performance-lab / modules / images / fetchpriority / load.php

load.php in Performance Lab 1.8.0, at modules/images/fetchpriority/load.php

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1	<?php
2	/**
3	* Module Name: Fetchpriority
4	* Description: Adds a fetchpriority hint for the primary content image on the page to load faster.
5	* Experimental: Yes
6	*
7	* @since 1.8.0
8	* @package performance-lab
9	*/
10
11	/**
12	* Filters an image tag in content to add the fetchpriority attribute if it is not lazy-loaded.
13	*
14	* @since 1.8.0
15	*
16	* @param string $filtered_image The image tag to filter.
17	* @param string $context The context of the image.
18	* @return string The filtered image tag.
19	*/
20	function fetchpriority_img_tag_add_attr( $filtered_image, $context ) {
21
22	if ( 'the_content' !== $context && 'the_post_thumbnail' !== $context ) {
23	return $filtered_image;
24	}
25
26	// Fetchpriority relies on lazy loading logic.
27	if ( ! wp_lazy_loading_enabled( 'img', $context ) ) {
28	return $filtered_image;
29	}
30
31	if ( ! empty( $filtered_image ) && strpos( $filtered_image, 'loading="lazy"' ) === false && strpos( $filtered_image, 'fetchpriority=' ) === false ) {
32	$filtered_image = str_replace( '<img ', '<img fetchpriority="high" ', $filtered_image );
33	remove_filter( 'wp_content_img_tag', 'fetchpriority_img_tag_add_attr' );
34	remove_filter( 'post_thumbnail_html', 'fetchpriority_filter_post_thumbnail_html' );
35	}
36
37	return $filtered_image;
38	}
39	add_filter( 'wp_content_img_tag', 'fetchpriority_img_tag_add_attr', 10, 2 );
40
41	/**
42	* Filters the post thumbnail HTML to conditionally add the fetchpriority attribute.
43	*
44	* @since 1.8.0
45	*
46	* @param string $html The post thumbnail HTML to filter.
47	* @return string The filtered post thumbnail HTML.
48	*/
49	function fetchpriority_filter_post_thumbnail_html( $html ) {
50	$html = fetchpriority_img_tag_add_attr( $html, 'the_post_thumbnail' );
51
52	return $html;
53	}
54	add_filter( 'post_thumbnail_html', 'fetchpriority_filter_post_thumbnail_html' );
55