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

module.php in Elementor Website Builder – more than just a page builder 4.2.0, 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
6	if ( ! defined( 'ABSPATH' ) ) {
7	exit; // Exit if accessed directly.
8	}
9
10	class Module extends BaseModule {
11	/**
12	* @var int Minimum square-pixels threshold.
13	*/
14	private $min_priority_img_pixels = 50000;
15
16	/**
17	* @var int The number of content media elements to not lazy-load.
18	*/
19	private $omit_threshold = 3;
20
21	/**
22	* @var array Keep a track of images for which loading optimization strategy were computed.
23	*/
24	private static $image_visited = [];
25
26	/**
27	* Get Module name.
28	*/
29	public function get_name() {
30	return 'image-loading-optimization';
31	}
32
33	/**
34	* Constructor.
35	*/
36	public function __construct() {
37	if ( ! static::is_optimized_image_loading_enabled() ) {
38	return;
39	}
40
41	parent::__construct();
42
43	// Stop wp core logic.
44	add_action( 'init', [ $this, 'stop_core_fetchpriority_high_logic' ] );
45	add_filter( 'wp_lazy_loading_enabled', '__return_false' );
46
47	// Run optimization logic on header.
48	add_action( 'get_header', [ $this, 'set_buffer' ] );
49
50	// Ensure buffer is flushed (if any) before the content logic.
51	add_filter( 'the_content', [ $this, 'flush_header_buffer' ], 0 );
52
53	// Run optimization logic on content.
54	add_filter( 'wp_content_img_tag', [ $this, 'loading_optimization_image' ] );
55	}
56
57	/**
58	* Check whether the "Optimized Image Loading" settings is enabled.
59	*
60	* The 'optimized_image_loading' option can be enabled/disabled from the Elementor settings.
61	*
62	* @since 3.21.0
63	* @access private
64	*/
65	private static function is_optimized_image_loading_enabled(): bool {
66	return '1' === get_option( 'elementor_optimized_image_loading', '1' );
67	}
68
69	/**
70	* Stop WordPress core fetchpriority logic by setting the wp_high_priority_element_flag flag to false.
71	*/
72	public function stop_core_fetchpriority_high_logic() {
73	wp_high_priority_element_flag( false );
74	}
75
76	/**
77	* Set buffer to handle header and footer content.
78	*/
79	public function set_buffer() {
80	ob_start( [ $this, 'handle_buffer_content' ] );
81	}
82
83	/**
84	* This function ensure that buffer if any is flushed before the content is called.
85	* This function behaves more like an action than a filter.
86	*
87	* @param string $content the content.
88	* @return string We simply return the content from parameter.
89	*/
90	public function flush_header_buffer( $content ) {
91	$buffer_status = ob_get_status();
92
93	if ( ! empty( $buffer_status ) &&
94	1 === $buffer_status['type'] &&
95	get_class( $this ) . '::handle_buffer_content' === $buffer_status['name'] ) {
96	ob_end_flush();
97	}
98
99	return $content;
100	}
101
102	/**
103	* Callback to handle image optimization logic on buffered content.
104	*
105	* @param string $buffer Buffered content.
106	* @return string Content with optimized images.
107	*/
108	public function handle_buffer_content( $buffer ) {
109	return $this->filter_images( $buffer );
110	}
111
112	/**
113	* Check for image in the content provided and apply optimization logic on them.
114	*
115	* @param string $content Content to be analyzed.
116	* @return string Content with optimized images.
117	*/
118	private function filter_images( $content ) {
119	return preg_replace_callback(
120	'/<img\s[^>]+>/',
121	function ( $matches ) {
122	return $this->loading_optimization_image( $matches[0] );
123	},
124	$content
125	);
126	}
127
128	/**
129	* Apply loading optimization logic on the image.
130	*
131	* @param mixed $image Original image tag.
132	* @return string Optimized image.
133	*/
134	public function loading_optimization_image( $image ) {
135	if ( isset( self::$image_visited[ $image ] ) ) {
136	return self::$image_visited[ $image ];
137	}
138
139	$optimized_image = $this->add_loading_optimization_attrs( $image );
140	self::$image_visited[ $image ] = $optimized_image;
141
142	return $optimized_image;
143	}
144
145	/**
146	* Adds optimization attributes to an `img` HTML tag.
