| 1 |
<?php |
| 2 |
/** |
| 3 |
* Lazy_Loader — rewrites img / iframe / video tags in rendered HTML to |
| 4 |
* add native `loading="lazy"` (or "eager" for above-the-fold) plus |
| 5 |
* `decoding="async"` on images. Also auto-adds missing width/height |
| 6 |
* attributes to prevent CLS. |
| 7 |
* |
| 8 |
* Why regex instead of DOMDocument: |
| 9 |
* - DOMDocument forces a full HTML5 parse round trip per filter call; |
| 10 |
* on a content-heavy post that's measurably slow. Regex over the |
| 11 |
* specific tags is ~10× faster. |
| 12 |
* - We don't need full DOM understanding — every rewrite is a tag- |
| 13 |
* local attribute injection. Regex is sufficient + predictable. |
| 14 |
* - Edge cases (img inside HTML comments, img in <script>) are rare |
| 15 |
* in real post content; we leave those alone with a pre-pass that |
| 16 |
* stubs out script / style / pre blocks before rewriting. |
| 17 |
* |
| 18 |
* @package XSpeed |
| 19 |
*/ |
| 20 |
|
| 21 |
declare(strict_types=1); |
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|
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namespace XSpeed; |
| 24 |
|
| 25 |
defined( 'ABSPATH' ) || exit; |
| 26 |
|
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final class Lazy_Loader { |
| 28 |
|
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/** |
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* In-process counter for above-the-fold skipping. Reset by |
| 31 |
* process_html on every call so a fresh post starts at 0. |
| 32 |
* |
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* @var int |
| 34 |
*/ |
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private static $image_counter = 0; |
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|
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/** |
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* Settings cache (one read per request). |
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* |
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* @var array|null |
| 41 |
*/ |
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private static $opts = null; |
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|
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/** |
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* Per-URL dimension cache (md5(src) => [w,h] | 0 for known-failure), |
| 46 |
* hydrated from the `xspeed_img_dims` transient once per request. |
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* |
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* @var array<string,mixed>|null |
| 49 |
*/ |
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private static $src_dims_cache = null; |
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|
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/** |
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* Main entry point: take rendered HTML, return rewritten HTML. |
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* Pure function aside from the static counters. |
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*/ |
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public static function process_html( string $html ): string { |
| 57 |
if ( '' === $html ) { |
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return $html; |
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} |
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$opts = self::opts(); |
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|
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// NOTE: the eager-load budget counter is NOT reset here. process_html |
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// runs once per filter pass — the_content, post_thumbnail_html, and |
| 64 |
// once per get_avatar — so resetting per call let the featured image, |
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// the first content image, AND every comment avatar each claim an |
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// "eager" slot, defeating the budget. The counter is reset once per |
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// page render via reset_state() on template_redirect, so it now |
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// accumulates across all passes as intended. (FBS-82172 Bug 1) |
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|
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// Stub out <script>, <style>, <noscript>, <pre>, <code> blocks |
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// so img tags embedded in them as text examples aren't |
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// rewritten. Restore after pass. |
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[ $work, $stubs ] = self::stub_safe_blocks( $html ); |
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|
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// Tag matcher that respects quoted attribute values, so a ">" inside |
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// an attribute (e.g. alt="a > b") doesn't end the match early and |
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// corrupt the tag. Matches: double-quoted runs, single-quoted runs, |
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// or any non-> char — repeated up to the real closing >. |
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// (FBS-82172 Bug 3) |
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$tag_re = static function ( string $name ): string { |
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return '#<' . $name . '\b(?:"[^"]*"|\'[^\']*\'|[^>"\'])*>#i'; |
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}; |
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|
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if ( ! empty( $opts['lazy_images'] ) || ! empty( $opts['add_missing_dimensions'] ) ) { |
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$work = preg_replace_callback( |
| 86 |
$tag_re( 'img' ), |
