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xSpeed Cache: AI-Powered Performance Hub with MCP, Caching & CDN / 1.3.6
xSpeed Cache: AI-Powered Performance Hub with MCP, Caching & CDN v1.3.6
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← All changes | includes/class-lazy-loader.php +1146 -31 1.1.5 → 1.3.6 View file →
@@ -34,8 +34,18 @@
34 34 */
35 35 private static $image_counter = 0;
36 36
37 37 /**
38 + * Eager budget for inline-style backgrounds. Separate from images: a
39 + * hero is either an <img> or a background, and the passes run one after
40 + * the other, so one shared counter would hand the budget to whichever
41 + * pass runs first rather than to what sits first on the page.
42 + *
43 + * @var int
44 + */
45 + private static $background_counter = 0;
46 +
47 + /**
38 48 * Settings cache (one read per request).
39 49 *
40 50 * @var array|null
41 51 */
@@ -49,8 +59,19 @@
49 59 */
50 60 private static $src_dims_cache = null;
51 61
52 62 /**
63 + * True while a background pass is resolving dimensions.
64 + *
65 + * Front-end renders read the cache and never fetch; a warm pass is the
66 + * one thing allowed to pay the network cost, because no visitor is
67 + * waiting on it.
68 + *
69 + * @var bool
70 + */
71 + private static $warming = false;
72 +
73 + /**
53 74 * Main entry point: take rendered HTML, return rewritten HTML.
54 75 * Pure function aside from the static counters.
55 76 */
56 77 public static function process_html( string $html ): string {
@@ -86,8 +107,13 @@
86 107 }
87 108 if ( ! empty( $opts['lazy_iframes'] ) ) {
88 109 $work = self::apply_pass( $work, $tag_re( 'iframe' ), array( __CLASS__, 'rewrite_iframe' ) );
89 110 }
111 + // Every opening tag is a candidate, so skip the pass on content with
112 + // no url( at all, which is most of it.
113 + if ( ! empty( $opts['lazy_background_images'] ) && false !== stripos( $work, 'url(' ) ) {
114 + $work = self::apply_pass( $work, '#<[a-z][a-z0-9-]*\b(?:"[^"]*"|\'[^\']*\'|[^>"\'])*>#i', array( __CLASS__, 'rewrite_background' ) );
115 + }
90 116 // Facade runs AFTER the lazy pass, deliberately. The facade keeps the
91 117 // original tag inside <noscript> as the JS-less fallback, and that
92 118 // fallback should carry loading="lazy" too — running this first would
93 119 // produce an eager iframe for exactly the visitors least able to
@@ -102,9 +128,9 @@
102 128 // unclosed iframe can't make the match run on to a LATER embed's
103 129 // closing tag and eat everything in between; an iframe with no
104 130 // closing tag simply doesn't match and passes through untouched.
105 131 if ( ! empty( $opts['video_facade'] ) ) {
106 - $work = self::apply_pass(
132 + $work = self::apply_facade_pass(
107 133 $work,
108 134 '#(<iframe\b(?:"[^"]*"|\'[^\']*\'|[^>"\'])*>)((?:(?!</?iframe\b).)*)</iframe\s*>#is',
109 135 array( __CLASS__, 'rewrite_iframe_facade' )
110 136 );
@@ -110,14 +136,154 @@
110 136 );
111 137 }
112 138 if ( ! empty( $opts['lazy_videos'] ) ) {
113 139 $work = self::apply_pass( $work, $tag_re( 'video' ), array( __CLASS__, 'rewrite_video' ) );
140 + // A page builder's video block renders no <video> server-side, so
141 + // the pass above sees nothing to rewrite. Note that such markup is
142 + // here anyway, so the restorer ships and can defer the element the
143 + // block's own script creates. (See detect_attribute_video().)
144 + self::detect_attribute_video( $work );
114 145 }
146 + // Self-hosted <video> facade — after the lazy pass for the same
147 + // reason as the iframe facade above: the original element lands in
148 + // <noscript> as the JS-less fallback, and that copy should carry
149 + // preload="none" too. Same whole-element, tempered match so an
150 + // unclosed <video> passes through rather than eating siblings.
151 + if ( ! empty( $opts['video_facade'] ) ) {
152 + $work = self::apply_facade_pass(
153 + $work,
154 + '#(<video\b(?:"[^"]*"|\'[^\']*\'|[^>"\'])*>)((?:(?!</?video\b).)*)</video\s*>#is',
155 + array( __CLASS__, 'rewrite_video_facade' )
156 + );
157 + }
115 158
116 159 return self::restore_safe_blocks( $work, $stubs );
117 160 }
118 161
119 162 /**
163 + * Hidden popup/lightbox templates a facade must never replace into.
164 + *
165 + * A lightbox plugin ships its player iframe in a hidden template div
166 + * and moves that markup into the popup when clicked. Facading the
167 + * template swaps its iframe for the play button, and the popup then
168 + * opens around a button its own CSS only sizes for an iframe — a blank
169 + * modal (found live: EmbedPress's "See it in action", an Essential
170 + * Addons lightbox whose Magnific popup opened empty). The template
171 + * iframe already carries loading="lazy" from the pass above, and a
172 + * hidden lazy iframe never loads until shown — so skipping the facade
173 + * here costs nothing on page load.
174 + */
175 + private const POPUP_TEMPLATE_CLASSES = array(
176 + 'eael-lightbox-popup-window', // Essential Addons lightbox template.
177 + 'mfp-hide', // Magnific Popup inline template.
178 + 'lity-hide', // Lity inline template.
179 + );
180 +
181 + /**
182 + * A facade pass that leaves popup-template containers alone.
183 + *
184 + * Same PCRE-bail contract as apply_pass(). Ranges are byte spans in
185 + * $html; PREG_OFFSET_CAPTURE offsets refer to the original subject, so
186 + * earlier replacements never shift the comparison.
187 + *
188 + * @param callable $callback Rewrite callback taking plain string matches.
189 + */
190 + private static function apply_facade_pass( string $html, string $pattern, callable $callback ): string {
191 + $ranges = self::popup_template_ranges( $html );
192 + if ( empty( $ranges ) ) {
193 + return self::apply_pass( $html, $pattern, $callback );
194 + }
195 +
196 + $result = preg_replace_callback(
197 + $pattern,
198 + static function ( array $m ) use ( $callback, $ranges ): string {
199 + $offset = (int) $m[0][1];
200 + foreach ( $ranges as $range ) {
201 + if ( $offset >= $range[0] && $offset < $range[1] ) {
202 + return (string) $m[0][0]; // Inside a template: untouched.
203 + }
204 + }
205 + return (string) call_user_func(
206 + $callback,
207 + array_map( static fn( $group ): string => (string) $group[0], $m )
208 + );
209 + },
210 + $html,
211 + -1,
212 + $count,
213 + PREG_OFFSET_CAPTURE
214 + );
215 +
216 + return is_string( $result ) ? $result : $html;
217 + }
218 +
219 + /**
220 + * Byte spans of every popup-template container in $html.
221 + *
222 + * The span is found by counting the container's own tag name to its
223 + * balancing close — templates are plain nested divs, so a same-tag
224 + * depth count is enough; a container whose close is never found is
225 + * dropped rather than guessed at (its iframes stay facade-eligible,
226 + * the pre-fix behavior).
227 + *
228 + * @return array<int, array{0:int, 1:int}>
229 + */
230 + private static function popup_template_ranges( string $html ): array {
231 + /**
232 + * Filter the class names marking a hidden popup/lightbox template
233 + * whose contents the video facade must leave alone.
234 + *
235 + * @param string[] $classes
236 + */
237 + $classes = (array) apply_filters( 'xspeed_video_facade_popup_classes', self::POPUP_TEMPLATE_CLASSES );
238 + $classes = array_values(
239 + array_filter(
240 + array_map( 'strval', $classes ),
241 + static fn( string $c ): bool => (bool) preg_match( '/^[A-Za-z0-9_-]+$/', $c )
242 + )
243 + );
244 + if ( empty( $classes ) ) {
245 + return array();
246 + }
247 +
248 + $pattern = '#<(div|section|span|aside)\b[^>]*\bclass\s*=\s*(["\'])[^"\']*(?<![A-Za-z0-9_-])(?:'
249 + . implode( '|', array_map( 'preg_quote', $classes ) )
250 + . ')(?![A-Za-z0-9_-])[^"\']*\2[^>]*>#i';
251 + if ( ! preg_match_all( $pattern, $html, $m, PREG_OFFSET_CAPTURE ) ) {
252 + return array();
253 + }
254 +
255 + $ranges = array();
256 + foreach ( $m[0] as $i => $hit ) {
257 + $start = (int) $hit[1];
258 + $end = self::same_tag_end( $html, $start, strtolower( (string) $m[1][ $i ][0] ) );
259 + if ( null !== $end ) {
260 + $ranges[] = array( $start, $end );
261 + }
262 + }
263 + return $ranges;
264 + }
265 +
266 + /**
267 + * The offset just past the close tag balancing the open tag at $offset,
268 + * counting only $tag's own opens and closes. Null when it never closes.
