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| 1 | +<?php |
| 2 | + |
| 3 | +class Jetpack_Lazy_Images { |
| 4 | + private static $__instance = null; |
| 5 | + |
| 6 | + /** |
| 7 | + * Singleton implementation |
| 8 | + * |
| 9 | + * @return object |
| 10 | + */ |
| 11 | + public static function instance() { |
| 12 | + if ( is_null( self::$__instance ) ) { |
| 13 | + self::$__instance = new Jetpack_Lazy_Images(); |
| 14 | + } |
| 15 | + |
| 16 | + return self::$__instance; |
| 17 | + } |
| 18 | + |
| 19 | + /** |
| 20 | + * Registers actions |
| 21 | + */ |
| 22 | + private function __construct() { |
| 23 | + if ( is_admin() ) { |
| 24 | + return; |
| 25 | + } |
| 26 | + |
| 27 | + /** |
| 28 | + * Whether the lazy-images module should load. |
| 29 | + * |
| 30 | + * This filter is not prefixed with jetpack_ to provide a smoother migration |
| 31 | + * process from the WordPress Lazy Load plugin. |
| 32 | + * |
| 33 | + * @module lazy-images |
| 34 | + * |
| 35 | + * @since 5.6.0 |
| 36 | + * |
| 37 | + * @param bool true Whether lazy image loading should occur. |
| 38 | + */ |
| 39 | + if ( ! apply_filters( 'lazyload_is_enabled', true ) ) { |
| 40 | + return; |
| 41 | + } |
| 42 | + |
| 43 | + 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 |
| 44 | + add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_assets' ) ); |
| 45 | + |
| 46 | + // Do not lazy load avatar in admin bar |
| 47 | + add_action( 'admin_bar_menu', array( $this, 'remove_filters' ), 0 ); |
| 48 | + } |
| 49 | + |
| 50 | + public function setup_filters() { |
| 51 | + add_filter( 'the_content', array( $this, 'add_image_placeholders' ), 99 ); // run this later, so other content filters have run, including image_add_wh on WP.com |
| 52 | + add_filter( 'post_thumbnail_html', array( $this, 'add_image_placeholders' ), 11 ); |
| 53 | + add_filter( 'get_avatar', array( $this, 'add_image_placeholders' ), 11 ); |
| 54 | + } |
| 55 | + |
| 56 | + public function remove_filters() { |
| 57 | + remove_filter( 'the_content', array( $this, 'add_image_placeholders' ), 99 ); |
| 58 | + remove_filter( 'post_thumbnail_html', array( $this, 'add_image_placeholders' ), 11 ); |
| 59 | + remove_filter( 'get_avatar', array( $this, 'add_image_placeholders' ), 11 ); |
| 60 | + } |
| 61 | + |
| 62 | + public function add_image_placeholders( $content ) { |
| 63 | + // Don't lazyload for feeds, previews |
| 64 | + if ( is_feed() || is_preview() ) { |
| 65 | + return $content; |
| 66 | + } |
| 67 | + |
| 68 | + // Don't lazy-load if the content has already been run through previously |
| 69 | + if ( false !== strpos( $content, 'data-lazy-src' ) ) { |
| 70 | + return $content; |
| 71 | + } |
| 72 | + |
| 73 | + // Don't lazyload for amp-wp content |
| 74 | + if ( function_exists( 'is_amp_endpoint' ) && is_amp_endpoint() ) { |
| 75 | + return $content; |
| 76 | + } |
| 77 | + |
| 78 | + // This is a pretty simple regex, but it works |
| 79 | + $content = preg_replace_callback( '#<(img)([^>]+?)(>(.*?)</\\1>|[\/]?>)#si', array( __CLASS__, 'process_image' ), $content ); |
| 80 | + |
| 81 | + return $content; |
| 82 | + } |
| 83 | + |
| 84 | + static function process_image( $matches ) { |
