From 8c4c35311bd5e2de2930864e8b0ebbc16bebf08b Mon Sep 17 00:00:00 2001
From: hellofromTonya <hellofromTonya@git.wordpress.org>
Date: Thu, 31 Aug 2023 21:49:20 +0000
Subject: [PATCH] Introduce font-face styles generator and printer.

Introducing Font Face, a server-side `@font-face` styles generator and printer.

tl;dr:
* Introduces Font Face.
* Deprecates `_wp_theme_json_webfonts_handler()`.

**Introduce Font Face**

From an array of fonts (i.e. each font-family and its font variations to be processed), it:

1. Validates each `font-face` declaration, i.e. the CSS property and value pairing. If validation fails, processing stops with no font-face styles printed.
3. Generates the `@font-face` CSS for each font-family.
4. Prints the CSS within a `<style id="wp-fonts-local">` element.

The entry point into Font Face is through a new global function called `wp_print_font_faces()`, which is automatically called:

* when the `'wp_head'` hook runs (for the front-end).
* when the `'admin_print_styles'` hook runs (for the back-end).
* when `_wp_get_iframed_editor_assets()` runs to inject the `@font-face` styles into the iframed editor.

Once called, it gets the fonts from Theme_JSON merged data layer, which includes theme defined fonts and user activated fonts (once the Font Library #59166 is introduced into Core).

For classic sites, themes and plugins can directly call `wp_print_font_faces()` and pass their fonts array to it for processing.

**Deprecates `_wp_theme_json_webfonts_handler()`.**

As Font Face is a direct replacement, the stopgap code in `_wp_theme_json_webfonts_handler()` (introduced in 6.0.0 via [53282]) is deprecated and unused in Core.

**Props note:**
There's a long multiple year history baked into Font Face, which dates back to the early versions of a web font API (see #46370 and [https://github.com/WordPress/gutenberg/issues/41479 roadmap]. The props list includes those who contributed from those early versions up to this commit.

**References:**
* #46370 original (Web)Fonts API proposal for registering and enqueuing web fonts.
* [https://github.com/WordPress/gutenberg/issues/41479 Gutenberg tracking issue] which includes the evolution from Webfonts API to Fonts API to Font Face.
* [53282] / #55567 Added the stopgap code `_wp_theme_json_webfonts_handler()` in 6.0.
* [https://developer.mozilla.org/en-US/docs/Web/CSS/@font-face @font-face on mdn web docs]
* #59166 Font Library: Font manager for WordPress

Follow-up to [53282].

Props aristath, jonoaldersonwp, hellofromTonya, andraganescu, annezazu, antonvlasenko, arena, askdesign, azaozz, bph, bradley2083, colorful-tones, costdev, davidbaumwald, desrosj, dingo_d, djcowan, domainsupport, dryanpress, elmastudio, flixos90, francina, garrett-eclipse, gigitux, grantmkin, grapplerulrich, gziolo, ironprogrammer, jb510, jeffpaul, jeremyyip, jffng, joostdevalk, jorgefilipecosta, juanmaguitar, mamaduka, matveb, mburridge, mitogh, ndiego, ntsekouras, oandregal, ocean90, oglekler, paaljoachim, pagelab, peterwilsoncc, poena, priethor, scruffian, SergeyBiryukov, shiloey, simison, skorasaurus, soean, westonruter, wildworks, zaguiini.
Fixes #59165.
Built from https://develop.svn.wordpress.org/trunk@56500


git-svn-id: http://core.svn.wordpress.org/trunk@56012 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-admin/includes/admin-filters.php           |   3 +
 wp-includes/block-editor.php                  |   1 +
 wp-includes/default-filters.php               |   4 +-
 wp-includes/deprecated.php                    | 503 ++++++++++++++++++
 wp-includes/fonts.php                         |  57 ++
 .../fonts/class-wp-font-face-resolver.php     | 154 ++++++
 wp-includes/fonts/class-wp-font-face.php      | 430 +++++++++++++++
 wp-includes/script-loader.php                 | 500 -----------------
 wp-includes/version.php                       |   2 +-
 wp-settings.php                               |   3 +
 10 files changed, 1155 insertions(+), 502 deletions(-)
 create mode 100644 wp-includes/fonts.php
 create mode 100644 wp-includes/fonts/class-wp-font-face-resolver.php
 create mode 100644 wp-includes/fonts/class-wp-font-face.php

diff --git a/wp-admin/includes/admin-filters.php b/wp-admin/includes/admin-filters.php
index 33354cb073..8e3da338c5 100644
--- a/wp-admin/includes/admin-filters.php
+++ b/wp-admin/includes/admin-filters.php
@@ -168,3 +168,6 @@ add_action( 'post_updated', array( 'WP_Privacy_Policy_Content', '_policy_page_up
 
 // Append '(Draft)' to draft page titles in the privacy page dropdown.
 add_filter( 'list_pages', '_wp_privacy_settings_filter_draft_page_titles', 10, 2 );
+
+// Font management.
+add_action( 'admin_print_styles', 'wp_print_font_faces', 50 );
diff --git a/wp-includes/block-editor.php b/wp-includes/block-editor.php
index 015a553f57..05bcd4e7c2 100644
--- a/wp-includes/block-editor.php
+++ b/wp-includes/block-editor.php
@@ -361,6 +361,7 @@ function _wp_get_iframed_editor_assets() {
 
 	ob_start();
 	wp_print_styles();
+	wp_print_font_faces();
 	$styles = ob_get_clean();
 
 	ob_start();
diff --git a/wp-includes/default-filters.php b/wp-includes/default-filters.php
index bf39f29b4d..c08073326c 100644
--- a/wp-includes/default-filters.php
+++ b/wp-includes/default-filters.php
@@ -358,7 +358,6 @@ add_action( 'start_previewing_theme', 'wp_clean_theme_json_cache' );
 add_action( 'after_switch_theme', '_wp_menus_changed' );
 add_action( 'after_switch_theme', '_wp_sidebars_changed' );
 add_action( 'wp_print_styles', 'print_emoji_styles' );
-add_action( 'plugins_loaded', '_wp_theme_json_webfonts_handler' );
 
 if ( isset( $_GET['replytocom'] ) ) {
 	add_filter( 'wp_robots', 'wp_robots_no_robots' );
@@ -719,4 +718,7 @@ add_action( 'init', 'wp_register_persisted_preferences_meta' );
 // CPT wp_block custom postmeta field.
 add_action( 'init', 'wp_create_initial_post_meta' );
 
