JS PhotoSwipe 相册插件

给网站的博客图片增加了点击预览功能，使用的 PhotoSwipe 插件。参照 Getting Started 中的代码，实现了点击图片时弹出图片预览功能（预览当前博客中的所有图片）。

1. 引用 CSS 和 JS 文件

这里使用了 BootCDN 。

<link href="https://cdn.bootcss.com/photoswipe/4.1.2/photoswipe.min.css" rel="stylesheet">
<link href="https://cdn.bootcss.com/photoswipe/4.1.2/default-skin/default-skin.min.css" rel="stylesheet">

<script src="https://cdn.bootcss.com/photoswipe/4.1.2/photoswipe.min.js"></script>
<script src="https://cdn.bootcss.com/photoswipe/4.1.2/photoswipe-ui-default.min.js"></script>

2. 在页面上添加 HTML 代码

<!-- 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>

3. 添加初始化的 JS 代码

  let initPhotoSwipeFromDOM = function (imgSelector) {
    // parse slide data (url, title, size ...) from DOM elements 
    // (children of imgSelector)
    let parseThumbnailElements = function (els) {
        let items = [];

        for (let i = 0; i < els.length; i++) {
            let el = els[i];
            // create slide object
            let item = {
                src: el.getAttribute('src'),
                w: el.naturalWidth,
                h: el.naturalHeight
            };

            if (el.getAttribute('alt').length > 1) {
                item.title = el.getAttribute('alt');
            }

            item.el = el; // save link to element for getThumbBoundsFn
            items.push(item);
        }

        return items;
    };

    // find nearest parent element
    let closest = function closest(el, fn) {
        return el && (fn(el) ? el : closest(el.parentNode, fn));
    };

    // triggers when user clicks on thumbnail
    let onThumbnailsClick = function (e) {
        e = e || window.event;
        e.preventDefault ? e.preventDefault() : e.returnValue = false;

        let clickedListItem = e.target || e.srcElement;

        if (!clickedListItem) {
            return;
        }

        let imgElements = document.querySelectorAll(clickedListItem.getAttribute('data-pswd-selector'));
        let index = clickedListItem.getAttribute('data-pswp-index');

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

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

        items = parseThumbnailElements(galleryElement);

        // define options (if needed)
        options = {
            getThumbBoundsFn: function (index) {
                // See Options -> getThumbBoundsFn section of documentation for more info
                let thumbnail = items[index],
                    pageYScroll = window.pageYOffset || document.documentElement.scrollTop,
                    rect = thumbnail;

                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 
                // http://photoswipe.com/documentation/faq.html#custom-pid-in-url
                for (let 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;
        }

        options.closeOnScroll = false;

        options.shareButtons = [
            { id: 'download', label: '下载图片', url: '{{raw_image_url}}', download: true }
        ],

        // 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
    let imgElements = document.querySelectorAll('img');

    for (let i = 0, l = imgElements.length; i < l; i++) {
        // imgElements[i].setAttribute('data-pswp-uid', i + 1);
        imgElements[i].setAttribute('data-pswp-index', i);
        imgElements[i].setAttribute('data-pswd-selector', imgSelector);
        imgElements[i].onclick = onThumbnailsClick;
    }
};

// execute above function
initPhotoSwipeFromDOM('.blog img');

附

1. Options

可以参照 Options 配置初始化选项。

2. Source

项目地址：https://github.com/dimsemenov/photoswipe