gutenberg / lib / experimental / theme-preview / load.php

load.php in Gutenberg 24.0.0, at lib/experimental/theme-preview/load.php

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1	<?php
2	/**
3	* Bootstraps the block theme preview page in wp-admin.
4	*
5	* Part of the extensible site editor experiment: only loaded while the
6	* `gutenberg-extensible-site-editor` experiment is enabled (see lib/load.php).
7	*
8	* @package gutenberg
9	*/
10
11	/**
12	* Builds the theme preview page URL for a theme.
13	*
14	* The page previews the theme named by the `wp_theme_preview` query
15	* parameter. Core's `wp-includes/theme-previews.php` reads that parameter on
16	* every request: it filters `stylesheet`/`template` (for users with
17	* `switch_themes`), attaches an apiFetch middleware that forwards the
18	* parameter on every REST request, and prints the activation nonce on
19	* `admin_head` — so the page needs no further wiring beyond carrying the
20	* parameter in its URL.
21	*
22	* @param string $stylesheet Stylesheet (directory name) of the theme to preview.
23	* @return string Theme preview page URL, not escaped for output.
24	*/
25	function gutenberg_get_theme_preview_url( $stylesheet ) {
26	static $base = null;
27	if ( null === $base ) {
28	// The page renders the styles route, registered at `/styles`.
29	$base = admin_url( 'admin.php?page=theme-preview-wp-admin&p=%2Fstyles' );
30	}
31
32	return add_query_arg(
33	'wp_theme_preview',
34	// `add_query_arg` does not encode new values, so encode subdirectory
35	// theme stylesheets like `parent/child` here.
36	rawurlencode( $stylesheet ),
37	$base
38	);
39	}
40
41	/**
42	* Registers the hidden wp-admin page that previews a block theme.
43	*/
44	function gutenberg_register_theme_preview_admin_page() {
45	// Register with an empty parent to create a hidden admin.php?page= route
46	// without adding an Appearance submenu item for a screen that requires a
47	// `wp_theme_preview` parameter.
48	$hook_suffix = add_submenu_page(
49	'',
50	__( 'Theme Preview', 'gutenberg' ),
51	__( 'Theme Preview', 'gutenberg' ),
52	'switch_themes',
53	'theme-preview-wp-admin',
54	'gutenberg_theme_preview_wp_admin_render_page'
55	);
56
57	if ( $hook_suffix ) {
58	add_action( "load-$hook_suffix", 'gutenberg_theme_preview_wp_admin_prepare_screen' );
59	}
60	}
61
62	/**
63	* Prepares the admin chrome before wp-admin/admin-header.php renders.
64	*
65	* @global string $title The admin page title.
66	* @global string $parent_file The current top-level menu item.
67	* @global string $submenu_file The current submenu item.
68	*/
69	function gutenberg_theme_preview_wp_admin_prepare_screen() {
70	global $title, $parent_file, $submenu_file;
71
72	// Hidden pages do not resolve a title from a visible menu item, so set one
73	// before admin-header.php formats the page title.
74	$title = __( 'Theme Preview', 'gutenberg' );
75
76	/*
77	* Take the page out of the hidden `''` submenu bucket it was registered in.
78	* Left in place, get_admin_page_parent() matches it there and resets
79	* $parent_file to '' — and it does so after the `parent_file` filter runs,
80	* so filtering cannot win. With no match it preserves a non-empty
81	* $parent_file instead.
82	*
83	* Safe at this point: `load-` fires after the capability check in admin.php,
84	* which needs the page registered, and before the menu is rendered.
85	*/
86	remove_submenu_page( '', 'theme-preview-wp-admin' );
87
88	// The preview is reached from the themes screen; keep Appearance current.
89	$parent_file = 'themes.php';
90	$submenu_file = 'themes.php';
91	}
92
93	/**
94	* Points the themes screen's block theme live preview links at the theme
95	* preview page.
96	*
97	* Core builds those links as `site-editor.php?wp_theme_preview=<stylesheet>`;
98	* rewriting them here saves the round trip through site-editor.php that the
99	* redirect below would otherwise take. The active theme's entry is left
100	* alone: it carries no `wp_theme_preview` parameter and links to the site
101	* editor as a customize action.
102	*
103	* @param array $prepared_themes Themes prepared for the themes screen.
104	* @return array Themes with rewritten live preview links.
105	*/
106	function gutenberg_use_theme_preview_page_for_live_preview_links( $prepared_themes ) {
107	if ( ! current_user_can( 'switch_themes' ) ) {
108	return $prepared_themes;
109	}
110
111	$current_stylesheet = get_stylesheet();
112	foreach ( $prepared_themes as $stylesheet => $theme_data ) {
113	if (
114	$stylesheet === $current_stylesheet
115	\|\| empty( $theme_data['blockTheme'] )
116	\|\| empty( $theme_data['actions']['customize'] )
117	) {
118	continue;
119	}
120	$prepared_themes[ $stylesheet ]['actions']['customize'] = esc_url( gutenberg_get_theme_preview_url( $stylesheet ) );
121	}
122
123	return $prepared_themes;
124	}
125
126	/**
127	* Redirects block theme previews from the site editor to the theme preview page.
128	*
129	* The links the filter above rewrites no longer reach site-editor.php; this
130	* catches the remaining entry points — bookmarks, hand-typed URLs, and the
131	* live preview link the theme installer renders after installing a theme.
132	* For users the preview filters ignore, site-editor.php behaves as before.
133	*/
134	function gutenberg_redirect_theme_preview_to_theme_preview_page() {
135	// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Reading the same unauthenticated query arg Core's theme-previews.php reads to decide whether a preview is requested.
136	$stylesheet = isset( $_GET['wp_theme_preview'] ) ? sanitize_text_field( wp_unslash( $_GET['wp_theme_preview'] ) ) : '';
137	if ( '' === $stylesheet ) {
138	return;
139	}
140
141	// Core ignores the preview for users without `switch_themes`; leave them
142	// on the site editor, which keeps showing the active theme.
143	if ( ! current_user_can( 'switch_themes' ) ) {
144	return;
145	}
146
147	wp_safe_redirect( gutenberg_get_theme_preview_url( $stylesheet ) );
148	exit;
149	}
150
151	// The render callback is generated into `build/pages`, which lib/load.php
152	// requires before this file: a build that predates the page has nothing to
153	// register, link, or redirect to.
154	if ( function_exists( 'gutenberg_theme_preview_wp_admin_render_page' ) ) {
155	add_action( 'admin_menu', 'gutenberg_register_theme_preview_admin_page' );
156	add_filter( 'wp_prepare_themes_for_js', 'gutenberg_use_theme_preview_page_for_live_preview_links' );
157	add_action( 'load-site-editor.php', 'gutenberg_redirect_theme_preview_to_theme_preview_page' );
158	}
159