+// Font management.
+add_action( 'wp_head', 'wp_print_font_faces', 50 );
+
 unset( $filter, $action );
diff --git a/wp-includes/deprecated.php b/wp-includes/deprecated.php
index 72bf98d832..1d3ddd519e 100644
--- a/wp-includes/deprecated.php
+++ b/wp-includes/deprecated.php
@@ -5367,3 +5367,506 @@ function block_core_navigation_submenu_build_css_colors( $context, $attributes,
 
 	return $colors;
 }
+
+/**
+ * Runs the theme.json webfonts handler.
+ *
+ * Using `WP_Theme_JSON_Resolver`, it gets the fonts defined
+ * in the `theme.json` for the current selection and style
+ * variations, validates the font-face properties, generates
+ * the '@font-face' style declarations, and then enqueues the
+ * styles for both the editor and front-end.
+ *
+ * Design Notes:
+ * This is not a public API, but rather an internal handler.
+ * A future public Webfonts API will replace this stopgap code.
+ *
+ * This code design is intentional.
+ *    a. It hides the inner-workings.
+ *    b. It does not expose API ins or outs for consumption.
+ *    c. It only works with a theme's `theme.json`.
+ *
+ * Why?
+ *    a. To avoid backwards-compatibility issues when
+ *       the Webfonts API is introduced in Core.
+ *    b. To make `fontFace` declarations in `theme.json` work.
+ *
+ * @link  https://github.com/WordPress/gutenberg/issues/40472
+ *
+ * @since 6.0.0
+ * @deprecated 6.4.0 Use wp_print_font_faces() instead.
+ * @access private
+ */
+function _wp_theme_json_webfonts_handler() {
+	_deprecated_function( __FUNCTION__, '6.4.0', 'wp_print_font_faces' );
+
+	// Block themes are unavailable during installation.
+	if ( wp_installing() ) {
+		return;
+	}
+
+	if ( ! wp_theme_has_theme_json() ) {
+		return;
+	}
+
+	// Webfonts to be processed.
+	$registered_webfonts = array();
+
+	/**
+	 * Gets the webfonts from theme.json.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @return array Array of defined webfonts.
+	 */
+	$fn_get_webfonts_from_theme_json = static function() {
+		// Get settings from theme.json.
+		$settings = WP_Theme_JSON_Resolver::get_merged_data()->get_settings();
+
+		// If in the editor, add webfonts defined in variations.
+		if ( is_admin() || ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) {
+			$variations = WP_Theme_JSON_Resolver::get_style_variations();
+			foreach ( $variations as $variation ) {
+				// Skip if fontFamilies are not defined in the variation.
+				if ( empty( $variation['settings']['typography']['fontFamilies'] ) ) {
+					continue;
+				}
+
+				// Initialize the array structure.
+				if ( empty( $settings['typography'] ) ) {
+					$settings['typography'] = array();
+				}
+				if ( empty( $settings['typography']['fontFamilies'] ) ) {
+					$settings['typography']['fontFamilies'] = array();
+				}
+				if ( empty( $settings['typography']['fontFamilies']['theme'] ) ) {
+					$settings['typography']['fontFamilies']['theme'] = array();
+				}
+
+				// Combine variations with settings. Remove duplicates.
+				$settings['typography']['fontFamilies']['theme'] = array_merge( $settings['typography']['fontFamilies']['theme'], $variation['settings']['typography']['fontFamilies']['theme'] );
+				$settings['typography']['fontFamilies']          = array_unique( $settings['typography']['fontFamilies'] );
+			}
+		}
+
+		// Bail out early if there are no settings for webfonts.
+		if ( empty( $settings['typography']['fontFamilies'] ) ) {
+			return array();
+		}
+
+		$webfonts = array();
+
+		// Look for fontFamilies.
+		foreach ( $settings['typography']['fontFamilies'] as $font_families ) {
+			foreach ( $font_families as $font_family ) {
+
+				// Skip if fontFace is not defined.
+				if ( empty( $font_family['fontFace'] ) ) {
+					continue;
+				}
+
+				// Skip if fontFace is not an array of webfonts.
+				if ( ! is_array( $font_family['fontFace'] ) ) {
+					continue;
+				}
+
+				$webfonts = array_merge( $webfonts, $font_family['fontFace'] );
+			}
+		}
+
+		return $webfonts;
+	};
+
+	/**
+	 * Transforms each 'src' into an URI by replacing 'file:./'
+	 * placeholder from theme.json.
+	 *
+	 * The absolute path to the webfont file(s) cannot be defined in
+	 * theme.json. `file:./` is the placeholder which is replaced by
+	 * the theme's URL path to the theme's root.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array $src Webfont file(s) `src`.
+	 * @return array Webfont's `src` in URI.
+	 */
+	$fn_transform_src_into_uri = static function( array $src ) {
+		foreach ( $src as $key => $url ) {
+			// Tweak the URL to be relative to the theme root.
+			if ( ! str_starts_with( $url, 'file:./' ) ) {
+				continue;
+			}
+
+			$src[ $key ] = get_theme_file_uri( str_replace( 'file:./', '', $url ) );
+		}
+
+		return $src;
+	};
+
+	/**
+	 * Converts the font-face properties (i.e. keys) into kebab-case.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array $font_face Font face to convert.
+	 * @return array Font faces with each property in kebab-case format.
+	 */
+	$fn_convert_keys_to_kebab_case = static function( array $font_face ) {
+		foreach ( $font_face as $property => $value ) {
+			$kebab_case               = _wp_to_kebab_case( $property );
+			$font_face[ $kebab_case ] = $value;
+			if ( $kebab_case !== $property ) {
+				unset( $font_face[ $property ] );
+			}
+		}
+
+		return $font_face;
+	};
+
+	/**
+	 * Validates a webfont.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array $webfont The webfont arguments.
+	 * @return array|false The validated webfont arguments, or false if the webfont is invalid.
+	 */
+	$fn_validate_webfont = static function( $webfont ) {
+		$webfont = wp_parse_args(
+				$webfont,
+				array(
+						'font-family'  => '',
+						'font-style'   => 'normal',
+						'font-weight'  => '400',
+						'font-display' => 'fallback',
+						'src'          => array(),
+				)
+		);
+
+		// Check the font-family.
+		if ( empty( $webfont['font-family'] ) || ! is_string( $webfont['font-family'] ) ) {
+			trigger_error( __( 'Webfont font family must be a non-empty string.' ) );
+
+			return false;
+		}
+
+		// Check that the `src` property is defined and a valid type.
+		if ( empty( $webfont['src'] ) || ( ! is_string( $webfont['src'] ) && ! is_array( $webfont['src'] ) ) ) {
+			trigger_error( __( 'Webfont src must be a non-empty string or an array of strings.' ) );
+
+			return false;
+		}
+
+		// Validate the `src` property.
+		foreach ( (array) $webfont['src'] as $src ) {
+			if ( ! is_string( $src ) || '' === trim( $src ) ) {
+				trigger_error( __( 'Each webfont src must be a non-empty string.' ) );
+
+				return false;
+			}
+		}
+
+		// Check the font-weight.
+		if ( ! is_string( $webfont['font-weight'] ) && ! is_int( $webfont['font-weight'] ) ) {
