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<?php |
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namespace ABlocks\Performance; |
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|
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if ( ! defined( 'ABSPATH' ) ) { |
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exit; |
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} |
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|
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use ABlocks\Helper; |
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|
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/** |
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* Performance Suite — preload the likely LCP image. |
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* |
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* PageSpeed's "LCP request discovery" audit wants the largest above-the-fold |
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* image to be discoverable as early as possible. This scans a singular post's |
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* content for the first aBlocks image and emits a high-priority |
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* `<link rel="preload" as="image">` (with a responsive imagesrcset) in the |
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* <head>, so the browser starts fetching it before it parses the body. |
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* |
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* Opt-in via `perf_preload_lcp`. Scoped to singular views for v1. |
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*/ |
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class LcpPreload { |
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|
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public static function init() { |
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if ( is_admin() ) { |
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return; |
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} |
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$enabled = (bool) apply_filters( |
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'ablocks/perf/perf_preload_lcp', |
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(bool) Helper::get_settings( 'perf_preload_lcp', true ) |
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); |
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if ( ! $enabled ) { |
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return; |
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} |
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$self = new self(); |
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add_action( 'wp_head', [ $self, 'print_preload' ], 2 ); |
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} |
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|
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public function print_preload() { |
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if ( ! is_singular() ) { |
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return; |
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} |
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$post = get_post(); |
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if ( ! $post || false === strpos( (string) $post->post_content, 'wp:ablocks/image' ) ) { |
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return; |
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} |
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|
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$image = $this->first_image_block( parse_blocks( $post->post_content ) ); |
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if ( ! $image ) { |
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return; |
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} |
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|
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$href = esc_url( $image['url'] ); |
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$attrs = 'rel="preload" as="image" fetchpriority="high" href="' . $href . '"'; |
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|
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if ( ! empty( $image['id'] ) ) { |
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$srcset = wp_get_attachment_image_srcset( (int) $image['id'], 'full' ); |
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if ( $srcset ) { |
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$sizes = wp_get_attachment_image_sizes( (int) $image['id'], 'full' ); |
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$attrs .= ' imagesrcset="' . esc_attr( $srcset ) . '"'; |
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if ( $sizes ) { |
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$attrs .= ' imagesizes="' . esc_attr( $sizes ) . '"'; |
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} |
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} |
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} |
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|
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echo "<link {$attrs}>\n"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped |
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} |
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|
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/** |
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* Depth-first search for the first aBlocks image block that carries a URL. |
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* Returns [ 'url' => …, 'id' => … ] or null. |
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*/ |
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private function first_image_block( $blocks ) { |
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foreach ( $blocks as $block ) { |
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if ( ! empty( $block['blockName'] ) && 'ablocks/image' === $block['blockName'] ) { |
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$url = $block['attrs']['imgUrl'] ?? ''; |
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if ( $url && 0 !== strpos( $url, 'ablocks_dc:' ) ) { |
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return [ |
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'url' => $url, |
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'id' => $block['attrs']['imgId'] ?? 0, |
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]; |
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} |
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} |
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if ( ! empty( $block['innerBlocks'] ) ) { |
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$found = $this->first_image_block( $block['innerBlocks'] ); |
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if ( $found ) { |
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return $found; |
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} |
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} |
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} |
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return null; |
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} |
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} |
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|
