elementor / modules / image-loading-optimization / module.php

module.php in Elementor Website Builder – more than just a page builder 3.20.4, at modules/image-loading-optimization/module.php

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1	<?php
2	namespace Elementor\Modules\ImageLoadingOptimization;
3
4	use Elementor\Core\Base\Module as BaseModule;
5	use Elementor\Core\Experiments\Manager as Experiments_Manager;
6
7	if ( ! defined( 'ABSPATH' ) ) {
8	exit; // Exit if accessed directly
9	}
10
11	class Module extends BaseModule {
12	/**
13	* @var string The experiment name.
14	*/
15	const EXPERIMENT_NAME = 'e_image_loading_optimization';
16
17	/**
18	* @var int Minimum square-pixels threshold.
19	*/
20	private $min_priority_img_pixels = 50000;
21
22	/**
23	* @var int The number of content media elements to not lazy-load.
24	*/
25	private $omit_threshold = 3;
26
27	/**
28	* @var array Keep a track of images for which loading optimization strategy were computed.
29	*/
30	private static $image_visited = [];
31
32	/**
33	* Get Module name.
34	*/
35	public function get_name() {
36	return 'image-loading-optimization';
37	}
38
39	/**
40	* Get experimental data.
41	*
42	* @return array Experimental settings.
43	*/
44	public static function get_experimental_data() {
45	return [
46	'name' => static::EXPERIMENT_NAME,
47	'title' => esc_html__( 'Optimize Image Loading', 'elementor' ),
48	'tag' => esc_html__( 'Performance', 'elementor' ),
49	'description' => sprintf(
50	/* translators: 1: fetchpriority attribute, 2: lazy loading attribute. */
51	esc_html__( 'Applying %1$s on LCP image and %2$s on images below the fold to improve performance scores.', 'elementor' ),
52	'<code>fetchpriority="high"</code>',
53	'<code>loading="lazy"</code>'
54	),
55	'generator_tag' => true,
56	'release_status' => Experiments_Manager::RELEASE_STATUS_STABLE,
57	'default' => Experiments_Manager::STATE_ACTIVE,
58	];
59	}
60
61	/**
62	* Constructor.
63	*/
64	public function __construct() {
65	parent::__construct();
66
67	// Stop wp core logic.
68	add_action( 'init', [ $this, 'stop_core_fetchpriority_high_logic' ] );
69	add_filter( 'wp_lazy_loading_enabled', '__return_false' );
70
71	// Run optimization logic on header.
72	add_action( 'get_header', [ $this, 'set_buffer' ] );
73
74	// Ensure buffer is flushed (if any) before the content logic.
75	add_filter( 'the_content', [ $this, 'flush_header_buffer' ], 0 );
76
77	// Run optimization logic on content.
78	add_filter( 'wp_content_img_tag', [ $this, 'loading_optimization_image' ] );
79	}
80
81	/**
82	* Stop WordPress core fetchpriority logic by setting the wp_high_priority_element_flag flag to false.
83	*/
84	public function stop_core_fetchpriority_high_logic() {
85	// wp_high_priority_element_flag was only introduced in 6.3.0
86	if ( function_exists( 'wp_high_priority_element_flag' ) ) {
87	wp_high_priority_element_flag( false );
88	}
89	}
90
91	/**
92	* Set buffer to handle header and footer content.
93	*/
94	public function set_buffer() {
95	ob_start( [ $this, 'handle_buffer_content' ] );
96	}
97
98	/**
99	* This function ensure that buffer if any is flushed before the content is called.
100	* This function behaves more like an action than a filter.
101	*
102	* @param string $content the content.
103	* @return string We simply return the content from parameter.
104	*/
105	public function flush_header_buffer( $content ) {
106	$buffer_status = ob_get_status();
107
108	if ( ! empty( $buffer_status ) &&
109	1 === $buffer_status['type'] &&
110	get_class( $this ) . '::handle_buffer_content' === $buffer_status['name'] ) {
111	ob_end_flush();
112	}
113
114	return $content;
115	}
116
117	/**
118	* Callback to handle image optimization logic on buffered content.
119	*
120	* @param string $buffer Buffered content.
121	* @return string Content with optimized images.
122	*/
123	public function handle_buffer_content( $buffer ) {
124	return $this->filter_images( $buffer );
125	}
126
127	/**
128	* Check for image in the content provided and apply optimization logic on them.
129	*
130	* @param string $content Content to be analyzed.
131	* @return string Content with optimized images.