+			trigger_error( __( 'Webfont font weight must be a properly formatted string or integer.' ) );
+
+			return false;
+		}
+
+		// Check the font-display.
+		if ( ! in_array( $webfont['font-display'], array( 'auto', 'block', 'fallback', 'optional', 'swap' ), true ) ) {
+			$webfont['font-display'] = 'fallback';
+		}
+
+		$valid_props = array(
+				'ascend-override',
+				'descend-override',
+				'font-display',
+				'font-family',
+				'font-stretch',
+				'font-style',
+				'font-weight',
+				'font-variant',
+				'font-feature-settings',
+				'font-variation-settings',
+				'line-gap-override',
+				'size-adjust',
+				'src',
+				'unicode-range',
+		);
+
+		foreach ( $webfont as $prop => $value ) {
+			if ( ! in_array( $prop, $valid_props, true ) ) {
+				unset( $webfont[ $prop ] );
+			}
+		}
+
+		return $webfont;
+	};
+
+	/**
+	 * Registers webfonts declared in theme.json.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @uses $registered_webfonts To access and update the registered webfonts registry (passed by reference).
+	 * @uses $fn_get_webfonts_from_theme_json To run the function that gets the webfonts from theme.json.
+	 * @uses $fn_convert_keys_to_kebab_case To run the function that converts keys into kebab-case.
+	 * @uses $fn_validate_webfont To run the function that validates each font-face (webfont) from theme.json.
+	 */
+	$fn_register_webfonts = static function() use ( &$registered_webfonts, $fn_get_webfonts_from_theme_json, $fn_convert_keys_to_kebab_case, $fn_validate_webfont, $fn_transform_src_into_uri ) {
+		$registered_webfonts = array();
+
+		foreach ( $fn_get_webfonts_from_theme_json() as $webfont ) {
+			if ( ! is_array( $webfont ) ) {
+				continue;
+			}
+
+			$webfont = $fn_convert_keys_to_kebab_case( $webfont );
+
+			$webfont = $fn_validate_webfont( $webfont );
+
+			$webfont['src'] = $fn_transform_src_into_uri( (array) $webfont['src'] );
+
+			// Skip if not valid.
+			if ( empty( $webfont ) ) {
+				continue;
+			}
+
+			$registered_webfonts[] = $webfont;
+		}
+	};
+
+	/**
+	 * Orders 'src' items to optimize for browser support.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array $webfont Webfont to process.
+	 * @return array Ordered `src` items.
+	 */
+	$fn_order_src = static function( array $webfont ) {
+		$src         = array();
+		$src_ordered = array();
+
+		foreach ( $webfont['src'] as $url ) {
+			// Add data URIs first.
+			if ( str_starts_with( trim( $url ), 'data:' ) ) {
+				$src_ordered[] = array(
+						'url'    => $url,
+						'format' => 'data',
+				);
+				continue;
+			}
+			$format         = pathinfo( $url, PATHINFO_EXTENSION );
+			$src[ $format ] = $url;
+		}
+
+		// Add woff2.
+		if ( ! empty( $src['woff2'] ) ) {
+			$src_ordered[] = array(
+					'url'    => sanitize_url( $src['woff2'] ),
+					'format' => 'woff2',
+			);
+		}
+
+		// Add woff.
+		if ( ! empty( $src['woff'] ) ) {
+			$src_ordered[] = array(
+					'url'    => sanitize_url( $src['woff'] ),
+					'format' => 'woff',
+			);
+		}
+
+		// Add ttf.
+		if ( ! empty( $src['ttf'] ) ) {
+			$src_ordered[] = array(
+					'url'    => sanitize_url( $src['ttf'] ),
+					'format' => 'truetype',
+			);
+		}
+
+		// Add eot.
+		if ( ! empty( $src['eot'] ) ) {
+			$src_ordered[] = array(
+					'url'    => sanitize_url( $src['eot'] ),
+					'format' => 'embedded-opentype',
+			);
+		}
+
+		// Add otf.
+		if ( ! empty( $src['otf'] ) ) {
+			$src_ordered[] = array(
+					'url'    => sanitize_url( $src['otf'] ),
+					'format' => 'opentype',
+			);
+		}
+		$webfont['src'] = $src_ordered;
+
+		return $webfont;
+	};
+
+	/**
+	 * Compiles the 'src' into valid CSS.
+	 *
+	 * @since 6.0.0
+	 * @since 6.2.0 Removed local() CSS.
+	 *
+	 * @param string $font_family Font family.
+	 * @param array  $value       Value to process.
+	 * @return string The CSS.
+	 */
+	$fn_compile_src = static function( $font_family, array $value ) {
+		$src = '';
+
+		foreach ( $value as $item ) {
+			$src .= ( 'data' === $item['format'] )
+					? ", url({$item['url']})"
+					: ", url('{$item['url']}') format('{$item['format']}')";
+		}
+
+		$src = ltrim( $src, ', ' );
+
+		return $src;
+	};
+
+	/**
+	 * Compiles the font variation settings.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @param array $font_variation_settings Array of font variation settings.
+	 * @return string The CSS.
+	 */
+	$fn_compile_variations = static function( array $font_variation_settings ) {
+		$variations = '';
+
+		foreach ( $font_variation_settings as $key => $value ) {
+			$variations .= "$key $value";
+		}
+
+		return $variations;
+	};
+
+	/**
+	 * Builds the font-family's CSS.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @uses $fn_compile_src To run the function that compiles the src.
+	 * @uses $fn_compile_variations To run the function that compiles the variations.
+	 *
+	 * @param array $webfont Webfont to process.
+	 * @return string This font-family's CSS.
+	 */
+	$fn_build_font_face_css = static function( array $webfont ) use ( $fn_compile_src, $fn_compile_variations ) {
+		$css = '';
+
+		// Wrap font-family in quotes if it contains spaces.
+		if (
+				str_contains( $webfont['font-family'], ' ' ) &&
+				! str_contains( $webfont['font-family'], '"' ) &&
+				! str_contains( $webfont['font-family'], "'" )
+		) {
+			$webfont['font-family'] = '"' . $webfont['font-family'] . '"';
+		}
+
+		foreach ( $webfont as $key => $value ) {
+			/*
+			 * Skip "provider", since it's for internal API use,
+			 * and not a valid CSS property.
+			 */
+			if ( 'provider' === $key ) {
+				continue;
+			}
+
+			// Compile the "src" parameter.
+			if ( 'src' === $key ) {
+				$value = $fn_compile_src( $webfont['font-family'], $value );
+			}
+
+			// If font-variation-settings is an array, convert it to a string.
+			if ( 'font-variation-settings' === $key && is_array( $value ) ) {
+				$value = $fn_compile_variations( $value );
+			}
+
+			if ( ! empty( $value ) ) {
+				$css .= "$key:$value;";
+			}
+		}
+
+		return $css;
+	};
+
+	/**
+	 * Gets the '@font-face' CSS styles for locally-hosted font files.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @uses $registered_webfonts To access and update the registered webfonts registry (passed by reference).
+	 * @uses $fn_order_src To run the function that orders the src.
+	 * @uses $fn_build_font_face_css To run the function that builds the font-face CSS.
+	 *
+	 * @return string The `@font-face` CSS.
+	 */
+	$fn_get_css = static function() use ( &$registered_webfonts, $fn_order_src, $fn_build_font_face_css ) {
+		$css = '';
+
+		foreach ( $registered_webfonts as $webfont ) {
+			// Order the webfont's `src` items to optimize for browser support.
+			$webfont = $fn_order_src( $webfont );
+
