Update: Backport block settings to core.

src/wp-includes/block-supports/settings.php

@@ -0,0 +1,146 @@
+<?php
+/**
+ * Block level presets support.
+ *
+ * @package WordPress
+ * @since 6.2.0
+ */
+
+/**
+ * Get the class name used on block level presets.
+ *
+ * @internal
+ *
+ * @since 6.2.0
+ * @access private
+ *
+ * @param array $block Block object.
+ * @return string      The unique class name.
+ */
+function _wp_get_presets_class_name( $block ) {
+	return 'wp-settings-' . md5( serialize( $block ) );
+}
+
+/**
+ * Update the block content with block level presets class name.
+ *
+ * @internal
+ *
+ * @since 6.2.0
+ * @access private
+ *
+ * @param  string $block_content Rendered block content.
+ * @param  array  $block         Block object.
+ * @return string                Filtered block content.
+ */
+function _wp_add_block_level_presets_class( $block_content, $block ) {
+	if ( ! $block_content ) {
+		return $block_content;
+	}
+
+	// return early if the block doesn't have support for settings.
+	$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
+	if ( ! block_has_support( $block_type, array( '__experimentalSettings' ), false ) ) {
+		return $block_content;
+	}
+
+	// return early if no settings are found on the block attributes.
+	$block_settings = _wp_array_get( $block, array( 'attrs', 'settings' ), null );
+	if ( empty( $block_settings ) ) {
+		return $block_content;
+	}
+
+	// Like the layout hook this assumes the hook only applies to blocks with a single wrapper.
+	// Add the class name to the first element, presuming it's the wrapper, if it exists.
+	$tags = new WP_HTML_Tag_Processor( $block_content );
+	if ( $tags->next_tag() ) {
+		$tags->add_class( _wp_get_presets_class_name( $block ) );
+	}
+
+	return $tags->get_updated_html();
+}
+
+/**
+ * Render the block level presets stylesheet.
+ *
+ * @internal
+ *
+ * @since 6.2.0
+ * @access private
+ *
+ * @param string|null $pre_render   The pre-rendered content. Default null.
+ * @param array       $block The block being rendered.
+ *
+ * @return null
+ */
+function _wp_add_block_level_preset_styles( $pre_render, $block ) {
+	// Return early if the block has not support for descendent block styles.
+	$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
+	if ( ! block_has_support( $block_type, array( '__experimentalSettings' ), false ) ) {
+		return null;
+	}
+
+	// return early if no settings are found on the block attributes.
+	$block_settings = _wp_array_get( $block, array( 'attrs', 'settings' ), null );
+	if ( empty( $block_settings ) ) {
+		return null;
+	}
+
+	$class_name = '.' . _wp_get_presets_class_name( $block );
+
+	// the root selector for preset variables needs to target every possible block selector
+	// in order for the general setting to override any bock specific setting of a parent block or
+	// the site root.
+	$variables_root_selector = '*,[class*="wp-block"]';
+	$registry                = WP_Block_Type_Registry::get_instance();
+	$blocks                  = $registry->get_all_registered();
+	foreach ( $blocks as $block_type ) {
+		if (
+			isset( $block_type->supports['__experimentalSelector'] ) &&
+			is_string( $block_type->supports['__experimentalSelector'] )
+		) {
+			$variables_root_selector .= ',' . $block_type->supports['__experimentalSelector'];
+		}
+	}
+	$variables_root_selector = WP_Theme_JSON::scope_selector( $class_name, $variables_root_selector );
+
+	// Remove any potentially unsafe styles.
+	$theme_json_shape  = WP_Theme_JSON::remove_insecure_properties(
+		array(
+			'version'  => WP_Theme_JSON::LATEST_SCHEMA,
+			'settings' => $block_settings,
+		)
+	);
+	$theme_json_object = new WP_Theme_JSON( $theme_json_shape );
+
+	$styles = '';
+
+	// include preset css variables declaration on the stylesheet.
+	$styles .= $theme_json_object->get_stylesheet(
+		array( 'variables' ),
+		null,
+		array(
+			'root_selector' => $variables_root_selector,
+			'scope'         => $class_name,
+		)
+	);
+
+	// include preset css classes on the the stylesheet.
+	$styles .= $theme_json_object->get_stylesheet(
+		array( 'presets' ),
+		null,
+		array(
+			'root_selector' => $class_name . ',' . $class_name . ' *',
+			'scope'         => $class_name,
+		)
+	);
+
+	if ( ! empty( $styles ) ) {
+		wp_enqueue_block_support_styles( $styles );
+	}
+
+	return null;
+}
+
+add_filter( 'render_block', '_wp_add_block_level_presets_class', 10, 2 );
+add_filter( 'pre_render_block', '_wp_add_block_level_preset_styles', 10, 2 );

src/wp-includes/class-wp-theme-json.php

@@ -943,9 +943,12 @@ public function get_settings() {
 	 *                       - `styles`: only the styles section in theme.json.
 	 *                       - `presets`: only the classes for the presets.
 	 * @param array $origins A list of origins to include. By default it includes VALID_ORIGINS.
+	 * @param array $options An array of options for now used for internal purposes only (may change without notice).
+	 *                       The options currently supported are 'scope' that makes sure all style are scoped to a given selector,
+	 *                       and root_selector which overwrites and forces a given selector to be used on the root node.
 	 * @return string The resulting stylesheet.
 	 */
-	public function get_stylesheet( $types = array( 'variables', 'styles', 'presets' ), $origins = null ) {
+	public function get_stylesheet( $types = array( 'variables', 'styles', 'presets' ), $origins = null, $options = array() ) {
 		if ( null === $origins ) {
 			$origins = static::VALID_ORIGINS;
 		}
@@ -966,30 +969,58 @@ public function get_stylesheet( $types = array( 'variables', 'styles', 'presets'
 		$style_nodes     = static::get_style_nodes( $this->theme_json, $blocks_metadata );
 		$setting_nodes   = static::get_setting_nodes( $this->theme_json, $blocks_metadata );
 
