xspeed / includes / modules / Lazy / LazyModule.php

LazyModule.php in xSpeed Cache: AI-Powered Performance Hub with MCP, Caching & CDN 1.3.7, at includes/modules/Lazy/LazyModule.php

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1	<?php
2	/**
3	* Lazy module — defers img / iframe / video loading via native browser
4	* lazy-load attributes. Also auto-fills missing image dimensions to
5	* prevent CLS.
6	*
7	* What WordPress core does already (since 5.5):
8	* - Adds loading="lazy" to the_content images.
9	*
10	* What this module adds:
11	* - First N images get loading="eager" so the LCP isn't deferred.
12	* - Adds decoding="async" (core doesn't).
13	* - Lazy-loads iframes (core's iframe lazy was reverted).
14	* - preload="none" on <video> (closest thing to native video lazy).
15	* - Auto-fills missing width / height attributes (best CLS win).
16	* - Excludes by substring patterns (src or class match) — useful for
17	* hero banner classes, logo files, etc.
18	*
19	* Tier: Free per FEATURES.md "Images" §1-6 (LiteSpeed parity — all
20	* Free in LS Cache).
21	*
22	* @package XSpeed
23	*/
24
25	declare(strict_types=1);
26
27	namespace XSpeed\Modules\Lazy;
28
29	defined( 'ABSPATH' ) \|\| exit;
30
31	use XSpeed\Lazy_Loader;
32	use XSpeed\Module;
33
34	final class LazyModule extends Module {
35
36	public const SLUG = 'lazy';
37	public const TIER = self::TIER_FREE;
38	public const VERSION = '1.0.0';
39
40	public function ui_metadata(): array {
41	return array(
42	'label' => __( 'Media Optimization', 'xspeed' ),
43	'tab_label' => __( 'Lazy Loading', 'xspeed' ), // its own tab on the Media Optimization page
44	'icon' => 'Image',
45	'description' => __( 'Loads images, videos and embeds only when visitors scroll to them.', 'xspeed' ),
46	'group' => 'performance',
47	// Host page: Lazy Loading (this module) + Image Optimization (Pro)
48	// + AI Suggestions (Pro) as tabs — everything a page loads on one
49	// page instead of separate rows (FBS-83633). Fonts is NOT here: it
50	// has its own Optimization card (#86).
51	'custom_panel' => 'MediaPanel',
52	);
53	}
54
55	public function settings_schema(): array {
56	return array(
57	'lazy_images' => array(
58	'type' => 'bool',
59	'default' => true,
60	'label' => __( 'Lazy-load images', 'xspeed' ),
61	'description' => __( 'Images load when the visitor scrolls near them. The first image on the page still loads right away.', 'xspeed' ),
62	),
63	'lazy_iframes' => array(
64	'type' => 'bool',
65	'default' => true,
66	'label' => __( 'Lazy-load embeds', 'xspeed' ),
67	'description' => __( 'Embedded content such as YouTube videos and maps loads when the visitor scrolls near it.', 'xspeed' ),
68	),
69	'video_facade' => array(
70	'type' => 'bool',
71	'default' => false,
72	'label' => __( 'Click-to-play videos', 'xspeed' ),
73	'description' => __( 'Shows a preview image with a play button in place of YouTube, Vimeo and your own videos that have a poster image. The video loads only when clicked. Autoplaying videos are left alone.', 'xspeed' ),
74	),
75	'lazy_videos' => array(
76	'type' => 'bool',
77	'default' => true,
78	'label' => __( 'Lazy-load your own videos', 'xspeed' ),
79	'description' => __( 'Videos uploaded to your site download only when played. Autoplaying videos are left alone.', 'xspeed' ),
80	),
81	'lazy_background_images' => array(
82	'type' => 'bool',
83	'default' => false,
84	'label' => __( 'Lazy-load background images', 'xspeed' ),
85	'description' => __( 'Hold back background images set in an element\'s inline style (a Cover or Group block, a page-builder section) until the element is near the screen. Uses a small script; visitors without JavaScript get every background as usual. The first N backgrounds on the page load straight away, like images. Backgrounds set in a stylesheet are not affected.', 'xspeed' ),
86	),
87	'eager_first_n' => array(
88	'type' => 'int',
89	'default' => 1,
90	'min' => 0,
91	'max' => 10,
92	'label' => __( 'Images to load right away', 'xspeed' ),
93	'description' => __( 'How many images at the top of the page skip lazy loading. Only the first of them also loads at high priority, and images in hidden or closed sections are not counted. Lazy-loaded background images use the same number. 1 suits most sites; 0 lazy-loads every image.', 'xspeed' ),
94	'advanced' => true,
95	// Both counters read this number (class-lazy-loader.php), so it
96	// shows while either kind of lazy loading is on.