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array( __CLASS__, 'rewrite_img' ), |
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$work |
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); |
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} |
| 91 |
if ( ! empty( $opts['lazy_iframes'] ) ) { |
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$work = preg_replace_callback( |
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$tag_re( 'iframe' ), |
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array( __CLASS__, 'rewrite_iframe' ), |
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$work |
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); |
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} |
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if ( ! empty( $opts['lazy_videos'] ) ) { |
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$work = preg_replace_callback( |
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$tag_re( 'video' ), |
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array( __CLASS__, 'rewrite_video' ), |
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$work |
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); |
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} |
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|
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return self::restore_safe_blocks( $work, $stubs ); |
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} |
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|
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private static function rewrite_img( array $m ): string { |
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$tag = $m[0]; |
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$opts = self::opts(); |
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|
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// Explicit skip flag, or matches an exclusion pattern: opt OUT of |
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// LAZY-LOADING only. Dimension injection (CLS protection) still |
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// applies — excluding an above-the-fold hero/logo from lazy-load is |
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// exactly when you most want its width/height kept. Previously both |
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// of these returned early, silently stripping dimensions too. |
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// (FBS-82172 Bug 2) |
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$skip_lazy = false !== stripos( $tag, 'data-skip-lazy' ) |
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|| false !== stripos( $tag, 'data-no-lazy' ) |
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|| self::is_excluded( $tag, $opts ); |
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|
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if ( $skip_lazy && ! empty( $opts['lazy_images'] ) ) { |
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// An EXCLUDED image is one the user marked as above-the-fold (a |
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// hero/logo) — the opposite of lazy. WordPress core adds |
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// `loading="lazy"` to images by default (since 5.5), so merely |
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// *skipping* our lazy pass would leave core's lazy attribute on |
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// the LCP hero and tank LCP. Actively make it eager + |
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// high-priority so an excluded hero loads immediately. |
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$tag = self::set_attr( $tag, 'loading', 'eager' ); |
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$tag = self::set_attr( $tag, 'fetchpriority', 'high', true ); |
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$tag = self::set_attr( $tag, 'decoding', 'async', true ); |
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} elseif ( ! empty( $opts['lazy_images'] ) ) { |
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// Above-the-fold skip: first N images get loading="eager" |
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// instead of "lazy" so the LCP image isn't deferred. Only |
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// non-excluded images consume the budget. |
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self::$image_counter++; |
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$is_above_fold = self::$image_counter <= max( 0, (int) ( $opts['eager_first_n'] ?? 1 ) ); |
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$tag = self::set_attr( $tag, 'loading', $is_above_fold ? 'eager' : 'lazy' ); |
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$tag = self::set_attr( $tag, 'decoding', 'async', true ); |
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// The eager hero should also drop any core `loading="lazy"`; the |
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// set_attr above already overrode it. Give the first eager image |
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// high fetch priority so it wins the LCP race. |
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if ( $is_above_fold ) { |
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$tag = self::set_attr( $tag, 'fetchpriority', 'high', true ); |
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} |
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} |
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|
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if ( ! empty( $opts['add_missing_dimensions'] ) ) { |
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$tag = self::ensure_dimensions( $tag ); |
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} |
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|
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return $tag; |