| 85 | + $old_attributes_str = $matches[2]; |
| 86 | + $old_attributes_kses_hair = wp_kses_hair( $old_attributes_str, wp_allowed_protocols() ); |
| 87 | + |
| 88 | + if ( empty( $old_attributes_kses_hair['src'] ) ) { |
| 89 | + return $matches[0]; |
| 90 | + } |
| 91 | + |
| 92 | + $old_attributes = self::flatten_kses_hair_data( $old_attributes_kses_hair ); |
| 93 | + $new_attributes = $old_attributes; |
| 94 | + |
| 95 | + // Set placeholder and lazy-src |
| 96 | + $new_attributes['src'] = self::get_placeholder_image(); |
| 97 | + $new_attributes['data-lazy-src'] = $old_attributes['src']; |
| 98 | + |
| 99 | + // Handle `srcset` |
| 100 | + if ( ! empty( $new_attributes['srcset'] ) ) { |
| 101 | + $new_attributes['data-lazy-srcset'] = $old_attributes['srcset']; |
| 102 | + unset( $new_attributes['srcset'] ); |
| 103 | + } |
| 104 | + |
| 105 | + // Handle `sizes` |
| 106 | + if ( ! empty( $new_attributes['sizes'] ) ) { |
| 107 | + $new_attributes['data-lazy-sizes'] = $old_attributes['sizes']; |
| 108 | + unset( $new_attributes['sizes'] ); |
| 109 | + } |
| 110 | + |
| 111 | + $new_attributes_str = self::build_attributes_string( $new_attributes ); |
| 112 | + |
| 113 | + return sprintf( '<img %1$s><noscript>%2$s</noscript>', $new_attributes_str, $matches[0] ); |
| 114 | + } |
| 115 | + |
| 116 | + private static function get_placeholder_image() { |
| 117 | + /** |
| 118 | + * Allows plugins and themes to modify the placeholder image. |
| 119 | + * |
| 120 | + * This filter is not prefixed with jetpack_ to provide a smoother migration |
| 121 | + * process from the WordPress Lazy Load plugin. |
| 122 | + * |
| 123 | + * @module lazy-images |
| 124 | + * |
| 125 | + * @since 5.6.0 |
| 126 | + * |
| 127 | + * @param string The URL to the placeholder image |
| 128 | + */ |
| 129 | + return apply_filters( |
| 130 | + 'lazyload_images_placeholder_image', |
| 131 | + plugins_url( 'modules/lazy-images/images/1x1.trans.gif', JETPACK__PLUGIN_FILE ) |
| 132 | + ); |
| 133 | + } |
| 134 | + |
| 135 | + private static function flatten_kses_hair_data( $attributes ) { |
| 136 | + $flattened_attributes = array(); |
| 137 | + foreach ( $attributes as $name => $attribute ) { |
| 138 | + $flattened_attributes[ $name ] = $attribute['value']; |
| 139 | + } |
| 140 | + return $flattened_attributes; |
| 141 | + } |
| 142 | + |
| 143 | + private static function build_attributes_string( $attributes ) { |
| 144 | + $string = array(); |
| 145 | + foreach ( $attributes as $name => $value ) { |
| 146 | + if ( '' === $value ) { |
| 147 | + $string[] = sprintf( '%s', $name ); |
| 148 | + } else { |
| 149 | + $string[] = sprintf( '%s="%s"', $name, esc_attr( $value ) ); |
| 150 | + } |
| 151 | + } |
| 152 | + return implode( ' ', $string ); |
| 153 | + } |
| 154 | + |
| 155 | + public function enqueue_assets() { |
| 156 | + wp_enqueue_script( |
| 157 | + 'jetpack-lazy-images', |
| 158 | + plugins_url( 'modules/lazy-images/js/lazy-images.js', JETPACK__PLUGIN_FILE ), |
| 159 | + array( 'jquery' ), |
| 160 | + JETPACK__VERSION, |
| 161 | + true |
| 162 | + ); |
| 163 | + } |
| 164 | +} |
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