269 + */
270 + private static function same_tag_end( string $html, int $offset, string $tag ): ?int {
271 + $depth = 0;
272 + $cursor = $offset;
273 + $re = '#<(/?)' . preg_quote( $tag, '#' ) . '\b(?:"[^"]*"|\'[^\']*\'|[^>"\'])*>#i';
274 + while ( preg_match( $re, $html, $t, PREG_OFFSET_CAPTURE, $cursor ) ) {
275 + $cursor = (int) $t[0][1] + strlen( (string) $t[0][0] );
276 + if ( '' === $t[1][0] ) {
277 + ++$depth;
278 + } elseif ( --$depth <= 0 ) {
279 + return $cursor;
280 + }
281 + }
282 + return null;
283 + }
284 +
285 + /**
120 286 * Run one rewrite pass, keeping the input if PCRE bails.
121 287 *
122 288 * preg_replace_callback() returns null when it hits the backtrack or
123 289 * recursion limit — on a large page that would otherwise blank the
@@ -141,10 +307,22 @@
141 307 // applies — excluding an above-the-fold hero/logo from lazy-load is
142 308 // exactly when you most want its width/height kept. Previously both
143 309 // of these returned early, silently stripping dimensions too.
144 310 // (FBS-82172 Bug 2)
311 + //
312 + // `fetchpriority="high"` joins that set: an image carrying it has been
313 + // declared the LCP element by whoever rendered it — WordPress core, the
314 + // theme, a page builder, or our own Resource_Hints_Processor. Lazy-
315 + // loading it contradicts that declaration, because the tag would then
316 + // tell the browser to fetch at top priority AND that it may defer the
317 + // fetch indefinitely. Browsers resolve that in favour of the deferral,
318 + // so the hero arrives late and any layout sized from it (a Kadence hero
319 + // row, for example) reflows when it finally paints — the "sometimes
320 + // broken, sometimes fine" symptom, because it depends on paint timing.
321 + // Treat the hint as authoritative and keep the image eager. (#269)
145 322 $skip_lazy = false !== stripos( $tag, 'data-skip-lazy' )
146 323 || false !== stripos( $tag, 'data-no-lazy' )
324 + || self::has_high_fetchpriority( $tag )
147 325 || self::is_excluded( $tag, $opts );
148 326
149 327 if ( $skip_lazy && ! empty( $opts['lazy_images'] ) ) {
150 328 // An EXCLUDED image is one the user marked as above-the-fold (a
@@ -178,8 +356,103 @@
178 356
179 357 return $tag;
180 358 }
181 359
360 + /** Class that holds an element's background back until it nears the viewport. */
361 + public const LAZY_BG_CLASS = 'xspeed-lazy-bg';
362 +
363 + private static function rewrite_background( array $m ): string {
364 + $tag = $m[0];
365 + if ( false === stripos( $tag, 'url(' ) ) {
366 + return $tag;
367 + }
368 + if ( ! preg_match( '#\sstyle\s*=\s*(?:"([^"]*)"|\'([^\']*)\')#i', $tag, $sm ) ) {
369 + return $tag;
370 + }
371 + $style = html_entity_decode( isset( $sm[2] ) && '' !== $sm[2] ? $sm[2] : $sm[1], ENT_QUOTES );
372 + if ( ! self::has_deferrable_background( $style ) ) {
373 + return $tag;
374 + }
375 + $opts = self::opts();
376 + if ( false !== stripos( $tag, 'data-skip-lazy' )
377 + || false !== stripos( $tag, 'data-no-lazy' )
378 + || self::is_excluded( $tag, $opts ) ) {
379 + return $tag;
380 + }
381 + self::$background_counter++;
382 + if ( self::$background_counter <= max( 0, (int) ( $opts['eager_first_n'] ?? 1 ) ) ) {
383 + return $tag;
384 + }
385 + return self::add_class( $tag, self::LAZY_BG_CLASS );
386 + }
387 +
388 + /**
389 + * Whether an inline style sets a background image we can hold back.
390 + *
391 + * The hold is a stylesheet rule with !important, which beats a normal
392 + * inline declaration but loses to an inline !important one; those are
393 + * left alone. data: URIs cost no request, so there is nothing to save.
394 + */
395 + public static function has_deferrable_background( string $style ): bool {
396 + $found = false;
397 + foreach ( explode( ';', $style ) as $decl ) {
398 + if ( ! preg_match( '#^\s*background(?:-image)?\s*:(.*)$#is', $decl, $dm ) ) {
399 + continue;
400 + }
401 + $value = $dm[1];
402 + if ( false !== stripos( $value, '!important' ) ) {
403 + return false;
404 + }
405 + if ( preg_match( '#url\(\s*[\'"]?(?!data:)[^)\s\'"]#i', $value ) ) {
406 + $found = true;
407 + }
408 + }
409 + return $found;
410 + }
411 +
412 + private static function add_class( string $tag, string $class ): string {
413 + if ( preg_match( '#\sclass\s*=\s*(?:"([^"]*)"|\'([^\']*)\'|([^\s"\'>=`]+))#i', $tag, $cm, PREG_OFFSET_CAPTURE ) ) {
414 + // An unquoted value (class=hero) is rewritten as a quoted one.
415 + // Adding a second class attribute would lose it: browsers keep
416 + // the first of two duplicates.
417 + if ( isset( $cm[3] ) && -1 !== $cm[3][1] ) {
418 + $group = $cm[3];
419 + return substr( $tag, 0, $group[1] ) . '"' . $group[0] . ' ' . $class . '"' . substr( $tag, $group[1] + strlen( $group[0] ) );
420 + }
421 + $group = isset( $cm[2] ) && -1 !== $cm[2][1] ? $cm[2] : $cm[1];
422 + $value = trim( $group[0] . ' ' . $class );
423 + return substr( $tag, 0, $group[1] ) . $value . substr( $tag, $group[1] + strlen( $group[0] ) );
424 + }
425 + return (string) preg_replace( '#^<([a-z][a-z0-9-]*)#i', '<$1 class="' . $class . '"', $tag, 1 );
426 + }
427 +
428 + /**
429 + * Scoped to a class the script puts on <html>, so without JavaScript the
430 + * rule never matches and every background loads normally.
431 + */
432 + public static function background_style(): string {
433 + return '.xspeed-lazy-bg-js .' . self::LAZY_BG_CLASS . '{background-image:none!important}';
434 + }
435 +
436 + /**
437 + * The MutationObserver is what keeps a background from staying blank:
438 + * carousel clones, infinite scroll and builder re-renders insert
439 + * elements carrying the class after DOMContentLoaded, and a one-time
440 + * scan never saw them.
441 + */
442 + public static function background_script(): string {
443 + return <<<'JS'
444 +(function(d,w){var h=d.documentElement,C='xspeed-lazy-bg';h.className+=' xspeed-lazy-bg-js';
445 +function show(el){el.classList.remove(C);}
446 +var io='IntersectionObserver' in w?new IntersectionObserver(function(es){es.forEach(function(e){if(e.isIntersecting){show(e.target);io.unobserve(e.target);}});},{rootMargin:'300px 0px'}):null;
447 +function watch(el){if(io)io.observe(el);else show(el);}
448 +function scan(r){if(r.classList&&r.classList.contains(C))watch(r);if(r.querySelectorAll){var l=r.querySelectorAll('.'+C);for(var i=0;i<l.length;i++)watch(l[i]);}}
449 +if('MutationObserver' in w)new MutationObserver(function(ms){for(var j=0;j<ms.length;j++){var a=ms[j].addedNodes;for(var i=0;i<a.length;i++)if(a[i].nodeType===1)scan(a[i]);}}).observe(h,{childList:true,subtree:true});
450 +function run(){scan(d);}
451 +if(d.readyState==='loading')d.addEventListener('DOMContentLoaded',run);else run();})(document,window);
452 +JS;
453 + }
454 +
182 455 private static function rewrite_iframe( array $m ): string {
183 456 $tag = $m[0];
184 457 if ( false !== stripos( $tag, 'data-skip-lazy' ) ) {
185 458 return $tag;
@@ -249,17 +522,98 @@
249 522 $tag = $m[0];
250 523 if ( false !== stripos( $tag, 'data-skip-lazy' ) ) {
251 524 return $tag;
252 525 }
526 + /*
527 + * An autoplaying video is the one case preload="none" cannot help:
528 + * browsers fetch an autoplay source regardless of preload, because
529 + * the author asked for it to start on its own. Setting the attribute
530 + * would only make the markup lie about what happens.
