手机端 HTML5使用photoswipe.js仿微信朋友圈图片放大效果

先来几张效果图：

点击其中一张照片可放大，可支持图片文字描述：

同时支持分享功能：

支持手势放大缩小

使用js框架是PhotoSwipe。 
PhotoSwipe是一个图片放大插件，兼容pc和移动端，经历过多个版本的迭代且一直在不断更新，踩过的坑不知凡几，在移动端有着巨大的优势。
1、可控制多种风格如：
标题、分享、全屏按钮，点击事件、是否加入字幕，背景透明等。
2、可支持移动端触摸手势兼容pc端
所有的基本手势支持：滑动下一个或上一个，拖动平移、缩放、放大或关闭，点击切换控件，双击放大或缩放。
3、分享
默认的UI有一个按钮，分享链接。默认的链接是facebook，推特和Pinterest，但你可以通过API设置分享类型。
4、用户界面
用户界面是完全从核心脚本分离。完全可以自定义界面。默认photoswipe UI是响应式的，桌面、平板电脑和移动设备完全可以使用。 
5、更多功能等你发现。 
官网：http://photoswipe.com/ 
github：https://github.com/dimsemenov/photoswipe

1、在官网下载PhotoSwipe，在页面中引入

<link rel="stylesheet prefetch" href="css/photoswipe.css">
<link rel="stylesheet prefetch" href="css/default-skin/default-skin.css">
<script src="js/photoswipe.js"></script>
<script src="js/photoswipe-ui-default.min.js"></script>

2、页面中必须加入以下代码结构（此结构是插件图片浏览必须代码，作者并没有集成到js中，所以使用者必须手动加入自己的网页中）：

<!-- 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>

 <!-- 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>

3、需要浏览的图片加入photoswipe结构代码，这里需要注意的是
 data-pswp-uid在每个相册中必须是唯一的，data-size是指定放大时图片显示的宽和高，若指定的宽高与图片不符会导致显示的图片变形；目前还没找到去掉 data-size的办法，但然有时间可以找下替代办法。

<!--data-pswp-uid在每个相册中必须是唯一的，data-size指定放大时图片显示的宽和高-->
<div class="my-gallery" data-pswp-uid="1">
　　<figure>
  <a href="img/m3.jpg" data-size="670x712">
  <img src="img/th1.jpg">
  </a>
  </figure>
</div>

4、加入js代码，此代码作者也没有集成到photoswipe框架中，需要自己手动加入网页里

<script type="text/javascript">
 var initPhotoSwipeFromDOM = function(gallerySelector) {

 // 解析来自DOM元素幻灯片数据（URL，标题，大小...）
 // (children of gallerySelector)
 var parseThumbnailElements = function(el) {
 var thumbElements = el.childNodes,
 numNodes = thumbElements.length,
 items = [],
 figureEl,
 linkEl,
 size,
 item;

 for(var i = 0; i < numNodes; i++) {

 figureEl = thumbElements[i]; // <figure> element

 // 仅包括元素节点
 if(figureEl.nodeType !== 1) {
 continue;
 } 25 linkEl = figureEl.children[0]; // <a> element
 
 size = linkEl.getAttribute('data-size').split('x');

 // 创建幻灯片对象
 item = {
 src: linkEl.getAttribute('href'),
 w: parseInt(size[0], 10),
 h: parseInt(size[1], 10)
 };


 if(figureEl.children.length > 1) {
 // <figcaption> content
 item.title = figureEl.children[1].innerHTML; 
 }

 if(linkEl.children.length > 0) {
 // <img> 缩略图节点, 检索缩略图网址
 item.msrc = linkEl.children[0].getAttribute('src');
 }

 item.el = figureEl; // 保存链接元素 for getThumbBoundsFn
 items.push(item);
 }

 return items;
 };

 // 查找最近的父节点
 var closest = function closest(el, fn) {
 return el && ( fn(el) ? el : closest(el.parentNode, fn) );
 };

 // 当用户点击缩略图触发
 var onThumbnailsClick = function(e) {
 e = e || window.event;
 e.preventDefault ? e.preventDefault() : e.returnValue = false;

 var eTarget = e.target || e.srcElement;

