Add: API to allow blocks to access global styles.

lib/class-wp-rest-block-editor-settings-controller.php

@@ -149,7 +149,7 @@ public function get_item_schema() {
 				'__experimentalStyles'                   => array(
 					'description' => __( 'Styles consolidated from core, theme, and user origins.', 'gutenberg' ),
 					'type'        => 'object',
-					'context'     => array( 'mobile' ),
+					'context'     => array( 'post-editor', 'widgets-editor', 'mobile' ),
 				),
 
 				'alignWide'                              => array(

lib/global-styles.php

@@ -111,7 +111,7 @@ function_exists( 'gutenberg_is_edit_site_page' ) &&
 	}
 	$consolidated = WP_Theme_JSON_Resolver_Gutenberg::get_merged_data( $settings, $origin );
 
-	if ( 'mobile' === $context ) {
+	if ( 'site-editor' !== $context ) {
 		$settings['__experimentalStyles'] = $consolidated->get_raw_data()['styles'];
 	}
 

packages/block-editor/src/components/index.js

@@ -147,3 +147,4 @@ export { default as __experimentalUseNoRecursiveRenders } from './use-no-recursi
 
 export { default as BlockEditorProvider } from './provider';
 export { default as useSetting } from './use-setting';
+export { default as __experimentalUseStyle } from './use-style';

packages/block-editor/src/components/line-height-control/index.js

@@ -15,7 +15,11 @@ import {
 	isLineHeightDefined,
 } from './utils';
 
-export default function LineHeightControl( { value: lineHeight, onChange } ) {
+export default function LineHeightControl( {
+	value: lineHeight,
+	onChange,
+	placeholder = BASE_DEFAULT_VALUE,
+} ) {
 	const isDefined = isLineHeightDefined( lineHeight );
 
 	const handleOnKeyDown = ( event ) => {
@@ -70,7 +74,7 @@ export default function LineHeightControl( { value: lineHeight, onChange } ) {
 				onKeyDown={ handleOnKeyDown }
 				onChange={ handleOnChange }
 				label={ __( 'Line height' ) }
-				placeholder={ BASE_DEFAULT_VALUE }
+				placeholder={ placeholder }
 				step={ STEP }
 				type="number"
 				value={ value }

packages/block-editor/src/components/use-style/index.js

@@ -0,0 +1,51 @@
+/**
+ * External dependencies
+ */
+import { get } from 'lodash';
+
+/**
+ * WordPress dependencies
+ */
+import { useSelect } from '@wordpress/data';
+import { useMemo } from '@wordpress/element';
+
+/**
+ * Internal dependencies
+ */
+import { useBlockEditContext } from '../block-edit';
+import { store as blockEditorStore } from '../../store';
+import { getValueFromVariable } from '../../utils/style-variable-resolution';
+
+/**
+ * Hook that retrieves the global styles of a block.
+ * It works with nested objects using by finding the value at path.
+ *
+ * @param {string|Array} path The path to the setting.
+ *
+ * @return {any} Returns the style value defined for the path.
+ *
+ * @example
+ * ```js
+ * const backgroundColor = useStyle( 'color.background' );
+ * ```
+ */
+export default function useStyle( path ) {
+	const { name: blockName } = useBlockEditContext();
+
+	const settings = useSelect( ( select ) => {
+		return select( blockEditorStore ).getSettings();
+	}, [] );
+	const stylesForBlock = get( settings, [
+		'__experimentalStyles',
+		'blocks',
+		blockName,
+	] );
+	const value = get( stylesForBlock, path );
+	return useMemo( () => {
+		return getValueFromVariable(
+			settings.__experimentalFeatures,
+			blockName,
+			value
+		);
+	}, [ settings.__experimentalFeatures, blockName, value ] );
+}

packages/block-editor/src/hooks/line-height.js

@@ -9,6 +9,7 @@ import { hasBlockSupport } from '@wordpress/blocks';
 import LineHeightControl from '../components/line-height-control';
 import { cleanEmptyObject } from './utils';
 import useSetting from '../components/use-setting';
+import useStyle from '../components/use-style';
 
 export const LINE_HEIGHT_SUPPORT_KEY = 'typography.lineHeight';
 
@@ -24,6 +25,7 @@ export function LineHeightEdit( props ) {
 		attributes: { style },
 	} = props;
 	const isDisabled = useIsLineHeightDisabled( props );
+	const defaultLineHeight = useStyle( [ 'typography', 'lineHeight' ] );
 
 	if ( isDisabled ) {
 		return null;
@@ -45,6 +47,7 @@ export function LineHeightEdit( props ) {
 		<LineHeightControl
 			value={ style?.typography?.lineHeight }
 			onChange={ onChange }
+			placeholder={ defaultLineHeight }
 		/>
 	);
 }

packages/block-editor/src/utils/index.js

@@ -1,3 +1,7 @@
 export { default as transformStyles } from './transform-styles';
 export * from './theme';
 export * from './block-variation-transforms';
+export {
+	getValueFromVariable as __experimentalGetValueFromVariable,
+	getPresetVariableFromValue as __experimentalGetPresetVariableFromValue,
+} from './style-variable-resolution';

