Block Styles: Extend block style variations as mechanism for achievin…

…g section styling (WordPress#57908)

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Co-authored-by: tellthemachines <isabel_brison@git.wordpress.org>
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backport-changelog/6.6/6662.md

@@ -0,0 +1,3 @@
+https://github.com/WordPress/wordpress-develop/pull/6662
+
+* https://github.com/WordPress/gutenberg/pull/57908

lib/block-supports/block-style-variations.php

@@ -0,0 +1,375 @@
+<?php
+/**
+ * Block support to enable per-section styling of block types via
+ * block style variations.
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Get the class name for this application of this block's variation styles.
+ *
+ * @since 6.6.0
+ *
+ * @param array  $block     Block object.
+ * @param string $variation Slug for the block style variation.
+ *
+ * @return string The unique class name.
+ */
+function gutenberg_get_block_style_variation_class_name( $block, $variation ) {
+	return 'is-style-' . $variation . '--' . md5( serialize( $block ) );
+}
+
+/**
+ * Determines the block style variation names within a CSS class string.
+ *
+ * @since 6.6.0
+ *
+ * @param string $class_string CSS class string to look for a variation in.
+ *
+ * @return array|null The block style variation name if found.
+ */
+function gutenberg_get_block_style_variation_name_from_class( $class_string ) {
+	if ( ! is_string( $class_string ) ) {
+		return null;
+	}
+
+	preg_match_all( '/\bis-style-(?!default)(\S+)\b/', $class_string, $matches );
+	return $matches[1] ?? null;
+}
+
+/**
+ * Render the block style variation's styles.
+ *
+ * In the case of nested blocks with variations applied, we want the parent
+ * variation's styles to be rendered before their descendants. This solves the
+ * issue of a block type being styled in both the parent and descendant: we want
+ * the descendant style to take priority, and this is done by loading it after,
+ * in the DOM order. This is why the variation stylesheet generation is in a
+ * different filter.
+ *
+ * @since 6.6.0
+ *
+ * @param array $parsed_block The parsed block.
+ *
+ * @return array The parsed block with block style variation classname added.
+ */
+function gutenberg_render_block_style_variation_support_styles( $parsed_block ) {
+	$classes    = $parsed_block['attrs']['className'] ?? null;
+	$variations = gutenberg_get_block_style_variation_name_from_class( $classes );
+
+	if ( ! $variations ) {
+		return $parsed_block;
+	}
+
+	$tree       = WP_Theme_JSON_Resolver_Gutenberg::get_merged_data();
+	$theme_json = $tree->get_raw_data();
+
+	// Only the first block style variation with data is supported.
+	$variation_data = array();
+	foreach ( $variations as $variation ) {
+		$variation_data = $theme_json['styles']['blocks'][ $parsed_block['blockName'] ]['variations'][ $variation ] ?? array();
+
+		if ( ! empty( $variation_data ) ) {
+			break;
+		}
+	}
+
+	if ( empty( $variation_data ) ) {
+		return $parsed_block;
+	}
+
+	$config = array(
+		'version' => WP_Theme_JSON_Gutenberg::LATEST_SCHEMA,
+		'styles'  => $variation_data,
+	);
+
+	$class_name         = gutenberg_get_block_style_variation_class_name( $parsed_block, $variation );
+	$updated_class_name = $parsed_block['attrs']['className'] . " $class_name";
+
+	$class_name = ".$class_name";
+
+	if ( ! is_admin() ) {
+		remove_filter( 'wp_theme_json_get_style_nodes', 'wp_filter_out_block_nodes' );
+	}
+
+	$variation_theme_json = new WP_Theme_JSON_Gutenberg( $config, 'blocks' );
+	$variation_styles     = $variation_theme_json->get_stylesheet(
+		array( 'styles' ),
+		array( 'custom' ),
+		array(
+			'root_selector'           => $class_name,
+			'skip_root_layout_styles' => true,
+			'scope'                   => $class_name,
+		)
+	);
+
+	if ( ! is_admin() ) {
+		add_filter( 'wp_theme_json_get_style_nodes', 'wp_filter_out_block_nodes' );
+	}
+
+	if ( empty( $variation_styles ) ) {
+		return $parsed_block;
+	}
+
+	wp_register_style( 'block-style-variation-styles', false, array( 'global-styles' ) );
+	wp_add_inline_style( 'block-style-variation-styles', $variation_styles );
+
+	/*
+	 * Add variation instance class name to block's className string so it can
+	 * be enforced in the block markup via render_block filter.
+	 */
+	_wp_array_set( $parsed_block, array( 'attrs', 'className' ), $updated_class_name );
+
+	return $parsed_block;
+}
+
+/**
+ * Ensure the variation block support class name generated and added to
+ * block attributes in the `render_block_data` filter gets applied to the
