Created
July 22, 2014 21:55
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| <?php | |
| /** | |
| * Plugin Name: Lazy Load | |
| * Description: Lazy load images to improve page load times. Uses jQuery.sonar to only load an image when it's visible in the viewport. | |
| * Version: 0.6 | |
| * | |
| * Code by the WordPress.com VIP team, TechCrunch 2011 Redesign team, and Jake Goldman (10up LLC). | |
| * Uses jQuery.sonar by Dave Artz (AOL): http://www.artzstudio.com/files/jquery-boston-2010/jquery.sonar/ | |
| * | |
| * License: GPL2 | |
| */ | |
| if ( ! class_exists( 'LazyLoad_Images' ) ) : | |
| class LazyLoad_Images { | |
| const version = '0.6'; | |
| protected static $enabled = true; | |
| static function init() { | |
| if ( is_admin() ) | |
| return; | |
| if ( ! apply_filters( 'lazyload_is_enabled', true ) ) { | |
| self::$enabled = false; | |
| return; | |
| } | |
| add_action( 'wp_enqueue_scripts', array( __CLASS__, 'add_scripts' ) ); | |
| add_action( 'wp_head', array( __CLASS__, 'setup_filters' ), 9999 ); // we don't really want to modify anything in <head> since it's mostly all metadata, e.g. OG tags | |
| } | |
| static function setup_filters() { | |
| add_filter( 'the_content', array( __CLASS__, 'add_image_placeholders' ), 99 ); // run this later, so other content filters have run, including image_add_wh on WP.com | |
| add_filter( 'post_thumbnail_html', array( __CLASS__, 'add_image_placeholders' ), 11 ); | |
| add_filter( 'get_avatar', array( __CLASS__, 'add_image_placeholders' ), 11 ); | |
| } | |
| static function add_scripts() { | |
| wp_enqueue_script( 'wpcom-lazy-load-images', self::get_url( 'js/lazy-load.js' ), array( 'jquery', 'jquery-sonar' ), self::version, true ); | |
| wp_enqueue_script( 'jquery-sonar', self::get_url( 'js/jquery.sonar.min.js' ), array( 'jquery' ), self::version, true ); | |
| } | |
| static function add_image_placeholders( $content ) { | |
| if ( ! self::is_enabled() ) | |
| return $content; | |
| // Don't lazyload for feeds, previews, mobile | |
| 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; | |
| // In case you want to change the placeholder image | |
| $placeholder_image = apply_filters( 'lazyload_images_placeholder_image', self::get_url( 'images/1x1.trans.gif' ) ); | |
| // This is a pretty simple regex, but it works | |
| $content = preg_replace( '#<img([^>]+?)src=[\'"]?([^\'"\s>]+)[\'"]?([^>]*)>#', sprintf( '<img${1}src="%s" data-lazy-src="${2}"${3}><noscript><img${1}src="${2}"${3}></noscript>', $placeholder_image ), $content ); | |
| return $content; | |
| } | |
| static function is_enabled() { | |
| return self::$enabled; | |
| } | |
| static function get_url( $path = '' ) { | |
| return plugins_url( ltrim( $path, '/' ), __FILE__ ); | |
| } | |
| } | |
| function lazyload_images_add_placeholders( $content ) { | |
| return LazyLoad_Images::add_image_placeholders( $content ); | |
| } | |
| add_action( 'init', array( 'LazyLoad_Images', 'init' ) ); | |
| endif; |
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