1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
|
<?php
class Jetpack_Lazy_Images {
private static $__instance = null;
/**
* Singleton implementation
*
* @return object
*/
public static function instance() {
if ( is_null( self::$__instance ) ) {
self::$__instance = new Jetpack_Lazy_Images();
}
return self::$__instance;
}
/**
* Registers actions
*/
private function __construct() {
if ( is_admin() ) {
return;
}
/**
* Whether the lazy-images module should load.
*
* This filter is not prefixed with jetpack_ to provide a smoother migration
* process from the WordPress Lazy Load plugin.
*
* @module lazy-images
*
* @since 5.6.0
*
* @param bool true Whether lazy image loading should occur.
*/
if ( ! apply_filters( 'lazyload_is_enabled', true ) ) {
return;
}
if ( Jetpack_AMP_Support::is_amp_request() ) {
return;
}
add_action( 'wp_head', array( $this, 'setup_filters' ), 9999 ); // we don't really want to modify anything in <head> since it's mostly all metadata
add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_assets' ) );
// Do not lazy load avatar in admin bar
add_action( 'admin_bar_menu', array( $this, 'remove_filters' ), 0 );
add_filter( 'wp_kses_allowed_html', array( $this, 'allow_lazy_attributes' ) );
add_action( 'wp_head', array( $this, 'add_nojs_fallback' ) );
}
public function setup_filters() {
add_filter( 'the_content', array( $this, 'add_image_placeholders' ), PHP_INT_MAX ); // run this later, so other content filters have run, including image_add_wh on WP.com
add_filter( 'post_thumbnail_html', array( $this, 'add_image_placeholders' ), PHP_INT_MAX );
add_filter( 'get_avatar', array( $this, 'add_image_placeholders' ), PHP_INT_MAX );
add_filter( 'widget_text', array( $this, 'add_image_placeholders' ), PHP_INT_MAX );
add_filter( 'get_image_tag', array( $this, 'add_image_placeholders' ), PHP_INT_MAX);
add_filter( 'wp_get_attachment_image_attributes', array( __CLASS__, 'process_image_attributes' ), PHP_INT_MAX );
}
public function remove_filters() {
remove_filter( 'the_content', array( $this, 'add_image_placeholders' ), PHP_INT_MAX );
remove_filter( 'post_thumbnail_html', array( $this, 'add_image_placeholders' ), PHP_INT_MAX );
remove_filter( 'get_avatar', array( $this, 'add_image_placeholders' ), PHP_INT_MAX );
remove_filter( 'widget_text', array( $this, 'add_image_placeholders' ), PHP_INT_MAX );
remove_filter( 'get_image_tag', array( $this, 'add_image_placeholders' ), PHP_INT_MAX);
remove_filter( 'wp_get_attachment_image_attributes', array( __CLASS__, 'process_image_attributes' ), PHP_INT_MAX );
}
/**
* Ensure that our lazy image attributes are not filtered out of image tags.
*
* @param array $allowed_tags The allowed tags and their attributes.
* @return array
*/
public function allow_lazy_attributes( $allowed_tags ) {
if ( ! isset( $allowed_tags['img'] ) ) {
return $allowed_tags;
}
// But, if images are allowed, ensure that our attributes are allowed!
$img_attributes = array_merge( $allowed_tags['img'], array(
'data-lazy-src' => 1,
'data-lazy-srcset' => 1,
'data-lazy-sizes' => 1,
) );
$allowed_tags['img'] = $img_attributes;
return $allowed_tags;
}
public function add_image_placeholders( $content ) {
// Don't lazyload for feeds, previews
if ( is_feed() || is_preview() ) {
return $content;
}
// Don't lazy-load if the content has already been run through previously
if ( false !== strpos( $content, 'data-lazy-src' ) ) {
return $content;
}
// This is a pretty simple regex, but it works
$content = preg_replace_callback( '#<(img)([^>]+?)(>(.*?)</\\1>|[\/]?>)#si', array( __CLASS__, 'process_image' ), $content );
return $content;
}
/**
* Returns true when a given string of classes contains a class signifying lazy images
* should not process the image.
*
* @since 5.9.0
*
* @param string $classes A string of space-separated classes.
* @return bool
*/
public static function should_skip_image_with_blacklisted_class( $classes ) {
$blacklisted_classes = array(
'skip-lazy',
'gazette-featured-content-thumbnail',
);
/**
* Allow plugins and themes to tell lazy images to skip an image with a given class.
*
* @module lazy-images
*
* @since 5.9.0
*
* @param array An array of strings where each string is a class.
*/
$blacklisted_classes = apply_filters( 'jetpack_lazy_images_blacklisted_classes', $blacklisted_classes );
if ( ! is_array( $blacklisted_classes ) || empty( $blacklisted_classes ) ) {
return false;
}
foreach ( $blacklisted_classes as $class ) {
if ( false !== strpos( $classes, $class ) ) {
return true;
}
}
return false;
}
/**
* Processes images in content by acting as the preg_replace_callback
*
* @since 5.6.0
*
* @param array $matches
*
* @return string The image with updated lazy attributes
*/
static function process_image( $matches ) {
$old_attributes_str = $matches[2];
$old_attributes_kses_hair = wp_kses_hair( $old_attributes_str, wp_allowed_protocols() );
if ( empty( $old_attributes_kses_hair['src'] ) ) {
return $matches[0];
}
$old_attributes = self::flatten_kses_hair_data( $old_attributes_kses_hair );
// If we didn't add lazy attributes, just return the original image source.
if ( ! empty( $old_attributes['class'] ) && false !== strpos( $old_attributes['class'], 'jetpack-lazy-image' ) ) {
return $matches[0];
}
$new_attributes = self::process_image_attributes( $old_attributes );
$new_attributes_str = self::build_attributes_string( $new_attributes );
return sprintf( '<img %1$s><noscript>%2$s</noscript>', $new_attributes_str, $matches[0] );
}
/**
* Given an array of image attributes, updates the `src`, `srcset`, and `sizes` attributes so
* that they load lazily.