+		$root_style_key    = array_search( static::ROOT_BLOCK_SELECTOR, array_column( $style_nodes, 'selector' ), true );
+		$root_settings_key = array_search( static::ROOT_BLOCK_SELECTOR, array_column( $setting_nodes, 'selector' ), true );
+
+		if ( ! empty( $options['scope'] ) ) {
+			foreach ( $setting_nodes as &$node ) {
+				$node['selector'] = static::scope_selector( $options['scope'], $node['selector'] );
+			}
+			foreach ( $style_nodes as &$node ) {
+				$node['selector'] = static::scope_selector( $options['scope'], $node['selector'] );
+			}
+		}
+
+		if ( ! empty( $options['root_selector'] ) ) {
+			if ( false !== $root_settings_key ) {
+				$setting_nodes[ $root_settings_key ]['selector'] = $options['root_selector'];
+			}
+			if ( false !== $root_style_key ) {
+				$setting_nodes[ $root_style_key ]['selector'] = $options['root_selector'];
+			}
+		}
+
 		$stylesheet = '';
 
 		if ( in_array( 'variables', $types, true ) ) {
 			$stylesheet .= $this->get_css_variables( $setting_nodes, $origins );
 		}
 
 		if ( in_array( 'styles', $types, true ) ) {
-			$root_block_key = array_search( static::ROOT_BLOCK_SELECTOR, array_column( $style_nodes, 'selector' ), true );
-
-			if ( false !== $root_block_key ) {
-				$stylesheet .= $this->get_root_layout_rules( static::ROOT_BLOCK_SELECTOR, $style_nodes[ $root_block_key ] );
+			if ( false !== $root_style_key ) {
+				$stylesheet .= $this->get_root_layout_rules( $style_nodes[ $root_style_key ]['selector'], $style_nodes[ $root_style_key ] );
 			}
 			$stylesheet .= $this->get_block_classes( $style_nodes );
 		} elseif ( in_array( 'base-layout-styles', $types, true ) ) {
+			$root_selector    = static::ROOT_BLOCK_SELECTOR;
+			$columns_selector = '.wp-block-columns';
+			if ( ! empty( $options['scope'] ) ) {
+				$root_selector    = static::scope_selector( $options['scope'], $root_selector );
+				$columns_selector = static::scope_selector( $options['scope'], $columns_selector );
+			}
+			if ( ! empty( $options['root_selector'] ) ) {
+				$root_selector = $options['root_selector'];
+			}
 			// Base layout styles are provided as part of `styles`, so only output separately if explicitly requested.
 			// For backwards compatibility, the Columns block is explicitly included, to support a different default gap value.
 			$base_styles_nodes = array(
 				array(
 					'path'     => array( 'styles' ),
-					'selector' => static::ROOT_BLOCK_SELECTOR,
+					'selector' => $root_selector,
 				),
 				array(
 					'path'     => array( 'styles', 'blocks', 'core/columns' ),
-					'selector' => '.wp-block-columns',
+					'selector' => $columns_selector,
 					'name'     => 'core/columns',
 				),
 			);
@@ -1490,18 +1521,27 @@ protected static function compute_preset_classes( $settings, $selector, $origins
 	 * @param string $selector Original selector.
 	 * @return string Scoped selector.
 	 */
-	protected static function scope_selector( $scope, $selector ) {
+	public static function scope_selector( $scope, $selector ) {
 		$scopes    = explode( ',', $scope );
 		$selectors = explode( ',', $selector );
 
 		$selectors_scoped = array();
 		foreach ( $scopes as $outer ) {
 			foreach ( $selectors as $inner ) {
-				$selectors_scoped[] = trim( $outer ) . ' ' . trim( $inner );
+				$outer = trim( $outer );
+				$inner = trim( $inner );
+				if ( ! empty( $outer ) && ! empty( $inner ) ) {
+					$selectors_scoped[] = $outer . ' ' . $inner;
+				} elseif ( empty( $outer ) ) {
+					$selectors_scoped[] = $inner;
+				} elseif ( empty( $inner ) ) {
+					$selectors_scoped[] = $outer;
+				}
 			}
 		}
 
-		return implode( ', ', $selectors_scoped );
+		$result = implode( ', ', $selectors_scoped );
+		return $result;
 	}
 
 	/**

src/wp-settings.php

@@ -338,6 +338,7 @@
 require ABSPATH . WPINC . '/block-supports/layout.php';
 require ABSPATH . WPINC . '/block-supports/spacing.php';
 require ABSPATH . WPINC . '/block-supports/typography.php';
+require ABSPATH . WPINC . '/block-supports/settings.php';
 require ABSPATH . WPINC . '/style-engine.php';
 require ABSPATH . WPINC . '/style-engine/class-wp-style-engine.php';
 require ABSPATH . WPINC . '/style-engine/class-wp-style-engine-css-declarations.php';