531 + *
532 + * But "starts on its own" does not mean "must download before the
533 + * visitor has scrolled anywhere near it". A page of nine autoplay
534 + * demo clips pulled 44 MB on load and held the browser's loading
535 + * indicator open for 33 s, while none of them were on screen.
536 + *
537 + * So defer the SOURCE and restore it when the element reaches the
538 + * viewport, which is the first moment autoplay is meant to be
539 + * visible anyway. The author's choice is honoured — the video still
540 + * plays by itself — it simply costs nothing until it can be seen.
541 + */
542 + if ( preg_match( '#\sautoplay(?=[\s/>=])#i', $tag ) ) {
543 + return self::defer_autoplay_source( $tag );
544 + }
253 545 // HTML5 `<video>` doesn't support loading=lazy yet (Chromium
254 546 // won't add it before there's broad support). What we CAN do
255 547 // is set preload="none" so the browser doesn't pre-fetch the
256 548 // video bytes until play is requested — that's the actual win
257 549 // users want from "lazy-load videos".
258 - if ( false === stripos( $tag, 'preload=' ) ) {
259 - $tag = self::set_attr( $tag, 'preload', 'none' );
550 + //
551 + // OVERRIDE an existing value rather than bailing on it: players
552 + // that ship preload="auto" or "metadata" (Elementor's video
553 + // widget, most block themes) are exactly the case this setting
554 + // exists for, and skipping them made it a no-op right where it
555 + // mattered. (#309 — a 924KB MP4 transferred in full on every run
556 + // with this setting on.)
557 + return self::set_attr( $tag, 'preload', 'none' );
558 + }
559 +
560 + /**
561 + * Swap a self-hosted <video> for the click-to-play facade.
562 + *
563 + * The easy case of the facade, not the hard one: no third-party player
564 + * to defer, and the element usually already carries a real poster
565 + * frame. Bails out — element returned untouched — whenever the facade
566 + * would be worse than the video:
567 + *
568 + * - `autoplay` is a deliberate author choice (a hero background); a
569 + * play button in its place changes the page, not just its weight.
570 + * - no `poster` means the facade renders as a blank black box, which
571 + * is worse than the preload="none" the lazy pass already applied.
572 + * - no resolvable source means there is nothing to play on click.
573 + *
574 + * $m[0] is the whole element, $m[1] the opening tag — same contract as
575 + * rewrite_iframe_facade() above, and the same rule: every bail-out
576 + * path returns the WHOLE element so the closing tag is never stranded.
577 + */
578 + private static function rewrite_video_facade( array $m ): string {
579 + $element = $m[0];
580 + $tag = $m[1];
581 +
582 + if ( false !== stripos( $tag, 'data-skip-lazy' ) ) {
583 + return $element;
260 584 }
261 - return $tag;
585 + if ( preg_match( '#\sautoplay(?=[\s/>=])#i', $tag ) ) {
586 + return $element;
587 + }
588 + if ( self::is_excluded( $tag, self::opts() ) ) {
589 + return $element;
590 + }
591 +
592 + if ( ! preg_match( '#\bposter\s*=\s*(["\'])(.*?)\1#i', $tag, $poster_m ) || '' === trim( $poster_m[2] ) ) {
593 + return $element;
594 + }
595 + $poster = $poster_m[2];
596 +
597 + // Source: the src attribute, else the first <source src="…"> child.
598 + $src = '';
599 + if ( preg_match( '#\bsrc\s*=\s*(["\'])(.*?)\1#i', $tag, $src_m ) ) {
600 + $src = $src_m[2];
601 + } elseif ( preg_match( '#<source\b[^>]*\bsrc\s*=\s*(["\'])(.*?)\1#i', $m[2], $src_m ) ) {
602 + $src = $src_m[2];
603 + }
604 + if ( '' === trim( $src ) ) {
605 + return $element;
606 + }
607 +
608 + $title = '';
609 + if ( preg_match( '#\btitle\s*=\s*(["\'])(.*?)\1#i', $tag, $title_m ) ) {
610 + $title = $title_m[2];
611 + }
612 +
613 + self::$facade_used = true;
614 +
615 + return Video_Facade::render_native( $element, $src, $poster, $title );
262 616 }
263 617
264 618 /**
265 619 * Add an attribute to an opening tag if it isn't already present.
@@ -265,10 +619,269 @@
265 619 * Add an attribute to an opening tag if it isn't already present.
266 620 * Pass $only_if_missing=false to override an existing value (e.g.
267 621 * flipping loading="lazy" → "eager" on the first image).
268 622 */
623 + /**
624 + * Hold an autoplay video's bytes until the element reaches the viewport.
625 + *
626 + * `preload="none"` is ignored for autoplay, so the only way to stop the
627 + * download is to take the source away and give it back later. We move
628 + * `src` to `data-xspeed-src` and drop `autoplay` — a `<video>` with no
629 + * resolvable source fetches nothing — then the script below restores
630 + * both when the element scrolls into view.
631 + *
632 + * Restoring `autoplay` rather than calling play() matters: play() from
633 + * a non-user gesture is refused unless the video is muted, and returns
634 + * a promise whose rejection most callers never handle. Setting the
635 + * attribute lets the browser apply its own autoplay policy exactly as
636 + * it would have on load.
637 + *
638 + * `<source>` children are handled too, since a video with multiple
639 + * formats carries no `src` of its own.
640 + *
641 + * Marked with a data attribute rather than a class so a theme's CSS
642 + * cannot accidentally select — or style away — the deferred state.
643 + */
644 + private static function defer_autoplay_source( string $tag ): string {
645 + // Already processed (a second pass, or another plugin got there).
646 + if ( false !== stripos( $tag, 'data-xspeed-src' ) ) {
647 + return $tag;
648 + }
649 +
650 + $deferred = false;
651 +
652 + // The element's own src, when it has one.
653 + if ( preg_match( '#\bsrc\s*=\s*(["\'])(.*?)\1#i', $tag, $m ) && '' !== trim( $m[2] ) ) {
654 + $tag = (string) preg_replace(
655 + '#\bsrc\s*=\s*(["\'])(.*?)\1#i',
656 + 'data-xspeed-src="' . esc_attr( $m[2] ) . '"',
657 + $tag,
658 + 1
659 + );
660 + $deferred = true;
661 + }
662 +
663 + if ( ! $deferred ) {
664 + // No src of its own — the <source> children carry it, and those
665 + // are outside this opening tag. Mark the element so the script
666 + // knows to move them, and let it do the work in the DOM where
667 + // the children are actually reachable.
668 + $tag = self::set_attr( $tag, 'data-xspeed-defer-sources', '1' );
669 + }
670 +
671 + // Without this the browser starts fetching the moment a source is
672 + // restored, which is what we want — but it must not autoplay before
673 + // then, and it must not report itself as autoplaying meanwhile.
674 + $tag = (string) preg_replace( '#\sautoplay(?=[\s/>=])#i', ' data-xspeed-autoplay="1"', $tag, 1 );
675 +
676 + // preload="none" as well: belt and braces for the window between
677 + // parse and the observer attaching.
678 + $tag = self::set_attr( $tag, 'preload', 'none' );
679 +
680 + self::$deferred_autoplay = true;
681 +
682 + return $tag;
683 + }
684 +
685 + /**
686 + * Did this response defer at least one autoplay video? Gates the script
687 + * so a page with no such video ships no extra bytes.
688 + *
689 + * @var bool
690 + */
691 + private static $deferred_autoplay = false;
692 +
693 + /** Whether the viewport script needs to be injected into this response. */
694 + public static function needs_autoplay_script(): bool {
695 + return self::$deferred_autoplay || self::$has_deferred_video_markup;
696 + }
697 +
698 + /**
699 + * Page-builder video blocks that render NO <video> tag server-side.
700 + *
701 + * Essential Blocks' advanced-video, and widgets shaped like it, ship a
702 + * plain <div> carrying the file URL in an attribute and let their own JS
703 + * build the player after load. The PHP pass cannot rewrite what is not
704 + * there, so a page of nine such blocks was completely untouched — which
705 + * is exactly the 44 MB case this feature exists for.
706 + *
707 + * We deliberately do NOT rewrite those attributes. They belong to
708 + * another plugin, whose script reads them on init; renaming one is how
709 + * you get a player that silently never appears. Instead we note that
710 + * such markup is present so the restorer ships, and let its
711 + * MutationObserver catch the <video> the block creates — at which point
712 + * it is an ordinary element we can defer like any other.
