wp-optimize / webp / class-wpo-webp-alter-html.php

class-wpo-webp-alter-html.php in WP-Optimize – Cache, Compress images, Minify & Clean database to boost page speed & performance 4.5.3, at webp/class-wpo-webp-alter-html.php

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1	<?php
2
3	if (!defined('ABSPATH')) die('No direct access allowed');
4
5	if (!class_exists('WPO_WebP_Alter_HTML')) :
6
7	class WPO_WebP_Alter_HTML {
8
9	private $tags = array('img', 'source', 'input', 'iframe', 'div', 'li', 'link', 'a', 'section', 'video');
10
11	/**
12	* Constructor
13	*/
14	private function __construct() {
15
16	}
17
18	/**
19	* Returns singleton instance
20	*
21	* @return WPO_WebP_Alter_HTML
22	*/
23	public static function get_instance() {
24	static $_instance = null;
25	if (null === $_instance) {
26	$_instance = new self();
27	}
28	return $_instance;
29	}
30
31	/**
32	* Alter html to change image related tags to specify webp images
33	*
34	* @param string $html - HTML document as string
35	* @return string
36	*/
37	public function alter_html(string $html): string {
38	if (apply_filters('wpo_disable_webp_alter_html', false)) {
39	return $html;
40	}
41
42	// MAX_FILE_SIZE is defined in simple_html_dom.
43	// For safety, we make sure it is defined before using
44	defined('MAX_FILE_SIZE') \|\| define('MAX_FILE_SIZE', 600000);
45
46	$dom = WP_Optimize_Utils::get_simple_html_dom_object($html);
47
48	if (false === $dom) {
49	if (strlen($html) > MAX_FILE_SIZE) {
50	return $html . "\n" . "<!-- Alter HTML was skipped because the HTML is too big to process! " .
51	"(limit is set to " . MAX_FILE_SIZE . " bytes) -->";
52	}
53	return $html . "\n" . "<!-- Alter HTML was skipped because the helper library refused to process the html -->";
54	}
55
56	// Replace attributes (src, srcset, data-src, etc)
57	foreach ($this->tags as $tag) {
58	$elems = $dom->find($tag);
59	foreach ($elems as $elem) {
60	$attributes = $elem->getAllAttributes();
61	foreach ($attributes as $attr_name => $attr_value) {
62	if ($this->is_image_attribute($attr_name)) {
63	$elem->setAttribute($attr_name, $this->handle_attribute($attr_value));
64	}
65	}
66	}
67	}
68
69	$result = $dom->save();
70	return $result;
71	}
72
73	/**
74	* Append image urls with `.webp` extension
75	*
76	* @param string $url - Image URL
77	* @return string
78	*/
79	private function replace_url($url) {
80	return $url . '.webp';
81	}
82
83	/**
84	* If webp version for supplied image url is available then replace extension
85	*
86	* @param string $url - URL of image
87	* @return string
88	*/
89	private function maybe_replace_url($url) {
90	if ($this->is_webp_version_available($url)) {
91	$url = $this->replace_url($url);
92	}
93	return $url;
94	}
95
96	/**
97	* Modifies src attribute value, if needed
98	*
99	* @param string $attr_value
100	* @return string
101	*/
102	private function handle_src($attr_value) {
103	return $this->maybe_replace_url($attr_value);
104	}
105
106	/**
107	* Modified `srcset` attribute value, if needed
108	*
109	* @param string $attr_value
110	* @return string
111	*/
112	private function handle_srcset($attr_value) {
113	// $attr_value is ie: <img data-x="1.jpg 1000w, 2.jpg">
114	$srcset_arr = explode(',', $attr_value);
115	foreach ($srcset_arr as $i => $srcset_entry) {
116	// $srcset_entry is ie "image.jpg 520w", but can also lack width, ie just "image.jpg"
117	// it can also be ie "image.jpg 2x"
118	$srcset_entry = trim($srcset_entry);
119	$entry_parts = preg_split('/\s+/', $srcset_entry, 2);
120	if (2 === count($entry_parts)) {
121	list($src, $descriptors) = $entry_parts;
122	} else {
123	$src = $srcset_entry;
124	$descriptors = null;
125	}
126
127	$url = $this->maybe_replace_url($src);
128	$srcset_arr[$i] = $url . (isset($descriptors) ? ' ' . $descriptors : '');
129	}
130	return implode(', ', $srcset_arr);
131	}
132
133	/**
134	* Decides whether given value is a `srcset` or not
135	*
136	* @param string $value
137	* @return bool
138	*/
139	private function looks_like_srcset($value) {
140	if (preg_match('#\s\d*(w\|x)#', $value)) {
141	return true;
142	}
143	return false;
144	}
145
146	/**
147	* Handle attribute value based on attribute name, src or srcset
148	*
149	* @param string $value
150	* @return string
151	*/
152	private function handle_attribute($value) {
153	if ($this->looks_like_srcset($value)) {
154	return $this->handle_srcset($value);
155	}
156	return $this->handle_src($value);
157	}
158
159	/**
160	* Decide whether given attribute name is an image attribute or not
161	*
162	* @param string $attr_name
163	* @return bool
164	*/
165	private function is_image_attribute($attr_name) {
166	return preg_match('#^(src\|srcset\|poster\|(data-[^=](lazy\|small\|slide\|img\|large\|src\|thumb\|source\|set\|bg-url)[^=]))$#i', $attr_name);
167	}
168
169	/**
170	* Does webp image file exists
171	*
172	* @param string $url
173	* @return boolean
174	*/
175	private function is_webp_version_available($url) {
176	$filename = WP_Optimize_Utils::get_file_path($url);
177	if (empty($filename)) return false;
178	return file_exists($filename . '.webp');
179	}
180	}
181
182	endif;
183