diff options
Diffstat (limited to 'plugins/jetpack/modules/lazy-images/lazy-images.php')
| -rw-r--r-- | plugins/jetpack/modules/lazy-images/lazy-images.php | 353 |
1 files changed, 353 insertions, 0 deletions
diff --git a/plugins/jetpack/modules/lazy-images/lazy-images.php b/plugins/jetpack/modules/lazy-images/lazy-images.php new file mode 100644 index 00000000..befa5ec8 --- /dev/null +++ b/plugins/jetpack/modules/lazy-images/lazy-images.php @@ -0,0 +1,353 @@ +<?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 + ); + } +} |