*
* @since 5.7.0
*
* @param array $attributes
*
* @return array The updated image attributes array with lazy load attributes
*/
static function process_image_attributes( $attributes ) {
if ( empty( $attributes['src'] ) ) {
return $attributes;
}
if ( ! empty( $attributes['class'] ) && self::should_skip_image_with_blacklisted_class( $attributes['class'] ) ) {
return $attributes;
}
/**
* Allow plugins and themes to conditionally skip processing an image via its attributes.
*
* @module-lazy-images
*
* @deprecated 6.5.0 Use jetpack_lazy_images_skip_image_with_attributes instead.
*
* @since 5.9.0
*
* @param bool Default to not skip processing the current image.
* @param array An array of attributes via wp_kses_hair() for the current image.
*/
if ( apply_filters( 'jetpack_lazy_images_skip_image_with_atttributes', false, $attributes ) ) {
return $attributes;
}
/**
* Allow plugins and themes to conditionally skip processing an image via its attributes.
*
* @module-lazy-images
*
* @since 6.5.0 Filter name was updated from jetpack_lazy_images_skip_image_with_atttributes to correct typo.
* @since 5.9.0
*
* @param bool Default to not skip processing the current image.
* @param array An array of attributes via wp_kses_hair() for the current image.
*/
if ( apply_filters( 'jetpack_lazy_images_skip_image_with_attributes', false, $attributes ) ) {
return $attributes;
}
$old_attributes = $attributes;
// Stash srcset and sizes in data attributes.
foreach ( array( 'srcset', 'sizes' ) as $attribute ) {
if ( isset( $old_attributes[ $attribute ] ) ) {
$attributes[ "data-lazy-$attribute" ] = $old_attributes[ $attribute ];
unset( $attributes[ $attribute ] );
}
}
// We set this, adding the query arg so that it doesn't exactly equal the src attribute, so that photon JavaScript
// will hold off on processing this image.
$attributes['data-lazy-src'] = esc_url_raw( add_query_arg( 'is-pending-load', true, $attributes['src'] ) );
$attributes['srcset'] = self::get_placeholder_image();
$attributes['class'] = sprintf(
'%s jetpack-lazy-image',
empty( $old_attributes['class'] )
? ''
: $old_attributes['class']
);
/**
* Allow plugins and themes to override the attributes on the image before the content is updated.
*
* One potential use of this filter is for themes that set `height:auto` on the `img` tag.
* With this filter, the theme could get the width and height attributes from the
* $attributes array and then add a style tag that sets those values as well, which could
* minimize reflow as images load.
*
* @module lazy-images
*
* @since 5.6.0
*
* @param array An array containing the attributes for the image, where the key is the attribute name
* and the value is the attribute value.
*/
return apply_filters( 'jetpack_lazy_images_new_attributes', $attributes );
}
/**
* Adds JavaScript to check if the current browser supports JavaScript as well as some styles to hide lazy
* images when the browser does not support JavaScript.
*
* @return void
*/
public function add_nojs_fallback() {
?>
<style type="text/css">
/* If html does not have either class, do not show lazy loaded images. */
html:not( .jetpack-lazy-images-js-enabled ):not( .js ) .jetpack-lazy-image {
display: none;
}
</style>
<script>
document.documentElement.classList.add(
'jetpack-lazy-images-js-enabled'
);
</script>
<?php
}
/**
* Retrieves the placeholder image after running it through the lazyload_images_placeholder_image filter.
*
* @return string The placeholder image source.
*/
private static function get_placeholder_image() {
/**
* Allows plugins and themes to modify the placeholder image.
*
* This filter is not prefixed with jetpack_ to provide a smoother migration
* process from the WordPress Lazy Load plugin.
*
* @module lazy-images
*
* @since 5.6.0
* @since 6.5.0 Default image is now a base64 encoded transparent gif.
*
* @param string The URL to the placeholder image
*/
return apply_filters(
'lazyload_images_placeholder_image',
'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7'
);
}
private static function flatten_kses_hair_data( $attributes ) {
$flattened_attributes = array();
foreach ( $attributes as $name => $attribute ) {
$flattened_attributes[ $name ] = $attribute['value'];
}
return $flattened_attributes;
}
private static function build_attributes_string( $attributes ) {
$string = array();
foreach ( $attributes as $name => $value ) {
if ( '' === $value ) {
$string[] = sprintf( '%s', $name );
} else {
$string[] = sprintf( '%s="%s"', $name, esc_attr( $value ) );
}
}
return implode( ' ', $string );
}
public function enqueue_assets() {
wp_enqueue_script(
'jetpack-lazy-images',
Jetpack::get_file_url_for_environment(
'_inc/build/lazy-images/js/lazy-images.min.js',
'modules/lazy-images/js/lazy-images.js'
),
array( 'jquery' ),
JETPACK__VERSION,
true
);
}
}
|
GitWeb