add_meta_box( string $id, string $title, callable $callback, string|array|WP_Screen $screen = null, string $context = ‘advanced’, string $priority = ‘default’, array $callback_args = null )

向一个或多个屏幕添加元框。
Adds a meta box to one or more screens.

无返回值

/**
 * Add a meta box to an edit form.
 *
 * @since 2.5.0
 *
 * @global array $wp_meta_boxes
 *
 * @param string           $id            String for use in the 'id' attribute of tags.
 * @param string           $title         Title of the meta box.
 * @param callback         $callback      Function that fills the box with the desired content.
 *                                        The function should echo its output.
 * @param string|WP_Screen $screen        Optional. The screen on which to show the box (like a post
 *                                        type, 'link', or 'comment'). Default is the current screen.
 * @param string           $context       Optional. The context within the screen where the boxes
 *                                        should display. Available contexts vary from screen to
 *                                        screen. Post edit screen contexts include 'normal', 'side',
 *                                        and 'advanced'. Comments screen contexts include 'normal'
 *                                        and 'side'. Menus meta boxes (accordion sections) all use
 *                                        the 'side' context. Global default is 'advanced'.
 * @param string           $priority      Optional. The priority within the context where the boxes
 *                                        should show ('high', 'low'). Default 'default'.
 * @param array            $callback_args Optional. Data that should be set as the $args property
 *                                        of the box array (which is the second parameter passed
 *                                        to your callback). Default null.
 */
function add_meta_box( $id, $title, $callback, $screen = null, $context = 'advanced', $priority = 'default', $callback_args = null ) {
    global $wp_meta_boxes;
 
    if ( empty( $screen ) )
        $screen = get_current_screen();
    elseif ( is_string( $screen ) )
        $screen = convert_to_screen( $screen );
 
    $page = $screen->id;
 
    if ( !isset($wp_meta_boxes) )
        $wp_meta_boxes = array();
    if ( !isset($wp_meta_boxes[$page]) )
        $wp_meta_boxes[$page] = array();
    if ( !isset($wp_meta_boxes[$page][$context]) )
        $wp_meta_boxes[$page][$context] = array();
 
    foreach ( array_keys($wp_meta_boxes[$page]) as $a_context ) {
        foreach ( array('high', 'core', 'default', 'low') as $a_priority ) {
            if ( !isset($wp_meta_boxes[$page][$a_context][$a_priority][$id]) )
                continue;
 
            // If a core box was previously added or removed by a plugin, don't add.
            if ( 'core' == $priority ) {
                // If core box previously deleted, don't add
                if ( false === $wp_meta_boxes[$page][$a_context][$a_priority][$id] )
                    return;
 
                /*
                 * If box was added with default priority, give it core priority to
                 * maintain sort order.
                 */
                if ( 'default' == $a_priority ) {
                    $wp_meta_boxes[$page][$a_context]['core'][$id] = $wp_meta_boxes[$page][$a_context]['default'][$id];
                    unset($wp_meta_boxes[$page][$a_context]['default'][$id]);
                }
                return;
            }
            // If no priority given and id already present, use existing priority.
            if ( empty($priority) ) {
                $priority = $a_priority;
            /*
             * Else, if we're adding to the sorted priority, we don't know the title
             * or callback. Grab them from the previously added context/priority.
             */
            } elseif ( 'sorted' == $priority ) {
                $title = $wp_meta_boxes[$page][$a_context][$a_priority][$id]['title'];
                $callback = $wp_meta_boxes[$page][$a_context][$a_priority][$id]['callback'];
                $callback_args = $wp_meta_boxes[$page][$a_context][$a_priority][$id]['args'];
            }
            // An id can be in only one priority and one context.
            if ( $priority != $a_priority || $context != $a_context )
                unset($wp_meta_boxes[$page][$a_context][$a_priority][$id]);
        }
    }
 
    if ( empty($priority) )
        $priority = 'low';
 
    if ( !isset($wp_meta_boxes[$page][$context][$priority]) )
        $wp_meta_boxes[$page][$context][$priority] = array();
 
    $wp_meta_boxes[$page][$context][$priority][$id] = array('id' => $id, 'title' => $title, 'callback' => $callback, 'args' => $callback_args);
}