​PhotoSwipe.js传入图片URL的同时，还需要配上图片的宽高，但这次的情况是无法预先知道宽高，所以先设置宽高100，然后查看或划动下一张图片的时候再更新当前图片宽高信息。

下面是做法：

<link rel="stylesheet prefetch" href="js/PhotoSwipe-master/dist/photoswipe.css">
<link rel="stylesheet prefetch" href="js/PhotoSwipe-master/dist/default-skin/default-skin.css">
<script src="js/jquery.min.js"></script>
<script src="js/PhotoSwipe-master/dist/photoswipe.js"></script>
<script src="js/PhotoSwipe-master/dist/photoswipe-ui-default.min.js"></script>
<!-- Root element of PhotoSwipe. Must have class pswp. -->
<div class="pswp" tabindex="-1" role="dialog" aria-hidden="true">
    <!-- Background of PhotoSwipe. 
         It's a separate element as animating opacity is faster than rgba(). -->
    <div class="pswp__bg"></div>
    <!-- Slides wrapper with overflow:hidden. -->
    <div class="pswp__scroll-wrap">
        <!-- Container that holds slides. 
            PhotoSwipe keeps only 3 of them in the DOM to save memory.
            Don't modify these 3 pswp__item elements, data is added later on. -->
        <div class="pswp__container">
            <div class="pswp__item"></div>
            <div class="pswp__item"></div>
            <div class="pswp__item"></div>
        </div>
        <!-- Default (PhotoSwipeUI_Default) interface on top of sliding area. Can be changed. -->
        <div class="pswp__ui pswp__ui--hidden">
            <div class="pswp__top-bar">
                <!--  Controls are self-explanatory. Order can be changed. -->
                <div class="pswp__counter"></div>
                <button class="pswp__button pswp__button--close" title="Close (Esc)"></button>
                <!--<button class="pswp__button pswp__button--share" title="Share"></button>-->
                <!--<button class="pswp__button pswp__button--fs" title="Toggle fullscreen"></button>-->
                <button class="pswp__button pswp__button--zoom" title="Zoom in/out"></button>
                <!-- Preloader demo http://codepen.io/dimsemenov/pen/yyBWoR -->
                <!-- element will get class pswp__preloader--active when preloader is running -->
                <div class="pswp__preloader">
                    <div class="pswp__preloader__icn">
                      <div class="pswp__preloader__cut">
                        <div class="pswp__preloader__donut"></div>
                      </div>
                    </div>
                </div>
            </div>
            <div class="pswp__share-modal pswp__share-modal--hidden pswp__single-tap">
                <div class="pswp__share-tooltip"></div> 
            </div>
            <button class="pswp__button pswp__button--arrow--left" title="Previous (arrow left)">
            </button>
            <button class="pswp__button pswp__button--arrow--right" title="Next (arrow right)">
            </button>
            <div class="pswp__caption">
                <div class="pswp__caption__center"></div>
            </div>
        </div>
    </div>
</div>
<script type="text/javascript">
var pswpElement = document.querySelectorAll('.pswp')[0];
var pswp =null;
var data= {
      startIndex:"",
      data: [{src:'a.png',w:'200',h:'200',updfsize:0},{src:'b.png',w:'200',h:'200',updfsize:0}]
  }
function img_obj(index){
  var imageSrc = data.data[index].src;  //获取图片真实尺寸
	var theImage = new Image();
  theImage.src = imageSrc;
	theImage.onload=function(){
		data.data[index].src=imageSrc;
		data.data[index].w=theImage.width;
		data.data[index].h=theImage.height;
		data.data[index].updfsize=1;		
		theImage=undefined;
		pswp.updateSize(true); //获取图片真实宽高后更新调整
	}
}    
function openPhotoViewer(file_url, ix) {
    var items = data.data;
    var options = {
        index: ix,
        shareButtons: false
    };
    pswp = new PhotoSwipe(pswpElement, PhotoSwipeUI_Default, items, options);
		pswp.listen('afterChange', function() {
				// 获取当前幻灯片的索引
				var currentIndex = pswp.getCurrentIndex(); 
				// 获取当前幻灯片对象
				var currentItem = pswp.getItemAt(currentIndex);		 
				// 获取当前幻灯片的宽度、高度、标题和URL
				var currentWidth = currentItem.w;
				var currentHeight = currentItem.h;
				var currentSrc = currentItem.src; // 图片的URL
				var updfsize = currentItem.updfsize; // 是否真实宽高
				if(updfsize==0){
					img_obj(currentIndex);
				}
		});
    pswp.init();		
}
openPhotoViewer('b.png',1)
</script>