97	'dependsOn' => array(
98	'any' => array(
99	array( 'field' => 'lazy_images' ),
100	array( 'field' => 'lazy_background_images' ),
101	),
102	),
103	),
104	'add_missing_dimensions' => array(
105	'type' => 'bool',
106	'default' => true,
107	'label' => __( 'Add missing image sizes', 'xspeed' ),
108	'description' => __( 'Adds width and height to images that lack them, using the media library. This stops the page from jumping as images load.', 'xspeed' ),
109	),
110	'excluded_images' => array(
111	'type' => 'list',
112	'default' => array(),
113	'item_type' => 'string',
114	'label' => __( 'Excluded images', 'xspeed' ),
115	'description' => __( 'Images and embeds whose tag contains a line here, such as a class or file name, are never lazy-loaded. Useful for logos and hero images.', 'xspeed' ),
116	),
117	);
118	}
119
120	public function conflicts(): array {
121	return array(
122	array(
123	'plugin' => 'wp-smushit/wp-smush.php',
124	'feature' => 'images.lazyload',
125	'strategy' => \XSpeed\Conflict_Registry::STRATEGY_WARN,
126	'reason' => 'Smush also offers lazy-loading; running both can cause double-rewriting.',
127	),
128	array(
129	'plugin' => 'a3-lazy-load/a3-lazy-load.php',
130	'feature' => 'images.lazyload',
131	'strategy' => \XSpeed\Conflict_Registry::STRATEGY_REFUSE,
132	'reason' => 'a3 Lazy Load is a dedicated lazy-load plugin; disable it before enabling xSpeed lazy-load.',
133	),
134	);
135	}
136
137	public function boot(): void {
138	/*
139	* Deferred to `init`. This module reads its own settings to decide
140	* what to hook, and reading settings builds settings_schema(), whose
141	* labels are declared through __(). boot() runs on `plugins_loaded`,
142	* before `after_setup_theme` — the point WordPress 6.7+ treats as the
143	* earliest safe moment to translate — so doing that here fires
144	* _load_textdomain_just_in_time on every request AND resolves the
145	* labels against a domain that is not loaded yet.
146	*
147	* Everything below hooks actions that fire after `init`, so running
148	* one hook later is equivalent.
149	*/
150	add_action( 'init', array( $this, 'boot_on_init' ) );
151	}
152
153	/**
154	* The real boot body — see boot() for why it runs on `init`.
155	*/
156	public function boot_on_init(): void {
157	// Bail entirely on admin / feed / cron / REST — same scope as
158	// Minifier. Lazy-loading rendered HTML only matters on real
159	// frontend page renders.
160	if ( is_admin() \|\| ( defined( 'DOING_AJAX' ) && DOING_AJAX ) \|\| ( defined( 'DOING_CRON' ) && DOING_CRON ) \|\| ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) {
161	return;
162	}
163
164	// Never lazy-load inside a builder editor: the builder measures and
165	// positions elements it expects to be loaded. (#281)
166	if ( \XSpeed\Builder_Editor::is_active() ) {
167	return;
168	}
169
170	$opts = $this->get_settings();
171	$any_enabled = ! empty( $opts['lazy_images'] )
172	\|\| ! empty( $opts['lazy_iframes'] )
173	\|\| ! empty( $opts['lazy_videos'] )
174	\|\| ! empty( $opts['video_facade'] )
175	\|\| ! empty( $opts['lazy_background_images'] )
176	\|\| ! empty( $opts['add_missing_dimensions'] );
177	if ( ! $any_enabled ) {
178	return;
179	}
180
181	// Reset the eager-load budget once per page render, before any
182	// content filter runs, so the "first N images eager" budget is
183	// shared across the featured image + content + avatars rather than
184	// restarting on every filter pass. (FBS-82172 Bug 1)
185	add_action( 'template_redirect', array( Lazy_Loader::class, 'reset_state' ) );
186
187	// Late priority so the_content runs after every other filter
188	// (shortcodes, do_blocks, embeds). Avoids rewriting tags that
189	// haven't been generated yet.
