Webfonts: scan content for font families and enqueue them (Attempt #2)

lib/compat/wordpress-6.0/scan-webfonts-used-in-blocks.php

@@ -0,0 +1,32 @@
+<?php
+/**
+ * Webfonts API: scan and enqueue webfonts used in blocks.
+ *
+ * @package Gutenberg
+ */
+
+if ( ! function_exists( 'gutenberg_enqueue_webfonts_used_in_block' ) ) {
+	/**
+	 * Looks for font families in the attributes and enqueue them.
+	 *
+	 * @param string $content The block content.
+	 * @param array  $parsed_block The parsed block attributes.
+	 *
+	 * @return array
+	 */
+	function gutenberg_enqueue_webfonts_used_in_block( $content, $parsed_block ) {
+		if ( isset( $parsed_block['attrs']['fontFamily'] ) ) {
+			wp_webfonts()->enqueue_webfont( $parsed_block['attrs']['fontFamily'] );
+		}
+
+		return $content;
+	}
+
+	/**
+	 * We are already enqueueing all registered fonts by default when loading the block editor,
+	 * so we only need to scan for webfonts when browsing as a guest.
+	 */
+	if ( ! is_admin() ) {
+		add_filter( 'pre_render_block', 'gutenberg_enqueue_webfonts_used_in_block', 10, 2 );
+	}
+}

lib/compat/wordpress-6.0/scan-webfonts-used-in-global-styles.php

@@ -0,0 +1,83 @@
+<?php
+/**
+ * Webfonts API: scan and enqueue webfonts used in Global Styles.
+ *
+ * @package Gutenberg
+ */
+
+if ( ! function_exists( 'gutenberg_enqueue_webfonts_used_in_global_styles' ) ) {
+	/**
+	 * Extract the font family slug from a settings object.
+	 *
+	 * @param object $setting The setting object.
+	 *
+	 * @return string|void
+	 */
+	function gutenberg_extract_font_slug_from_setting( $setting ) {
+		if ( isset( $setting['typography'] ) && isset( $setting['typography']['fontFamily'] ) ) {
+			$font_family = $setting['typography']['fontFamily'];
+
+			// Full string: var(--wp--preset--font-family--slug).
+			// We do not care about the origin of the font, only its slug.
+			preg_match( '/font-family--(?P<slug>.+)\)$/', $font_family, $matches );
+
+			if ( isset( $matches['slug'] ) ) {
+				return $matches['slug'];
+			}
+
+			// Full string: var:preset|font-family|slug
+			// We do not care about the origin of the font, only its slug.
+			preg_match( '/font-family\|(?P<slug>.+)$/', $font_family, $matches );
+
+			if ( isset( $matches['slug'] ) ) {
+				return $matches['slug'];
+			}
+
+			return $font_family;
+		}
+	}
+
+	/**
+	 * Looks for font families in the global styles and enqueue them.
+	 */
+	function gutenberg_enqueue_webfonts_used_in_global_styles() {
+		$global_styles = gutenberg_get_global_styles();
+
+		// Scan block presets looking for webfonts...
+		if ( isset( $global_styles['blocks'] ) ) {
+			foreach ( $global_styles['blocks'] as $setting ) {
+				$font_slug = gutenberg_extract_font_slug_from_setting( $setting );
+
+				if ( $font_slug ) {
+					wp_webfonts()->enqueue_webfont( $font_slug );
+				}
+			}
+		}
+
+		// Scan HTML element presets looking for webfonts...
+		if ( isset( $global_styles['elements'] ) ) {
+			foreach ( $global_styles['elements'] as $setting ) {
+				$font_slug = gutenberg_extract_font_slug_from_setting( $setting );
+
+				if ( $font_slug ) {
+					wp_webfonts()->enqueue_webfont( $font_slug );
+				}
+			}
+		}
+
+		// Check if a global typography setting was defined.
+		$font_slug = gutenberg_extract_font_slug_from_setting( $global_styles );
+
+		if ( $font_slug ) {
+			wp_webfonts()->enqueue_webfont( $font_slug );
+		}
+	}
+
+	/**
+	 * We are already enqueueing all registered fonts by default when loading the block editor,
+	 * so we only need to scan for webfonts when browsing as a guest.
+	 */
+	if ( ! is_admin() ) {
+		add_action( 'wp_loaded', 'gutenberg_enqueue_webfonts_used_in_global_styles' );
+	}
+}

lib/load.php

@@ -102,6 +102,8 @@ function gutenberg_is_experiment_enabled( $name ) {
 require __DIR__ . '/compat/wordpress-6.0/block-patterns.php';
 require __DIR__ . '/compat/wordpress-6.0/block-template.php';
 require __DIR__ . '/compat/wordpress-6.0/register-webfonts-from-theme-json.php';
+require __DIR__ . '/compat/wordpress-6.0/scan-webfonts-used-in-global-styles.php';
+require __DIR__ . '/compat/wordpress-6.0/scan-webfonts-used-in-blocks.php';
 require __DIR__ . '/compat/wordpress-6.0/class-wp-theme-json-resolver-gutenberg.php';
 require __DIR__ . '/compat/wordpress-6.0/class-wp-webfonts.php';
 require __DIR__ . '/compat/wordpress-6.0/class-wp-webfonts-provider.php';