heli-agri/lib/source/ImageArcGISRest.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/ImageArcGISRest
 */

import EventType from '../events/EventType.js';
import ImageSource, {defaultImageLoadFunction} from './Image.js';
import ImageWrapper from '../Image.js';
import {appendParams} from '../uri.js';
import {assert} from '../asserts.js';
import {containsExtent, getHeight, getWidth} from '../extent.js';
import {createCanvasContext2D} from '../dom.js';

/**
 * @typedef {Object} Options
 * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
 * @property {null|string} [crossOrigin] The `crossOrigin` attribute for loaded images.  Note that
 * you must provide a `crossOrigin` value if you want to access pixel data with the Canvas renderer.
 * See https://developer.mozilla.org/en-US/docs/Web/HTML/CORS_enabled_image for more detail.
 * @property {boolean} [hidpi=true] Use the `ol/Map#pixelRatio` value when requesting the image from
 * the remote server.
 * @property {import("../Image.js").LoadFunction} [imageLoadFunction] Optional function to load an image given
 * a URL.
 * @property {boolean} [interpolate=true] Use interpolated values when resampling.  By default,
 * linear interpolation is used when resampling.  Set to false to use the nearest neighbor instead.
 * @property {Object<string,*>} [params] ArcGIS Rest parameters. This field is optional. Service
 * defaults will be used for any fields not specified. `FORMAT` is `PNG32` by default. `F` is
 * `IMAGE` by default. `TRANSPARENT` is `true` by default.  `BBOX`, `SIZE`, `BBOXSR`, and `IMAGESR`
 * will be set dynamically. Set `LAYERS` to override the default service layer visibility. See
 * https://developers.arcgis.com/rest/services-reference/export-map.htm
 * for further reference.
 * @property {import("../proj.js").ProjectionLike} [projection] Projection. Default is the view projection.
 * The projection code must contain a numeric end portion separated by :
 * or the entire code must form a valid ArcGIS SpatialReference definition.
 * @property {number} [ratio=1.5] Ratio. `1` means image requests are the size of the map viewport,
 * `2` means twice the size of the map viewport, and so on.
 * @property {Array<number>} [resolutions] Resolutions. If specified, requests will be made for
 * these resolutions only.
 * @property {string} [url] ArcGIS Rest service URL for a Map Service or Image Service. The url
 * should include /MapServer or /ImageServer.
 */

/**
 * @classdesc
 * Source for data from ArcGIS Rest services providing single, untiled images.
 * Useful when underlying map service has labels.
 *
 * If underlying map service is not using labels,
 * take advantage of ol image caching and use
 * {@link module:ol/source/TileArcGISRest~TileArcGISRest} data source.
 *
 * @fires module:ol/source/Image.ImageSourceEvent
 * @api
 */
class ImageArcGISRest extends ImageSource {
  /**
   * @param {Options} [options] Image ArcGIS Rest Options.
   */
  constructor(options) {
    options = options ? options : {};

    super({
      attributions: options.attributions,
      interpolate: options.interpolate,
      projection: options.projection,
      resolutions: options.resolutions,
    });

    /**
     * @private
     * @type {CanvasRenderingContext2D}
     */
    this.context_ = createCanvasContext2D(1, 1);

    /**
     * @private
     * @type {?string}
     */
    this.crossOrigin_ =
      options.crossOrigin !== undefined ? options.crossOrigin : null;

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

    /**
     * @private
     * @type {string|undefined}
     */
    this.url_ = options.url;

    /**
     * @private
     * @type {import("../Image.js").LoadFunction}
     */
    this.imageLoadFunction_ =
      options.imageLoadFunction !== undefined
        ? options.imageLoadFunction
        : defaultImageLoadFunction;

    /**
     * @private
     * @type {!Object}
     */
    this.params_ = options.params || {};

    /**
     * @private
     * @type {import("../Image.js").default}
     */
    this.image_ = null;

    /**
     * @private
     * @type {import("../size.js").Size}
     */
    this.imageSize_ = [0, 0];

    /**
     * @private
     * @type {number}
     */
    this.renderedRevision_ = 0;

    /**
     * @private
     * @type {number}
     */
    this.ratio_ = options.ratio !== undefined ? options.ratio : 1.5;
  }

  /**
   * Get the user-provided params, i.e. those passed to the constructor through
   * the "params" option, and possibly updated using the updateParams method.
   * @return {Object} Params.
   * @api
   */
  getParams() {
    return this.params_;
  }