147	*
148	* @param string $image The HTML `img` tag where the attribute should be added.
149	* @return string Converted `img` tag with optimization attributes added.
150	*/
151	private function add_loading_optimization_attrs( $image ) {
152	$width = preg_match( '/ width=["\']([0-9]+)["\']/', $image, $match_width ) ? (int) $match_width[1] : null;
153	$height = preg_match( '/ height=["\']([0-9]+)["\']/', $image, $match_height ) ? (int) $match_height[1] : null;
154	$loading_val = preg_match( '/ loading=["\']([A-Za-z]+)["\']/', $image, $match_loading ) ? $match_loading[1] : null;
155	$fetchpriority_val = preg_match( '/ fetchpriority=["\']([A-Za-z]+)["\']/', $image, $match_fetchpriority ) ? $match_fetchpriority[1] : null;
156
157	// Images should have height and dimension width for the loading optimization attributes to be added.
158	if ( ! str_contains( $image, ' width="' ) \|\| ! str_contains( $image, ' height="' ) ) {
159	return $image;
160	}
161
162	$optimization_attrs = $this->get_loading_optimization_attributes(
163	[
164	'width' => $width,
165	'height' => $height,
166	'loading' => $loading_val,
167	'fetchpriority' => $fetchpriority_val,
168	]
169	);
170
171	if ( ! empty( $optimization_attrs['fetchpriority'] ) ) {
172	$image = str_replace( '<img', '<img fetchpriority="' . esc_attr( $optimization_attrs['fetchpriority'] ) . '"', $image );
173	}
174
175	if ( ! empty( $optimization_attrs['loading'] ) ) {
176	$image = str_replace( '<img', '<img loading="' . esc_attr( $optimization_attrs['loading'] ) . '"', $image );
177	}
178
179	return $image;
180	}
181
182	/**
183	* Return loading Loading optimization attributes for a image with give attribute.
184	*
185	* @param array $attr Existing image attributes.
186	* @return array Loading optimization attributes.
187	*/
188	private function get_loading_optimization_attributes( $attr ) {
189	$loading_attrs = [];
190
191	// For any resources, width and height must be provided, to avoid layout shifts.
192	if ( ! isset( $attr['width'], $attr['height'] ) ) {
193	return $loading_attrs;
194	}
195
196	/*
197	* The key function logic starts here.
198	*/
199	$maybe_in_viewport = null;
200	$increase_count = false;
201	$maybe_increase_count = false;
202
203	/*
204	* Logic to handle a `loading` attribute that is already provided.
205	*
206	* Copied from `wp_get_loading_optimization_attributes()`.
207	*/
208	if ( isset( $attr['loading'] ) ) {
209	/*
210	* Interpret "lazy" as not in viewport. Any other value can be
211	* interpreted as in viewport (realistically only "eager" or `false`
212	* to force-omit the attribute are other potential values).
213	*/
214	if ( 'lazy' === $attr['loading'] ) {
215	$maybe_in_viewport = false;
216	} else {
217	$maybe_in_viewport = true;
218	}
219	}
220
221	// Logic to handle a `fetchpriority` attribute that is already provided.
222	$has_fetchpriority_high_attr = ( isset( $attr['fetchpriority'] ) && 'high' === $attr['fetchpriority'] );
223
224	/*
225	* Handle cases where a `fetchpriority="high"` has already been set.
226	*
227	* Copied from `wp_get_loading_optimization_attributes()`.
228	*/
229	if ( $has_fetchpriority_high_attr ) {
230	/*
231	* If the image was already determined to not be in the viewport (e.g.
232	* from an already provided `loading` attribute), trigger a warning.
233	* Otherwise, the value can be interpreted as in viewport, since only
234	* the most important in-viewport image should have `fetchpriority` set
235	* to "high".
236	*/
237	if ( false === $maybe_in_viewport ) {
238	_doing_it_wrong(
239	__FUNCTION__,
240	esc_html__( 'An image should not be lazy-loaded and marked as high priority at the same time.', 'elementor' ),
241	''
242	);
243
244	/*
245	* Set `fetchpriority` here for backward-compatibility as we should
246	* not override what a developer decided, even though it seems
247	* incorrect.
