jetpack / jetpack_vendor / automattic / jetpack-post-list / src / class-post-thumbnail.php

class-post-thumbnail.php in Jetpack – WP Security, Backup, Speed, & Growth 16.2, at jetpack_vendor/automattic/jetpack-post-list/src/class-post-thumbnail.php

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1	<?php
2	/**
3	* This file contains the Post_Thumbnail class used for finding a suitable thumbnail for a post.
4	*
5	* @package automattic/jetpack-post-list
6	*/
7
8	namespace Automattic\Jetpack\Post_List;
9
10	/**
11	* The Post_Thumbnail class contains methods to find and return a suitable thumbnail for a post.
12	*/
13	class Post_Thumbnail {
14	/**
15	* Returns the featured image thumbnail or if no featured image is set, return the first image in the post. If
16	* neither exists returns the image array with null values.
17	*
18	* @param object $post The current post.
19	* @return array\|null The thumbnail image id and URLs
20	*/
21	public static function get_post_thumbnail( $post ) {
22	$image_id = null;
23	$image_url = null;
24	$image_alt = null;
25	$image_thumb = false;
26
27	$post_id = $post->ID;
28
29	// If a featured image exists for the post, use that thumbnail.
30	if ( has_post_thumbnail( $post_id ) ) {
31	$image_id = get_post_thumbnail_id( $post_id );
32	$image_url = get_the_post_thumbnail_url( $post_id );
33	$image_thumb = get_the_post_thumbnail_url( $post_id, array( 50, 50 ) );
34	$image_alt = get_post_meta( $image_id, '_wp_attachment_image_alt', true );
35	} else {
36	// If a featured image does not exist look for the first "media library" hosted image on the post.
37	$attachment_id = self::get_first_image_id_from_post_content( $post->post_content );
38
39	if ( null !== $attachment_id ) {
40	$image_id = $attachment_id;
41	$image_url = wp_get_attachment_image_url( $attachment_id, 'full-size' );
42	$image_thumb = wp_get_attachment_image_url( $attachment_id, array( 50, 50 ) );
43	$image_alt = get_post_meta( $attachment_id, '_wp_attachment_image_alt', true );
44	}
45	}
46
47	// If no thumbnail is found return null.
48	if ( false === $image_thumb ) {
49	return null;
50	}
51
52	// Escape values just in case.
53	return array(
54	'id' => esc_attr( $image_id ),
55	'url' => esc_url( $image_url ),
56	'thumb' => esc_url( $image_thumb ),
57	'alt' => esc_attr( $image_alt ),
58	);
59	}
60
61	/**
62	* Looks for the first image in the post content containing a class value of 'wp-image-{$attachment_id}' and
63	* returns the $attachment_id from that class value.
64	*
65	* @param string $post_content The current post's HTML content.
66	* @return int The image attachment id.
67	*/
68	public static function get_first_image_id_from_post_content( $post_content ) {
69	// If $post_content does not contain a value of substance, return null right away and avoid trying to parse it.
70	if ( empty( $post_content ) ) {
71	return null;
72	}
73
74	$attachment_id = null;
75	$dom = new \DOMDocument();
76
77	// libxml_use_internal_errors(true) silences PHP warnings and errors from malformed HTML in loadHTML().
78	// you can consult libxml_get_last_error() or libxml_get_errors() to check for errors if needed.
79	libxml_use_internal_errors( true );
80	$dom->loadHTML( $post_content );
81
82	// Media library images have a class attribute value containing 'wp-image-{$attachment_id}'.
83	// Use DomXPath to parse the post content and get the first img tag containing 'wp-image-' as a class value.
84	$class_name = 'wp-image-';
85	$dom_x_path = new \DomXPath( $dom );
86	$nodes = $dom_x_path->query( "//img[contains(@class, '$class_name')]/@class" );
87
88	if ( $nodes->length > 0 ) {
89	// Get the class attribute value of the 1st image node (aka index 0).
90	$class_value = $nodes[0]->value;
91
92	// Ignore all class attribute values except 'wp-image{$attachment_id}'.
93	// Regex english translation: Look for a word \b, that does not start or end with a hyphen (?!-), that
94	// starts with 'wp-image-', and ends with a number of any length \d+.
95	$class_name_found = preg_match( '/\b(?!-)wp-image-\d+(?!-)\b/', $class_value, $class_value );
96
97	if ( $class_name_found ) {
98	// Get the $attachment_id from the end of the class name value.
99	$attachment_id = str_replace( $class_name, '', $class_value[0] );
100
101	// If the ID we found is numeric, cast it as an int. Else, make it null.
102	if ( is_numeric( $attachment_id ) ) {
103	$attachment_id = (int) $attachment_id;
104	} else {
105	$attachment_id = null;
106	}
107	}
108	}
109
110	return $attachment_id;
111	}
112	}
113