+ * block's markup.
+ *
+ * @see gutenberg_render_block_style_variation_support_styles
+ *
+ * @since 6.6.0
+ *
+ * @param  string $block_content Rendered block content.
+ * @param  array  $block         Block object.
+ *
+ * @return string                Filtered block content.
+ */
+function gutenberg_render_block_style_variation_class_name( $block_content, $block ) {
+	if ( ! $block_content || empty( $block['attrs']['className'] ) ) {
+		return $block_content;
+	}
+
+	/*
+	 * Matches a class prefixed by `is-style`, followed by the
+	 * variation slug, then `--`, and finally a hash.
+	 *
+	 * See `gutenberg_get_block_style_variation_class_name` for class generation.
+	 */
+	preg_match( '/\bis-style-(\S+?--\w+)\b/', $block['attrs']['className'], $matches );
+
+	if ( empty( $matches ) ) {
+		return $block_content;
+	}
+
+	$tags = new WP_HTML_Tag_Processor( $block_content );
+
+	if ( $tags->next_tag() ) {
+		/*
+		 * Ensure the variation instance class name set in the
+		 * `render_block_data` filter is applied in markup.
+		 * See `gutenberg_render_block_style_variation_support_styles`.
+		 */
+		$tags->add_class( $matches[0] );
+	}
+
+	return $tags->get_updated_html();
+}
+
+/**
+ * Collects block style variation data for merging with theme.json data.
+ * As each block style variation is processed it is registered if it hasn't
+ * been already. This registration is required for later sanitization of
+ * theme.json data.
+ *
+ * @since 6.6.0
+ *
+ * @param array $variations Shared block style variations.
+ *
+ * @return array Block variations data to be merged under styles.blocks
+ */
+function gutenberg_resolve_and_register_block_style_variations( $variations ) {
+	$variations_data = array();
+
+	if ( empty( $variations ) ) {
+		return $variations_data;
+	}
+
+	$registry              = WP_Block_Styles_Registry::get_instance();
+	$have_named_variations = ! wp_is_numeric_array( $variations );
+
+	foreach ( $variations as $key => $variation ) {
+		$supported_blocks = $variation['blockTypes'] ?? array();
+
+		/*
+		 * Standalone theme.json partial files for block style variations
+		 * will have their styles under a top-level property by the same name.
+		 * Variations defined within an existing theme.json or theme style
+		 * variation will themselves already be the required styles data.
+		 */
+		$variation_data = $variation['styles'] ?? $variation;
+
+		if ( empty( $variation_data ) ) {
+			continue;
+		}
+
+		/*
+		 * Block style variations read in via standalone theme.json partials
+		 * need to have their name set to the kebab case version of their title.
+		 */
+		$variation_name  = $have_named_variations ? $key : _wp_to_kebab_case( $variation['title'] );
+		$variation_label = $variation['title'] ?? $variation_name;
+
+		foreach ( $supported_blocks as $block_type ) {
+			$registered_styles = $registry->get_registered_styles_for_block( $block_type );
+
+			// Register block style variation if it hasn't already been registered.
+			if ( ! array_key_exists( $variation_name, $registered_styles ) ) {
+				gutenberg_register_block_style(
+					$block_type,
+					array(
+						'name'  => $variation_name,
+						'label' => $variation_label,
+					)
+				);
+			}
+
+			// Add block style variation data under current block type.
+			$path = array( $block_type, 'variations', $variation_name );
+			_wp_array_set( $variations_data, $path, $variation_data );
+		}
+	}
+
+	return $variations_data;
+}
+
+/**
+ * Merges variations data with existing theme.json data ensuring that the
+ * current theme.json data values take precedence.
+ *
+ * @since 6.6.0
+ *
+ * @param array                        $variations_data Block style variations data keyed by block type.
+ * @param WP_Theme_JSON_Data_Gutenberg $theme_json      Current theme.json data.
+ * @param string                       $origin          Origin for the theme.json data.
+ *
+ * @return WP_Theme_JSON_Gutenberg The merged theme.json data.
+ */
+function gutenberg_merge_block_style_variations_data( $variations_data, $theme_json, $origin = 'theme' ) {
+	if ( empty( $variations_data ) ) {
+		return $theme_json;
+	}
+
+	$variations_theme_json_data = array(
+		'version' => WP_Theme_JSON_Gutenberg::LATEST_SCHEMA,
+		'styles'  => array( 'blocks' => $variations_data ),
+	);
+
+	$variations_theme_json = new WP_Theme_JSON_Data_Gutenberg( $variations_theme_json_data, $origin );
+
+	/*
+	 * Merge the current theme.json data over shared variation data so that
+	 * any explicit per block variation values take precedence.
+	 */