 // find root element of slide
 var clickedListItem = closest(eTarget, function(el) {
 return (el.tagName && el.tagName.toUpperCase() === 'FIGURE');
 });

 if(!clickedListItem) {
 return;
 }

 // find index of clicked item by looping through all child nodes
 // alternatively, you may define index via data- attribute
 var clickedGallery = clickedListItem.parentNode,
 childNodes = clickedListItem.parentNode.childNodes,
 numChildNodes = childNodes.length,
 nodeIndex = 0,
 index;

 for (var i = 0; i < numChildNodes; i++) {
 if(childNodes[i].nodeType !== 1) { 
 continue; 
 }

 if(childNodes[i] === clickedListItem) {
 index = nodeIndex;
 break;
 }
 nodeIndex++;
 }


 if(index >= 0) {
 // open PhotoSwipe if valid index found
 openPhotoSwipe( index, clickedGallery );
 }
 return false;
 };

 // parse picture index and gallery index from URL (#&pid=1&gid=2)
 var photoswipeParseHash = function() {
 var hash = window.location.hash.substring(1),
 params = {};

 if(hash.length < 5) {
 return params;
 }

 var vars = hash.split('&');
 for (var i = 0; i < vars.length; i++) {
 if(!vars[i]) {
 continue;
 }
 var pair = vars[i].split('='); 
 if(pair.length < 2) {
 continue;
 } 
 params[pair[0]] = pair[1];
 }

 if(params.gid) {
 params.gid = parseInt(params.gid, 10);
 }

 return params;
 };

 var openPhotoSwipe = function(index, galleryElement, disableAnimation, fromURL) {
 var pswpElement = document.querySelectorAll('.pswp')[0],
 gallery,
 options,
 items;

 items = parseThumbnailElements(galleryElement);

 // 这里可以定义参数
 options = {
 barsSize: { 
 top: 100,
 bottom: 100
 }, 
 fullscreenEl : false, // 是否支持全屏按钮
 shareButtons: [
 {id:'wechat', label:'分享微信', url:'#'},
 {id:'weibo', label:'新浪微博', url:'#'},
 {id:'download', label:'保存图片', url:'{{raw_image_url}}', download:true}
 ], // 分享按钮

 // define gallery index (for URL)
 galleryUID: galleryElement.getAttribute('data-pswp-uid'),

 getThumbBoundsFn: function(index) {
 // See Options -> getThumbBoundsFn section of documentation for more info
 var thumbnail = items[index].el.getElementsByTagName('img')[0], // find thumbnail
  pageYScroll = window.pageYOffset || document.documentElement.scrollTop,
  rect = thumbnail.getBoundingClientRect();

 return {x:rect.left, y:rect.top + pageYScroll, w:rect.width};
 }

 };

 // PhotoSwipe opened from URL
 if(fromURL) {
 if(options.galleryPIDs) {
 // parse real index when custom PIDs are used 
 for(var j = 0; j < items.length; j++) {
  if(items[j].pid == index) {
  options.index = j;
  break;
  }
 }
 } else {
 // in URL indexes start from 1
 options.index = parseInt(index, 10) - 1;
 }
 } else {
 options.index = parseInt(index, 10);
 }

 // exit if index not found
 if( isNaN(options.index) ) {
 return;
 }

 if(disableAnimation) {
 options.showAnimationDuration = 0;
 }

 // Pass data to PhotoSwipe and initialize it
 gallery = new PhotoSwipe( pswpElement, PhotoSwipeUI_Default, items, options);
 gallery.init();
 };

 // loop through all gallery elements and bind events
 var galleryElements = document.querySelectorAll( gallerySelector );

 for(var i = 0, l = galleryElements.length; i < l; i++) {
 galleryElements[i].setAttribute('data-pswp-uid', i+1);
 galleryElements[i].onclick = onThumbnailsClick;
 }

 // Parse URL and open gallery if it contains #&pid=3&gid=1
 var hashData = photoswipeParseHash();
 if(hashData.pid && hashData.gid) {
 openPhotoSwipe( hashData.pid , galleryElements[ hashData.gid - 1 ], true, true );
 }
 };

 // execute above function
 initPhotoSwipeFromDOM('.my-gallery');
</script>

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