}
     */
    this.projection = getProjection(options.projection);

    /**
     * @private
     * @type {?Attribution}
     */
    this.attributions_ = adaptAttributions(options.attributions);

    /**
     * @private
     * @type {boolean}
     */
    this.attributionsCollapsible_ =
      options.attributionsCollapsible !== undefined
        ? options.attributionsCollapsible
        : true;

    /**
     * This source is currently loading data. Sources that defer loading to the
     * map's tile queue never set this to `true`.
     * @type {boolean}
     */
    this.loading = false;

    /**
     * @private
     * @type {import("./Source.js").State}
     */
    this.state_ = options.state !== undefined ? options.state : 'ready';

    /**
     * @private
     * @type {boolean}
     */
    this.wrapX_ = options.wrapX !== undefined ? options.wrapX : false;

    /**
     * @private
     * @type {boolean}
     */
    this.interpolate_ = !!options.interpolate;

    /**
     * @protected
     * @type {function(import("../View.js").ViewOptions):void}
     */
    this.viewResolver = null;

    /**
     * @protected
     * @type {function(Error):void}
     */
    this.viewRejector = null;

    const self = this;
    /**
     * @private
     * @type {Promise<import("../View.js").ViewOptions>}
     */
    this.viewPromise_ = new Promise(function (resolve, reject) {
      self.viewResolver = resolve;
      self.viewRejector = reject;
    });
  }

  /**
   * Get the attribution function for the source.
   * @return {?Attribution} Attribution function.
   * @api
   */
  getAttributions() {
    return this.attributions_;
  }

  /**
   * @return {boolean} Attributions are collapsible.
   * @api
   */
  getAttributionsCollapsible() {
    return this.attributionsCollapsible_;
  }

  /**
   * Get the projection of the source.
   * @return {import("../proj/Projection.js").default|null} Projection.
   * @api
   */
  getProjection() {
    return this.projection;
  }

  /**
   * @param {import("../proj/Projection").default} [projection] Projection.
   * @return {Array<number>|null} Resolutions.
   */
  getResolutions(projection) {
    return null;
  }

  /**
   * @return {Promise<import("../View.js").ViewOptions>} A promise for view-related properties.
   */
  getView() {
    return this.viewPromise_;
  }

  /**
   * Get the state of the source, see {@link import("./Source.js").State} for possible states.
   * @return {import("./Source.js").State} State.
   * @api
   */
  getState() {
    return this.state_;
  }

  /**
   * @return {boolean|undefined} Wrap X.
   */
  getWrapX() {
    return this.wrapX_;
  }

  /**
   * @return {boolean} Use linear interpolation when resampling.
   */
  getInterpolate() {
    return this.interpolate_;
  }

  /**
   * Refreshes the source. The source will be cleared, and data from the server will be reloaded.
   * @api
   */
  refresh() {
    this.changed();
  }

  /**
   * Set the attributions of the source.
   * @param {AttributionLike|undefined} attributions Attributions.
   *     Can be passed as `string`, `Array<string>`, {@link module:ol/source/Source~Attribution},
   *     or `undefined`.
   * @api
   */
  setAttributions(attributions) {
    this.attributions_ = adaptAttributions(attributions);
    this.changed();
  }

  /**
   * Set the state of the source.
   * @param {import("./Source.js").State} state State.
   */
  setState(state) {
    this.state_ = state;
    this.changed();
  }
}

/**
 * Turns the attributions option into an attributions function.
 * @param {AttributionLike|undefined} attributionLike The attribution option.
 * @return {Attribution|null} An attribution function (or null).
 */
function adaptAttributions(attributionLike) {
  if (!attributionLike) {
    return null;
  }
  if (Array.isArray(attributionLike)) {
    return function (frameState) {
      return attributionLike;
    };
  }

  if (typeof attributionLike === 'function') {
    return attributionLike;
  }

  return function (frameState) {
    return [attributionLike];
  };
}

export default Source;