_wp_theme_json_webfonts_handler()

In this article

This function has been deprecated. Use wp_print_font_faces() instead.

This function’s access is marked private. This means it is not intended for use by plugin or theme developers, only in other core functions. It is listed here for completeness.

Runs the theme.json webfonts handler.

Description

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.

Source

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 );
}

Changelog

VersionDescription
6.4.0Use wp_print_font_faces() instead.
6.0.0Introduced.

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