190	add_filter( 'the_content', array( Lazy_Loader::class, 'process_html' ), 999 );
191	add_filter( 'post_thumbnail_html', array( Lazy_Loader::class, 'process_html' ), 999 );
192	add_filter( 'get_avatar', array( Lazy_Loader::class, 'process_html' ), 999 );
193	add_filter( 'widget_text_content', array( Lazy_Loader::class, 'process_html' ), 999 );
194
195	// The facade's click handler is printed only on pages that actually
196	// rendered a facade — a page with no embeds should not carry the
197	// script that reveals them.
198	if ( ! empty( $opts['video_facade'] ) ) {
199	add_action( 'wp_footer', array( $this, 'print_facade_script' ), 99 );
200	// The layout rule goes in the HEAD, unconditionally, while the
201	// handler stays conditional in the footer. Whether a facade
202	// renders isn't known until the content filter has run — long
203	// after wp_head — and a layout rule that arrives in the footer
204	// fixes the gap only after the visitor has already seen it.
205	add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_facade_style' ) );
206	// Embeds that never touch the HTML: a builder widget builds its
207	// YouTube iframe from script, so the buffer pass has nothing to
208	// rewrite. Head, priority 1, for the same reason as the autoplay
209	// restorer below — it must be listening before the widget's
210	// script sets a src and commits the fetch.
211	add_action( 'wp_head', array( $this, 'print_observer_script' ), 1 );
212	}
213
214	// Head, because the rule that holds a background back has to apply
215	// before first paint, or the browser has already requested it.
216	if ( ! empty( $opts['lazy_background_images'] ) ) {
217	add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_background_style' ) );
218	add_action( 'wp_head', array( $this, 'print_background_script' ), 1 );
219	}
220
221	// Same conditional-footer treatment for the autoplay restorer: it is
222	// only printed on a response that actually deferred one.
223	if ( ! empty( $opts['lazy_videos'] ) ) {
224	/*
225	* HEAD, not footer — and as early as anything can run.
226	*
227	* A page-builder video block creates its <video> from its own
228	* script. Ours has to be listening BEFORE that happens: printed
229	* in the footer it loaded after the block's script had already
230	* built the player and started the fetch, so the bytes were
231	* committed before we could defer them. Measured on a live page,
232	* our restorer sat ~17KB after the first block script in the
233	* document, and the videos still downloaded on load.
234	*
235	* It costs ~1KB inline and installs only observers, so running it
236	* early is cheap; a MutationObserver on documentElement catches
237	* every <video> the moment it is inserted, whichever script did
238	* the inserting.
239	*/
240	add_action( 'wp_head', array( $this, 'print_autoplay_script' ), 1 );
241	}
242	}
243
244	/**
245	* Register the facade's layout rule as an inline style on a
246	* dependency-free handle — ~150 bytes, so a separate file would cost
247	* more than the CSS.
248	*/
249	public function enqueue_facade_style(): void {
250	wp_register_style( 'xspeed-video-facade', false, array(), XSPEED_VERSION );
251	wp_enqueue_style( 'xspeed-video-facade' );
252	wp_add_inline_style( 'xspeed-video-facade', \XSpeed\Video_Facade::facade_style() );
253	}
254
255	public function enqueue_background_style(): void {
256	wp_register_style( 'xspeed-lazy-bg', false, array(), XSPEED_VERSION );
257	wp_enqueue_style( 'xspeed-lazy-bg' );
258	wp_add_inline_style( 'xspeed-lazy-bg', Lazy_Loader::background_style() );
259	}
260
261	/**
262	* data-xs-nodelay: Delay JS would otherwise hold this back until the
263	* first interaction, and every held background would stay blank.
