PhotoSwipe HTML

functions.php

<?php

function photoswipe_html() {
	global $post;
	if ($post->ID !== 21801) {
		return;
	}
	echo <<<'EOD'
	<div class="pswp" tabindex="-1" role="dialog" aria-hidden="true">
	   <div class="pswp__bg"></div>
	   <div class="pswp__scroll-wrap">
	      <div class="pswp__container">
	         <div class="pswp__item"></div>
	         <div class="pswp__item"></div>
	         <div class="pswp__item"></div>
	      </div>
	      <div class="pswp__ui pswp__ui--hidden pswp__ca_center">
	         <div class="pswp__top-bar">
	            <div class="pswp__counter"></div>
	            <span class="pswp__button pswp__button--close" title="Close (Esc)"></span>
	            <span class="pswp__button pswp__button--share" title="Share"></span>
	            <span class="pswp__button pswp__button--fs" title="Toggle fullscreen"></span>
	            <span class="pswp__button pswp__button--zoom" title="Zoom in/out"></span>
	            <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>
	         <span class="pswp__button pswp__button--arrow--left" title="Previous (arrow left)"></span>
	         <span class="pswp__button pswp__button--arrow--right" title="Next (arrow right)"></span>
	         <div class="pswp__caption">
	            <div class="pswp__caption__center"></div>
	         </div>
	      </div>
	   </div>
	</div>
EOD;
}
add_action( 'wp_footer', 'photoswipe_html' );