713 + *
714 + * @var bool
715 + */
716 + private static $has_deferred_video_markup = false;
717 +
718 + /**
719 + * Does this HTML carry a video URL in an attribute rather than a tag?
720 + *
721 + * Matched on the URL, not on any one plugin's attribute name: `data-url`
722 + * is Essential Blocks, but `data-src`, `data-video-url` and others are
723 + * equally common, and a rule keyed to one vendor would miss the rest.
724 + */
725 + private static function detect_attribute_video( string $html ): void {
726 + if ( self::$has_deferred_video_markup ) {
727 + return;
728 + }
729 + if ( preg_match( '#\sdata-[\w-]+\s*=\s*(["\'])[^"\']*\.(?:mp4|webm|m4v|ogv|mov)(?:\?[^"\']*)?\1#i', $html ) ) {
730 + self::$has_deferred_video_markup = true;
731 + }
732 + }
733 +
734 + /**
735 + * Restore the source when the video reaches the viewport.
736 + *
737 + * Dependency-free and tiny, matching Video_Facade::facade_script(). The
738 + * rootMargin starts the fetch slightly before the element is visible so
739 + * playback begins without a visible stall.
740 + */
741 + public static function autoplay_script(): string {
742 + return <<<'JS'
743 +(function(){
744 +var S='video[data-xspeed-src],video[data-xspeed-defer-sources]';
745 +
746 +/*
747 + * Intercept the ASSIGNMENT, because observing the DOM is always too late.
748 + *
749 + * Measured on a live page: a builder's video player creates nine elements
750 + * and sets `src` BEFORE inserting them, so a MutationObserver watching for
751 + * insertions saw zero of them — and the browser had already begun fetching
752 + * by the time any observer could run. The order is: setAttribute('src'),
753 + * then setAttribute('preload','auto'), then insert. Only the first of those
754 + * matters, and it happens off-DOM.
755 + *
756 + * So wrap the two ways a source can be set on a media element and hold the
757 + * value instead of applying it. Nothing else can start a download: a
758 + * <video> with no resolvable source fetches nothing. The value is stored on
759 + * the element and handed back by go() when it reaches the viewport.
760 + *
761 + * Scoped to <video> only. <audio> is small and usually deliberate, and
762 + * touching it would change behaviour nobody complained about.
763 + */
764 +try{
765 +var VP=window.HTMLMediaElement&&HTMLMediaElement.prototype;
766 +var SD=VP&&Object.getOwnPropertyDescriptor(VP,'src');
767 +var hold=function(el,val){
768 +if(el.tagName!=='VIDEO')return false;
769 +if(el.getAttribute('data-xspeed-loaded'))return false; // released: let it through
770 +if(!val)return false;
771 +el.setAttribute('data-xspeed-src',String(val));
772 +el.setAttribute('data-xspeed-adopted','1');
773 +return true;
774 +};
775 +if(SD&&SD.set){
776 +Object.defineProperty(VP,'src',{configurable:true,enumerable:SD.enumerable,
777 +get:function(){return SD.get.call(this);},
778 +set:function(v){if(hold(this,v))return;return SD.set.call(this,v);}});
779 +}
780 +var SA=Element.prototype.setAttribute;
781 +Element.prototype.setAttribute=function(n,v){
782 +if(n==='src'&&hold(this,v))return;
783 +// An eager preload on a held video would re-arm the fetch the moment a
784 +// source comes back; keep it at none until we release it deliberately.
785 +if(n==='preload'&&this.tagName==='VIDEO'&&this.getAttribute('data-xspeed-src')&&v!=='none')
786 +return SA.call(this,'preload','none');
787 +return SA.call(this,n,v);
788 +};
789 +}catch(e){}
790 +function go(v){
791 +if(v.getAttribute('data-xspeed-loaded'))return;
792 +v.setAttribute('data-xspeed-loaded','1');
793 +var s=v.getAttribute('data-xspeed-src');
794 +if(s){v.setAttribute('src',s);v.removeAttribute('data-xspeed-src');}
795 +if(v.getAttribute('data-xspeed-defer-sources')){
796 +var c=v.querySelectorAll('source[data-xspeed-src]');
797 +for(var i=0;i<c.length;i++){c[i].setAttribute('src',c[i].getAttribute('data-xspeed-src'));c[i].removeAttribute('data-xspeed-src');}
798 +v.removeAttribute('data-xspeed-defer-sources');
799 +}
800 +
801 +if(v.getAttribute('data-xspeed-autoplay')){v.setAttribute('autoplay','');v.removeAttribute('data-xspeed-autoplay');}
802 +v.removeAttribute('preload');
803 +// load() picks up the sources we just restored; without it a <video>
804 +// that has already failed to resolve a source will not retry.
805 +if(v.load)v.load();
806 +}
807 +// A multi-format <video> carries no src of its own — the <source> children
808 +// do, and those sit outside the opening tag PHP rewrote. Strip them here,
809 +// as early as this script runs, then restore on intersect like the rest.
810 +function strip(){
811 +var d=document.querySelectorAll('video[data-xspeed-defer-sources]');
812 +for(var i=0;i<d.length;i++){
813 +if(d[i].getAttribute('data-xspeed-loaded'))continue;
814 +var c=d[i].querySelectorAll('source[src]');
815 +for(var j=0;j<c.length;j++){c[j].setAttribute('data-xspeed-src',c[j].getAttribute('src'));c[j].removeAttribute('src');}
816 +if(c.length&&d[i].load)d[i].load();
817 +}
818 +}
819 +// A page-builder block builds its <video> after load, so PHP never saw it
820 +// and it arrives with a live src and autoplay already set. Defer it here,
821 +// the same way the server would have, BEFORE the browser gets far into
822 +// fetching it. Only autoplay videos: anything else is already covered by
823 +// preload="none" and taking a source from a user-controlled player would
824 +// break its own play button.
825 +function adopt(){
826 +// Any JS-built <video> that would fetch on sight — NOT just autoplay.
827 +// Measured on a live page: a builder's video block creates nine elements
828 +// with autoplay=false and preload="auto", so an autoplay-only selector
829 +// skipped every one of them and 40 MB still downloaded. preload="auto" is
830 +// the same eager-fetch instruction by another name, and the server pass
831 +// would have rewritten it to "none" had the element existed in the HTML.
832 +var a=document.querySelectorAll('video[autoplay]:not([data-xspeed-loaded]):not([data-xspeed-adopted]),video[preload="auto"]:not([data-xspeed-loaded]):not([data-xspeed-adopted]),video[preload="metadata"]:not([data-xspeed-loaded]):not([data-xspeed-adopted])');
833 +for(var i=0;i<a.length;i++){
834 +var v=a[i];
835 +v.setAttribute('data-xspeed-adopted','1');
836 +var auto=v.hasAttribute('autoplay');
837 +var s=v.getAttribute('src');
838 +if(s){v.setAttribute('data-xspeed-src',s);v.removeAttribute('src');}
839 +var c=v.querySelectorAll('source[src]');
840 +for(var j=0;j<c.length;j++){c[j].setAttribute('data-xspeed-src',c[j].getAttribute('src'));c[j].removeAttribute('src');}
841 +if(c.length)v.setAttribute('data-xspeed-defer-sources','1');
842 +// Only remember autoplay for the ones that actually had it — restoring it
843 +// on a video the author left click-to-play would start playback nobody
844 +// asked for.
845 +if(auto){v.removeAttribute('autoplay');v.setAttribute('data-xspeed-autoplay','1');}
846 +v.setAttribute('preload','none');
847 +if(v.load)v.load();
848 +}
849 +}
850 +function scan(){
851 +strip();
852 +adopt();
853 +var v=document.querySelectorAll(S);
854 +if(!('IntersectionObserver'in window)){for(var i=0;i<v.length;i++)go(v[i]);return;}
855 +var o=new IntersectionObserver(function(es){
856 +for(var i=0;i<es.length;i++){if(es[i].isIntersecting){go(es[i].target);o.unobserve(es[i].target);}}
857 +},{rootMargin:'200px'});
858 +for(var j=0;j<v.length;j++)o.observe(v[j]);
859 +}
860 +if(document.readyState!=='loading')scan();else document.addEventListener('DOMContentLoaded',scan);
861 +// Players that build their <video> after load (page-builder video blocks)
862 +// must be caught the INSTANT the element lands. A debounce loses the race:
863 +// the browser begins fetching as soon as a src is set, so by the time a
864 +// timer fires the bytes are already committed. adopt() is idempotent and
865 +// cheap (one guarded querySelectorAll), so run it synchronously on every
866 +// mutation and only debounce the fuller scan that attaches observers.
