diff -r 7b1b88e27a20 -r 48c4eec2b7e6 wp/wp-includes/fonts/class-wp-font-face-resolver.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/fonts/class-wp-font-face-resolver.php	Fri Sep 05 18:40:08 2025 +0200
@@ -0,0 +1,173 @@
+<?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 "fontFace" is not defined, meaning there are no variations.
+				if ( empty( $definition['fontFace'] ) ) {
+					continue;
+				}
+
+				// Skip if "fontFamily" is not defined.
+				if ( empty( $definition['fontFamily'] ) ) {
+					continue;
+				}
+
+				$font_family_name = static::maybe_parse_name_from_comma_separated_list( $definition['fontFamily'] );
+
+				// Skip if no font family is defined.
+				if ( empty( $font_family_name ) ) {
+					continue;
+				}
+
+				$fonts[] = static::convert_font_face_properties( $definition['fontFace'], $font_family_name );
+			}
+		}
+
+		return $fonts;
+	}
+
+	/**
+	 * Parse font-family name from comma-separated lists.
+	 *
+	 * If the given `fontFamily` is a comma-separated lists (example: "Inter, sans-serif" ),
+	 * parse and return the fist font from the list.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param string $font_family Font family `fontFamily' to parse.
+	 * @return string Font-family name.
+	 */
+	private static function maybe_parse_name_from_comma_separated_list( $font_family ) {
+		if ( str_contains( $font_family, ',' ) ) {
+			$font_family = explode( ',', $font_family )[0];
+		}
+
+		return trim( $font_family, "\"'" );
+	}
+
+	/**
+	 * 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;
+	}
+}