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<?php |
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/** |
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* Lazy module — defers img / iframe / video loading via native browser |
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* lazy-load attributes. Also auto-fills missing image dimensions to |
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* prevent CLS. |
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* |
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* What WordPress core does already (since 5.5): |
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* - Adds loading="lazy" to the_content images. |
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* |
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* What this module adds: |
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* - First N images get loading="eager" so the LCP isn't deferred. |
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* - Adds decoding="async" (core doesn't). |
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* - Lazy-loads iframes (core's iframe lazy was reverted). |
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* - preload="none" on <video> (closest thing to native video lazy). |
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* - Auto-fills missing width / height attributes (best CLS win). |
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* - Excludes by substring patterns (src or class match) — useful for |
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* hero banner classes, logo files, etc. |
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* |
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* Tier: Free per FEATURES.md "Images" §1-6 (LiteSpeed parity — all |
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* Free in LS Cache). |
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* |
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* @package XSpeed |
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*/ |
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|
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declare(strict_types=1); |
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|
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namespace XSpeed\Modules\Lazy; |
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|
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defined( 'ABSPATH' ) || exit; |
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|
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use XSpeed\Lazy_Loader; |
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use XSpeed\Module; |
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|
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final class LazyModule extends Module { |
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|
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public const SLUG = 'lazy'; |
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public const TIER = self::TIER_FREE; |
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public const VERSION = '1.0.0'; |
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|
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public function ui_metadata(): array { |
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return array( |
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'label' => __( 'Media Optimization', 'xspeed' ), |
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'tab_label' => __( 'Lazy Loading', 'xspeed' ), // its own tab on the Media Optimization page |
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'icon' => 'Image', |
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'description' => __( 'Control how images, iframes, and videos load — lazy-loading, missing dimensions, and format optimization.', 'xspeed' ), |
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// Host page: Lazy Loading (this module) + Image Optimization (Pro) |
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// + AI Suggestions (Pro) as tabs — everything a page loads on one |
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// page instead of separate rows (FBS-83633). Fonts is NOT here: it |
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// has its own Optimization card (#86). |
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'custom_panel' => 'MediaPanel', |
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); |
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} |
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|
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public function settings_schema(): array { |
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return array( |
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'lazy_images' => array( |
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'type' => 'bool', |
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'default' => true, |
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'label' => __( 'Lazy-load Images', 'xspeed' ), |
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'description' => __( 'Add loading="lazy" + decoding="async" to <img> tags in post content. The first images on the page get loading="eager" so the LCP image is not deferred.', 'xspeed' ), |
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), |
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'lazy_iframes' => array( |
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'type' => 'bool', |
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'default' => true, |
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'label' => __( 'Lazy-load Iframes', 'xspeed' ), |
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'description' => __( 'Add loading="lazy" to <iframe> tags. Useful for YouTube / Vimeo embeds + map widgets that pull a lot of bytes.', 'xspeed' ), |
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), |
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'video_facade' => array( |
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'type' => 'bool', |
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'default' => false, |
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'label' => __( 'Click-to-Play Video Facade', 'xspeed' ), |
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'description' => __( 'Replace YouTube and Vimeo embeds — and self-hosted <video> tags that have a poster — with the poster image and a play button. The video only loads when a visitor clicks it, so a page with embeds no longer pays ~1MB of third-party JavaScript, or the full weight of a hosted video file, for visitors who never press play. Autoplaying videos are left alone. Falls back to the normal embed when JavaScript is off.', 'xspeed' ), |
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), |
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'lazy_videos' => array( |
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'type' => 'bool', |
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'default' => true, |
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'label' => __( 'Lazy-load HTML5 Videos', 'xspeed' ), |
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'description' => __( 'Set preload="none" on self-hosted <video> tags, overriding a player\'s own preload="auto"/"metadata". Autoplaying videos are left alone — they need their bytes regardless. Browsers do not yet support loading="lazy" on video; preload="none" is the closest equivalent.', 'xspeed' ), |
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), |
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'lazy_background_images' => array( |
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'type' => 'bool', |
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'default' => false, |
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'label' => __( 'Lazy-load Background Images', 'xspeed' ), |
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'description' => __( 'Hold back background images set in an element\'s inline style (a Cover or Group block, a page-builder section) until the element is near the screen. Uses a small script; visitors without JavaScript get every background as usual. The first N backgrounds on the page load straight away, like images. Backgrounds set in a stylesheet are not affected.', 'xspeed' ), |
