single-galleries.php(with photoswipe)

<?php 

/*

- This is a template used by 6 posts within a CPT
- Each post contains some text in the content editor and an ACF Gallery. 
- Each image is tagged witha category(ies) using Enhanced Media Categories plugin.
- The categories used on each page are being echoed out to provide a means to filter the images
- The lightbox being used is http://photoswipe.com


Thanks to @kevinwhoffman for helping with the gallery filter. 
And to /susanlangenes for showing how to access image sizes in the <figure>

*/

 ?>

*/

<?php 

/*
	Template Name: (Single)Galleries Page
*/

 ?>

<?php get_header(); ?>


<?php if ( have_posts() ) while ( have_posts() ) : the_post(); ?>

 	<h1 class = "page-title"><?php the_title(); ?></h1>
 	
 		<!--add introduction from the content editor on each post-->
 		<div class="gallery-intro">
 		  
 				<?php the_content(); ?>
 			
 		</div> <!-- /gallery-intro -->

<!--output categories assigned to each photo via Enhanced Media Categories plugin. -->
	<div class="gallery-filter">
	        <ul id="filters">
	            <li><a href="#" data-filter="*" class="active">All</a></li>
	            <?php
	                $images = get_field('images');
	                $image_terms = array();
	                $all_used_terms = array();
	                foreach( $images as $image ) {
	                	//loop over images and get which categories are being used
	                    $image_terms = wp_get_post_terms($image['ID'], 'media_category', array('fields' => 'slugs'));
	                    // print_r($image_terms);
	                    // echo '<pre>'; var_dump( $image_terms ); echo '</pre>';
	                    
	                    // get all categories and remove duplicates
	                    $all_used_terms = array_unique( array_merge( $all_used_terms, $image_terms ) );
	                }
	                foreach ( $all_used_terms as $term ) {
	                	//outputting slug so need to remove - and make first letter uppercase
	                    echo '<li><a href="#" data-filter="' . $term . '">' . ucwords(preg_replace('/-/', ' ', $term)) . '</a></li>';
	                }
	            ?>
	        </ul>
	</div><!-- /gallery-filter -->
	

 	<!--loop over all images available for post -->
 	<!--Images are part of an ACF Gallery - see documentation 
 	http://www.advancedcustomfields.com/resources/gallery/-->
 <div class="wrapper-gallery" itemscope itemtype="http://schema.org/ImageGallery">
  		<?php 
  		$images = get_field('images');
	
  		if( $images ) : ?>		
	        <?php foreach( $images as $image ) : 
	        	$terms = wp_get_object_terms($image['ID'], 'media_category');
	    	  ?>
	    	  
			<!--echo out the tagged category as a class and data-category in the figure-->

	              <figure class="gallery-image <?php if($terms) { foreach ($terms as $term) { echo $term->slug . ' ';}}?>" 
        	    data-catagory="<?php if($terms) { foreach ($terms as $term) { echo $term->slug . ' ';}}	?>" itemprop="associatedMedia" itemscope itemtype="http://schema.org/ImageObject">
	                <a href="<?php echo $image['url']; ?>" itemprop="contentUrl" data-size="<?php echo $image['width'] . 'x' . $image['height']; ?>">
	               		   	<img class="" src="<?php echo $image['sizes']['large']; ?>" itemprop="thumbnail" alt="<?php echo $image['alt']; ?>" />
	                </a>
	                <figcaption itemprop="caption description"><?php echo $image['caption']; ?></figcaption>                
	              </figure>
			        
	   		<?php endforeach; ?>		    
  		<?php endif; ?>
  		
 </div> <!-- gallery-wrapper -->
<?php endwhile; ?>

  	<?php next_post_link('%link', '<i class="fa fa-long-arrow-left"></i>'); ?>

  	<a href="<?php bloginfo('url'); ?>/?p=44"><i class="fa fa-th-large"></i></a>

  	<?php previous_post_link ('%link', '<i class="fa fa-long-arrow-right"></i>'); ?>




<!-- Photoswipe HTML.  Requried for the overlay. -->

<!-- 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 slides in 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>
<!-- end Photoswipe HTML -->


<?php get_footer(); ?>

<!--Vanilla JavaScript from the photoswipe documentation. Copied directly with only container name change on last line.-->
<!--http://photoswipe.com/documentation/getting-started.html-->

<script>
var initPhotoSwipeFromDOM = function(gallerySelector) {
    // parse slide data (url, title, size ...) from DOM elements 
    // (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
            // include only element nodes 
            if(figureEl.nodeType !== 1) {
                continue;
            }
            linkEl = figureEl.children[0]; // <a> element
            size = linkEl.getAttribute('data-size').split('x');
            // create slide object
            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> thumbnail element, retrieving thumbnail url
                item.msrc = linkEl.children[0].getAttribute('src');
            } 
            item.el = figureEl; // save link to element for getThumbBoundsFn
            items.push(item);
        }
        return items;
    };
    // find nearest parent element
    var closest = function closest(el, fn) {
        return el && ( fn(el) ? el : closest(el.parentNode, fn) );
    };
    // triggers when user clicks on thumbnail
    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);
        // define options (if needed)
        options = {
          // make it so it's not janky going fron the square thumbnail to the full size not-square image
          // http://photoswipe.com/documentation/faq.html#different-thumbnail-dimensions
            showHideOpacity:true,
            showAnimationDuration:0,
            // 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 
                // http://photoswipe.com/documentation/faq.html#custom-pid-in-url
                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('.gallery_container');
</script>