132	*/
133	private function filter_images( $content ) {
134	return preg_replace_callback(
135	'/<img\s[^>]+>/',
136	function ( $matches ) {
137	return $this->loading_optimization_image( $matches[0] );
138	},
139	$content
140	);
141	}
142
143	/**
144	* Apply loading optimization logic on the image.
145	*
146	* @param mixed $image Original image tag.
147	* @return string Optimized image.
148	*/
149	public function loading_optimization_image( $image ) {
150	if ( isset( self::$image_visited[ $image ] ) ) {
151	return self::$image_visited[ $image ];
152	}
153
154	$optimized_image = $this->add_loading_optimization_attrs( $image );
155	self::$image_visited[ $image ] = $optimized_image;
156
157	return $optimized_image;
158	}
159
160	/**
161	* Adds optimization attributes to an `img` HTML tag.
162	*
163	* @param string $image The HTML `img` tag where the attribute should be added.
164	* @return string Converted `img` tag with optimization attributes added.
165	*/
166	private function add_loading_optimization_attrs( $image ) {
167	$width = preg_match( '/ width=["\']([0-9]+)["\']/', $image, $match_width ) ? (int) $match_width[1] : null;
168	$height = preg_match( '/ height=["\']([0-9]+)["\']/', $image, $match_height ) ? (int) $match_height[1] : null;
169	$loading_val = preg_match( '/ loading=["\']([A-Za-z]+)["\']/', $image, $match_loading ) ? $match_loading[1] : null;
170	$fetchpriority_val = preg_match( '/ fetchpriority=["\']([A-Za-z]+)["\']/', $image, $match_fetchpriority ) ? $match_fetchpriority[1] : null;
171
172	// Images should have height and dimension width for the loading optimization attributes to be added.
173	if ( ! str_contains( $image, ' width="' ) \|\| ! str_contains( $image, ' height="' ) ) {
174	return $image;
175	}
176
177	$optimization_attrs = $this->get_loading_optimization_attributes(
178	[
179	'width' => $width,
180	'height' => $height,
181	'loading' => $loading_val,
182	'fetchpriority' => $fetchpriority_val,
183	]
184	);
185
186	if ( ! empty( $optimization_attrs['fetchpriority'] ) ) {
187	$image = str_replace( '<img', '<img fetchpriority="' . esc_attr( $optimization_attrs['fetchpriority'] ) . '"', $image );
188	}
189
190	if ( ! empty( $optimization_attrs['loading'] ) ) {
191	$image = str_replace( '<img', '<img loading="' . esc_attr( $optimization_attrs['loading'] ) . '"', $image );
192	}
193
194	return $image;
195	}
196
197	/**
198	* Return loading Loading optimization attributes for a image with give attribute.
199	*
200	* @param array $attr Existing image attributes.
201	* @return array Loading optimization attributes.
202	*/
203	private function get_loading_optimization_attributes( $attr ) {
204	$loading_attrs = [];
205
206	// For any resources, width and height must be provided, to avoid layout shifts.
207	if ( ! isset( $attr['width'], $attr['height'] ) ) {
208	return $loading_attrs;
209	}
210
211	/*
212	* The key function logic starts here.
213	*/
214	$maybe_in_viewport = null;
215	$increase_count = false;
216	$maybe_increase_count = false;
217
218	/*
219	* Logic to handle a `loading` attribute that is already provided.
220	*
221	* Copied from `wp_get_loading_optimization_attributes()`.
222	*/
223	if ( isset( $attr['loading'] ) ) {
224	/*
225	* Interpret "lazy" as not in viewport. Any other value can be
226	* interpreted as in viewport (realistically only "eager" or `false`
227	* to force-omit the attribute are other potential values).
228	*/
229	if ( 'lazy' === $attr['loading'] ) {
230	$maybe_in_viewport = false;
231	} else {
232	$maybe_in_viewport = true;
233	}
234	}
235
236	// Logic to handle a `fetchpriority` attribute that is already provided.
237	$has_fetchpriority_high_attr = ( isset( $attr['fetchpriority'] ) && 'high' === $attr['fetchpriority'] );
238
239	/*
240	* Handle cases where a `fetchpriority="high"` has already been set.
241	*
242	* Copied from `wp_get_loading_optimization_attributes()`.
243	*/
244	if ( $has_fetchpriority_high_attr ) {
245	/*
246	* If the image was already determined to not be in the viewport (e.g.
247	* from an already provided `loading` attribute), trigger a warning.
