register_and_do_post_meta_boxes

register_and_do_post_meta_boxes: 这个函数为当前的文章注册和显示元数据框。它首先调用add_meta_boxes来注册元数据框，然后调用do_meta_boxes来显示它们。

注册默认的文章元框，并运行`do_meta_boxes`动作。

function register_and_do_post_meta_boxes( $post ) {
	$post_type        = $post->post_type;
	$post_type_object = get_post_type_object( $post_type );

	$thumbnail_support = current_theme_supports( 'post-thumbnails', $post_type ) && post_type_supports( $post_type, 'thumbnail' );
	if ( ! $thumbnail_support && 'attachment' === $post_type && $post->post_mime_type ) {
		if ( wp_attachment_is( 'audio', $post ) ) {
			$thumbnail_support = post_type_supports( 'attachment:audio', 'thumbnail' ) || current_theme_supports( 'post-thumbnails', 'attachment:audio' );
		} elseif ( wp_attachment_is( 'video', $post ) ) {
			$thumbnail_support = post_type_supports( 'attachment:video', 'thumbnail' ) || current_theme_supports( 'post-thumbnails', 'attachment:video' );
		}
	}

	$publish_callback_args = array( '__back_compat_meta_box' => true );

	if ( post_type_supports( $post_type, 'revisions' ) && 'auto-draft' !== $post->post_status ) {
		$revisions = wp_get_latest_revision_id_and_total_count( $post->ID );

		// We should aim to show the revisions meta box only when there are revisions.
		if ( ! is_wp_error( $revisions ) && $revisions['count'] > 1 ) {
			$publish_callback_args = array(
				'revisions_count'        => $revisions['count'],
				'revision_id'            => $revisions['latest_id'],
				'__back_compat_meta_box' => true,
			);

			add_meta_box( 'revisionsdiv', __( 'Revisions' ), 'post_revisions_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
		}
	}

	if ( 'attachment' === $post_type ) {
		wp_enqueue_script( 'image-edit' );
		wp_enqueue_style( 'imgareaselect' );
		add_meta_box( 'submitdiv', __( 'Save' ), 'attachment_submit_meta_box', null, 'side', 'core', array( '__back_compat_meta_box' => true ) );
		add_action( 'edit_form_after_title', 'edit_form_image_editor' );

		if ( wp_attachment_is( 'audio', $post ) ) {
			add_meta_box( 'attachment-id3', __( 'Metadata' ), 'attachment_id3_data_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
		}
	} else {
		add_meta_box( 'submitdiv', __( 'Publish' ), 'post_submit_meta_box', null, 'side', 'core', $publish_callback_args );
	}

	if ( current_theme_supports( 'post-formats' ) && post_type_supports( $post_type, 'post-formats' ) ) {
		add_meta_box( 'formatdiv', _x( 'Format', 'post format' ), 'post_format_meta_box', null, 'side', 'core', array( '__back_compat_meta_box' => true ) );
	}

	// All taxonomies.
	foreach ( get_object_taxonomies( $post ) as $tax_name ) {
		$taxonomy = get_taxonomy( $tax_name );
		if ( ! $taxonomy->show_ui || false === $taxonomy->meta_box_cb ) {
			continue;
		}

		$label = $taxonomy->labels->name;

		if ( ! is_taxonomy_hierarchical( $tax_name ) ) {
			$tax_meta_box_id = 'tagsdiv-' . $tax_name;
		} else {
			$tax_meta_box_id = $tax_name . 'div';
		}

		add_meta_box(
			$tax_meta_box_id,
			$label,
			$taxonomy->meta_box_cb,
			null,
			'side',
			'core',
			array(
				'taxonomy'               => $tax_name,
				'__back_compat_meta_box' => true,
			)
		);
	}

	if ( post_type_supports( $post_type, 'page-attributes' ) || count( get_page_templates( $post ) ) > 0 ) {
		add_meta_box( 'pageparentdiv', $post_type_object->labels->attributes, 'page_attributes_meta_box', null, 'side', 'core', array( '__back_compat_meta_box' => true ) );
	}

	if ( $thumbnail_support && current_user_can( 'upload_files' ) ) {
		add_meta_box( 'postimagediv', esc_html( $post_type_object->labels->featured_image ), 'post_thumbnail_meta_box', null, 'side', 'low', array( '__back_compat_meta_box' => true ) );
	}