248	*/
249	$loading_attrs['fetchpriority'] = 'high';
250	} else {
251	$maybe_in_viewport = true;
252	}
253	}
254
255	if ( null === $maybe_in_viewport && ! is_admin() ) {
256	$content_media_count = $this->increase_content_media_count( 0 );
257	$increase_count = true;
258	if ( $content_media_count < $this->omit_threshold ) {
259	$maybe_in_viewport = true;
260	} else {
261	$maybe_in_viewport = false;
262	}
263	}
264
265	if ( $maybe_in_viewport ) {
266	$loading_attrs = $this->maybe_add_fetchpriority_high_attr( $loading_attrs, $attr );
267	} else {
268	$loading_attrs['loading'] = 'lazy';
269	}
270
271	if ( $increase_count ) {
272	$this->increase_content_media_count();
273	} elseif ( $maybe_increase_count ) {
274	if ( $this->get_min_priority_img_pixels() <= $attr['width'] * $attr['height'] ) {
275	$this->increase_content_media_count();
276	}
277	}
278
279	return $loading_attrs;
280	}
281
282	/**
283	* Helper to get the minimum threshold for number of pixels an image needs to have to be considered "priority".
284	*
285	* @return int The minimum number of pixels (width * height). Default is 50000.
286	*/
287	private function get_min_priority_img_pixels() {
288	/**
289	* Filter the minimum pixel threshold used to determine if an image should have fetchpriority="high" applied.
290	*
291	* @see https://developer.wordpress.org/reference/hooks/wp_min_priority_img_pixels/
292	*
293	* @param int $pixels The minimum number of pixels (with * height).
294	* @return int The filtered value.
295	*/
296	return apply_filters( 'elementor/image-loading-optimization/min_priority_img_pixels', $this->min_priority_img_pixels );
297	}
298
299	/**
300	* Keeps a count of media image.
301	*
302	* @param int $amount Amount by which count must be increased.
303	* @return int current image count.
304	*/
305	private function increase_content_media_count( $amount = 1 ) {
306	static $content_media_count = 0;
307
308	$content_media_count += $amount;
309
310	return $content_media_count;
311	}
312
313	/**
314	* Determines whether to add `fetchpriority='high'` to loading attributes.
315	*
316	* @param array $loading_attrs Array of the loading optimization attributes for the element.
317	* @param array $attr Array of the attributes for the element.
318	* @return array Updated loading optimization attributes for the element.
319	*/
320	private function maybe_add_fetchpriority_high_attr( $loading_attrs, $attr ) {
321	if ( isset( $attr['fetchpriority'] ) ) {
322	if ( 'high' === $attr['fetchpriority'] ) {
323	$loading_attrs['fetchpriority'] = 'high';
324	$this->high_priority_element_flag( false );
325	}
326
327	return $loading_attrs;
328	}
329
330	// Lazy-loading and `fetchpriority="high"` are mutually exclusive.
331	if ( isset( $loading_attrs['loading'] ) && 'lazy' === $loading_attrs['loading'] ) {
332	return $loading_attrs;
333	}
334
335	if ( ! $this->high_priority_element_flag() ) {
336	return $loading_attrs;
337	}
338
339	if ( $this->get_min_priority_img_pixels() <= $attr['width'] * $attr['height'] ) {
340	$loading_attrs['fetchpriority'] = 'high';
341	$this->high_priority_element_flag( false );
342	}
343
344	return $loading_attrs;
345	}
346
347	/**
348	* Accesses a flag that indicates if an element is a possible candidate for `fetchpriority='high'`.
349	*
350	* @param bool $value Optional. Used to change the static variable. Default null.
351	* @return bool Returns true if high-priority element was marked already, otherwise false.
352	*/
353	private function high_priority_element_flag( $value = null ) {
354	static $high_priority_element = true;
355
356	if ( is_bool( $value ) ) {
357	$high_priority_element = $value;
358	}
359
360	return $high_priority_element;
361	}
362	}
363