Block Editor: Backport block styles server functions from block editor.

This commit backports the block styles functionality added to the block editor in WordPress/gutenberg#16356.

Props: youknowriad, aduth, swissspidy.
Fixes #48039.

git-svn-id: https://develop.svn.wordpress.org/trunk@46111 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/blocks.php

@@ -356,3 +356,31 @@ function _restore_wpautop_hook( $content ) {
 function block_version( $content ) {
 	return has_blocks( $content ) ? 1 : 0;
 }
+
+/**
+ * Registers a new block style.
+ *
+ * @since 5.3.0
+ *
+ * @param string $block_name       Block type name including namespace.
+ * @param array  $style_properties Array containing the properties of the style name, label, style (name of the stylesheet to be enqueued), inline_style (string containing the CSS to be added).
+ *
+ * @return boolean True if the block style was registered with success and false otherwise.
+ */
+function register_block_style( $block_name, $style_properties ) {
+	return WP_Block_Styles_Registry::get_instance()->register( $block_name, $style_properties );
+}
+
+/**
+ * Unregisters a block style.
+ *
+ * @since 5.3.0
+ *
+ * @param string $block_name       Block type name including namespace.
+ * @param array  $block_style_name Block style name.
+ *
+ * @return boolean True if the block style was unregistered with success and false otherwise.
+ */
+function unregister_block_style( $block_name, $block_style_name ) {
+	return WP_Block_Styles_Registry::get_instance()->unregister( $block_name, $block_style_name );
+}

src/wp-includes/class-wp-block-styles-registry.php

@@ -0,0 +1,161 @@
+<?php
+/**
+ * Blocks API: WP_Block_Styles_Registry class
+ *
+ * @package Gutenberg
+ * @since 5.3.0
+ */
+
+/**
+ * Class used for interacting with block styles.
+ *
+ * @since 5.3.0
+ */
+final class WP_Block_Styles_Registry {
+	/**
+	 * Registered block styles, as `$block_name => $block_style_name => $block_style_properties` multidimensional arrays.
+	 *
+	 * @since 5.3.0
+	 * @var array
+	 */
+	private $registered_block_styles = array();
+
+	/**
+	 * Container for the main instance of the class.
+	 *
+	 * @since 5.3.0
+	 * @var WP_Block_Styles_Registry|null
+	 */
+	private static $instance = null;
+
+	/**
+	 * Registers a block style.
+	 *
+	 * @since 5.3.0
+	 *
+	 * @param string $block_name       Block type name including namespace.
+	 * @param array  $style_properties Array containing the properties of the style name, label, style (name of the stylesheet to be enqueued), inline_style (string containing the CSS to be added).
+	 *
+	 * @return boolean True if the block style was registered with success and false otherwise.
+	 */
+	public function register( $block_name, $style_properties ) {
+
+		if ( ! isset( $block_name ) || ! is_string( $block_name ) ) {
+			$message = __( 'Block name name must be a string.', 'gutenberg' );
+			_doing_it_wrong( __METHOD__, $message, '6.2.0' );
+			return false;
+		}
+
+		if ( ! isset( $style_properties['name'] ) || ! is_string( $style_properties['name'] ) ) {
+			$message = __( 'Block style name must be a string.', 'gutenberg' );
+			_doing_it_wrong( __METHOD__, $message, '6.2.0' );
+			return false;
+		}
+
+		$block_style_name = $style_properties['name'];
+
+		if ( ! isset( $this->registered_block_styles[ $block_name ] ) ) {
+			$this->registered_block_styles[ $block_name ] = array();
+		}
+		$this->registered_block_styles[ $block_name ][ $block_style_name ] = $style_properties;
+
+		return true;
+	}
+
+	/**
+	 * Unregisters a block style.
+	 *
+	 * @param string $block_name       Block type name including namespace.
+	 * @param array  $block_style_name Block style name.
+	 *
+	 * @return boolean True if the block style was unregistered with success and false otherwise.
+	 */
+	public function unregister( $block_name, $block_style_name ) {
+		if ( ! $this->is_registered( $block_name, $block_style_name ) ) {
+			/* translators: 1: block name, 2: block style name */
+			$message = sprintf( __( 'Block "%1$s" does not contain a style named "%2$s.".', 'gutenberg' ), $block_name, $block_style_name );
+			_doing_it_wrong( __METHOD__, $message, '6.2.0' );
+			return false;
+		}
+
+		unset( $this->registered_block_styles[ $block_name ][ $block_style_name ] );
+
+		return true;
+	}
+
+	/**
+	 * Retrieves an array containing the properties of a registered block style.
+	 *
+	 * @since 5.3.0
+	 *
+	 * @param string $block_name       Block type name including namespace.
+	 * @param array  $block_style_name Block style name.
+	 *
+	 * @return array Registered block style properties.
+	 */
+	public function get_registered( $block_name, $block_style_name ) {
+		if ( ! $this->is_registered( $block_name, $block_style_name ) ) {
+			return null;
+		}
+
+		return $this->registered_block_styles[ $block_name ][ $block_style_name ];
+	}
+
+	/**
+	 * Retrieves all registered block styles.
+	 *
+	 * @since 5.3.0
+	 *
+	 * @return array Array of arrays containing the registered block styles properties grouped per block, and per style.
+	 */
+	public function get_all_registered() {
+		return $this->registered_block_styles;
+	}
+
+	/**
+	 * Retrieves registered block styles for a specific block.
+	 *
+	 * @since 5.3.0
+	 *
+	 * @param string $block_name Block type name including namespace.
+	 *
+	 * @return array Array whose keys are block style names and whose value are block style properties.
+	 */
+	public function get_registered_styles_for_block( $block_name ) {
+		if ( isset( $this->registered_block_styles[ $block_name ] ) ) {
+			return $this->registered_block_styles[ $block_name ];
+		}
+		return array();
+	}
+
+	/**
+	 * Checks if a block style is registered.
+	 *
+	 * @since 5.3.0
+	 *
+	 * @param string $block_name       Block type name including namespace.
+	 * @param array  $block_style_name Block style name.
+	 *
+	 * @return bool True if the block style is registered, false otherwise.
+	 */
+	public function is_registered( $block_name, $block_style_name ) {
+		return isset( $this->registered_block_styles[ $block_name ][ $block_style_name ] );
+	}
+
+	/**
+	 * Utility method to retrieve the main instance of the class.
+	 *
+	 * The instance will be created if it does not exist yet.
+	 *
+	 * @since 5.3.0
+	 *
+	 * @return WP_Block_Styles_Registry The main instance.
+	 */
+	public static function get_instance() {
+		if ( null === self::$instance ) {
+			self::$instance = new self();
+		}
+
+		return self::$instance;
+	}
+}