248	* Otherwise, the value can be interpreted as in viewport, since only
249	* the most important in-viewport image should have `fetchpriority` set
250	* to "high".
251	*/
252	if ( false === $maybe_in_viewport ) {
253	_doing_it_wrong(
254	__FUNCTION__,
255	esc_html__( 'An image should not be lazy-loaded and marked as high priority at the same time.', 'elementor' ),
256	''
257	);
258	/*
259	* Set `fetchpriority` here for backward-compatibility as we should
260	* not override what a developer decided, even though it seems
261	* incorrect.
262	*/
263	$loading_attrs['fetchpriority'] = 'high';
264	} else {
265	$maybe_in_viewport = true;
266	}
267	}
268
269	if ( null === $maybe_in_viewport && ! is_admin() ) {
270	$content_media_count = $this->increase_content_media_count( 0 );
271	$increase_count = true;
272	if ( $content_media_count < $this->omit_threshold ) {
273	$maybe_in_viewport = true;
274	} else {
275	$maybe_in_viewport = false;
276	}
277	}
278
279	if ( $maybe_in_viewport ) {
280	$loading_attrs = $this->maybe_add_fetchpriority_high_attr( $loading_attrs, $attr );
281	} else {
282	$loading_attrs['loading'] = 'lazy';
283	}
284
285	if ( $increase_count ) {
286	$this->increase_content_media_count();
287	} elseif ( $maybe_increase_count ) {
288	if ( $this->get_min_priority_img_pixels() <= $attr['width'] * $attr['height'] ) {
289	$this->increase_content_media_count();
290	}
291	}
292
293	return $loading_attrs;
294	}
295
296	/**
297	* Helper to get the minimum threshold for number of pixels an image needs to have to be considered "priority".
298	*
299	* @return int The minimum number of pixels (width * height). Default is 50000.
300	*/
301	private function get_min_priority_img_pixels() {
302	/**
303	* Filter the minimum pixel threshold used to determine if an image should have fetchpriority="high" applied.
304	*
305	* @see https://developer.wordpress.org/reference/hooks/wp_min_priority_img_pixels/
306	*
307	* @param int $pixels The minimum number of pixels (with * height).
308	* @return int The filtered value.
309	*/
310	return apply_filters( 'elementor/image-loading-optimization/min_priority_img_pixels', $this->min_priority_img_pixels );
311	}
312
313	/**
314	* Keeps a count of media image.
315	*
316	* @param int $amount Amount by which count must be increased.
317	* @return int current image count.
318	*/
319	private function increase_content_media_count( $amount = 1 ) {
320	static $content_media_count = 0;
321
322	$content_media_count += $amount;
323
324	return $content_media_count;
325	}
326
327	/**
328	* Determines whether to add `fetchpriority='high'` to loading attributes.
329	*
330	* @param array $loading_attrs Array of the loading optimization attributes for the element.
331	* @param array $attr Array of the attributes for the element.
332	* @return array Updated loading optimization attributes for the element.
333	*/
334	private function maybe_add_fetchpriority_high_attr( $loading_attrs, $attr ) {
335	if ( isset( $attr['fetchpriority'] ) ) {
336	if ( 'high' === $attr['fetchpriority'] ) {
337	$loading_attrs['fetchpriority'] = 'high';
338	$this->high_priority_element_flag( false );
339	}
340
341	return $loading_attrs;
342	}
343
344	// Lazy-loading and `fetchpriority="high"` are mutually exclusive.
345	if ( isset( $loading_attrs['loading'] ) && 'lazy' === $loading_attrs['loading'] ) {
346	return $loading_attrs;
347	}
348
349	if ( ! $this->high_priority_element_flag() ) {
350	return $loading_attrs;
351	}
352
353	if ( $this->get_min_priority_img_pixels() <= $attr['width'] * $attr['height'] ) {
354	$loading_attrs['fetchpriority'] = 'high';
355	$this->high_priority_element_flag( false );
356	}
357
358	return $loading_attrs;
359	}
360
361	/**
362	* Accesses a flag that indicates if an element is a possible candidate for `fetchpriority='high'`.
363	*
364	* @param bool $value Optional. Used to change the static variable. Default null.
365	* @return bool Returns true if high-priority element was marked already, otherwise false.
366	*/
367	private function high_priority_element_flag( $value = null ) {
368	static $high_priority_element = true;
369
370	if ( is_bool( $value ) ) {
371	$high_priority_element = $value;
372	}
373
374	return $high_priority_element;
375	}
376	}
377