867 +if(window.MutationObserver){
868 +var t;
869 +new MutationObserver(function(){
870 +adopt();
871 +clearTimeout(t);t=setTimeout(scan,200);
872 +}).observe(document.documentElement,{childList:true,subtree:true});
873 +}
874 +})();
875 +JS;
876 + }
877 +
269 878 private static function set_attr( string $tag, string $name, string $value, bool $only_if_missing = false ): string {
270 - $pattern = '#\b' . preg_quote( $name, '#' ) . '\s*=\s*(["\'][^"\']*["\']|\S+)#i';
879 + // Lookbehind, not `\b`: writing `width` onto a tag carrying
880 + // `data-width="800"` matched the DATA attribute and rewrote it to the
881 + // file's intrinsic size — corrupting a slider's own configuration and
882 + // leaving the tag with no real width at all. (#333 review round 3)
883 + $pattern = '#(?<![-\w])' . preg_quote( $name, '#' ) . '\s*=\s*(["\'][^"\']*["\']|\S+)#i';
271 884 if ( preg_match( $pattern, $tag ) ) {
272 885 if ( $only_if_missing ) {
273 886 return $tag;
274 887 }
@@ -288,10 +901,19 @@
288 901 * filesystem when src points at the uploads dir. Skip when we can't
289 902 * resolve cheaply — never block the request on a remote getimagesize.
290 903 */
291 904 private static function ensure_dimensions( string $tag ): string {
292 - $has_w = (bool) preg_match( '#\bwidth\s*=#i', $tag );
293 - $has_h = (bool) preg_match( '#\bheight\s*=#i', $tag );
905 + // `\b` sits between `-` and `w`, so a bare `\bwidth=` also matched
906 + // `data-width=` — a slider's own metadata, not a rendered dimension.
907 + // The tag then looked half-sized: apply_dimensions() derived the other
908 + // dimension from the ratio and wrote ONLY that, so a tag carrying
909 + // `data-width="800"` came out with `height="533"` and no width and
910 + // laid out at 41x30. Harmless while the URL never resolved; this
911 + // branch made it resolve, which is what exposed it. Half a pair is
912 + // worse than none, as the docblock below already says.
913 + // (#333 review round 3, issue 2)
914 + $has_w = (bool) preg_match( '#(?<![-\w])width\s*=#i', $tag );
915 + $has_h = (bool) preg_match( '#(?<![-\w])height\s*=#i', $tag );
294 916 if ( $has_w && $has_h ) {
295 917 return $tag;
296 918 }
297 919
@@ -309,12 +931,15 @@
309 931 // on those images (issue #37). Resolve from the src instead, but only
310 932 // when the tag doesn't already tell us it renders at some other size:
311 933 // stamping the intrinsic file size onto a responsive or CSS-sized
312 934 // image would CREATE the layout shift this feature exists to remove.
313 - if ( ! self::has_constrained_render( $tag ) && preg_match( '#\bsrc\s*=\s*["\']([^"\']+)["\']#i', $tag, $sm ) ) {
314 - $dims = self::dimensions_for_src( $sm[1] );
315 - if ( $dims ) {
316 - return self::apply_dimensions( $tag, $dims, $has_w, $has_h );
935 + if ( ! self::has_constrained_render( $tag ) ) {
936 + $url = self::resolvable_image_url( $tag );
937 + if ( '' !== $url ) {
938 + $dims = self::dimensions_for_src( $url );
939 + if ( $dims ) {
940 + return self::apply_dimensions( $tag, $dims, $has_w, $has_h );
941 + }
317 942 }
318 943 }
319 944
320 945 // Couldn't resolve. Leave the tag alone — better no dimensions
@@ -322,8 +947,201 @@
322 947 return $tag;
323 948 }
324 949
325 950 /**
951 + * The URL to measure an image by: its real `src`, or the lazy-loading
952 + * attribute holding the URL when `src` is absent or a placeholder.
953 + *
954 + * Page-builder sliders (Essential Blocks among them) ship the image with
955 + * NO `src` at all — the URL lives in `data-lazy`, and their own JS moves
956 + * it across at runtime. Resolving only from `src` left every one of those
957 + * images without dimensions (issue #328, the miss that #37 did not cover:
958 + * that one was about the missing `wp-image-N` class, this one is about the
959 + * URL not being in `src` in the first place).
960 + *
961 + * A placeholder `src` — a data: URI or the 1x1 spacer GIF these libraries
962 + * use — is treated as absent: measuring it would stamp the spacer's size
963 + * onto the tag and CREATE a layout shift.
964 + *
965 + * Note the explicit `(?<![-\w])src` boundary. `\bsrc=` also matches the
966 + * tail of `data-src=` and `data-lazy-src=` (a hyphen is a non-word
967 + * character, so `\b` sits between `-` and `s`), which is why those two
968 + * attributes happened to work before this method existed while `data-lazy`
969 + * and `data-original` did not. Relying on that accident meant the URL a
970 + * tag was measured by depended on how its attribute was spelled.
971 + *
972 + * Pure — unit-tested — EXCEPT when `$may_measure` is true and every
973 + * candidate was refused by name, which is the one branch that touches the
974 + * filesystem. Callers that are themselves arranging a measurement pass
975 + * false; see the note at that branch.
976 + *
977 + * @param string $tag The <img> tag.
978 + * @param bool $may_measure Whether a name-refused URL may be settled by
979 + * reading the file. False for the warm-up
980 + * collector, which would otherwise deadlock.
981 + */
982 + public static function resolvable_image_url( string $tag, bool $may_measure = true ): string {
983 + $src = '';
984 + $named_out = '';
985 + if ( preg_match( '#(?<![-\w])src\s*=\s*["\']([^"\']+)["\']#i', $tag, $m ) ) {
986 + $src = trim( $m[1] );
987 + if ( '' !== $src && ! self::is_placeholder_src( $src ) ) {
988 + return $src;
989 + }
990 + }
991 +
992 + foreach ( array( 'data-lazy', 'data-src', 'data-lazy-src', 'data-original' ) as $attr ) {
993 + // Anchor with a negative lookbehind, not `\b` and not
994 + // whitespace. `\b` sits between `-` and `d`, so a bare
995 + // `\bdata-src=` also matched the TAIL of `x-data-src=` and took
996 + // the wrong image's URL — worse than no size, because it reserves
997 + // a wrongly shaped box and CAUSES the shift.
998 + //
999 + // Requiring whitespace instead was my first fix and it was wrong:
1000 + // attributes are not always separated by one (`alt="31"srcset=`
1001 + // is valid), so that anchor silently stopped matching and handed
1002 + // back a size for a tag the guard should have skipped. The
1003 + // lookbehind rejects the same prefixed decoys without depending on
1004 + // spacing, and is what `src` already uses two methods below.
1005 + // (#333 review rounds 2 and 3, issue 1)
1006 + if ( preg_match( '#(?<![-\w])' . preg_quote( $attr, '#' ) . '\s*=\s*["\']([^"\']+)["\']#i', $tag, $m ) ) {
1007 + $url = trim( $m[1] );
1008 + if ( '' === $url ) {
1009 + continue;
1010 + }
1011 + if ( ! self::is_placeholder_src( $url ) ) {
1012 + return $url;
1013 + }
1014 + // Refused on its NAME. Remember it — if nothing else in the
1015 + // tag resolves, the file itself gets the final say below.
1016 + if ( '' === $named_out ) {
1017 + $named_out = $url;
1018 + }
1019 + }
1020 + }
1021 +
1022 + // Every candidate was refused on its NAME alone. A name is a guess;
1023 + // the file is the fact. Someone who uploads a photograph called
1024 + // `placeholder.jpg` — an entirely ordinary thing to find in a media
1025 + // library — got no dimensions at all, and neither did any of the
1026 + // copies WordPress generates from it, so the layout shift this
1027 + // feature removes came straight back for those images with nothing on
1028 + // screen to explain why. (#333 review round 2, issue 1)
1029 + //
1030 + // Only reached when nothing else in the tag resolved, so the cost is a
1031 + // lookup that was about to be skipped entirely, never an extra one.
1032 + // A genuine stand-in fails this test on its own merits: a data: URI
1033 + // never gets here, and a 1x1 spacer measures 1x1.
1034 + //
1035 + // The lazy attribute is preferred over `src`, matching the order
1036 + // above: when a tag carries both, the lazy one names the real image
1037 + // and `src` holds the stand-in.
