ShortCodeScriptLoader.php

<?php
/*
    "Contact Form to Database" Copyright (C) 2011-2012 Michael Simpson  (email : michael.d.simpson@gmail.com)

    This file is part of Contact Form to Database.

    Contact Form to Database is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    Contact Form to Database is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Contact Form to Database.
    If not, see <http://www.gnu.org/licenses/>.
*/

require_once('ShortCodeLoader.php');

/**
 * Adapted from this excellent article:
 * http://scribu.net/wordpress/optimal-script-loading.html
 *
 * The idea is you have a shortcode that needs a script loaded, but you only
 * want to load it if the shortcode is actually called.
 */
abstract class ShortCodeScriptLoader extends ShortCodeLoader {

    var $doAddScript;

    public function register($shortcodeName) {
        $this->registerShortcodeToFunction($shortcodeName, 'handleShortcodeWrapper');

        // It will be too late to enqueue the script in the header,
        // so have to add it to the footer
        add_action('wp_footer', array($this, 'addScriptWrapper'));
    }

    public function handleShortcodeWrapper($atts, $content = null) {
        // Flag that we need to add the script
        $this->doAddScript = true;
        return $this->handleShortcode($atts, $content);
    }

    // Defined in super-class:
    //public abstract function handleShortcode($atts);

    public function addScriptWrapper() {
        // Only add the script if the shortcode was actually called
        if ($this->doAddScript) {
            $this->addScript();
        }
    }

    /**
     * @abstract override this function with calls to insert scripts needed by your shortcode in the footer
     * Example:
     *   wp_register_script('my-script', plugins_url('my-script.js', __FILE__), array('jquery'), '1.0', true);
     *   wp_print_scripts('my-script');
     * @return void
     */
    public abstract function addScript();

}