Plugin: Deprecate metabox supports, fall back to core (#13449)

* Plugin: Emulate is_block_editor for Gutenberg screen

* Plugin: Deprecate metabox supports, fall back to core

docs/designers-developers/developers/backward-compatibility/deprecations.md

@@ -44,6 +44,18 @@ The Gutenberg project's deprecation policy is intended to support backward compa
 - The PHP function `gutenberg_check_if_classic_needs_warning_about_blocks` has been removed.
 - The PHP function `gutenberg_warn_classic_about_blocks` has been removed.
 - The PHP function `gutenberg_show_privacy_policy_help_text` has been removed.
+- The PHP function `gutenberg_common_scripts_and_styles` has been removed. Use [`wp_common_block_scripts_and_styles`](https://developer.wordpress.org/reference/functions/wp_common_block_scripts_and_styles/) instead.
+- The PHP function `gutenberg_enqueue_registered_block_scripts_and_styles` has been removed. Use [`wp_enqueue_registered_block_scripts_and_styles`](https://developer.wordpress.org/reference/functions/wp_enqueue_registered_block_scripts_and_styles/) instead.
+- The PHP function `gutenberg_meta_box_save` has been removed.
+- The PHP function `gutenberg_meta_box_save_redirect` has been removed.
+- The PHP function `gutenberg_filter_meta_boxes` has been removed.
+- The PHP function `gutenberg_intercept_meta_box_render` has been removed.
+- The PHP function `gutenberg_override_meta_box_callback` has been removed.
+- The PHP function `gutenberg_show_meta_box_warning` has been removed.
+- The PHP function `the_gutenberg_metaboxes` has been removed. Use [`the_block_editor_meta_boxes`](https://developer.wordpress.org/reference/functions/the_block_editor_meta_boxes/) instead.
+- The PHP function `gutenberg_meta_box_post_form_hidden_fields` has been removed. Use [`the_block_editor_meta_box_post_form_hidden_fields`](https://developer.wordpress.org/reference/functions/the_block_editor_meta_box_post_form_hidden_fields/) instead.
+- The PHP function `gutenberg_toggle_custom_fields` has been removed.
+- The PHP function `gutenberg_collect_meta_box_data` has been removed. Use [`register_and_do_post_meta_boxes`](https://developer.wordpress.org/reference/functions/register_and_do_post_meta_boxes/) instead.
 
 ## 4.5.0
 - `Dropdown.refresh()` has been deprecated as the contained `Popover` is now automatically refreshed.

gutenberg.php

@@ -52,8 +52,8 @@ function the_gutenberg_project() {
 	<div class="block-editor gutenberg">
 		<h1 class="screen-reader-text"><?php echo esc_html( $post_type_object->labels->edit_item ); ?></h1>
 		<div id="editor" class="block-editor__container gutenberg__editor"></div>
-		<div id="metaboxes" style="display: none;">
-			<?php the_gutenberg_metaboxes(); ?>
+		<div id="metaboxes" class="hidden">
+			<?php the_block_editor_meta_boxes(); ?>
 		</div>
 	</div>
 	<?php
@@ -211,6 +211,15 @@ function gutenberg_init( $return, $post ) {
 		return false;
 	}
 
+	// Instruct WordPress that this is the block editor. Without this, a call
+	// to `is_block_editor()` would yield `false` while editing a post with
+	// Gutenberg.
+	//
+	// [TODO]: This is temporary so long as Gutenberg is implemented to use
+	// `replace_editor`, rather than allow `edit-form-blocks.php` from core to
+	// take effect, where this would otherwise be assigned.
+	get_current_screen()->is_block_editor( true );
+
 	add_action( 'admin_enqueue_scripts', 'gutenberg_editor_scripts_and_styles' );
 	add_filter( 'screen_options_show_screen', '__return_false' );
 	add_filter( 'admin_body_class', 'gutenberg_add_admin_body_class' );
@@ -237,7 +246,7 @@ function gutenberg_init( $return, $post ) {
 	 * includes/meta-boxes is typically loaded from edit-form-advanced.php.
 	 */
 	require_once ABSPATH . 'wp-admin/includes/meta-boxes.php';
-	gutenberg_collect_meta_box_data();
+	register_and_do_post_meta_boxes( $post );
 
 	require_once ABSPATH . 'wp-admin/admin-header.php';
 	the_gutenberg_project();