+			// Build the @font-face CSS for this webfont.
+			$css .= '@font-face{' . $fn_build_font_face_css( $webfont ) . '}';
+		}
+
+		return $css;
+	};
+
+	/**
+	 * Generates and enqueues webfonts styles.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @uses $fn_get_css To run the function that gets the CSS.
+	 */
+	$fn_generate_and_enqueue_styles = static function() use ( $fn_get_css ) {
+		// Generate the styles.
+		$styles = $fn_get_css();
+
+		// Bail out if there are no styles to enqueue.
+		if ( '' === $styles ) {
+			return;
+		}
+
+		// Enqueue the stylesheet.
+		wp_register_style( 'wp-webfonts', '' );
+		wp_enqueue_style( 'wp-webfonts' );
+
+		// Add the styles to the stylesheet.
+		wp_add_inline_style( 'wp-webfonts', $styles );
+	};
+
+	/**
+	 * Generates and enqueues editor styles.
+	 *
+	 * @since 6.0.0
+	 *
+	 * @uses $fn_get_css To run the function that gets the CSS.
+	 */
+	$fn_generate_and_enqueue_editor_styles = static function() use ( $fn_get_css ) {
+		// Generate the styles.
+		$styles = $fn_get_css();
+
+		// Bail out if there are no styles to enqueue.
+		if ( '' === $styles ) {
+			return;
+		}
+
+		wp_add_inline_style( 'wp-block-library', $styles );
+	};
+
+	add_action( 'wp_loaded', $fn_register_webfonts );
+	add_action( 'wp_enqueue_scripts', $fn_generate_and_enqueue_styles );
+	add_action( 'admin_init', $fn_generate_and_enqueue_editor_styles );
+}
diff --git a/wp-includes/fonts.php b/wp-includes/fonts.php
new file mode 100644
index 0000000000..b628db18cf
--- /dev/null
+++ b/wp-includes/fonts.php
@@ -0,0 +1,57 @@
+<?php
+/**
+ * Fonts functions.
+ *
+ * @package    WordPress
+ * @subpackage Fonts
+ * @since      6.4.0
+ */
+
+/**
+ * Generates and prints font-face styles for given fonts or theme.json fonts.
+ *
+ * @since 6.4.0
+ *
+ * @param array[][] $fonts {
+ *     Optional. The font-families and their font variations. Default empty array.
+ *
+ *     @type string $font-family => array[] $variations {
+ *         Optional. An associated array of font variations for this font-family.
+ *         Each variation has the following structure.
+ *
+ *         @type array $font_variation {
+ *             @type string          $font-family             The font-family property.
+ *             @type string|string[] $src                     The URL(s) to each resource containing the font data.
+ *             @type string          $font_style              Optional. The font-style property. Default 'normal'.
+ *             @type string          $font-weight             Optional. The font-weight property. Default '400'.
+ *             @type string          $font-display            Optional. The font-display property. Default 'fallback'.
+ *             @type string          $ascent-override         Optional. The ascent-override property.
+ *             @type string          $descent-override        Optional. The descent-override property.
+ *             @type string          $font-stretch            Optional. The font-stretch property.
+ *             @type string          $font-variant            Optional. The font-variant property.
+ *             @type string          $font-feature-settings   Optional. The font-feature-settings property.
+ *             @type string          $font-variation-settings Optional. The font-variation-settings property.
+ *             @type string          $line-gap-override       Optional. The line-gap-override property.
+ *             @type string          $size-adjust             Optional. The size-adjust property.
+ *             @type string          $unicode-range           Optional. The unicode-range property.
+ *         }
+ *     }
+ * }
+ */
+function wp_print_font_faces( $fonts = array() ) {
+	static $wp_font_face = null;
+
+	if ( empty( $fonts ) ) {
+		$fonts = WP_Font_Face_Resolver::get_fonts_from_theme_json();
+	}
+
+	if ( empty( $fonts ) ) {
+		return;
+	}
+
+	if ( null === $wp_font_face ) {
+		$wp_font_face = new WP_Font_Face();
+	}
+
+	$wp_font_face->generate_and_print( $fonts );
+}
diff --git a/wp-includes/fonts/class-wp-font-face-resolver.php b/wp-includes/fonts/class-wp-font-face-resolver.php
new file mode 100644
index 0000000000..da1ea1c711
--- /dev/null
+++ b/wp-includes/fonts/class-wp-font-face-resolver.php
@@ -0,0 +1,154 @@
+<?php
+/**
+ * WP_Font_Face_Resolver class.
+ *
+ * @package    WordPress
+ * @subpackage Fonts
+ * @since      6.4.0
+ */
+
+/**
+ * The Font Face Resolver abstracts the processing of different data sources
+ * (such as theme.json) for processing within the Font Face.
+ *
+ * This class is for internal core usage and is not supposed to be used by
+ * extenders (plugins and/or themes).
+ *
+ * @access private
+ */
+class WP_Font_Face_Resolver {
+
+	/**
+	 * Gets fonts defined in theme.json.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @return array Returns the font-families, each with their font-face variations.
+	 */
+	public static function get_fonts_from_theme_json() {
+		$settings = wp_get_global_settings();
+
+		// Bail out early if there are no font settings.
+		if ( empty( $settings['typography']['fontFamilies'] ) ) {
+			return array();
+		}
+
+		return static::parse_settings( $settings );
+	}
+
+	/**
+	 * Parse theme.json settings to extract font definitions with variations grouped by font-family.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $settings Font settings to parse.
+	 * @return array Returns an array of fonts, grouped by font-family.
+	 */
+	private static function parse_settings( array $settings ) {
+		$fonts = array();
+
+		foreach ( $settings['typography']['fontFamilies'] as $font_families ) {
+			foreach ( $font_families as $definition ) {
+
+				// Skip if font-family "name" is not defined.
+				if ( empty( $definition['name'] ) ) {
+					continue;
+				}
+
+				// Skip if "fontFace" is not defined, meaning there are no variations.
+				if ( empty( $definition['fontFace'] ) ) {
+					continue;
+				}
+
+				$font_family = $definition['name'];
+
+				// Prepare the fonts array structure for this font-family.
+				if ( ! array_key_exists( $font_family, $fonts ) ) {
+					$fonts[ $font_family ] = array();
+				}
+
+				$fonts[ $font_family ] = static::convert_font_face_properties( $definition['fontFace'], $font_family );
+			}
+		}
+
+		return $fonts;
+	}
+
+	/**
+	 * Converts font-face properties from theme.json format.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array  $font_face_definition The font-face definitions to convert.
+	 * @param string $font_family_property The value to store in the font-face font-family property.
+	 * @return array Converted font-face properties.
+	 */
+	private static function convert_font_face_properties( array $font_face_definition, $font_family_property ) {