packages/block-editor/src/utils/style-variable-resolution.js

@@ -0,0 +1,188 @@
+/**
+ * External dependencies
+ */
+import { get, find, isString, kebabCase } from 'lodash';
+
+/**
+ * WordPress dependencies
+ */
+import { __EXPERIMENTAL_PRESET_METADATA as PRESET_METADATA } from '@wordpress/blocks';
+
+const STYLE_PROPERTIES_TO_CSS_VAR_INFIX = {
+	linkColor: 'color',
+	backgroundColor: 'color',
+	background: 'gradient',
+};
+
+function findInPresetsBy(
+	features,
+	blockName,
+	presetPath,
+	presetProperty,
+	presetValueValue
+) {
+	// Block presets take priority above root level presets.
+	const orderedPresetsByOrigin = [
+		get( features, [ 'blocks', blockName, ...presetPath ] ),
+		get( features, presetPath ),
+	];
+	for ( const presetByOrigin of orderedPresetsByOrigin ) {
+		if ( presetByOrigin ) {
+			// Preset origins ordered by priority.
+			const origins = [ 'user', 'theme', 'core' ];
+			for ( const origin of origins ) {
+				const presets = presetByOrigin[ origin ];
+				if ( presets ) {
+					const presetObject = find(
+						presets,
+						( preset ) =>
+							preset[ presetProperty ] === presetValueValue
+					);
+					if ( presetObject ) {
+						if ( presetProperty === 'slug' ) {
+							return presetObject;
+						}
+						// if there is a highest priority preset with the same slug but different value the preset we found was overwritten and should be ignored.
+						const highestPresetObjectWithSameSlug = findInPresetsBy(
+							features,
+							blockName,
+							presetPath,
+							'slug',
+							presetObject.slug
+						);
+						if (
+							highestPresetObjectWithSameSlug[
+								presetProperty
+							] === presetObject[ presetProperty ]
+						) {
+							return presetObject;
+						}
+						return undefined;
+					}
+				}
+			}
+		}
+	}
+}
+
+function getValueFromPresetVariable(
+	features,
+	blockName,
+	variable,
+	[ presetType, slug ]
+) {
+	const metadata = find( PRESET_METADATA, [ 'cssVarInfix', presetType ] );
+	if ( ! metadata ) {
+		return variable;
+	}
+
+	const presetObject = findInPresetsBy(
+		features,
+		blockName,
+		metadata.path,
+		'slug',
+		slug
+	);
+
+	if ( presetObject ) {
+		const { valueKey } = metadata;
+		const result = presetObject[ valueKey ];
+		return getValueFromVariable( features, blockName, result );
+	}
+
+	return variable;
+}
+
+function getValueFromCustomVariable( features, blockName, variable, path ) {
+	const result =
+		get( features, [ 'blocks', blockName, 'custom', ...path ] ) ??
+		get( features, [ 'custom', ...path ] );
+	if ( ! result ) {
+		return variable;
+	}
+	// A variable may reference another variable so we need recursion until we find the value.
+	return getValueFromVariable( features, blockName, result );
+}
+
+export function getValueFromVariable( features, blockName, variable ) {
+	if ( ! variable || ! isString( variable ) ) {
+		return variable;
+	}
+	const USER_VALUE_PREFIX = 'var:';
+	const THEME_VALUE_PREFIX = 'var(--wp--';
+	const THEME_VALUE_SUFFIX = ')';
+
+	let parsedVar;
+
+	if ( variable.startsWith( USER_VALUE_PREFIX ) ) {
+		parsedVar = variable.slice( USER_VALUE_PREFIX.length ).split( '|' );
+	} else if (
+		variable.startsWith( THEME_VALUE_PREFIX ) &&
+		variable.endsWith( THEME_VALUE_SUFFIX )
+	) {
+		parsedVar = variable
+			.slice( THEME_VALUE_PREFIX.length, -THEME_VALUE_SUFFIX.length )
+			.split( '--' );
+	} else {
+		// We don't know how to parse the value: either is raw of uses complex CSS such as `calc(1px * var(--wp--variable) )`
+		return variable;
+	}
+
+	const [ type, ...path ] = parsedVar;
+	if ( type === 'preset' ) {
+		return getValueFromPresetVariable(
+			features,
+			blockName,
+			variable,
+			path
+		);
+	}
+	if ( type === 'custom' ) {
+		return getValueFromCustomVariable(
+			features,
+			blockName,
+			variable,
+			path
+		);
+	}
+	return variable;
+}
+
+export function getPresetVariableFromValue(
+	features,
+	blockName,
+	presetPropertyName,
+	presetPropertyValue
+) {
+	if ( ! presetPropertyValue ) {
+		return presetPropertyValue;
+	}
+
+	const cssVarInfix =
+		STYLE_PROPERTIES_TO_CSS_VAR_INFIX[ presetPropertyName ] ||
+		kebabCase( presetPropertyName );
+
+	const metadata = find( PRESET_METADATA, [ 'cssVarInfix', cssVarInfix ] );
+	if ( ! metadata ) {
+		// The property doesn't have preset data
+		// so the value should be returned as it is.
+		return presetPropertyValue;
+	}
+	const { valueKey, path } = metadata;
+
+	const presetObject = findInPresetsBy(
+		features,
+		blockName,
+		path,
+		valueKey,
+		presetPropertyValue
+	);
+
+	if ( ! presetObject ) {
+		// Value wasn't found in the presets,
+		// so it must be a custom value.
+		return presetPropertyValue;
+	}
+
+	return `var:preset|${ cssVarInfix }|${ presetObject.slug }`;
+}