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} |
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|
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private static function rewrite_iframe( array $m ): string { |
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$tag = $m[0]; |
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if ( false !== stripos( $tag, 'data-skip-lazy' ) ) { |
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return $tag; |
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} |
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if ( self::is_excluded( $tag, self::opts() ) ) { |
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return $tag; |
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} |
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return self::set_attr( $tag, 'loading', 'lazy' ); |
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} |
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|
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private static function rewrite_video( array $m ): string { |
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$tag = $m[0]; |
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if ( false !== stripos( $tag, 'data-skip-lazy' ) ) { |
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return $tag; |
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} |
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// HTML5 `<video>` doesn't support loading=lazy yet (Chromium |
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// won't add it before there's broad support). What we CAN do |
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// is set preload="none" so the browser doesn't pre-fetch the |
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// video bytes until play is requested — that's the actual win |
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// users want from "lazy-load videos". |
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if ( false === stripos( $tag, 'preload=' ) ) { |
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$tag = self::set_attr( $tag, 'preload', 'none' ); |
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} |
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return $tag; |
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} |
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|
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/** |
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* Add an attribute to an opening tag if it isn't already present. |
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* Pass $only_if_missing=false to override an existing value (e.g. |
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* flipping loading="lazy" → "eager" on the first image). |
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*/ |
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private static function set_attr( string $tag, string $name, string $value, bool $only_if_missing = false ): string { |
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$pattern = '#\b' . preg_quote( $name, '#' ) . '\s*=\s*(["\'][^"\']*["\']|\S+)#i'; |
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if ( preg_match( $pattern, $tag ) ) { |
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if ( $only_if_missing ) { |
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return $tag; |
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} |
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return (string) preg_replace( $pattern, $name . '="' . $value . '"', $tag, 1 ); |
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} |
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// Inject before the closing > (preserving self-closing `/>` if present). |
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if ( preg_match( '#(/?>)$#', $tag, $m ) ) { |
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$close = $m[1]; |
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return substr( $tag, 0, -strlen( $close ) ) . ' ' . $name . '="' . $value . '"' . $close; |
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} |
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return $tag; |
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} |
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|
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/** |
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* Attempt to fill in missing width / height from either an attached |
| 206 |
* media library record (when class="wp-image-N") or from the local |
| 207 |
* filesystem when src points at the uploads dir. Skip when we can't |
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* resolve cheaply — never block the request on a remote getimagesize. |
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*/ |
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private static function ensure_dimensions( string $tag ): string { |
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$has_w = (bool) preg_match( '#\bwidth\s*=#i', $tag ); |
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$has_h = (bool) preg_match( '#\bheight\s*=#i', $tag ); |
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if ( $has_w && $has_h ) { |
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return $tag; |
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} |
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|
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// Try wp-image-<id> class first (cheapest path; one DB-cached |
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// get_post_meta call). |
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if ( preg_match( '#\bclass\s*=\s*["\']([^"\']*)["\']#i', $tag, $cm ) && preg_match( '#wp-image-(\d+)#i', $cm[1], $idm ) ) { |
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$dims = self::dimensions_for_attachment( (int) $idm[1] ); |
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if ( $dims ) { |