+		$converted_font_faces = array();
+
+		foreach ( $font_face_definition as $font_face ) {
+			// Add the font-family property to the font-face.
+			$font_face['font-family'] = $font_family_property;
+
+			// Converts the "file:./" src placeholder into a theme font file URI.
+			if ( ! empty( $font_face['src'] ) ) {
+				$font_face['src'] = static::to_theme_file_uri( (array) $font_face['src'] );
+			}
+
+			// Convert camelCase properties into kebab-case.
+			$font_face = static::to_kebab_case( $font_face );
+
+			$converted_font_faces[] = $font_face;
+		}
+
+		return $converted_font_faces;
+	}
+
+	/**
+	 * Converts each 'file:./' placeholder into a URI to the font file in the theme.
+	 *
+	 * The 'file:./' is specified in the theme's `theme.json` as a placeholder to be
+	 * replaced with the URI to the font file's location in the theme. When a "src"
+	 * beings with this placeholder, it is replaced, converting the src into a URI.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $src An array of font file sources to process.
+	 * @return array An array of font file src URI(s).
+	 */
+	private static function to_theme_file_uri( array $src ) {
+		$placeholder = 'file:./';
+
+		foreach ( $src as $src_key => $src_url ) {
+			// Skip if the src doesn't start with the placeholder, as there's nothing to replace.
+			if ( ! str_starts_with( $src_url, $placeholder ) ) {
+				continue;
+			}
+
+			$src_file        = str_replace( $placeholder, '', $src_url );
+			$src[ $src_key ] = get_theme_file_uri( $src_file );
+		}
+
+		return $src;
+	}
+
+	/**
+	 * Converts all first dimension keys into kebab-case.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $data The array to process.
+	 * @return array Data with first dimension keys converted into kebab-case.
+	 */
+	private static function to_kebab_case( array $data ) {
+		foreach ( $data as $key => $value ) {
+			$kebab_case          = _wp_to_kebab_case( $key );
+			$data[ $kebab_case ] = $value;
+			if ( $kebab_case !== $key ) {
+				unset( $data[ $key ] );
+			}
+		}
+
+		return $data;
+	}
+}
diff --git a/wp-includes/fonts/class-wp-font-face.php b/wp-includes/fonts/class-wp-font-face.php
new file mode 100644
index 0000000000..974e13ed1d
--- /dev/null
+++ b/wp-includes/fonts/class-wp-font-face.php
@@ -0,0 +1,430 @@
+<?php
+/**
+ * WP_Font_Face class.
+ *
+ * @package    WordPress
+ * @subpackage Fonts
+ * @since      6.4.0
+ */
+
+/**
+ * Font Face generates and prints `@font-face` styles for given fonts.
+ *
+ * @since 6.4.0
+ */
+class WP_Font_Face {
+
+	/**
+	 * The font-face property defaults.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @var string[]
+	 */
+	private $font_face_property_defaults = array(
+		'font-family'  => '',
+		'font-style'   => 'normal',
+		'font-weight'  => '400',
+		'font-display' => 'fallback',
+	);
+
+	/**
+	 * Valid font-face property names.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @var string[]
+	 */
+	private $valid_font_face_properties = array(
+		'ascent-override',
+		'descent-override',
+		'font-display',
+		'font-family',
+		'font-stretch',
+		'font-style',
+		'font-weight',
+		'font-variant',
+		'font-feature-settings',
+		'font-variation-settings',
+		'line-gap-override',
+		'size-adjust',
+		'src',
+		'unicode-range',
+	);
+
+	/**
+	 * Valid font-display values.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @var string[]
+	 */
+	private $valid_font_display = array( 'auto', 'block', 'fallback', 'swap', 'optional' );
+
+	/**
+	 * Array of font-face style tag's attribute(s)
+	 * where the key is the attribute name and the
+	 * value is its value.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @var string[]
+	 */
+	private $style_tag_attrs = array();
+
+	/**
+	 * Creates and initializes an instance of WP_Font_Face.
+	 *
+	 * @since 6.4.0
+	 */
+	public function __construct() {
+		if (
+			function_exists( 'is_admin' ) && ! is_admin()
+			&&
+			function_exists( 'current_theme_supports' ) && ! current_theme_supports( 'html5', 'style' )
+		) {
+			$this->style_tag_attrs = array( 'type' => 'text/css' );
+		}
+	}
+
+	/**
+	 * Generates and prints the `@font-face` styles for the given fonts.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array[][] $fonts Optional. The font-families and their font variations.
+	 *                         See {@see wp_print_font_faces()} for the supported fields.
+	 *                         Default empty array.
+	 */
+	public function generate_and_print( array $fonts ) {
+		$fonts = $this->validate_fonts( $fonts );
+
+		// Bail out if there are no fonts are given to process.
+		if ( empty( $fonts ) ) {
+			return;
+		}
+
+		$css = $this->get_css( $fonts );
+
+		/*
+		 * The font-face CSS is contained within <style> tags and can only be interpreted
+		 * as CSS in the browser. Using wp_strip_all_tags() is sufficient escaping
+		 * to avoid malicious attempts to close </style> and open a <script>.
+		 */
+		$css = wp_strip_all_tags( $css );
+
+		// Bail out if there is no CSS to print.
+		if ( empty( $css ) ) {
+			return;
+		}
+
+		printf( $this->get_style_element(), $css );
+	}
+
+	/**
+	 * Validates each of the font-face properties.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $fonts The fonts to valid.
+	 * @return array Prepared font-faces organized by provider and font-family.
+	 */
+	private function validate_fonts( array $fonts ) {
+		$validated_fonts = array();
+
+		foreach ( $fonts as $font_faces ) {
+			foreach ( $font_faces as $font_face ) {
+				$font_face = $this->validate_font_face_declarations( $font_face );
+				// Skip if failed validation.
+				if ( false === $font_face ) {
+					continue;
+				}
+
+				$validated_fonts[] = $font_face;
+			}
+		}
+
+		return $validated_fonts;
+	}
+
+	/**
+	 * Validates each font-face declaration (property and value pairing).
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $font_face Font face property and value pairings to validate.
+	 * @return array|false Validated font-face on success, or false on failure.
+	 */
+	private function validate_font_face_declarations( array $font_face ) {
+		$font_face = wp_parse_args( $font_face, $this->font_face_property_defaults );
+
+		// Check the font-family.
+		if ( empty( $font_face['font-family'] ) || ! is_string( $font_face['font-family'] ) ) {
+			// @todo replace with `wp_trigger_error()`.
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Font font-family must be a non-empty string.' ),
+				'6.4.0'
+			);
+			return false;
+		}
+
+		// Make sure that local fonts have 'src' defined.
+		if ( empty( $font_face['src'] ) || ( ! is_string( $font_face['src'] ) && ! is_array( $font_face['src'] ) ) ) {
+			// @todo replace with `wp_trigger_error()`.