lib/client-assets.php

@@ -721,72 +721,26 @@ function gutenberg_prepare_blocks_for_js() {
  * are loaded last.
  *
  * @since 0.4.0
+ * @deprecated 5.0.0 wp_common_block_scripts_and_styles
  */
 function gutenberg_common_scripts_and_styles() {
-	if ( ! is_gutenberg_page() && is_admin() ) {
-		return;
-	}
-
-	// Enqueue basic styles built out of Gutenberg through `npm build`.
-	wp_enqueue_style( 'wp-block-library' );
-
-	/*
-	 * Enqueue block styles built through plugins.  This lives in a separate
-	 * action for a couple of reasons: (1) we want to load these assets
-	 * (usually stylesheets) in *both* frontend and editor contexts, and (2)
-	 * one day we may need to be smarter about whether assets are included
-	 * based on whether blocks are actually present on the page.
-	 */
+	_deprecated_function( __FUNCTION__, '5.0.0', 'wp_common_block_scripts_and_styles' );
 
-	/**
-	 * Fires after enqueuing block assets for both editor and front-end.
-	 *
-	 * Call `add_action` on any hook before 'wp_enqueue_scripts'.
-	 *
-	 * In the function call you supply, simply use `wp_enqueue_script` and
-	 * `wp_enqueue_style` to add your functionality to the Gutenberg editor.
-	 *
-	 * @since 0.4.0
-	 */
-	do_action( 'enqueue_block_assets' );
+	wp_common_block_scripts_and_styles();
 }
-add_action( 'wp_enqueue_scripts', 'gutenberg_common_scripts_and_styles' );
-add_action( 'admin_enqueue_scripts', 'gutenberg_common_scripts_and_styles' );
 
 /**
  * Enqueues registered block scripts and styles, depending on current rendered
  * context (only enqueuing editor scripts while in context of the editor).
  *
  * @since 2.0.0
+ * @deprecated 5.0.0 wp_enqueue_registered_block_scripts_and_styles
  */
 function gutenberg_enqueue_registered_block_scripts_and_styles() {
-	$is_editor = ( 'enqueue_block_editor_assets' === current_action() );
+	_deprecated_function( __FUNCTION__, '5.0.0', 'wp_enqueue_registered_block_scripts_and_styles' );
 
-	$block_registry = WP_Block_Type_Registry::get_instance();
-	foreach ( $block_registry->get_all_registered() as $block_name => $block_type ) {
-		// Front-end styles.
-		if ( ! empty( $block_type->style ) ) {
-			wp_enqueue_style( $block_type->style );
-		}
-
-		// Front-end script.
-		if ( ! empty( $block_type->script ) ) {
-			wp_enqueue_script( $block_type->script );
-		}
-
-		// Editor styles.
-		if ( $is_editor && ! empty( $block_type->editor_style ) ) {
-			wp_enqueue_style( $block_type->editor_style );
-		}
-
-		// Editor script.
-		if ( $is_editor && ! empty( $block_type->editor_script ) ) {
-			wp_enqueue_script( $block_type->editor_script );
-		}
-	}
+	wp_enqueue_registered_block_scripts_and_styles();
 }
-add_action( 'enqueue_block_assets', 'gutenberg_enqueue_registered_block_scripts_and_styles' );
-add_action( 'enqueue_block_editor_assets', 'gutenberg_enqueue_registered_block_scripts_and_styles' );
 
 /**
  * Assigns a default editor template with a default block by post format, if
@@ -1074,10 +1028,10 @@ function gutenberg_editor_scripts_and_styles( $hook ) {
 	$meta_box_url = admin_url( 'post.php' );
 	$meta_box_url = add_query_arg(
 		array(
-			'post'           => $post->ID,
-			'action'         => 'edit',
-			'classic-editor' => true,
-			'meta_box'       => true,
+			'post'            => $post->ID,
+			'action'          => 'edit',
+			'meta-box-loader' => true,
+			'_wpnonce'        => wp_create_nonce( 'meta-box-loader' ),
 		),
 		$meta_box_url
 	);
@@ -1277,7 +1231,7 @@ function gutenberg_editor_scripts_and_styles( $hook ) {
 
 	$init_script = <<<JS
 	( function() {
-		window._wpLoadGutenbergEditor = new Promise( function( resolve ) {
+		window._wpLoadGutenbergEditor = window._wpLoadBlockEditor = new Promise( function( resolve ) {
 			wp.domReady( function() {
 				resolve( wp.editPost.initializeEditor( 'editor', "%s", %d, %s, %s ) );
 			} );