constructor(options, itemData, index, pswp) {
    this.pswp = pswp;
    this.options = options;
    this.itemData = itemData;
    this.index = index;
    /** @type { Point | null } */

    this.panAreaSize = null;
    /** @type { Point | null } */

    this.elementSize = null;
    this.fit = 1;
    this.fill = 1;
    this.vFill = 1;
    this.initial = 1;
    this.secondary = 1;
    this.max = 1;
    this.min = 1;
  }
@param {PhotoSwipeOptions} options PhotoSwipe options
@param {SlideData} itemData Slide data
@param {number} index Slide index
@param {PhotoSwipe} [pswp] PhotoSwipe instance, can be undefined if not initialized yet