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), |
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'eager_first_n' => array( |
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'type' => 'int', |
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'default' => 1, |
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'min' => 0, |
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'max' => 10, |
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'label' => __( 'Eager-load First N Images', 'xspeed' ), |
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'description' => __( 'How many images at the top of the post get loading="eager". 1 is usually right (the LCP hero image). 0 to lazy-load everything. Lazy-loaded background images use the same number.', 'xspeed' ), |
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), |
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'add_missing_dimensions' => array( |
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'type' => 'bool', |
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'default' => true, |
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'label' => __( 'Add Missing Image Dimensions', 'xspeed' ), |
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'description' => __( 'When an <img class="wp-image-N"> has no width/height, look the values up from the media library and inject them. Prevents the page-layout shift that hurts CLS scores.', 'xspeed' ), |
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), |
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'excluded_images' => array( |
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'type' => 'list', |
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'default' => array(), |
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'item_type' => 'string', |
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'label' => __( 'Excluded Images', 'xspeed' ), |
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'description' => __( 'Substring patterns that, if found anywhere in the <img> / <iframe> tag (typically a class or filename), exempt that element from lazy-loading. Useful for hero / logo / sprite images. Or add data-skip-lazy to the tag directly.', 'xspeed' ), |
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), |
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); |
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} |
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|
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public function conflicts(): array { |
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return array( |
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array( |
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'plugin' => 'wp-smushit/wp-smush.php', |
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'feature' => 'images.lazyload', |
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'strategy' => \XSpeed\Conflict_Registry::STRATEGY_WARN, |
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'reason' => 'Smush also offers lazy-loading; running both can cause double-rewriting.', |
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), |
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array( |
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'plugin' => 'a3-lazy-load/a3-lazy-load.php', |
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'feature' => 'images.lazyload', |
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'strategy' => \XSpeed\Conflict_Registry::STRATEGY_REFUSE, |
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'reason' => 'a3 Lazy Load is a dedicated lazy-load plugin; disable it before enabling xSpeed lazy-load.', |
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), |
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); |
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} |
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|
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public function boot(): void { |
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/* |
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* Deferred to `init`. This module reads its own settings to decide |
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* what to hook, and reading settings builds settings_schema(), whose |
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* labels are declared through __(). boot() runs on `plugins_loaded`, |
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* before `after_setup_theme` — the point WordPress 6.7+ treats as the |
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* earliest safe moment to translate — so doing that here fires |
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* _load_textdomain_just_in_time on every request AND resolves the |
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* labels against a domain that is not loaded yet. |
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* |
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* Everything below hooks actions that fire after `init`, so running |
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* one hook later is equivalent. |
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*/ |
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add_action( 'init', array( $this, 'boot_on_init' ) ); |
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} |
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|
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/** |
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* The real boot body — see boot() for why it runs on `init`. |
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*/ |
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public function boot_on_init(): void { |
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// Bail entirely on admin / feed / cron / REST — same scope as |
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// Minifier. Lazy-loading rendered HTML only matters on real |
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// frontend page renders. |
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if ( is_admin() || ( defined( 'DOING_AJAX' ) && DOING_AJAX ) || ( defined( 'DOING_CRON' ) && DOING_CRON ) || ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) { |
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return; |
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} |
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|
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// Never lazy-load inside a builder editor: the builder measures and |
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// positions elements it expects to be loaded. (#281) |
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if ( \XSpeed\Builder_Editor::is_active() ) { |
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return; |
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} |
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|
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$opts = $this->get_settings(); |
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$any_enabled = ! empty( $opts['lazy_images'] ) |
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|| ! empty( $opts['lazy_iframes'] ) |
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|| ! empty( $opts['lazy_videos'] ) |
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|| ! empty( $opts['video_facade'] ) |
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|| ! empty( $opts['lazy_background_images'] ) |
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|| ! empty( $opts['add_missing_dimensions'] ); |
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if ( ! $any_enabled ) { |
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return; |
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} |
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|
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// Reset the eager-load budget once per page render, before any |
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// content filter runs, so the "first N images eager" budget is |