264	*/
265	public function print_background_script(): void {
266	wp_print_inline_script_tag(
267	Lazy_Loader::background_script(),
268	array(
269	'id' => 'xspeed-lazy-bg',
270	'data-xs-nodelay' => true,
271	)
272	);
273	}
274
275	/**
276	* Emit the click-to-play handler inline. Inline (not enqueued) because
277	* it is ~400 bytes — a separate request would cost more than the code.
278	*/
279	public function print_facade_script(): void {
280	// No longer gated on facade_used(): the observer script can build a
281	// facade for a JS-injected embed on a page where the server pass
282	// rendered none, and a facade without its click handler is a play
283	// button that plays nothing. ~400 bytes on facade-less pages is the
284	// cost of never shipping that.
285	wp_print_inline_script_tag( \XSpeed\Video_Facade::facade_script(), array( 'id' => 'xspeed-video-facade' ) );
286	}
287
288	/**
289	* Emit the interceptor for JS-injected embeds (see
290	* Video_Facade::observer_script() for the mechanism and why the
291	* footer is too late).
292	*/
293	public function print_observer_script(): void {
294	wp_print_inline_script_tag( \XSpeed\Video_Facade::observer_script(), array( 'id' => 'xspeed-video-facade-observer' ) );
295	}
296
297	/**
298	* Emit the viewport restorer for deferred AUTOPLAY videos.
299	*
300	* Separate from the facade script because the two are independent: a
301	* page can defer an autoplay hero without any click-to-play facade on
302	* it, and vice versa. Both are gated on having actually rewritten
303	* something, so a page with no video ships neither.
304	*/
305	public function print_autoplay_script(): void {
306	/*
307	* Deliberately NOT gated on needs_autoplay_script().
308	*
309	* That flag is only meaningful after the content filter has run, and
310	* this prints in wp_head — long before. The facade script above can
311	* afford to be conditional because it only has to be present by the
312	* time a human clicks; this one has to be listening before another
313	* plugin's script builds a <video> and starts fetching it, which
314	* happens well before wp_footer.
315	*
316	* The cost of being unconditional is ~1KB inline on pages with no
317	* video, and the script installs observers only — it does no work
318	* and touches nothing when it finds no autoplay video. That is a
319	* better trade than missing the one case the feature exists for.
320	*/
321	wp_print_inline_script_tag( Lazy_Loader::autoplay_script(), array( 'id' => 'xspeed-lazy-autoplay' ) );
322	}
323
324	public function cli_commands(): array {
325	return array(
326	array(
327	'name' => 'xspeed lazy',
328	'callback' => array( $this, 'cli_handler' ),
329	'shortdesc' => 'Show which lazy-load toggles are active.',
330	'ai_hint' => 'Which lazy-loading and image optimizations are on (images, iframes, missing width/height)? Use for questions about images loading too early, layout shift (CLS), or offscreen images flagged by PageSpeed.',
331	'synopsis' => array(),
332	),
333	);
334	}
335
336	public function cli_handler( array $args, array $assoc ): void {
337	$opts = $this->get_settings();
338	foreach ( $opts as $key => $value ) {
339	$display = is_array( $value ) ? implode( ',', $value ) : ( $value ? 'on' : ( is_numeric( $value ) ? (string) $value : 'off' ) );
340	if ( is_int( $value ) ) {
341	$display = (string) $value;
342	}
343	\WP_CLI::log( sprintf( '%-30s %s', $key, $display ) );
344	}
345	}
346
347	/**
348	* Lazy has no master switch -- it is on when any of lazy_images /
349	* lazy_iframes / video_facade / lazy_videos is set. (#363)
350	*/
351	public function is_active(): ?bool {
352	return $this->any_bool_flag_on();
353	}
354	}
355