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return self::apply_dimensions( $tag, $dims, $has_w, $has_h ); |
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} |
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} |
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|
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// No wp-image-N class — page-builder markup (Essential Blocks and |
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// friends) never emits it, which is why the setting silently failed |
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// on those images (issue #37). Resolve from the src instead, but only |
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// when the tag doesn't already tell us it renders at some other size: |
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// stamping the intrinsic file size onto a responsive or CSS-sized |
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// image would CREATE the layout shift this feature exists to remove. |
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if ( ! self::has_constrained_render( $tag ) && preg_match( '#\bsrc\s*=\s*["\']([^"\']+)["\']#i', $tag, $sm ) ) { |
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$dims = self::dimensions_for_src( $sm[1] ); |
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if ( $dims ) { |
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return self::apply_dimensions( $tag, $dims, $has_w, $has_h ); |
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} |
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} |
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|
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// Couldn't resolve. Leave the tag alone — better no dimensions |
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// than wrong ones. |
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return $tag; |
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} |
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|
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/** |
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* True when the tag says it renders at a size other than the file's |
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* intrinsic one — a `srcset`/`sizes` pair (the browser picks a |
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* candidate) or an inline width/height style. |
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* |
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* Only guards the src-suffix fallback. The `wp-image-N` path stays |
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* unguarded: attachment metadata is authoritative, and WordPress' |
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* own `wp_filter_content_tags()` adds dimensions to responsive |
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* images the same way. Pure — unit-tested. |
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*/ |
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public static function has_constrained_render( string $tag ): bool { |
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if ( preg_match( '#\bsrcset\s*=#i', $tag ) || preg_match( '#\bsizes\s*=#i', $tag ) ) { |
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return true; |
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} |
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if ( preg_match( '#\bstyle\s*=\s*["\']([^"\']*)["\']#i', $tag, $m ) ) { |
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// width/height in the inline style wins over the attribute, so |
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// the file's intrinsic size would disagree with the layout. |
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return 1 === preg_match( '#(?:^|;)\s*(?:max-)?(?:width|height)\s*:#i', $m[1] ); |
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} |
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return false; |
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} |
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|
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/** @param int[] $dims [width, height]. */ |
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private static function apply_dimensions( string $tag, array $dims, bool $has_w, bool $has_h ): string { |
| 268 |
if ( ! $has_w ) { |
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$tag = self::set_attr( $tag, 'width', (string) $dims[0] ); |
| 270 |
} |
| 271 |
if ( ! $has_h ) { |
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$tag = self::set_attr( $tag, 'height', (string) $dims[1] ); |
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} |
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return $tag; |
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} |
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|
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/** |
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* WordPress names resized files `<name>-WxH.<ext>` — when the suffix is |
| 279 |
* present it IS the rendered size, resolvable with zero I/O (works for |
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* CDN-hosted copies too). Pure — unit-tested. |
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* |
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* @return int[]|null [width, height] or null. |
| 283 |
*/ |
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public static function parse_size_suffix( string $src ): ?array { |
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$path = (string) preg_replace( '/[?#].*$/', '', $src ); |
| 286 |
if ( preg_match( '#-(\d{1,4})x(\d{1,4})\.(?:jpe?g|png|gif|webp|avif)$#i', $path, $m ) ) { |
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$w = (int) $m[1]; |
| 288 |
$h = (int) $m[2]; |
| 289 |
if ( $w > 0 && $h > 0 ) { |
| 290 |
return array( $w, $h ); |
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} |