src/wp-includes/default-filters.php

@@ -501,6 +501,8 @@
 add_filter( 'wp_print_scripts', 'wp_just_in_time_script_localization' );
 add_filter( 'print_scripts_array', 'wp_prototype_before_jquery' );
 add_filter( 'customize_controls_print_styles', 'wp_resource_hints', 1 );
+add_action( 'enqueue_block_assets', 'enqueue_block_styles_assets', 30 );
+add_action( 'enqueue_block_editor_assets', 'enqueue_editor_block_styles_assets' );
 
 add_action( 'wp_default_styles', 'wp_default_styles' );
 add_filter( 'style_loader_src', 'wp_style_loader_src', 10, 2 );

src/wp-includes/script-loader.php

@@ -2780,3 +2780,54 @@ function wp_enqueue_registered_block_scripts_and_styles() {
 		}
 	}
 }
+
+/**
+ * Function responsible for enqueuing the styles required for block styles functionality on the editor and on the frontend.
+ *
+ * @since 5.3.0
+ */
+function enqueue_block_styles_assets() {
+	$block_styles = WP_Block_Styles_Registry::get_instance()->get_all_registered();
+
+	foreach ( $block_styles as $styles ) {
+		foreach ( $styles as $style_properties ) {
+			if ( isset( $style_properties['style_handle'] ) ) {
+				wp_enqueue_style( $style_properties['style_handle'] );
+			}
+			if ( isset( $style_properties['inline_style'] ) ) {
+				wp_add_inline_style( 'wp-block-library', $style_properties['inline_style'] );
+			}
+		}
+	}
+}
+
+/**
+ * Function responsible for enqueuing the assets required for block styles functionality on the editor.
+ *
+ * @since 5.3.0
+ */
+function enqueue_editor_block_styles_assets() {
+	$block_styles = WP_Block_Styles_Registry::get_instance()->get_all_registered();
+
+	$register_script_lines = array( '( function() {' );
+	foreach ( $block_styles as $block_name => $styles ) {
+		foreach ( $styles as $style_properties ) {
+			$register_script_lines[] = sprintf(
+				'	wp.blocks.registerBlockStyle( \'%s\', %s );',
+				$block_name,
+				wp_json_encode(
+					array(
+						'name'  => $style_properties['name'],
+						'label' => $style_properties['label'],
+					)
+				)
+			);
+		}
+	}
+	$register_script_lines[] = '} )();';
+	$inline_script           = implode( "\n", $register_script_lines );
+
+	wp_register_script( 'wp-block-styles', false, array( 'wp-blocks' ), true, true );
+	wp_add_inline_script( 'wp-block-styles', $inline_script );
+	wp_enqueue_script( 'wp-block-styles' );
+}

src/wp-settings.php

@@ -256,6 +256,7 @@
 require( ABSPATH . WPINC . '/rest-api/search/class-wp-rest-search-handler.php' );
 require( ABSPATH . WPINC . '/rest-api/search/class-wp-rest-post-search-handler.php' );
 require( ABSPATH . WPINC . '/class-wp-block-type.php' );
+require( ABSPATH . WPINC . '/class-wp-block-styles-registry.php' );
 require( ABSPATH . WPINC . '/class-wp-block-type-registry.php' );
 require( ABSPATH . WPINC . '/class-wp-block-parser.php' );
 require( ABSPATH . WPINC . '/blocks.php' );