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// shared across the featured image + content + avatars rather than |
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// restarting on every filter pass. (FBS-82172 Bug 1) |
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add_action( 'template_redirect', array( Lazy_Loader::class, 'reset_state' ) ); |
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|
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// Late priority so the_content runs after every other filter |
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// (shortcodes, do_blocks, embeds). Avoids rewriting tags that |
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// haven't been generated yet. |
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add_filter( 'the_content', array( Lazy_Loader::class, 'process_html' ), 999 ); |
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add_filter( 'post_thumbnail_html', array( Lazy_Loader::class, 'process_html' ), 999 ); |
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add_filter( 'get_avatar', array( Lazy_Loader::class, 'process_html' ), 999 ); |
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add_filter( 'widget_text_content', array( Lazy_Loader::class, 'process_html' ), 999 ); |
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|
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// The facade's click handler is printed only on pages that actually |
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// rendered a facade — a page with no embeds should not carry the |
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// script that reveals them. |
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if ( ! empty( $opts['video_facade'] ) ) { |
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add_action( 'wp_footer', array( $this, 'print_facade_script' ), 99 ); |
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// The layout rule goes in the HEAD, unconditionally, while the |
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// handler stays conditional in the footer. Whether a facade |
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// renders isn't known until the content filter has run — long |
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// after wp_head — and a layout rule that arrives in the footer |
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// fixes the gap only after the visitor has already seen it. |
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add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_facade_style' ) ); |
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// Embeds that never touch the HTML: a builder widget builds its |
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// YouTube iframe from script, so the buffer pass has nothing to |
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// rewrite. Head, priority 1, for the same reason as the autoplay |
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// restorer below — it must be listening before the widget's |
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// script sets a src and commits the fetch. |
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add_action( 'wp_head', array( $this, 'print_observer_script' ), 1 ); |
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} |
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|
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// Head, because the rule that holds a background back has to apply |
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// before first paint, or the browser has already requested it. |
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if ( ! empty( $opts['lazy_background_images'] ) ) { |
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add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_background_style' ) ); |
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add_action( 'wp_head', array( $this, 'print_background_script' ), 1 ); |
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} |
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|
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// Same conditional-footer treatment for the autoplay restorer: it is |
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// only printed on a response that actually deferred one. |
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if ( ! empty( $opts['lazy_videos'] ) ) { |
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/* |
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* HEAD, not footer — and as early as anything can run. |
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* |
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* A page-builder video block creates its <video> from its own |
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* script. Ours has to be listening BEFORE that happens: printed |
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* in the footer it loaded after the block's script had already |
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* built the player and started the fetch, so the bytes were |
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* committed before we could defer them. Measured on a live page, |
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* our restorer sat ~17KB after the first block script in the |
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* document, and the videos still downloaded on load. |
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* |
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* It costs ~1KB inline and installs only observers, so running it |
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* early is cheap; a MutationObserver on documentElement catches |
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* every <video> the moment it is inserted, whichever script did |
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* the inserting. |
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*/ |
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add_action( 'wp_head', array( $this, 'print_autoplay_script' ), 1 ); |
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} |
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} |
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|
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/** |
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* Register the facade's layout rule as an inline style on a |
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* dependency-free handle — ~150 bytes, so a separate file would cost |
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* more than the CSS. |
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*/ |
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public function enqueue_facade_style(): void { |
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wp_register_style( 'xspeed-video-facade', false, array(), XSPEED_VERSION ); |
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wp_enqueue_style( 'xspeed-video-facade' ); |
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wp_add_inline_style( 'xspeed-video-facade', \XSpeed\Video_Facade::facade_style() ); |
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} |
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|
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public function enqueue_background_style(): void { |
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wp_register_style( 'xspeed-lazy-bg', false, array(), XSPEED_VERSION ); |
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wp_enqueue_style( 'xspeed-lazy-bg' ); |
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wp_add_inline_style( 'xspeed-lazy-bg', Lazy_Loader::background_style() ); |
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} |
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|
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/** |
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* data-xs-nodelay: Delay JS would otherwise hold this back until the |
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* first interaction, and every held background would stay blank. |
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*/ |
