Utility functions for working with fonts.

Since: 6.5.0
Source: wp-includes/fonts/class-wp-font-utils.php
Access: Private (internal core usage)

Description

Provides utility functions for font family sanitization, slug generation, schema-based sanitization, and MIME type handling. These utilities are intended for internal use.

Methods

sanitize_font_family()

Sanitizes and formats font family names.

public static function sanitize_font_family( string $font_family ): string

Parameters:

Returns: Sanitized and formatted font family string.

Processing:

1. Applies sanitize_text_field()
2. Splits comma-separated values
3. Adds quotes to names with special characters
4. Rejoins with proper formatting

Examples:

WP_Font_Utils::sanitize_font_family( 'Inter' );
// 'Inter'

WP_Font_Utils::sanitize_font_family( 'Open Sans' );
// '"Open Sans"'

WP_Font_Utils::sanitize_font_family( 'Inter, sans-serif' );
// 'Inter, sans-serif'

WP_Font_Utils::sanitize_font_family( 'Open Sans, Arial, sans-serif' );
// '"Open Sans", Arial, sans-serif'

Quoting Rules (CSS Fonts Module Level 4):

• Generic families (serif, sans-serif, etc.) are not quoted
• Names with spaces or special characters are quoted
• generic(family-name) syntax is not quoted

get_font_face_slug()

Generates a unique slug from font face properties.

public static function get_font_face_slug( array $settings ): string

Parameters:

Settings:

Returns: Slug in format family;style;weight;stretch;range

Example:

WP_Font_Utils::get_font_face_slug([
    'fontFamily'  => 'Inter',
    'fontWeight'  => '700',
    'fontStyle'   => 'italic',
]);
// 'inter;italic;700;100%;U+0-10FFFF'

Purpose:

Used to detect duplicate font faces that would match the same CSS font matching criteria.

sanitize_from_schema()

Sanitizes a data tree using a schema.

public static function sanitize_from_schema( array $tree, array $schema ): array

Parameters:

Returns: Sanitized data with unknown keys removed.

Schema Structure:

$schema = [
    'name' => 'sanitize_text_field',
    'url'  => 'sanitize_url',
    'items' => [
        [
            'title' => 'sanitize_text_field',
            'count' => 'absint',
        ],
    ],
    'custom' => function( $value ) {
        return custom_sanitizer( $value );
    },
];

Rules:

• Each schema value is a callable (function name or closure)
• Nested arrays are traversed recursively
• Indexed arrays apply schema[0] to each item
• Keys not in schema are removed
• Empty values are removed

Example:

$data = [
    'name'    => '<script>alert("xss")</script>Name',
    'url'     => 'https://example.com',
    'unknown' => 'will be removed',
];

$schema = [
    'name' => 'sanitize_text_field',
    'url'  => 'sanitize_url',
];

$result = WP_Font_Utils::sanitize_from_schema( $data, $schema );
// [
//     'name' => 'Name',
//     'url'  => 'https://example.com',
// ]

get_allowed_font_mime_types()

Returns allowed MIME types for font files.

public static function get_allowed_font_mime_types(): array

Returns: Array of MIME types keyed by extension.

PHP Version Variations:

MIME types vary by PHP version due to changes in finfo_file() detection.

Example:

$mime_types = WP_Font_Utils::get_allowed_font_mime_types();
// [
//     'otf'   => 'application/vnd.ms-opentype',
//     'ttf'   => 'font/sfnt',
//     'woff'  => 'font/woff',
//     'woff2' => 'font/woff2',
// ]

Private Methods

maybe_add_quotes()

Adds quotes to font family names with special characters.

private static function maybe_add_quotes( string $item ): string

Rules:

• Names with only letters/hyphens: no quotes
• Names matching generic(...) syntax: no quotes
• All other names: wrapped in double quotes

apply_sanitizer()

Applies a sanitizer function to a value.

private static function apply_sanitizer( mixed $value, callable $sanitizer ): mixed

Usage

// Sanitize font family for CSS output
$family = WP_Font_Utils::sanitize_font_family( 'Open Sans, Arial' );

// Generate slug for deduplication
$slug = WP_Font_Utils::get_font_face_slug( $font_face_settings );

// Schema-based sanitization
$clean = WP_Font_Utils::sanitize_from_schema( $data, $schema );

// Get allowed MIME types for uploads
$types = WP_Font_Utils::get_allowed_font_mime_types();