1038 + // The warm-up collector passes false here, and must. Deciding this by
1039 + // MEASURING is circular for the caller whose whole job is to arrange
1040 + // the measurement: remote lookups are gated off until `$warming` is
1041 + // true, `$warming` only becomes true inside warm_dimensions(), and
1042 + // warm_dimensions() is never reached because this returned ''. A
1043 + // remote `placeholder.jpg` — a real photograph on a CDN — was warmable
1044 + // before this branch and stopped being, with a failure cached against
1045 + // it for good measure. The collector takes the URL the tag offers and
1046 + // lets warm_dimensions() be the thing that decides.
1047 + // (#333 review round 3, issue 3)
1048 + if ( ! $may_measure ) {
1049 + return '' !== $named_out ? $named_out : $src;
1050 + }
1051 +
1052 + foreach ( array( $named_out, $src ) as $candidate ) {
1053 + if ( '' !== $candidate && self::is_real_image( $candidate ) ) {
1054 + return $candidate;
1055 + }
1056 + }
1057 +
1058 + return '';
1059 + }
1060 +
1061 + /**
1062 + * Does this URL resolve to something too big to be a lazy-load stand-in?
1063 + *
1064 + * The stand-ins this guards against are 1x1 spacers and inline data: URIs.
1065 + * Anything with real extent is a real image, whatever it is called — which
1066 + * is what lets a photograph named `placeholder.jpg` keep its dimensions
1067 + * while `spacer.gif` still loses them.
1068 + *
1069 + * Deliberately conservative: an unresolvable URL returns false, so the
1070 + * name-based verdict stands and the tag is left alone. Better no
1071 + * dimensions than wrong ones. Uses the same resolver (and therefore the
1072 + * same cache) as the normal path, so this costs no extra lookup.
1073 + */
1074 + private static function is_real_image( string $src ): bool {
1075 + $dims = self::dimensions_for_src( $src );
1076 + if ( ! is_array( $dims ) ) {
1077 + return false;
1078 + }
1079 + // Indexed [ width, height ] — the shape apply_dimensions() consumes.
1080 + $w = isset( $dims[0] ) ? (int) $dims[0] : 0;
1081 + $h = isset( $dims[1] ) ? (int) $dims[1] : 0;
1082 +
1083 + // A few pixels either way is still a spacer — some libraries ship a
1084 + // 2x2 or 4x4 rather than a true 1x1. Anything above that has extent a
1085 + // stand-in does not.
1086 + return $w > 4 && $h > 4;
1087 + }
1088 +
1089 + /**
1090 + * True for the stand-in a lazy-loader parks in `src` until its JS swaps
1091 + * the real URL in: an inline data: URI, or a `spacer`/`blank`/`placeholder`
1092 + * asset. Measuring one of these would stamp the spacer's dimensions onto
1093 + * the tag. Pure — unit-tested.
1094 + *
1095 + * Matched on the WHOLE filename stem, not a word inside it. A word-boundary
1096 + * search anywhere in the last segment caught every real image whose name
1097 + * merely contains one of these ordinary words — `blank-space-cover.png`,
1098 + * `placeholder-portrait.png`, `spacer-hero-banner.jpg` — and silently
1099 + * stopped sizing them, which brings back the very layout shift this
1100 + * feature exists to prevent, with nothing on screen to explain it
1101 + * (#333 review, issue 1).
1102 + *
1103 + * A real stand-in is named for what it is and nothing else: `blank.gif`,
1104 + * `spacer.png`, `lazy-loader.svg`, optionally with a dimension or version
1105 + * suffix (`blank-1x1.gif`, `[email protected]`). A descriptive tail is what
1106 + * separates a photograph from a spacer, so the tail is what decides.
1107 + */
1108 + public static function is_placeholder_src( string $src ): bool {
1109 + if ( 0 === stripos( $src, 'data:' ) ) {
1110 + return true;
1111 + }
1112 +
1113 + // Last path segment, without the query string or fragment —
1114 + // `?v=placeholder` is a cache-buster on a real image, not a name.
1115 + // Plain string work on purpose: this method is pure and unit-tested
1116 + // with no WordPress loaded, so wp_parse_url() is not available.
1117 + $path = strtok( $src, '?#' );
1118 + if ( ! is_string( $path ) || '' === $path ) {
1119 + $path = $src;
1120 + }
1121 + $name = strtolower( basename( $path ) );
1122 +
1123 + // Drop the extension, then any trailing dimension/DPR/version marker.
1124 + $stem = preg_replace( '#\.[a-z0-9]+$#', '', $name );
1125 + $stem = (string) preg_replace( '#[-_@]?(?:\d+x\d+|\d+x|x\d+|v\d+|\d+)$#', '', (string) $stem );
1126 + $stem = trim( $stem, '-_.' );
1127 +
1128 + return 1 === preg_match( '#^(?:spacer|blank|placeholder|lazy-?loader|transparent|pixel|dummy)$#', $stem );
1129 + }
1130 +
1131 + /**
1132 + * True when the tag already declares itself the LCP image via
1133 + * `fetchpriority="high"`.
1134 + *
1135 + * Only "high" counts. `fetchpriority="low"` and `="auto"` say the opposite
1136 + * (or nothing), and an image marked low-priority is a perfectly good
1137 + * lazy-load candidate. Pure — unit-tested.
1138 + */
1139 + public static function has_high_fetchpriority( string $tag ): bool {
1140 + return 1 === preg_match( '#\bfetchpriority\s*=\s*["\']?high\b#i', $tag );
1141 + }
1142 +
1143 + /**
326 1144 * True when the tag says it renders at a size other than the file's
327 1145 * intrinsic one — a `srcset`/`sizes` pair (the browser picks a
328 1146 * candidate) or an inline width/height style.
329 1147 *
@@ -332,9 +1150,22 @@
332 1150 * own `wp_filter_content_tags()` adds dimensions to responsive
333 1151 * images the same way. Pure — unit-tested.
334 1152 */
335 1153 public static function has_constrained_render( string $tag ): bool {
336 - if ( preg_match( '#\bsrcset\s*=#i', $tag ) || preg_match( '#\bsizes\s*=#i', $tag ) ) {
1154 + // `\b` sits between `-` and `s`, so a bare \bsrcset also matched
1155 + // `data-srcset` — a lazy attribute the browser has NOT applied yet.
1156 + // That made an unset attribute suppress dimensions on exactly the
1157 + // slider images this feature exists to size, for the same
1158 + // accidental-text-match reason the URL lookup moved away from
1159 + // (#333 review, issue 3).
1160 + //
1161 + // The anchor is a negative lookbehind rather than "start or
1162 + // whitespace": HTML does not require a space between attributes, so
1163 + // `alt="31"srcset="..."` slipped past a whitespace anchor and this
1164 + // guard stopped firing — the tag then got the file's intrinsic size
1165 + // stamped on it while the browser rendered a differently-shaped
1166 + // srcset candidate. (#333 review round 3, issue 1)
1167 + if ( preg_match( '#(?<![-\w])(?:srcset|sizes)\s*=#i', $tag ) ) {
337 1168 return true;
338 1169 }
339 1170 if ( preg_match( '#\bstyle\s*=\s*["\']([^"\']*)["\']#i', $tag, $m ) ) {
340 1171 // width/height in the inline style wins over the attribute, so
@@ -345,8 +1176,44 @@
345 1176 }
346 1177
347 1178 /** @param int[] $dims [width, height]. */
348 1179 private static function apply_dimensions( string $tag, array $dims, bool $has_w, bool $has_h ): string {
1180 + // One dimension already present: derive the other from the file's
1181 + // real aspect ratio rather than stamping its intrinsic size.
1182 + //
1183 + // A tag that says width="300" on a 1200x800 file renders 300x200. If
1184 + // we wrote height="800" the browser would reserve a box two and a
1185 + // half times too tall, then snap when the image painted — CREATING
1186 + // the shift this feature exists to remove. Scaling keeps the reserved
1187 + // box the shape the image will actually be.
1188 + if ( $has_w !== $has_h ) {
1189 + if ( $dims[0] <= 0 || $dims[1] <= 0 ) {
1190 + return $tag;
1191 + }
1192 + $from = $has_w ? 'width' : 'height';
1193 + $declared = self::attr_int( $tag, $from );
1194 + // A declared value we cannot read in pixels (`50%`, `auto`) means
1195 + // we do not know the rendered size, so there is no ratio to scale
1196 + // from. Stamping the intrinsic size here is exactly the bug this
1197 + // branch exists to avoid, so the tag is left alone.