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public function print_background_script(): void { |
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wp_print_inline_script_tag( |
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Lazy_Loader::background_script(), |
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array( |
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'id' => 'xspeed-lazy-bg', |
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'data-xs-nodelay' => true, |
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) |
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); |
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} |
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|
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/** |
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* Emit the click-to-play handler inline. Inline (not enqueued) because |
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* it is ~400 bytes — a separate request would cost more than the code. |
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*/ |
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public function print_facade_script(): void { |
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// No longer gated on facade_used(): the observer script can build a |
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// facade for a JS-injected embed on a page where the server pass |
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// rendered none, and a facade without its click handler is a play |
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// button that plays nothing. ~400 bytes on facade-less pages is the |
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// cost of never shipping that. |
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wp_print_inline_script_tag( \XSpeed\Video_Facade::facade_script(), array( 'id' => 'xspeed-video-facade' ) ); |
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} |
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|
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/** |
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* Emit the interceptor for JS-injected embeds (see |
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* Video_Facade::observer_script() for the mechanism and why the |
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* footer is too late). |
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*/ |
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public function print_observer_script(): void { |
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wp_print_inline_script_tag( \XSpeed\Video_Facade::observer_script(), array( 'id' => 'xspeed-video-facade-observer' ) ); |
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} |
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|
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/** |
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* Emit the viewport restorer for deferred AUTOPLAY videos. |
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* |
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* Separate from the facade script because the two are independent: a |
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* page can defer an autoplay hero without any click-to-play facade on |
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* it, and vice versa. Both are gated on having actually rewritten |
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* something, so a page with no video ships neither. |
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*/ |
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public function print_autoplay_script(): void { |
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/* |
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* Deliberately NOT gated on needs_autoplay_script(). |
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* |
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* That flag is only meaningful after the content filter has run, and |
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* this prints in wp_head — long before. The facade script above can |
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* afford to be conditional because it only has to be present by the |
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* time a human clicks; this one has to be listening before another |
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* plugin's script builds a <video> and starts fetching it, which |
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* happens well before wp_footer. |
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* |
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* The cost of being unconditional is ~1KB inline on pages with no |
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* video, and the script installs observers only — it does no work |
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* and touches nothing when it finds no autoplay video. That is a |
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* better trade than missing the one case the feature exists for. |
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*/ |
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wp_print_inline_script_tag( Lazy_Loader::autoplay_script(), array( 'id' => 'xspeed-lazy-autoplay' ) ); |
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} |
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|
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public function cli_commands(): array { |
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return array( |
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array( |
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'name' => 'xspeed lazy', |
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'callback' => array( $this, 'cli_handler' ), |
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'shortdesc' => 'Show which lazy-load toggles are active.', |
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'ai_hint' => 'Which lazy-loading and image optimizations are on (images, iframes, missing width/height)? Use for questions about images loading too early, layout shift (CLS), or offscreen images flagged by PageSpeed.', |
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'synopsis' => array(), |
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), |
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); |
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} |
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|
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public function cli_handler( array $args, array $assoc ): void { |
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$opts = $this->get_settings(); |
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foreach ( $opts as $key => $value ) { |
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$display = is_array( $value ) ? implode( ',', $value ) : ( $value ? 'on' : ( is_numeric( $value ) ? (string) $value : 'off' ) ); |
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if ( is_int( $value ) ) { |
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$display = (string) $value; |
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} |
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\WP_CLI::log( sprintf( '%-30s %s', $key, $display ) ); |
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} |
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} |
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|
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/** |
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* Lazy has no master switch -- it is on when any of lazy_images / |
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* lazy_iframes / video_facade / lazy_videos is set. (#363) |
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*/ |
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public function is_active(): ?bool { |
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return $this->any_bool_flag_on(); |
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} |
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} |
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|
