Removes all default scripts and styles outputted by the Nextgen Gallery plugin. It also outputs the necessary code to replace the lightbox with the Foundation 5 reveal modal.

ngg-customizations.php

<?php

new Nextgen_Gallery_Customizations();

/**
 * Class Nextgen_Gallery_Customizations
 *
 * The class responsible for removing all of the default scripts and
 * styles that Nextgen outputs and replacing the scripts with the
 * necessary jQuery to activate the Foundation 5 Reveal modal.  This
 * class doesn't handle outputting the actual Foundation 5 Reveal modal
 * script.
 */
class Nextgen_Gallery_Customizations {

    /**
     * Registers all of our main actions
     *
     * @param none
     * @return none
     *
     * @since 1.0.0
     */
    function __construct() {

        add_action( 'init', array($this, 'hide_nextgen_scripts') );
        add_action( 'wp_footer', array($this, 'output_ngg_reveal_modal') );
        add_action( 'wp_print_footer_scripts', array($this, 'output_reveal_script') );

    }


    /**
     * Hides the Nextgen scripts and styles.  We have all of the
     * styles and scripts covered in our theme, so there's
     * no need to output Nextgen's styles.
     *
     * @param none
     * @return none
     *
     * @since 1.0.0
     */
    function hide_nextgen_scripts() {

        if ( !is_admin() ) {
            define('NGG_SKIP_LOAD_SCRIPTS', true);
            add_action( 'wp_print_styles', function() { wp_deregister_style('NextGEN'); }, 100);
        }

    }


    /**
     * Check if the given post uses a shortcode.
     *
     * @param string $shortcode
     * @return bool
     *
     * @since 1.0.0
     */
    function post_has_shortcode( $shortcode = '', $id = NULL ) {
      
        global $post;
        $post_id = !empty($id) ? $id : $post->ID;
        $post_to_check = get_post($post_id);

        // false because we have to search through the post content first
        $found = false;

        // if no short code was provided, return false
        if (!$shortcode) {
            return $found;
        }
        // check the post content for the short code
        if ( stripos($post_to_check->post_content, '[' . $shortcode) !== false ) {
            // we have found the short code
            $found = true;
        }

        // return our final results
        return $found;
        
    }


    /**
     * Check if the given post has a NextGen Gallery shortcode
     *
     * @param none
     * @return none
     *
     * @since 1.0.0
     */
    function has_nextgen_shortcode() {
      
        global $post;

        $nextgen_shortcodes = array(
            'nggalbum',
            'album',
            'ngg-images',
            'random',
            'recent',
            'thumb',
            'slideshow',
            'nggallery',
            'nggtags',
            'nggslideshow',
            'nggrandom',
            'nggrecent',
            'nggthumb',
            'imagebrowser',
            'nggimagebrowser',
            'singlepic',
            'nggsinglepic',
            'tagcloud',
            'nggtagcloud',
        );

        $has_nextgen_shortcode = false;

        // Check whether the page has one of the shortcodes
        foreach($nextgen_shortcodes as $shortcode)
        {
            if ( $this->post_has_shortcode($shortcode) )
            {
                $has_nextgen_shortcode = true;
                break;
            }
        }

        // Check if the post content has the image placeholder instead of
        // a shortcode
        $content = $post->post_content;

        if ( stristr($content, 'ngg_displayed_gallery') ) {
            $has_nextgen_shortcode = true;
        }

        return $has_nextgen_shortcode;
        
    }


    /**
     * Outputs the code for a reveal modal if the current
     * page has a gallery on it.
     *
     * @param none
     * @return none
     */
    function output_ngg_reveal_modal() {

        if ( !is_admin() && $this->has_nextgen_shortcode() ) {
            echo '<div id="ngg-modal" class="reveal-modal" data-reveal><div class="ngg-image"></div><a class="close-reveal-modal" aria-label="Close">&#215;</a></div>';
        }

    }


    /**
     * Outputs some custom jQuery that will activate the Foundation 5 Reveal
     * modal when clicking on a Nextgen thumbnail image.
     *
     * @param none
     * @return none
     *
     * @since 1.0.0
     */
    function output_reveal_script() {
        ?>
        <script type="text/javascript">
            (function($) {
                $('a.ngg-fancybox').on('click', function() {
                    var img = $(this).data('src');
                    var revealId = 'ngg-modal';
                    $('#' + revealId + ' .ngg-image').html('<img src="' + img + '" alt="" style="max-width: 100%; height: auto; display: block; margin: 0 auto;" />');
                    $('#' + revealId).foundation('reveal','open');
                    return false;
                });
            })(jQuery);
        </script>
        <?php
    }

}