	if ( post_type_supports( $post_type, 'excerpt' ) ) {
		add_meta_box( 'postexcerpt', __( 'Excerpt' ), 'post_excerpt_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
	}

	if ( post_type_supports( $post_type, 'trackbacks' ) ) {
		add_meta_box( 'trackbacksdiv', __( 'Send Trackbacks' ), 'post_trackback_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
	}

	if ( post_type_supports( $post_type, 'custom-fields' ) ) {
		add_meta_box(
			'postcustom',
			__( 'Custom Fields' ),
			'post_custom_meta_box',
			null,
			'normal',
			'core',
			array(
				'__back_compat_meta_box'             => ! (bool) get_user_meta( get_current_user_id(), 'enable_custom_fields', true ),
				'__block_editor_compatible_meta_box' => true,
			)
		);
	}

	/**
	 * Fires in the middle of built-in meta box registration.
	 *
	 * @since 2.1.0
	 * @deprecated 3.7.0 Use {@see 'add_meta_boxes'} instead.
	 *
	 * @param WP_Post $post Post object.
	 */
	do_action_deprecated( 'dbx_post_advanced', array( $post ), '3.7.0', 'add_meta_boxes' );

	// Allow the Discussion meta box to show up if the post type supports comments,
	// or if comments or pings are open.
	if ( comments_open( $post ) || pings_open( $post ) || post_type_supports( $post_type, 'comments' ) ) {
		add_meta_box( 'commentstatusdiv', __( 'Discussion' ), 'post_comment_status_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
	}

	$stati = get_post_stati( array( 'public' => true ) );
	if ( empty( $stati ) ) {
		$stati = array( 'publish' );
	}
	$stati[] = 'private';

	if ( in_array( get_post_status( $post ), $stati, true ) ) {
		// If the post type support comments, or the post has comments,
		// allow the Comments meta box.
		if ( comments_open( $post ) || pings_open( $post ) || $post->comment_count > 0 || post_type_supports( $post_type, 'comments' ) ) {
			add_meta_box( 'commentsdiv', __( 'Comments' ), 'post_comment_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
		}
	}

	if ( ! ( 'pending' === get_post_status( $post ) && ! current_user_can( $post_type_object->cap->publish_posts ) ) ) {
		add_meta_box( 'slugdiv', __( 'Slug' ), 'post_slug_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
	}

	if ( post_type_supports( $post_type, 'author' ) && current_user_can( $post_type_object->cap->edit_others_posts ) ) {
		add_meta_box( 'authordiv', __( 'Author' ), 'post_author_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
	}

	/**
	 * Fires after all built-in meta boxes have been added.
	 *
	 * @since 3.0.0
	 *
	 * @param string  $post_type Post type.
	 * @param WP_Post $post      Post object.
	 */
	do_action( 'add_meta_boxes', $post_type, $post );

	/**
	 * Fires after all built-in meta boxes have been added, contextually for the given post type.
	 *
	 * The dynamic portion of the hook name, `$post_type`, refers to the post type of the post.
	 *
	 * Possible hook names include:
	 *
	 *  - `add_meta_boxes_post`
	 *  - `add_meta_boxes_page`
	 *  - `add_meta_boxes_attachment`
	 *
	 * @since 3.0.0
	 *
	 * @param WP_Post $post Post object.
	 */
	do_action( "add_meta_boxes_{$post_type}", $post );

	/**
	 * Fires after meta boxes have been added.
	 *
	 * Fires once for each of the default meta box contexts: normal, advanced, and side.
	 *
	 * @since 3.0.0
	 *
	 * @param string                $post_type Post type of the post on Edit Post screen, 'link' on Edit Link screen,
	 *                                         'dashboard' on Dashboard screen.
	 * @param string                $context   Meta box context. Possible values include 'normal', 'advanced', 'side'.
	 * @param WP_Post|object|string $post      Post object on Edit Post screen, link object on Edit Link screen,
	 *                                         an empty string on Dashboard screen.
	 */
	do_action( 'do_meta_boxes', $post_type, 'normal', $post );
	/** This action is documented in wp-admin/includes/meta-boxes.php */
	do_action( 'do_meta_boxes', $post_type, 'advanced', $post );
	/** This action is documented in wp-admin/includes/meta-boxes.php */
	do_action( 'do_meta_boxes', $post_type, 'side', $post );
}