Add API to access global settings, styles, and stylesheet

lib/block-supports/layout.php

@@ -116,10 +116,9 @@ function gutenberg_render_layout_support_flag( $block_content, $block ) {
 		return $block_content;
 	}
 
-	$tree                  = WP_Theme_JSON_Resolver_Gutenberg::get_merged_data( array(), 'theme' );
-	$theme_settings        = $tree->get_settings();
-	$default_layout        = _wp_array_get( $theme_settings, array( 'layout' ) );
-	$has_block_gap_support = isset( $theme_settings['spacing']['blockGap'] ) ? null !== $theme_settings['spacing']['blockGap'] : false;
+	$block_gap             = gutenberg_get_global_settings( array( 'spacing', 'blockGap' ) );
+	$default_layout        = gutenberg_get_global_settings( array( 'layout' ) );
+	$has_block_gap_support = isset( $block_gap ) ? null !== $block_gap : false;
 	$default_block_layout  = _wp_array_get( $block_type->supports, array( '__experimentalLayout', 'default' ), array() );
 	$used_layout           = isset( $block['attrs']['layout'] ) ? $block['attrs']['layout'] : $default_block_layout;
 	if ( isset( $used_layout['inherit'] ) && $used_layout['inherit'] ) {

lib/compat/wordpress-5.9/get-global-styles-and-settings.php

@@ -0,0 +1,125 @@
+<?php
+/**
+ * API to interact with global settings & styles.
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Function to get the settings resulting of merging core, theme, and user data.
+ *
+ * @param array  $path              Path to the specific setting to retrieve. Optional.
+ *                                  If empty, will return all settings.
+ * @param string $block_name        Which block to retrieve the settings from. Optional
+ *                                  If empty, it'll return the settings for the global context.
+ * @param string $origin            Which origin to take data from. Optional.
+ *                                  It can be 'all' (core, theme, and user) or 'base' (core and theme).
+ *                                  If empty or unknown, 'all' is used.
+ *
+ * @return array The settings to retrieve.
+ */
+function gutenberg_get_global_settings( $path = array(), $block_name = '', $origin = 'all' ) {
+	if ( '' !== $block_name ) {
+		$path = array_merge( array( 'blocks', $block_name ), $path );
+	}
+
+	if ( 'base' === $origin ) {
+		$origin = 'theme';
+	} else {
+		$origin = 'user';
+	}
+
+	$theme_supports = gutenberg_get_default_block_editor_settings();
+	$settings       = WP_Theme_JSON_Resolver_Gutenberg::get_merged_data( $theme_supports, $origin )->get_settings();
+
+	return _wp_array_get( $settings, $path, $settings );
+}
+
+/**
+ * Function to get the styles resulting of merging core, theme, and user data.
+ *
+ * @param array  $path              Path to the specific style to retrieve. Optional.
+ *                                  If empty, will return all styles.
+ * @param string $block_name        Which block to retrieve the styles from. Optional.
+ *                                  If empty, it'll return the styles for the global context.
+ * @param string $origin            Which origin to take data from. Optional.
+ *                                  It can be 'all' (core, theme, and user) or 'base' (core and theme).
+ *                                  If empty or unknown, 'all' is used.
+ *
+ * @return array The styles to retrieve.
+ */
+function gutenberg_get_global_styles( $path = array(), $block_name = '', $origin = 'all' ) {
+	if ( '' !== $block_name ) {
+		$path = array_merge( array( 'blocks', $block_name ), $path );
+	}
+
+	if ( 'base' === $origin ) {
+		$origin = 'theme';
+	} else {
+		$origin = 'user';
+	}
+
+	$theme_supports = gutenberg_get_default_block_editor_settings();
+	$styles         = WP_Theme_JSON_Resolver_Gutenberg::get_merged_data( $theme_supports, $origin )->get_raw_data()['styles'];
+
+	return _wp_array_get( $styles, $path, $styles );
+}
+
+/**
+ * Returns the stylesheet resulting of merging core, theme, and user data.
+ *
+ * @param string $type     Type of the stylesheet. Optional.
+ *                         It accepts 'all', 'block_styles', 'css_variables', 'presets'.
+ *                         If empty, it'll resolve to all (theme with theme.json support)
+ *                         or 'presets' (theme without theme.json support).
+ *
+ * @return string Stylesheet.
+ */
+function gutenberg_get_global_stylesheet( $type = '' ) {
+	// Return cached value if it can be used and exists.
+	// It's cached by theme to make sure that theme switching clears the cache.
+	$can_use_cached = (
+		( 'all' === $type ) &&
+		( ! defined( 'WP_DEBUG' ) || ! WP_DEBUG ) &&
+		( ! defined( 'SCRIPT_DEBUG' ) || ! SCRIPT_DEBUG ) &&
+		( ! defined( 'REST_REQUEST' ) || ! REST_REQUEST ) &&
+		! is_admin()
+	);
+	$transient_name = 'gutenberg_global_styles_' . get_stylesheet();
+	if ( $can_use_cached ) {
+		$cached = get_transient( $transient_name );
+		if ( $cached ) {
+			return $cached;
+		}
+	}
+
+	$supports_theme_json = WP_Theme_JSON_Resolver_Gutenberg::theme_has_support();
+	$supports_link_color = get_theme_support( 'experimental-link-color' );
+	if ( empty( $type ) && ! $supports_theme_json ) {
+		$type = 'presets';
+	} elseif ( empty( $type ) ) {
+		$type = 'all';
+	}
+
+	$origins = array( 'core', 'theme', 'user' );
+	if ( ! $supports_theme_json && ! $supports_link_color ) {
+		// In this case we only enqueue the core presets (CSS Custom Properties + the classes).
+		$origins = array( 'core' );
+	} elseif ( ! $supports_theme_json && $supports_link_color ) {
+		// For the legacy link color feauter to work, the CSS Custom Properties
+		// should be in scope (either the core or the theme ones).
+		$origins = array( 'core', 'theme' );
+	}
+
+	$theme_supports = gutenberg_get_default_block_editor_settings();
+	$tree           = WP_Theme_JSON_Resolver_Gutenberg::get_merged_data( $theme_supports );
+	$stylesheet     = $tree->get_stylesheet( $type, $origins );
+
+	if ( $can_use_cached ) {
+		// Cache for a minute.
+		// This cache doesn't need to be any longer, we only want to avoid spikes on high-traffic sites.
+		set_transient( $transient_name, $stylesheet, MINUTE_IN_SECONDS );
+	}
+
+	return $stylesheet;
+}

lib/global-styles.php

@@ -71,10 +71,7 @@ function gutenberg_experimental_global_styles_get_stylesheet( $tree, $type = nul
  * and enqueues the resulting stylesheet.
  */
 function gutenberg_experimental_global_styles_enqueue_assets() {
-	$settings = gutenberg_get_default_block_editor_settings();
-	$all      = WP_Theme_JSON_Resolver_Gutenberg::get_merged_data( $settings );
-
-	$stylesheet = gutenberg_experimental_global_styles_get_stylesheet( $all );
+	$stylesheet = gutenberg_get_global_stylesheet();
 	if ( empty( $stylesheet ) ) {
 		return;
 	}

lib/load.php

@@ -84,6 +84,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 require __DIR__ . '/compat/wordpress-5.8/index.php';
 require __DIR__ . '/compat/wordpress-5.8.1/index.php';
 require __DIR__ . '/compat/wordpress-5.9/default-editor-styles.php';
+require __DIR__ . '/compat/wordpress-5.9/get-global-styles-and-settings.php';
 require __DIR__ . '/utils.php';
 require __DIR__ . '/editor-settings.php';