  /**
   * @param {import("../extent.js").Extent} extent Extent.
   * @param {number} resolution Resolution.
   * @param {number} pixelRatio Pixel ratio.
   * @param {import("../proj/Projection.js").default} projection Projection.
   * @return {import("../Image.js").default} Single image.
   */
  getImageInternal(extent, resolution, pixelRatio, projection) {
    if (this.url_ === undefined) {
      return null;
    }

    resolution = this.findNearestResolution(resolution);
    pixelRatio = this.hidpi_ ? pixelRatio : 1;

    const image = this.image_;
    if (
      image &&
      this.renderedRevision_ == this.getRevision() &&
      image.getResolution() == resolution &&
      image.getPixelRatio() == pixelRatio &&
      containsExtent(image.getExtent(), extent)
    ) {
      return image;
    }

    const params = {
      'F': 'image',
      'FORMAT': 'PNG32',
      'TRANSPARENT': true,
    };
    Object.assign(params, this.params_);

    extent = extent.slice();
    const centerX = (extent[0] + extent[2]) / 2;
    const centerY = (extent[1] + extent[3]) / 2;
    if (this.ratio_ != 1) {
      const halfWidth = (this.ratio_ * getWidth(extent)) / 2;
      const halfHeight = (this.ratio_ * getHeight(extent)) / 2;
      extent[0] = centerX - halfWidth;
      extent[1] = centerY - halfHeight;
      extent[2] = centerX + halfWidth;
      extent[3] = centerY + halfHeight;
    }

    const imageResolution = resolution / pixelRatio;

    // Compute an integer width and height.
    const width = Math.ceil(getWidth(extent) / imageResolution);
    const height = Math.ceil(getHeight(extent) / imageResolution);

    // Modify the extent to match the integer width and height.
    extent[0] = centerX - (imageResolution * width) / 2;
    extent[2] = centerX + (imageResolution * width) / 2;
    extent[1] = centerY - (imageResolution * height) / 2;
    extent[3] = centerY + (imageResolution * height) / 2;

    this.imageSize_[0] = width;
    this.imageSize_[1] = height;

    const url = this.getRequestUrl_(
      extent,
      this.imageSize_,
      pixelRatio,
      projection,
      params
    );

    this.image_ = new ImageWrapper(
      extent,
      resolution,
      pixelRatio,
      url,
      this.crossOrigin_,
      this.imageLoadFunction_,
      this.context_
    );

    this.renderedRevision_ = this.getRevision();

    this.image_.addEventListener(
      EventType.CHANGE,
      this.handleImageChange.bind(this)
    );

    return this.image_;
  }

  /**
   * Return the image load function of the source.
   * @return {import("../Image.js").LoadFunction} The image load function.
   * @api
   */
  getImageLoadFunction() {
    return this.imageLoadFunction_;
  }

  /**
   * @param {import("../extent.js").Extent} extent Extent.
   * @param {import("../size.js").Size} size Size.
   * @param {number} pixelRatio Pixel ratio.
   * @param {import("../proj/Projection.js").default} projection Projection.
   * @param {Object} params Params.
   * @return {string} Request URL.
   * @private
   */
  getRequestUrl_(extent, size, pixelRatio, projection, params) {
    // ArcGIS Server only wants the numeric portion of the projection ID.
    // (if there is no numeric portion the entire projection code must
    // form a valid ArcGIS SpatialReference definition).
    const srid = projection
      .getCode()
      .split(/:(?=\d+$)/)
      .pop();

    params['SIZE'] = size[0] + ',' + size[1];
    params['BBOX'] = extent.join(',');
    params['BBOXSR'] = srid;
    params['IMAGESR'] = srid;
    params['DPI'] = Math.round(90 * pixelRatio);

    const url = this.url_;

    const modifiedUrl = url
      .replace(/MapServer\/?$/, 'MapServer/export')
      .replace(/ImageServer\/?$/, 'ImageServer/exportImage');
    if (modifiedUrl == url) {
      assert(false, 50); // `options.featureTypes` should be an Array
    }
    return appendParams(modifiedUrl, params);
  }

  /**
   * Return the URL used for this ArcGIS source.
   * @return {string|undefined} URL.
   * @api
   */
  getUrl() {
    return this.url_;
  }

  /**
   * Set the image load function of the source.
   * @param {import("../Image.js").LoadFunction} imageLoadFunction Image load function.
   * @api
   */
  setImageLoadFunction(imageLoadFunction) {
    this.image_ = null;
    this.imageLoadFunction_ = imageLoadFunction;
    this.changed();
  }

  /**
   * Set the URL to use for requests.
   * @param {string|undefined} url URL.
   * @api
   */
  setUrl(url) {
    if (url != this.url_) {
      this.url_ = url;
      this.image_ = null;
      this.changed();
    }
  }

  /**
   * Update the user-provided params.
   * @param {Object} params Params.
   * @api
   */
  updateParams(params) {
    Object.assign(this.params_, params);
    this.image_ = null;
    this.changed();
  }
}

export default ImageArcGISRest;