1198 + if ( $declared <= 0 ) {
1199 + return $tag;
1200 + }
1201 + if ( $has_w ) {
1202 + $height = (int) round( $dims[1] * $declared / $dims[0] );
1203 + return $height > 0 ? self::set_attr( $tag, 'height', (string) $height ) : $tag;
1204 + }
1205 + $width = (int) round( $dims[0] * $declared / $dims[1] );
1206 + return $width > 0 ? self::set_attr( $tag, 'width', (string) $width ) : $tag;
1207 + }
1208 +
1209 + // A header that reported 0 for either side is not a measurement. Half
1210 + // a dimension pair is worse than none: the browser reserves a box of
1211 + // the wrong shape and still shifts when the real image lands.
1212 + if ( $dims[0] <= 0 || $dims[1] <= 0 ) {
1213 + return $tag;
1214 + }
1215 +
349 1216 if ( ! $has_w ) {
350 1217 $tag = self::set_attr( $tag, 'width', (string) $dims[0] );
351 1218 }
352 1219 if ( ! $has_h ) {
@@ -355,8 +1222,32 @@
355 1222 return $tag;
356 1223 }
357 1224
358 1225 /**
1226 + * Read one numeric attribute off a tag.
1227 + *
1228 + * Returns 0 for anything that is not a plain number — `width="50%"` and
1229 + * `width="auto"` are CSS-ish values whose pixel size we do not know, and
1230 + * scaling from them would invent a box rather than reserve one.
1231 + *
1232 + * @param string $tag The tag.
1233 + * @param string $name Attribute name.
1234 + */
1235 + private static function attr_int( string $tag, string $name ): int {
1236 + // The value must be ENTIRELY digits. Matching a leading run would read
1237 + // `width="50%"` as 50 and scale from a percentage as though it were
1238 + // pixels — inventing a box rather than declining to guess.
1239 + // Lookbehind for the same reason as set_attr(): `\bwidth=` also reads
1240 + // `data-width=`, so a slider's own metadata was scaled from as though
1241 + // it were a rendered dimension.
1242 + if ( ! preg_match( '#(?<![-\w])' . preg_quote( $name, '#' ) . '\s*=\s*(?:"(\d+)"|\'(\d+)\'|(\d+)(?=[\s/>]))#i', $tag, $m ) ) {
1243 + return 0;
1244 + }
1245 + $value = '' !== ( $m[1] ?? '' ) ? $m[1] : ( '' !== ( $m[2] ?? '' ) ? $m[2] : ( $m[3] ?? '' ) );
1246 + return (int) $value;
1247 + }
1248 +
1249 + /**
359 1250 * WordPress names resized files `<name>-WxH.<ext>` — when the suffix is
360 1251 * present it IS the rendered size, resolvable with zero I/O (works for
361 1252 * CDN-hosted copies too). Pure — unit-tested.
362 1253 *
@@ -374,8 +1265,105 @@
374 1265 return null;
375 1266 }
376 1267
377 1268 /**
1269 + * Intrinsic size of an image hosted on another domain.
1270 + *
1271 + * An image the site does not host is still an image whose dimensions
1272 + * decide whether the page jumps while it loads. Refusing to look them up
1273 + * was leaving real layout shift unfixed on any site that embeds media from
1274 + * a CDN, a sister site, or a shared asset host — and telling the owner to
1275 + * go and edit their content, which is not a fix a caching plugin should be
1276 + * proud of.
1277 + *
1278 + * The reason for the old refusal was sound but too broad: a page render
1279 + * must never block on somebody else's server. So this fetches only the
1280 + * first few KB — enough for the header of every format WordPress
1281 + * supports — with a short timeout, and caches the answer (successes AND
1282 + * failures) so a URL is fetched once rather than once per pageview.
1283 + *
1284 + * By default it runs only when something has already warmed the cache
1285 + * off-request (the preloader, a cron pass, WP-CLI). A visitor's request
1286 + * therefore never waits on it. A site that would rather pay the cost
1287 + * inline can opt in:
1288 + *
1289 + * add_filter( 'xspeed_lazy_remote_dimensions_inline', '__return_true' );
1290 + *
1291 + * and one that wants nothing fetched from other hosts at all can opt out:
1292 + *
1293 + * add_filter( 'xspeed_lazy_remote_dimensions', '__return_false' );
1294 + *
1295 + * @param string $src Absolute URL on another host.
1296 + * @return int[]|null [width, height] or null when it cannot be resolved.
1297 + */
1298 + private static function remote_dimensions( string $src ): ?array {
1299 + /**
1300 + * Whether to resolve dimensions for images on other hosts at all.
1301 + *
1302 + * @param bool $enabled Default true.
1303 + * @param string $src The image URL.
1304 + */
1305 + if ( ! apply_filters( 'xspeed_lazy_remote_dimensions', true, $src ) ) {
1306 + return null;
1307 + }
1308 +
1309 + if ( ! function_exists( 'wp_remote_get' ) ) {
1310 + return null;
1311 + }
1312 +
1313 + // Only http(s). A data: or blob: src has no server to ask.
1314 + if ( ! preg_match( '#^https?://#i', $src ) ) {
1315 + return null;
1316 + }
1317 +
1318 + /**
1319 + * Whether a front-end request may perform the fetch itself.
1320 + *
1321 + * Off by default: the whole point of the cache is that a visitor
1322 + * never waits on another host. Warm passes (cron, preloader, CLI)
1323 + * set this true for themselves.
1324 + *
1325 + * @param bool $inline Default false.
1326 + */
1327 + $inline = (bool) apply_filters( 'xspeed_lazy_remote_dimensions_inline', self::$warming );
1328 + if ( ! $inline ) {
1329 + return null;
1330 + }
1331 +
1332 + // 32KB covers the header of JPEG, PNG, GIF, WebP and AVIF. Range is a
1333 + // request, not a guarantee — a server that ignores it sends the whole
1334 + // file, which the timeout still bounds.
1335 + $resp = wp_remote_get(
1336 + $src,
1337 + array(
1338 + 'timeout' => 5,
1339 + 'headers' => array( 'Range' => 'bytes=0-32767' ),
1340 + 'user-agent' => 'xSpeed/dimension-probe',
1341 + )
1342 + );
1343 + if ( is_wp_error( $resp ) ) {
1344 + return null;
1345 + }
1346 + $code = (int) wp_remote_retrieve_response_code( $resp );
1347 + if ( 200 !== $code && 206 !== $code ) {
1348 + return null;
1349 + }
1350 +
1351 + $body = (string) wp_remote_retrieve_body( $resp );
1352 + if ( '' === $body ) {
1353 + return null;
1354 + }
1355 +
1356 + // getimagesizefromstring reads the header out of the bytes we already
1357 + // have — no second request, no temp file.
1358 + $size = @getimagesizefromstring( $body ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- a truncated or non-image body must degrade to null, not warn.
1359 + if ( is_array( $size ) && ! empty( $size[0] ) && ! empty( $size[1] ) ) {
1360 + return array( (int) $size[0], (int) $size[1] );
1361 + }
1362 + return null;
1363 + }
1364 +
1365 + /**
378 1366 * Resolve dimensions from an image URL, cheapest first:
379 1367 * 1. `-WxH` filename suffix (no I/O).
380 1368 * 2. Intrinsic size of the local file when src is under uploads
381 1369 * (getimagesize on the header — no remote fetches, ever).
@@ -396,12 +1384,12 @@
396 1384 }
397 1385 $uploads = wp_get_upload_dir();
398 1386 $baseurl = isset( $uploads['baseurl'] ) ? (string) $uploads['baseurl'] : '';
399 1387 $basedir = isset( $uploads['basedir'] ) ? (string) $uploads['basedir'] : '';
400 - if ( '' === $baseurl || '' === $basedir || 0 !== strpos( $src, $baseurl ) ) {
401 - return null; // External image — never fetch remotely for a size.
402 - }
403 1388
1389 + // The cache is consulted BEFORE the local/remote split, so a remote
1390 + // image pays its lookup once for the life of the transient rather
1391 + // than once per page render.
404 1392 if ( null === self::$src_dims_cache ) {
405 1393 $stored = get_transient( 'xspeed_img_dims' );
406 1394 self::$src_dims_cache = is_array( $stored ) ? $stored : array();
407 1395 }
@@ -407,29 +1395,52 @@
407 1395 }
408 1396 $key = md5( $src );
409 1397 if ( array_key_exists( $key, self::$src_dims_cache ) ) {
410 1398 $hit = self::$src_dims_cache[ $key ];
411 - return is_array( $hit ) ? $hit : null; // 0 = cached failure.