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Font src must be a non-empty string or an array of strings.' ),
+				'6.4.0'
+			);
+			return false;
+		}
+
+		// Validate the 'src' property.
+		foreach ( (array) $font_face['src'] as $src ) {
+			if ( empty( $src ) || ! is_string( $src ) ) {
+				// @todo replace with `wp_trigger_error()`.
+				_doing_it_wrong(
+					__METHOD__,
+					__( 'Each font src must be a non-empty string.' ),
+					'6.4.0'
+				);
+				return false;
+			}
+		}
+
+		// Check the font-weight.
+		if ( ! is_string( $font_face['font-weight'] ) && ! is_int( $font_face['font-weight'] ) ) {
+			// @todo replace with `wp_trigger_error()`.
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Font font-weight must be a properly formatted string or integer.' ),
+				'6.4.0'
+			);
+			return false;
+		}
+
+		// Check the font-display.
+		if ( ! in_array( $font_face['font-display'], $this->valid_font_display, true ) ) {
+			$font_face['font-display'] = $this->font_face_property_defaults['font-display'];
+		}
+
+		// Remove invalid properties.
+		foreach ( $font_face as $property => $value ) {
+			if ( ! in_array( $property, $this->valid_font_face_properties, true ) ) {
+				unset( $font_face[ $property ] );
+			}
+		}
+
+		return $font_face;
+	}
+
+	/**
+	 * Gets the style element for wrapping the `@font-face` CSS.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @return string The style element.
+	 */
+	private function get_style_element() {
+		$attributes = $this->generate_style_element_attributes();
+
+		return "<style id='wp-fonts-local'{$attributes}>\n%s\n</style>\n";
+	}
+
+	/**
+	 * Gets the defined <style> element's attributes.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @return string A string of attribute=value when defined, else, empty string.
+	 */
+	private function generate_style_element_attributes() {
+		$attributes = '';
+		foreach ( $this->style_tag_attrs as $name => $value ) {
+			$attributes .= " {$name}='{$value}'";
+		}
+		return $attributes;
+	}
+
+	/**
+	 * Gets the `@font-face` CSS styles for locally-hosted font files.
+	 *
+	 * This method does the following processing tasks:
+	 *    1. Orchestrates an optimized `src` (with format) for browser support.
+	 *    2. Generates the `@font-face` for all its fonts.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $font_faces The font-faces to generate @font-face CSS styles.
+	 * @return string The `@font-face` CSS styles.
+	 */
+	private function get_css( $font_faces ) {
+		$css = '';
+
+		foreach ( $font_faces as $font_face ) {
+				// Order the font's `src` items to optimize for browser support.
+				$font_face = $this->order_src( $font_face );
+
+				// Build the @font-face CSS for this font.
+				$css .= '@font-face{' . $this->build_font_face_css( $font_face ) . '}' . "\n";
+		}
+
+		// Don't print the last newline character.
+		return rtrim( $css, "\n" );
+	}
+
+	/**
+	 * Orders `src` items to optimize for browser support.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $font_face Font face to process.
+	 * @return array Font-face with ordered src items.
+	 */
+	private function order_src( array $font_face ) {
+		if ( ! is_array( $font_face['src'] ) ) {
+			$font_face['src'] = (array) $font_face['src'];
+		}
+
+		$src         = array();
+		$src_ordered = array();
+
+		foreach ( $font_face['src'] as $url ) {
+			// Add data URIs first.
+			if ( str_starts_with( trim( $url ), 'data:' ) ) {
+				$src_ordered[] = array(
+					'url'    => $url,
+					'format' => 'data',
+				);
+				continue;
+			}
+			$format         = pathinfo( $url, PATHINFO_EXTENSION );
+			$src[ $format ] = $url;
+		}
+
+		// Add woff2.
+		if ( ! empty( $src['woff2'] ) ) {
+			$src_ordered[] = array(
+				'url'    => $src['woff2'],
+				'format' => 'woff2',
+			);
+		}
+
+		// Add woff.
+		if ( ! empty( $src['woff'] ) ) {
+			$src_ordered[] = array(
+				'url'    => $src['woff'],
+				'format' => 'woff',
+			);
+		}
+
+		// Add ttf.
+		if ( ! empty( $src['ttf'] ) ) {
+			$src_ordered[] = array(
+				'url'    => $src['ttf'],
+				'format' => 'truetype',
+			);
+		}
+
+		// Add eot.
+		if ( ! empty( $src['eot'] ) ) {
+			$src_ordered[] = array(
+				'url'    => $src['eot'],
+				'format' => 'embedded-opentype',
+			);
+		}
+
+		// Add otf.
+		if ( ! empty( $src['otf'] ) ) {
+			$src_ordered[] = array(
+				'url'    => $src['otf'],
+				'format' => 'opentype',
+			);
+		}
+		$font_face['src'] = $src_ordered;
+
+		return $font_face;
+	}
+
+	/**
+	 * Builds the font-family's CSS.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $font_face Font face to process.
+	 * @return string This font-family's CSS.
+	 */
+	private function build_font_face_css( array $font_face ) {
+		$css = '';
+
+		/*
+		 * Wrap font-family in quotes if it contains spaces
+		 * and is not already wrapped in quotes.
+		 */
+		if (
+			str_contains( $font_face['font-family'], ' ' ) &&
+			! str_contains( $font_face['font-family'], '"' ) &&
+			! str_contains( $font_face['font-family'], "'" )
+		) {
+			$font_face['font-family'] = '"' . $font_face['font-family'] . '"';
+		}
+
+		foreach ( $font_face as $key => $value ) {
+			// Compile the "src" parameter.
+			if ( 'src' === $key ) {
+				$value = $this->compile_src( $value );
+			}
+
+			// If font-variation-settings is an array, convert it to a string.
+			if ( 'font-variation-settings' === $key && is_array( $value ) ) {
+				$value = $this->compile_variations( $value );
+			}
+
+			if ( ! empty( $value ) ) {
+				$css .= "$key:$value;";
+			}
+		}
+
+		return $css;
+	}
+
+	/**
+	 * Compiles the `src` into valid CSS.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $value Value to process.
+	 * @return string The CSS.
+	 */
+	private function compile_src( array $value ) {
+		$src = '';
+
+		foreach ( $value as $item ) {
+			$src .= ( 'data' === $item['format'] )
+				? ", url({$item['url']})"
+				: ", url('{$item['url']}') format('{$item['format']}')";
+		}
+
+		$src = ltrim( $src, ', ' );
+		return $src;
+	}
+
+	/**
+	 * Compiles the font variation settings.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param array $font_variation_settings Array of font variation settings.
+	 * @return string The CSS.
+	 */
+	private function compile_variations( array $font_variation_settings ) {
+		$variations = '';
+
+		foreach ( $font_variation_settings as $key => $value ) {
+			$variations .= "$key $value";
+		}
+
+		return $variations;
+	}
+}
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index 85cb58f56b..d99cc9b035 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -3223,506 +3223,6 @@ function wp_enqueue_block_style( $block_name, $args ) {
 	add_action( 'enqueue_block_assets', $callback );
 }
 
