Créer un widget WordPress, méthode officielle

<?php class YouTube_Simple_Stats extends WP_Widget {

    // Configuration globale du widget
    function __construct() {

        $widget_args = array(
            'classname' => 'widget_yt_simple_stats',
            'description' => 'Affiche un rapide résumé d\'un profil d\'utilisateur YouTube'
        );

        $control_args = array(
            'width' => 450
        );

        parent::__construct(
            'yt_simple_stats',
            __('Statistiques simples YouTube'),
            $widget_args,
            $control_args
        );
    }

    // Affichage en front-end
    function widget($args, $instance) {
        extract($args);
        $title = strip_tags($instance['title']);
        $description = $instance['description'];
        $username = strip_tags($instance['username']);

        echo $before_widget;

        echo $before_title . $title . $after_title;

        echo $description . '<hr>';

        set_include_path(get_template_directory() . '/inc/ZendGData');
        require_once 'Zend/Loader.php';
        Zend_Loader::loadClass('Zend_Gdata_YouTube');

        $youtube = new Zend_Gdata_YouTube();

        $user_videos = $youtube->retrieveAllEntriesForFeed($youtube->getUserUploads($username));
        $total_videos = count($user_videos);
        $total_duration = 0;

        foreach ($user_videos as $video) {
            $total_duration = $total_duration + (int)$video->getVideoDuration();
        }

        $duration_h = floor($total_duration / 3600);
        $duration_m = floor(($total_duration - ($duration_h * 3600)) / 60);

        echo '<strong>J\'ai publié ' . $total_videos . ' vidéos </strong> totalisant ' . $duration_h . ' heures et ' . $duration_m . ' minutes de tutoriels gratuits.';

        echo $after_widget;
    }

    // Traitement des données avant sauvegarde
    function update( $new_instance, $old_instance ) {
        $new_instance['title'] = strip_tags($new_instance['title']);
        $new_instance['username'] = strip_tags($new_instance['username']);
        return $new_instance;
    }

    // Affichage du formulaire de réglages du widget en back-end
    function form($instance) {
        $instance = wp_parse_args(
            $instance,
            array(
                'title' => 'Statistiques YouTube',
                'description' => '',
                'username' => 'pierresaikali'
            )
        );

        $title = strip_tags($instance['title']);
        $description = $instance['description'];
        $username = strip_tags($instance['username']);

        ?>

        <p>
            <label for="<?php echo $this->get_field_id('title'); ?>">Titre :</label>
            <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo esc_attr($title); ?>" />
        </p>

        <p>
            <label for="<?php echo $this->get_field_id('description'); ?>">Description :</label>
            <textarea class="widefat" rows="16" col="20" id="<?php echo $this->get_field_id('description'); ?>" name="<?php echo $this->get_field_name('description'); ?>"><?php echo esc_textarea($description); ?></textarea>
        </p>

        <p>
            <label for="<?php echo $this->get_field_id('username'); ?>">Nom d'utilisateur :</label>
            <input class="widefat" id="<?php echo $this->get_field_id('username'); ?>" name="<?php echo $this->get_field_name('username'); ?>" type="text" value="<?php echo esc_attr($username); ?>" />
        </p>



    <?php }
}

function init_youtube_widget() {
    register_widget('YouTube_Simple_Stats');
}
add_action('widgets_init', 'init_youtube_widget');