1399 + if ( is_array( $hit ) ) {
1400 + return $hit;
1401 + }
1402 + // A cached FAILURE, not a cached answer. A front-end render
1403 + // honours it — that is the whole point, one failed lookup must
1404 + // not cost a request on every pageview. A warm pass does NOT:
1405 + // it was asked to resolve these, nothing is waiting on it, and
1406 + // the usual reason for a failure is a moment of bad luck rather
1407 + // than an image that can never be measured.
1408 + //
1409 + // Without this, one slow response poisoned a URL for the life of
1410 + // the transient. It happened on a real site: 15 images cached as
1411 + // failures, and every later warm returned "resolved: 0" while the
1412 + // page kept shifting.
1413 + if ( ! self::$warming || ! self::failure_is_retryable( $hit ) ) {
1414 + return null;
1415 + }
412 1416 }
413 1417
414 - $dims = null;
415 - $relative = (string) preg_replace( '/[?#].*$/', '', substr( $src, strlen( $baseurl ) ) );
416 - if ( false === strpos( $relative, '..' ) ) {
417 - $file = $basedir . $relative;
418 - if ( is_file( $file ) ) {
419 - $size = @getimagesize( $file ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- non-image/corrupt file must degrade to null, not warn.
420 - if ( is_array( $size ) && ! empty( $size[0] ) && ! empty( $size[1] ) ) {
421 - $dims = array( (int) $size[0], (int) $size[1] );
1418 + $is_local = '' !== $baseurl && '' !== $basedir && 0 === strpos( $src, $baseurl );
1419 +
1420 + $dims = null;
1421 +
1422 + if ( $is_local ) {
1423 + $relative = (string) preg_replace( '/[?#].*$/', '', substr( $src, strlen( $baseurl ) ) );
1424 + if ( false === strpos( $relative, '..' ) ) {
1425 + $file = $basedir . $relative;
1426 + if ( is_file( $file ) ) {
1427 + $size = @getimagesize( $file ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- non-image/corrupt file must degrade to null, not warn.
1428 + if ( is_array( $size ) && ! empty( $size[0] ) && ! empty( $size[1] ) ) {
1429 + $dims = array( (int) $size[0], (int) $size[1] );
1430 + }
422 1431 }
423 1432 }
424 - }
425 1433
426 - // File not on disk (offloaded originals) — one DB lookup by URL.
427 - if ( null === $dims && function_exists( 'attachment_url_to_postid' ) ) {
428 - $id = (int) attachment_url_to_postid( $src );
429 - if ( $id > 0 ) {
430 - $dims = self::dimensions_for_attachment( $id );
1434 + // File not on disk (offloaded originals) — one DB lookup by URL.
1435 + if ( null === $dims && function_exists( 'attachment_url_to_postid' ) ) {
1436 + $id = (int) attachment_url_to_postid( $src );
1437 + if ( $id > 0 ) {
1438 + $dims = self::dimensions_for_attachment( $id );
1439 + }
431 1440 }
1441 + } else {
1442 + $dims = self::remote_dimensions( $src );
432 1443 }
433 1444
434 1445 // Cache success AND failure (0), bounded so the blob can't grow
435 1446 // unbounded on media-heavy sites.
@@ -435,9 +1446,14 @@
435 1446 // unbounded on media-heavy sites.
436 1447 if ( count( self::$src_dims_cache ) >= 500 ) {
437 1448 self::$src_dims_cache = array_slice( self::$src_dims_cache, 250, null, true );
438 1449 }
439 - self::$src_dims_cache[ $key ] = null === $dims ? 0 : $dims;
1450 + // A resolved size is permanent — the file's intrinsic dimensions do
1451 + // not change under the same URL. A failure is a snapshot of one
1452 + // moment, so it is stored as a TIMESTAMP rather than a bare 0 and
1453 + // stops counting after a while. Storing both the same way is what let
1454 + // a transient blip look identical to "this can never be measured".
1455 + self::$src_dims_cache[ $key ] = null === $dims ? time() : $dims;
440 1456 if ( function_exists( 'set_transient' ) ) {
441 1457 set_transient( 'xspeed_img_dims', self::$src_dims_cache, DAY_IN_SECONDS );
442 1458 }
443 1459 return $dims;
@@ -510,13 +1526,112 @@
510 1526 return self::$opts;
511 1527 }
512 1528
513 1529 /**
1530 + * How long a failed lookup is trusted before a warm pass tries again.
1531 + *
1532 + * Long enough that a genuinely unmeasurable URL is not re-fetched on every
1533 + * crawl, short enough that an outage does not cost a day of layout shift.
1534 + */
1535 + private const FAILURE_RETRY_AFTER = 900; // 15 minutes.
1536 +
1537 + /**
1538 + * Whether a stored failure is old enough to be worth retrying.
1539 + *
1540 + * Legacy entries were written as a bare `0` with no timestamp. Those are
1541 + * always retryable: they predate this distinction, and one extra request
1542 + * for each is a far better outcome than leaving a site permanently unable
1543 + * to resolve images it could resolve today.
1544 + *
1545 + * @param mixed $entry Stored cache value.
1546 + */
1547 + private static function failure_is_retryable( $entry ): bool {
1548 + if ( ! is_int( $entry ) || $entry <= 0 ) {
1549 + return true; // legacy `0`, or nonsense — retry.
1550 + }
1551 + return ( time() - $entry ) >= self::FAILURE_RETRY_AFTER;
1552 + }
1553 +
1554 + /**
1555 + * Whether this URL's dimensions are already known (or known-unresolvable).
1556 + *
1557 + * Lets a caller skip URLs that would cost nothing to look up, so a bounded
1558 + * batch spends its budget on images it has not seen. Without this a capped
1559 + * collector re-picks the same first N images every pass — they are always
1560 + * in the same DOM order — and anything past the cap is never resolved at
1561 + * all, however many times the crawl runs.
1562 + *
1563 + * Reads the cache only; never fetches.
1564 + *
1565 + * @param string $src Absolute image URL.
1566 + */
1567 + public static function dimensions_known( string $src ): bool {
1568 + if ( ! function_exists( 'get_transient' ) ) {
1569 + return false;
1570 + }
1571 + if ( null === self::$src_dims_cache ) {
1572 + $stored = get_transient( 'xspeed_img_dims' );
1573 + self::$src_dims_cache = is_array( $stored ) ? $stored : array();
1574 + }
1575 + $key = md5( $src );
1576 + if ( ! array_key_exists( $key, self::$src_dims_cache ) ) {
1577 + return false;
1578 + }
1579 + $hit = self::$src_dims_cache[ $key ];
1580 + if ( is_array( $hit ) ) {
1581 + return true;
1582 + }
1583 + // A failure that has aged out is NOT known — reporting it as known
1584 + // would make the crawl skip the one URL that has become worth
1585 + // retrying.
1586 + return ! self::failure_is_retryable( $hit );
1587 + }
1588 +
1589 + /**
1590 + * Resolve and cache dimensions for a batch of image URLs.
1591 + *
1592 + * Meant for anything running OFF a visitor's request — the preloader
1593 + * crawling the sitemap, a cron pass, `wp xspeed lazy warm-dimensions`.
1594 + * Once warmed, the front end serves the dimensions from cache, so the
1595 + * layout shift is fixed without a single visitor waiting on another host.
1596 + *
1597 + * @param string[] $urls Absolute image URLs.
1598 + * @return int How many were resolved.
1599 + */
1600 + public static function warm_dimensions( array $urls ): int {
1601 + $resolved = 0;
1602 + self::$warming = true;
1603 + try {
1604 + foreach ( array_unique( $urls ) as $url ) {
1605 + if ( ! is_string( $url ) || '' === $url ) {
1606 + continue;
1607 + }
1608 + if ( self::dimensions_for_src( $url ) ) {
1609 + $resolved++;
1610 + }
1611 + }
1612 + } finally {
1613 + // In a finally so a throw mid-batch cannot leave the flag set and
1614 + // silently turn every later front-end render into a fetcher.
1615 + self::$warming = false;
1616 + }
1617 + return $resolved;
1618 + }
1619 +
1620 + /**
514 1621 * Test-only: clear cached opts + counter between assertions.
515 1622 */
516 1623 public static function reset_state(): void {
517 1624 self::$opts = null;
518 1625 self::$image_counter = 0;
1626 + self::$background_counter = 0;
519 1627 self::$src_dims_cache = null;
520 1628 self::$facade_used = false;
1629 + self::$warming = false;
1630 + // Both gate whether the autoplay restorer is printed. Left set, one
1631 + // page carrying a video would make every later response in the same
1632 + // process ship the script — and, worse for the preloader, a warmed
1633 + // page could inherit a decision made for a different URL.
1634 + self::$deferred_autoplay = false;
1635 + self::$has_deferred_video_markup = false;
521 1636 }
522 1637 }