-/**
- * Runs the theme.json webfonts handler.
- *
- * Using `WP_Theme_JSON_Resolver`, it gets the fonts defined
- * in the `theme.json` for the current selection and style
- * variations, validates the font-face properties, generates
- * the '@font-face' style declarations, and then enqueues the
- * styles for both the editor and front-end.
- *
- * Design Notes:
- * This is not a public API, but rather an internal handler.
- * A future public Webfonts API will replace this stopgap code.
- *
- * This code design is intentional.
- *    a. It hides the inner-workings.
- *    b. It does not expose API ins or outs for consumption.
- *    c. It only works with a theme's `theme.json`.
- *
- * Why?
- *    a. To avoid backwards-compatibility issues when
- *       the Webfonts API is introduced in Core.
- *    b. To make `fontFace` declarations in `theme.json` work.
- *
- * @link  https://github.com/WordPress/gutenberg/issues/40472
- *
- * @since 6.0.0
- * @access private
- */
-function _wp_theme_json_webfonts_handler() {
-	// Block themes are unavailable during installation.
-	if ( wp_installing() ) {
-		return;
-	}
-
-	if ( ! wp_theme_has_theme_json() ) {
-		return;
-	}
-
-	// Webfonts to be processed.
-	$registered_webfonts = array();
-
-	/**
-	 * Gets the webfonts from theme.json.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @return array Array of defined webfonts.
-	 */
-	$fn_get_webfonts_from_theme_json = static function() {
-		// Get settings from theme.json.
-		$settings = WP_Theme_JSON_Resolver::get_merged_data()->get_settings();
-
-		// If in the editor, add webfonts defined in variations.
-		if ( is_admin() || ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) {
-			$variations = WP_Theme_JSON_Resolver::get_style_variations();
-			foreach ( $variations as $variation ) {
-				// Skip if fontFamilies are not defined in the variation.
-				if ( empty( $variation['settings']['typography']['fontFamilies'] ) ) {
-					continue;
-				}
-
-				// Initialize the array structure.
-				if ( empty( $settings['typography'] ) ) {
-					$settings['typography'] = array();
-				}
-				if ( empty( $settings['typography']['fontFamilies'] ) ) {
-					$settings['typography']['fontFamilies'] = array();
-				}
-				if ( empty( $settings['typography']['fontFamilies']['theme'] ) ) {
-					$settings['typography']['fontFamilies']['theme'] = array();
-				}
-
-				// Combine variations with settings. Remove duplicates.
-				$settings['typography']['fontFamilies']['theme'] = array_merge( $settings['typography']['fontFamilies']['theme'], $variation['settings']['typography']['fontFamilies']['theme'] );
-				$settings['typography']['fontFamilies']          = array_unique( $settings['typography']['fontFamilies'] );
-			}
-		}
-
-		// Bail out early if there are no settings for webfonts.
-		if ( empty( $settings['typography']['fontFamilies'] ) ) {
-			return array();
-		}
-
-		$webfonts = array();
-
-		// Look for fontFamilies.
-		foreach ( $settings['typography']['fontFamilies'] as $font_families ) {
-			foreach ( $font_families as $font_family ) {
-
-				// Skip if fontFace is not defined.
-				if ( empty( $font_family['fontFace'] ) ) {
-					continue;
-				}
-
-				// Skip if fontFace is not an array of webfonts.
-				if ( ! is_array( $font_family['fontFace'] ) ) {
-					continue;
-				}
-
-				$webfonts = array_merge( $webfonts, $font_family['fontFace'] );
-			}
-		}
-
-		return $webfonts;
-	};
-
-	/**
-	 * Transforms each 'src' into an URI by replacing 'file:./'
-	 * placeholder from theme.json.
-	 *
-	 * The absolute path to the webfont file(s) cannot be defined in
-	 * theme.json. `file:./` is the placeholder which is replaced by
-	 * the theme's URL path to the theme's root.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @param array $src Webfont file(s) `src`.
-	 * @return array Webfont's `src` in URI.
-	 */
-	$fn_transform_src_into_uri = static function( array $src ) {
-		foreach ( $src as $key => $url ) {
-			// Tweak the URL to be relative to the theme root.
-			if ( ! str_starts_with( $url, 'file:./' ) ) {
-				continue;
-			}
-
-			$src[ $key ] = get_theme_file_uri( str_replace( 'file:./', '', $url ) );
-		}
-
-		return $src;
-	};
-
-	/**
-	 * Converts the font-face properties (i.e. keys) into kebab-case.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @param array $font_face Font face to convert.
-	 * @return array Font faces with each property in kebab-case format.
-	 */
-	$fn_convert_keys_to_kebab_case = static function( array $font_face ) {
-		foreach ( $font_face as $property => $value ) {
-			$kebab_case               = _wp_to_kebab_case( $property );
-			$font_face[ $kebab_case ] = $value;
-			if ( $kebab_case !== $property ) {
-				unset( $font_face[ $property ] );
-			}
-		}
-
-		return $font_face;
-	};
-
-	/**
-	 * Validates a webfont.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @param array $webfont The webfont arguments.
-	 * @return array|false The validated webfont arguments, or false if the webfont is invalid.
-	 */
-	$fn_validate_webfont = static function( $webfont ) {
-		$webfont = wp_parse_args(
-			$webfont,
-			array(
-				'font-family'  => '',
-				'font-style'   => 'normal',
-				'font-weight'  => '400',
-				'font-display' => 'fallback',
-				'src'          => array(),
-			)
-		);
-
-		// Check the font-family.
-		if ( empty( $webfont['font-family'] ) || ! is_string( $webfont['font-family'] ) ) {
-			trigger_error( __( 'Webfont font family must be a non-empty string.' ) );
-
-			return false;
-		}
-
-		// Check that the `src` property is defined and a valid type.
-		if ( empty( $webfont['src'] ) || ( ! is_string( $webfont['src'] ) && ! is_array( $webfont['src'] ) ) ) {
-			trigger_error( __( 'Webfont src must be a non-empty string or an array of strings.' ) );
-
-			return false;
-		}
-
-		// Validate the `src` property.
-		foreach ( (array) $webfont['src'] as $src ) {
-			if ( ! is_string( $src ) || '' === trim( $src ) ) {
-				trigger_error( __( 'Each webfont src must be a non-empty string.' ) );
-
-				return false;
-			}
-		}
-
-		// Check the font-weight.
-		if ( ! is_string( $webfont['font-weight'] ) && ! is_int( $webfont['font-weight'] ) ) {
-			trigger_error( __( 'Webfont font weight must be a properly formatted string or integer.' ) );
-
-			return false;
-		}
-
-		// Check the font-display.
-		if ( ! in_array( $webfont['font-display'], array( 'auto', 'block', 'fallback', 'optional', 'swap' ), true ) ) {
-			$webfont['font-display'] = 'fallback';
-		}
-
-		$valid_props = array(
-			'ascend-override',
-			'descend-override',
-			'font-display',
-			'font-family',
-			'font-stretch',
-			'font-style',
-			'font-weight',
-			'font-variant',
-			'font-feature-settings',
-			'font-variation-settings',
-			'line-gap-override',
-			'size-adjust',
-			'src',
-			'unicode-range',
-		);
-
-		foreach ( $webfont as $prop => $value ) {
-			if ( ! in_array( $prop, $valid_props, true ) ) {
-				unset( $webfont[ $prop ] );
-			}
-		}
-
-		return $webfont;
-	};
-
-	/**
-	 * Registers webfonts declared in theme.json.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @uses $registered_webfonts To access and update the registered webfonts registry (passed by reference).
-	 * @uses $fn_get_webfonts_from_theme_json To run the function that gets the webfonts from theme.json.
-	 * @uses $fn_convert_keys_to_kebab_case To run the function that converts keys into kebab-case.
-	 * @uses $fn_validate_webfont To run the function that validates each font-face (webfont) from theme.json.
-	 */