+	return $variations_theme_json->update_with( $theme_json->get_data() );
+}
+
+/**
+ * Merges any shared block style variation definitions from a theme style
+ * variation into their appropriate block type within theme json styles. Any
+ * custom user selections already made will take precedence over the shared
+ * style variation value.
+ *
+ * @since 6.6.0
+ *
+ * @param WP_Theme_JSON_Data_Gutenberg $theme_json Current theme.json data.
+ *
+ * @return WP_Theme_JSON_Data_Gutenberg
+ */
+function gutenberg_resolve_block_style_variations_from_theme_style_variation( $theme_json ) {
+	$theme_json_data   = $theme_json->get_data();
+	$shared_variations = $theme_json_data['styles']['blocks']['variations'] ?? array();
+	$variations_data   = gutenberg_resolve_and_register_block_style_variations( $shared_variations );
+
+	return gutenberg_merge_block_style_variations_data( $variations_data, $theme_json, 'user' );
+}
+
+/**
+ * Merges block style variation data sourced from standalone partial
+ * theme.json files.
+ *
+ * @since 6.6.0
+ *
+ * @param WP_Theme_JSON_Data_Gutenberg $theme_json Current theme.json data.
+ *
+ * @return WP_Theme_JSON_Data_Gutenberg
+ */
+function gutenberg_resolve_block_style_variations_from_theme_json_partials( $theme_json ) {
+	$block_style_variations = WP_Theme_JSON_Resolver_Gutenberg::get_style_variations( 'block' );
+	$variations_data        = gutenberg_resolve_and_register_block_style_variations( $block_style_variations );
+
+	return gutenberg_merge_block_style_variations_data( $variations_data, $theme_json );
+}
+
+/**
+ * Merges shared block style variations registered within the
+ * `styles.blocks.variations` property of the primary theme.json file.
+ *
+ * @since 6.6.0
+ *
+ * @param WP_Theme_JSON_Data_Gutenberg $theme_json Current theme.json data.
+ *
+ * @return WP_Theme_JSON_Data_Gutenberg
+ */
+function gutenberg_resolve_block_style_variations_from_primary_theme_json( $theme_json ) {
+	$theme_json_data        = $theme_json->get_data();
+	$block_style_variations = $theme_json_data['styles']['blocks']['variations'] ?? array();
+	$variations_data        = gutenberg_resolve_and_register_block_style_variations( $block_style_variations );
+
+	return gutenberg_merge_block_style_variations_data( $variations_data, $theme_json );
+}
+
+/**
+ * Merges block style variations registered via the block styles registry with a
+ * style object, under their appropriate block types within theme.json styles.
+ * Any variation values defined within the theme.json specific to a block type
+ * will take precedence over these shared definitions.
+ *
+ * @since 6.6.0
+ *
+ * @param WP_Theme_JSON_Data_Gutenberg $theme_json Current theme.json data.
+ *
+ * @return WP_Theme_JSON_Data_Gutenberg
+ */
+function gutenberg_resolve_block_style_variations_from_styles_registry( $theme_json ) {
+	$registry        = WP_Block_Styles_Registry::get_instance();
+	$styles          = $registry->get_all_registered();
+	$variations_data = array();
+
+	foreach ( $styles as $block_type => $variations ) {
+		foreach ( $variations as $variation_name => $variation ) {
+			if ( ! empty( $variation['style_data'] ) ) {
+				$path = array( $block_type, 'variations', $variation_name );
+				_wp_array_set( $variations_data, $path, $variation['style_data'] );
+			}
+		}
+	}
+
+	return gutenberg_merge_block_style_variations_data( $variations_data, $theme_json );
+}
+
+/**
+ * Enqueues styles for block style variations.
+ *
+ * @since 6.6.0
+ */
+function gutenberg_enqueue_block_style_variation_styles() {
+	wp_enqueue_style( 'block-style-variation-styles' );
+}
+
+// Register the block support.
+WP_Block_Supports::get_instance()->register( 'block-style-variation', array() );
+
+add_filter( 'render_block_data', 'gutenberg_render_block_style_variation_support_styles', 10, 2 );
+add_filter( 'render_block', 'gutenberg_render_block_style_variation_class_name', 10, 2 );
+add_action( 'wp_enqueue_scripts', 'gutenberg_enqueue_block_style_variation_styles', 1 );
+
+// Resolve block style variations from all their potential sources. The order here is deliberate.
+add_filter( 'wp_theme_json_data_theme', 'gutenberg_resolve_block_style_variations_from_primary_theme_json', 10, 1 );
+add_filter( 'wp_theme_json_data_theme', 'gutenberg_resolve_block_style_variations_from_theme_json_partials', 10, 1 );
+add_filter( 'wp_theme_json_data_theme', 'gutenberg_resolve_block_style_variations_from_styles_registry', 10, 1 );
+
+add_filter( 'wp_theme_json_data_user', 'gutenberg_resolve_block_style_variations_from_theme_style_variation', 10, 1 );