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 3.5.0, at webp/class-wpo-webp-alter-html.php

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1	<?php
2
3	if (!defined('WPO_VERSION')) die('No direct access allowed');
4
5	if (!class_exists('WPO_WebP_Alter_HTML')) :
6
7	class WPO_WebP_Alter_HTML {
8
9	private $tags = array('img', 'source', 'input', 'iframe', 'div', 'li', 'link', 'a', 'section', 'video');
10
11	/**
12	* Constructor
13	*/
14	private function __construct() {
15	add_action('template_redirect', array($this, 'start'), 9999);
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	* Start to alter html in output buffer
33	*/
34	public function start() {
35	if (apply_filters('wpo_disable_webp_alter_html', false)) {
36	return;
37	}
38
39	if (!is_admin() \|\| (defined('DOING_AJAX') && DOING_AJAX)) {
40	ob_start(array(__CLASS__, 'alter_html'));
41	}
42	}
43
44	/**
45	* Alter html to change image related tags to specify webp images
46	*
47	* @param string $html - HTML document as string
48	* @return string
49	*/
50	public function alter_html($html) {
51
52	if (!WP_Optimize_Utils::is_valid_html($html)) return $html;
53
54	$this->maybe_include_simple_html_dom();
55
56	$dom = str_get_html($html, false, false, 'UTF-8', false, DEFAULT_BR_TEXT, DEFAULT_SPAN_TEXT, false);
57
58	// MAX_FILE_SIZE is defined in simple_html_dom.
59	// For safety sake, we make sure it is defined before using
60	defined('MAX_FILE_SIZE') \|\| define('MAX_FILE_SIZE', 600000);
61
62	if (false === $dom) {
63	if (strlen($html) > MAX_FILE_SIZE) {
64	return '<!-- Alter HTML was skipped because the HTML is too big to process! ' .
65	'(limit is set to ' . MAX_FILE_SIZE . ' bytes) -->' . "\n" . $html;
66	}
67	return '<!-- Alter HTML was skipped because the helper library refused to process the html -->' .
68	"\n" . $html;
69	}
70
71	// Replace attributes (src, srcset, data-src, etc)
72	foreach ($this->tags as $tag) {
73	$elems = $dom->find($tag);
74	foreach ($elems as $elem) {
75	$attributes = $elem->getAllAttributes();
76	foreach ($attributes as $attr_name => $attr_value) {
77	if ($this->is_image_attribute($attr_name)) {
78	$elem->setAttribute($attr_name, $this->handle_attribute($attr_value));
79	}
80	}
81	}
82	}
83
84	return $dom->save();
85	}
86
87	/**
88	* Include simple html dom script if not available
89	*/
90	private function maybe_include_simple_html_dom() {
91	if (!function_exists('str_get_html')) {
92	require_once WPO_PLUGIN_MAIN_PATH . 'vendor/simplehtmldom/simplehtmldom/simple_html_dom.php';
93	}
94	}
95
96	/**
97	* Append image urls with `.webp` extension
98	*
99	* @param strinng $url - Image URL
100	* @return string
101	*/
102	private function replace_url($url) {
103	return $url . '.webp';
104	}
105
106	/**
107	* If webp version for supplied image url is available then replace extension
108	*
109	* @param string $url - URL of image
110	* @return string
111	*/
112	private function maybe_replace_url($url) {
113	if ($this->is_webp_version_available($url)) {
114	$url = $this->replace_url($url);
115	}
116	return $url;
117	}
118
119	/**
120	* Modifies src attribute value, if needed
121	*
122	* @param string $attr_value
123	* @return string
124	*/
125	private function handle_src($attr_value) {
126	return $this->maybe_replace_url($attr_value);
127	}
128
129	/**
130	* Modified `srcset` attribute value, if needed
131	*
132	* @param string $attr_value
133	* @return string
134	*/
135	private function handle_srcset($attr_value) {
136	// $attr_value is ie: <img data-x="1.jpg 1000w, 2.jpg">
137	$srcset_arr = explode(',', $attr_value);
138	foreach ($srcset_arr as $i => $srcset_entry) {
139	// $srcset_entry is ie "image.jpg 520w", but can also lack width, ie just "image.jpg"
140	// it can also be ie "image.jpg 2x"
141	$srcset_entry = trim($srcset_entry);
142	$entry_parts = preg_split('/\s+/', $srcset_entry, 2);
143	if (count($entry_parts) == 2) {
144	list($src, $descriptors) = $entry_parts;
145	} else {
146	$src = $srcset_entry;
147	$descriptors = null;
148	}
149
150	$url = $this->maybe_replace_url($src);
151	$srcset_arr[$i] = $url . (isset($descriptors) ? ' ' . $descriptors : '');
152	}
153	return implode(', ', $srcset_arr);
154	}
155
156	/**
157	* Decides whether given value is a `srcset` or not
158	*
159	* @return bool
160	*/
161	private function looks_like_srcset($value) {
162	if (preg_match('#\s\d*(w\|x)#', $value)) {
163	return true;
164	}
165	return false;
166	}
167
168	/**
169	* Handle attribute value based on attribute name, src or srcset
170	*
171	* @return string
172	*/
173	private function handle_attribute($value) {
174	if ($this->looks_like_srcset($value)) {
175	return $this->handle_srcset($value);
176	}
177	return $this->handle_src($value);
178	}
179
180	/**
181	* Decide whether given attribute name is an image attribute or not
182	*
183	* @return bool
184	*/
185	private function is_image_attribute($attr_name) {
186	return preg_match('#^(src\|srcset\|poster\|(data-[^=](lazy\|small\|slide\|img\|large\|src\|thumb\|source\|set\|bg-url)[^=]))$#i', $attr_name);
187	}
188
189	/**
190	* Does webp image file exists
191	*
192	* @param string $url
193	* @return boolean
194	*/
195	private function is_webp_version_available($url) {
196	$filename = WP_Optimize_Utils::get_file_path($url);
197	if (empty($filename)) return false;
198	return file_exists($filename . '.webp');
199	}
200	}
201
202	endif;
203