-	$fn_register_webfonts = static function() use ( &$registered_webfonts, $fn_get_webfonts_from_theme_json, $fn_convert_keys_to_kebab_case, $fn_validate_webfont, $fn_transform_src_into_uri ) {
-		$registered_webfonts = array();
-
-		foreach ( $fn_get_webfonts_from_theme_json() as $webfont ) {
-			if ( ! is_array( $webfont ) ) {
-				continue;
-			}
-
-			$webfont = $fn_convert_keys_to_kebab_case( $webfont );
-
-			$webfont = $fn_validate_webfont( $webfont );
-
-			$webfont['src'] = $fn_transform_src_into_uri( (array) $webfont['src'] );
-
-			// Skip if not valid.
-			if ( empty( $webfont ) ) {
-				continue;
-			}
-
-			$registered_webfonts[] = $webfont;
-		}
-	};
-
-	/**
-	 * Orders 'src' items to optimize for browser support.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @param array $webfont Webfont to process.
-	 * @return array Ordered `src` items.
-	 */
-	$fn_order_src = static function( array $webfont ) {
-		$src         = array();
-		$src_ordered = array();
-
-		foreach ( $webfont['src'] as $url ) {
-			// Add data URIs first.
-			if ( str_starts_with( trim( $url ), 'data:' ) ) {
-				$src_ordered[] = array(
-					'url'    => $url,
-					'format' => 'data',
-				);
-				continue;
-			}
-			$format         = pathinfo( $url, PATHINFO_EXTENSION );
-			$src[ $format ] = $url;
-		}
-
-		// Add woff2.
-		if ( ! empty( $src['woff2'] ) ) {
-			$src_ordered[] = array(
-				'url'    => sanitize_url( $src['woff2'] ),
-				'format' => 'woff2',
-			);
-		}
-
-		// Add woff.
-		if ( ! empty( $src['woff'] ) ) {
-			$src_ordered[] = array(
-				'url'    => sanitize_url( $src['woff'] ),
-				'format' => 'woff',
-			);
-		}
-
-		// Add ttf.
-		if ( ! empty( $src['ttf'] ) ) {
-			$src_ordered[] = array(
-				'url'    => sanitize_url( $src['ttf'] ),
-				'format' => 'truetype',
-			);
-		}
-
-		// Add eot.
-		if ( ! empty( $src['eot'] ) ) {
-			$src_ordered[] = array(
-				'url'    => sanitize_url( $src['eot'] ),
-				'format' => 'embedded-opentype',
-			);
-		}
-
-		// Add otf.
-		if ( ! empty( $src['otf'] ) ) {
-			$src_ordered[] = array(
-				'url'    => sanitize_url( $src['otf'] ),
-				'format' => 'opentype',
-			);
-		}
-		$webfont['src'] = $src_ordered;
-
-		return $webfont;
-	};
-
-	/**
-	 * Compiles the 'src' into valid CSS.
-	 *
-	 * @since 6.0.0
-	 * @since 6.2.0 Removed local() CSS.
-	 *
-	 * @param string $font_family Font family.
-	 * @param array  $value       Value to process.
-	 * @return string The CSS.
-	 */
-	$fn_compile_src = static function( $font_family, array $value ) {
-		$src = '';
-
-		foreach ( $value as $item ) {
-			$src .= ( 'data' === $item['format'] )
-				? ", url({$item['url']})"
-				: ", url('{$item['url']}') format('{$item['format']}')";
-		}
-
-		$src = ltrim( $src, ', ' );
-
-		return $src;
-	};
-
-	/**
-	 * Compiles the font variation settings.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @param array $font_variation_settings Array of font variation settings.
-	 * @return string The CSS.
-	 */
-	$fn_compile_variations = static function( array $font_variation_settings ) {
-		$variations = '';
-
-		foreach ( $font_variation_settings as $key => $value ) {
-			$variations .= "$key $value";
-		}
-
-		return $variations;
-	};
-
-	/**
-	 * Builds the font-family's CSS.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @uses $fn_compile_src To run the function that compiles the src.
-	 * @uses $fn_compile_variations To run the function that compiles the variations.
-	 *
-	 * @param array $webfont Webfont to process.
-	 * @return string This font-family's CSS.
-	 */
-	$fn_build_font_face_css = static function( array $webfont ) use ( $fn_compile_src, $fn_compile_variations ) {
-		$css = '';
-
-		// Wrap font-family in quotes if it contains spaces.
-		if (
-			str_contains( $webfont['font-family'], ' ' ) &&
-			! str_contains( $webfont['font-family'], '"' ) &&
-			! str_contains( $webfont['font-family'], "'" )
-		) {
-			$webfont['font-family'] = '"' . $webfont['font-family'] . '"';
-		}
-
-		foreach ( $webfont as $key => $value ) {
-			/*
-			 * Skip "provider", since it's for internal API use,
-			 * and not a valid CSS property.
-			 */
-			if ( 'provider' === $key ) {
-				continue;
-			}
-
-			// Compile the "src" parameter.
-			if ( 'src' === $key ) {
-				$value = $fn_compile_src( $webfont['font-family'], $value );
-			}
-
-			// If font-variation-settings is an array, convert it to a string.
-			if ( 'font-variation-settings' === $key && is_array( $value ) ) {
-				$value = $fn_compile_variations( $value );
-			}
-
-			if ( ! empty( $value ) ) {
-				$css .= "$key:$value;";
-			}
-		}
-
-		return $css;
-	};
-
-	/**
-	 * Gets the '@font-face' CSS styles for locally-hosted font files.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @uses $registered_webfonts To access and update the registered webfonts registry (passed by reference).
-	 * @uses $fn_order_src To run the function that orders the src.
-	 * @uses $fn_build_font_face_css To run the function that builds the font-face CSS.
-	 *
-	 * @return string The `@font-face` CSS.
-	 */
-	$fn_get_css = static function() use ( &$registered_webfonts, $fn_order_src, $fn_build_font_face_css ) {
-		$css = '';
-
-		foreach ( $registered_webfonts as $webfont ) {
-			// Order the webfont's `src` items to optimize for browser support.
-			$webfont = $fn_order_src( $webfont );
-
-			// Build the @font-face CSS for this webfont.
-			$css .= '@font-face{' . $fn_build_font_face_css( $webfont ) . '}';
-		}
-
-		return $css;
-	};
-
-	/**
-	 * Generates and enqueues webfonts styles.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @uses $fn_get_css To run the function that gets the CSS.
-	 */
-	$fn_generate_and_enqueue_styles = static function() use ( $fn_get_css ) {
-		// Generate the styles.
-		$styles = $fn_get_css();
-
-		// Bail out if there are no styles to enqueue.
-		if ( '' === $styles ) {
-			return;
-		}
-
-		// Enqueue the stylesheet.
-		wp_register_style( 'wp-webfonts', '' );
-		wp_enqueue_style( 'wp-webfonts' );
-
-		// Add the styles to the stylesheet.
-		wp_add_inline_style( 'wp-webfonts', $styles );
-	};
-
-	/**
-	 * Generates and enqueues editor styles.
-	 *
-	 * @since 6.0.0
-	 *
-	 * @uses $fn_get_css To run the function that gets the CSS.
-	 */
-	$fn_generate_and_enqueue_editor_styles = static function() use ( $fn_get_css ) {
-		// Generate the styles.
-		$styles = $fn_get_css();
-
-		// Bail out if there are no styles to enqueue.
-		if ( '' === $styles ) {
-			return;
-		}
-
-		wp_add_inline_style( 'wp-block-library', $styles );
-	};
-
-	add_action( 'wp_loaded', $fn_register_webfonts );
-	add_action( 'wp_enqueue_scripts', $fn_generate_and_enqueue_styles );
-	add_action( 'admin_init', $fn_generate_and_enqueue_editor_styles );
-}
-
 /**
  * Loads classic theme styles on classic themes in the frontend.
  *
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 49aaf303cd..450ee7a147 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-alpha-56499';
+$wp_version = '6.4-alpha-56500';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-settings.php b/wp-settings.php
index 9760b519a7..7b6aff30fe 100644
--- a/wp-settings.php
+++ b/wp-settings.php
@@ -360,6 +360,9 @@ require ABSPATH . WPINC . '/style-engine/class-wp-style-engine-css-declarations.
 require ABSPATH . WPINC . '/style-engine/class-wp-style-engine-css-rule.php';
 require ABSPATH . WPINC . '/style-engine/class-wp-style-engine-css-rules-store.php';
 require ABSPATH . WPINC . '/style-engine/class-wp-style-engine-processor.php';
+require ABSPATH . WPINC . '/fonts/class-wp-font-face-resolver.php';
+require ABSPATH . WPINC . '/fonts/class-wp-font-face.php';
+require ABSPATH . WPINC . '/fonts.php';
 
 $GLOBALS['wp_embed'] = new WP_Embed();