| 292 |
} |
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return null; |
| 294 |
} |
| 295 |
|
| 296 |
/** |
| 297 |
* Resolve dimensions from an image URL, cheapest first: |
| 298 |
* 1. `-WxH` filename suffix (no I/O). |
| 299 |
* 2. Intrinsic size of the local file when src is under uploads |
| 300 |
* (getimagesize on the header — no remote fetches, ever). |
| 301 |
* 3. Attachment lookup by URL (uploads-hosted src only). |
| 302 |
* Results — including failures — are cached per URL in a bounded |
| 303 |
* transient so each image pays the lookup once, not per pageview. |
| 304 |
* |
| 305 |
* @return int[]|null [width, height] or null. |
| 306 |
*/ |
| 307 |
private static function dimensions_for_src( string $src ): ?array { |
| 308 |
$suffix = self::parse_size_suffix( $src ); |
| 309 |
if ( $suffix ) { |
| 310 |
return $suffix; |
| 311 |
} |
| 312 |
|
| 313 |
if ( ! function_exists( 'wp_get_upload_dir' ) || ! function_exists( 'get_transient' ) ) { |
| 314 |
return null; |
| 315 |
} |
| 316 |
$uploads = wp_get_upload_dir(); |
| 317 |
$baseurl = isset( $uploads['baseurl'] ) ? (string) $uploads['baseurl'] : ''; |
| 318 |
$basedir = isset( $uploads['basedir'] ) ? (string) $uploads['basedir'] : ''; |
| 319 |
if ( '' === $baseurl || '' === $basedir || 0 !== strpos( $src, $baseurl ) ) { |
| 320 |
return null; // External image — never fetch remotely for a size. |
| 321 |
} |
| 322 |
|
| 323 |
if ( null === self::$src_dims_cache ) { |
| 324 |
$stored = get_transient( 'xspeed_img_dims' ); |
| 325 |
self::$src_dims_cache = is_array( $stored ) ? $stored : array(); |
| 326 |
} |
| 327 |
$key = md5( $src ); |
| 328 |
if ( array_key_exists( $key, self::$src_dims_cache ) ) { |
| 329 |
$hit = self::$src_dims_cache[ $key ]; |
| 330 |
return is_array( $hit ) ? $hit : null; // 0 = cached failure. |
| 331 |
} |
| 332 |
|
| 333 |
$dims = null; |
| 334 |
$relative = (string) preg_replace( '/[?#].*$/', '', substr( $src, strlen( $baseurl ) ) ); |
| 335 |
if ( false === strpos( $relative, '..' ) ) { |
| 336 |
$file = $basedir . $relative; |
| 337 |
if ( is_file( $file ) ) { |
| 338 |
$size = @getimagesize( $file ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- non-image/corrupt file must degrade to null, not warn. |
| 339 |
if ( is_array( $size ) && ! empty( $size[0] ) && ! empty( $size[1] ) ) { |
| 340 |
$dims = array( (int) $size[0], (int) $size[1] ); |
| 341 |
} |
| 342 |
} |
| 343 |
} |
| 344 |
|
| 345 |
// File not on disk (offloaded originals) — one DB lookup by URL. |
| 346 |
if ( null === $dims && function_exists( 'attachment_url_to_postid' ) ) { |
| 347 |
$id = (int) attachment_url_to_postid( $src ); |
| 348 |
if ( $id > 0 ) { |
| 349 |
$dims = self::dimensions_for_attachment( $id ); |
| 350 |
} |
| 351 |
} |
| 352 |
|
| 353 |
// Cache success AND failure (0), bounded so the blob can't grow |
| 354 |
// unbounded on media-heavy sites. |
| 355 |
if ( count( self::$src_dims_cache ) >= 500 ) { |
| 356 |
self::$src_dims_cache = array_slice( self::$src_dims_cache, 250, null, true ); |
| 357 |
} |
| 358 |
self::$src_dims_cache[ $key ] = null === $dims ? 0 : $dims; |
| 359 |
if ( function_exists( 'set_transient' ) ) { |
| 360 |
set_transient( 'xspeed_img_dims', self::$src_dims_cache, DAY_IN_SECONDS ); |
| 361 |
} |
| 362 |
return $dims; |
| 363 |
} |
| 364 |
|
| 365 |
/** |
| 366 |
* @return int[]|null [width, height] or null |
| 367 |
*/ |
| 368 |
private static function dimensions_for_attachment( int $attachment_id ): ?array { |
| 369 |
if ( ! function_exists( 'wp_get_attachment_metadata' ) ) { |
| 370 |
return null; |
| 371 |
} |
| 372 |
$meta = wp_get_attachment_metadata( $attachment_id ); |
| 373 |
if ( ! is_array( $meta ) || empty( $meta['width'] ) || empty( $meta['height'] ) ) { |
| 374 |
return null; |
| 375 |
} |
| 376 |
return array( (int) $meta['width'], (int) $meta['height'] ); |
| 377 |
} |
| 378 |
|
| 379 |
private static function is_excluded( string $tag, array $opts ): bool { |
| 380 |
$excluded = $opts['excluded_images'] ?? array(); |
| 381 |
if ( ! is_array( $excluded ) || empty( $excluded ) ) { |
| 382 |
return false; |
| 383 |
} |
| 384 |
foreach ( $excluded as $pattern ) { |
| 385 |
$pattern = (string) $pattern; |
| 386 |
if ( '' === $pattern ) { |
| 387 |
continue; |
| 388 |
} |
| 389 |
if ( false !== stripos( $tag, $pattern ) ) { |
| 390 |
return true; |
| 391 |
} |
| 392 |
} |
| 393 |
return false; |
| 394 |
} |
| 395 |
|
| 396 |
/** |
| 397 |
* Replace <script>, <style>, <noscript>, <pre>, <code> blocks with |
| 398 |
* placeholder tokens before tag rewriting. Returns [stubbed_html, |
| 399 |
* stubs_map]. Restore via restore_safe_blocks(). |
| 400 |
* |
| 401 |
* @return array{0: string, 1: array<string,string>} |
| 402 |
*/ |
| 403 |
private static function stub_safe_blocks( string $html ): array { |
| 404 |
$stubs = array(); |
| 405 |
$re = '#<(script|style|noscript|pre|code)\b[^>]*>.*?</\1>#is'; |
| 406 |
$out = preg_replace_callback( |
| 407 |
$re, |
| 408 |
static function ( $m ) use ( &$stubs ) { |
| 409 |
$key = '<!--XSPEED_LAZY_STUB_' . count( $stubs ) . '-->'; |
| 410 |
$stubs[ $key ] = $m[0]; |
| 411 |
return $key; |
| 412 |
}, |
| 413 |
$html |
| 414 |
); |
| 415 |
return array( (string) $out, $stubs ); |
| 416 |
} |
| 417 |
|
| 418 |
private static function restore_safe_blocks( string $html, array $stubs ): string { |
| 419 |
if ( empty( $stubs ) ) { |
| 420 |
return $html; |
| 421 |
} |
| 422 |
return strtr( $html, $stubs ); |
| 423 |
} |
| 424 |
|
| 425 |
private static function opts(): array { |
| 426 |
if ( null === self::$opts ) { |
| 427 |
self::$opts = Settings_Manager::get( 'lazy' ); |
| 428 |
} |
| 429 |
return self::$opts; |
| 430 |
} |
| 431 |
|
| 432 |
/** |
| 433 |
* Test-only: clear cached opts + counter between assertions. |
| 434 |
*/ |
| 435 |
public static function reset_state(): void { |
| 436 |
self::$opts = null; |
| 437 |
self::$image_counter = 0; |
| 438 |
self::$src_dims_cache = null; |
| 439 |
} |
| 440 |
} |
| 441 |
|
