Editor: Add hook to disable the Font Library

src/wp-admin/font-library.php

@@ -10,6 +10,14 @@
 /** WordPress Administration Bootstrap */
 require_once __DIR__ . '/admin.php';
 
+if ( ! wp_is_font_library_enabled() ) {
+	wp_die(
+		'<h1>' . __( 'Font Library is not available.' ) . '</h1>' .
+		'<p>' . __( 'The Font Library has been disabled on this site.' ) . '</p>',
+		403
+	);
+}
+
 if ( ! current_user_can( 'edit_theme_options' ) ) {
 	wp_die(
 		'<h1>' . __( 'You need a higher level of permission.' ) . '</h1>' .

src/wp-admin/menu.php

@@ -237,7 +237,9 @@
 }
 
 // Font Library menu item.
-$submenu['themes.php'][9] = array( __( 'Fonts' ), 'edit_theme_options', 'font-library.php' );
+if ( wp_is_font_library_enabled() ) {
+	$submenu['themes.php'][9] = array( __( 'Fonts' ), 'edit_theme_options', 'font-library.php' );
+}
 
 $customize_url = add_query_arg( 'return', urlencode( remove_query_arg( wp_removable_query_args(), wp_unslash( $_SERVER['REQUEST_URI'] ) ) ), 'customize.php' );
 

src/wp-includes/fonts.php

@@ -109,6 +109,30 @@ function wp_unregister_font_collection( string $slug ) {
 	return WP_Font_Library::get_instance()->unregister_font_collection( $slug );
 }
 
+/**
+ * Determines whether the Font Library is enabled.
+ *
+ * The Font Library lets users with the `edit_theme_options` capability install
+ * and manage fonts from the admin interface. Returning false from the
+ * {@see 'wp_is_font_library_enabled'} filter removes the Font Library admin
+ * menu item and screen, which is useful for sites where fonts are managed by
+ * the theme and the feature is not needed in the interface.
+ *
+ * @since 7.1.0
+ *
+ * @return bool True if the Font Library is enabled, false otherwise.
+ */
+function wp_is_font_library_enabled() {
+	/**
+	 * Filters whether the Font Library is enabled.
+	 *
+	 * @since 7.1.0
+	 *
+	 * @param bool $enabled Whether the Font Library is enabled. Default true.
+	 */
+	return (bool) apply_filters( 'wp_is_font_library_enabled', true );
+}
+
 /**
  * Retrieves font uploads directory information.
  *

tests/phpunit/tests/fonts/font-library/wpIsFontLibraryEnabled.php

@@ -0,0 +1,39 @@
+<?php
+/**
+ * Test wp_is_font_library_enabled().
+ *
+ * @package WordPress
+ * @subpackage Font Library
+ *
+ * @group fonts
+ * @group font-library
+ *
+ * @covers ::wp_is_font_library_enabled
+ */
+class Tests_Fonts_WpIsFontLibraryEnabled extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 65550
+	 */
+	public function test_is_enabled_by_default() {
+		$this->assertTrue( wp_is_font_library_enabled() );
+	}
+
+	/**
+	 * @ticket 65550
+	 */
+	public function test_can_be_disabled_via_filter() {
+		add_filter( 'wp_is_font_library_enabled', '__return_false' );
+
+		$this->assertFalse( wp_is_font_library_enabled() );
+	}
+
+	/**
+	 * @ticket 65550
+	 */
+	public function test_filtered_value_is_cast_to_boolean() {
+		add_filter( 'wp_is_font_library_enabled', '__return_zero' );
+
+		$this->assertFalse( wp_is_font_library_enabled() );
+	}
+}