c8y-openlayer/ol/image.js

This module is designed to help integrate Openlayer with Cumulocity IoT

import _ol_ from './index.js';
import _ol_ImageBase_ from './imagebase.js';
import _ol_ImageState_ from './imagestate.js';
import _ol_events_ from './events.js';
import _ol_events_EventType_ from './events/eventtype.js';
import _ol_extent_ from './extent.js';

/**
 * @constructor
 * @extends {ol.ImageBase}
 * @param {ol.Extent} extent Extent.
 * @param {number|undefined} resolution Resolution.
 * @param {number} pixelRatio Pixel ratio.
 * @param {string} src Image source URI.
 * @param {?string} crossOrigin Cross origin.
 * @param {ol.ImageLoadFunctionType} imageLoadFunction Image load function.
 */
var _ol_Image_ = function(extent, resolution, pixelRatio, src, crossOrigin, imageLoadFunction) {

  _ol_ImageBase_.call(this, extent, resolution, pixelRatio, _ol_ImageState_.IDLE);

  /**
   * @private
   * @type {string}
   */
  this.src_ = src;

  /**
   * @private
   * @type {HTMLCanvasElement|Image|HTMLVideoElement}
   */
  this.image_ = new Image();
  if (crossOrigin !== null) {
    this.image_.crossOrigin = crossOrigin;
  }

  /**
   * @private
   * @type {Array.<ol.EventsKey>}
   */
  this.imageListenerKeys_ = null;

  /**
   * @protected
   * @type {ol.ImageState}
   */
  this.state = _ol_ImageState_.IDLE;

  /**
   * @private
   * @type {ol.ImageLoadFunctionType}
   */
  this.imageLoadFunction_ = imageLoadFunction;

};

_ol_.inherits(_ol_Image_, _ol_ImageBase_);


/**
 * @inheritDoc
 * @api
 */
_ol_Image_.prototype.getImage = function() {
  return this.image_;
};


/**
 * Tracks loading or read errors.
 *
 * @private
 */
_ol_Image_.prototype.handleImageError_ = function() {
  this.state = _ol_ImageState_.ERROR;
  this.unlistenImage_();
  this.changed();
};


/**
 * Tracks successful image load.
 *
 * @private
 */
_ol_Image_.prototype.handleImageLoad_ = function() {
  if (this.resolution === undefined) {
    this.resolution = _ol_extent_.getHeight(this.extent) / this.image_.height;
  }
  this.state = _ol_ImageState_.LOADED;
  this.unlistenImage_();
  this.changed();
};


/**
 * Load the image or retry if loading previously failed.
 * Loading is taken care of by the tile queue, and calling this method is
 * only needed for preloading or for reloading in case of an error.
 * @override
 * @api
 */
_ol_Image_.prototype.load = function() {
  if (this.state == _ol_ImageState_.IDLE || this.state == _ol_ImageState_.ERROR) {
    this.state = _ol_ImageState_.LOADING;
    this.changed();
    this.imageListenerKeys_ = [
      _ol_events_.listenOnce(this.image_, _ol_events_EventType_.ERROR,
          this.handleImageError_, this),
      _ol_events_.listenOnce(this.image_, _ol_events_EventType_.LOAD,
          this.handleImageLoad_, this)
    ];
    this.imageLoadFunction_(this, this.src_);
  }
};


/**
 * @param {HTMLCanvasElement|Image|HTMLVideoElement} image Image.
 */
_ol_Image_.prototype.setImage = function(image) {
  this.image_ = image;
};


/**
 * Discards event handlers which listen for load completion or errors.
 *
 * @private
 */
_ol_Image_.prototype.unlistenImage_ = function() {
  this.imageListenerKeys_.forEach(_ol_events_.unlistenByKey);
  this.imageListenerKeys_ = null;
};
export default _ol_Image_;