TimberPhoton.php

<?php
/*
Plugin Name: Timber with Jetpack Photon
Plugin URI: http://slimndap.com
Description: Make the Timber plugin work with Jetpack's Photon. Once installed, all TimberImages will use Photon as a CDN and for image manipulation (eg. resize).
Author: Jeroen Schmit
Version: 0.4
Author URI: http://slimndap.com
*/	

class TimberPhoton {
	function __construct() {
		$this->admin_notices = array();
		$this->photon_hosts = array(
			'i0.wp.com', 
			'i1.wp.com',
			'i2.wp.com'
		);
		
		add_action('plugins_loaded',array($this,'plugins_loaded'));
		
	}
	
	function twig_apply_filters($twig) {
		$twig->addFilter('resize', new Twig_Filter_Function(array($this, 'resize')));
		$twig->addFilter('letterbox', new Twig_Filter_Function(array($this, 'letterbox')));
		return $twig;
	}
	
	function admin_notices() {
		if (!empty($this->admin_notices)) {
			echo '<div class="error"><p>';
			if (in_array('timber', $this->admin_notices)) {
				_e('Timber with Jetpack Photon requires the Timber plugin to be installed and activated. <a href="http://jarednova.github.io/timber/">Get it here</a>.');				
			}
			if (in_array('photon', $this->admin_notices)) {
				_e('Timber with Jetpack Photon requires the Jetpack plugin to be installed with Photon activated.');				
			}
			echo '</p></div>';
		}
	}
	
	
	function letterbox($src, $w, $h, $color = '#000000', $force = false) {

		/* 
		 * Translate the URL.
		 * Only necessary for Timber versions (0.18.0 and older) that lack the 'timber_image_src' filter.
		 */
		 
		$src = $this->photon_url($src);
				
		/* Apply letterbox
		 * Photon docs: Add black letterboxing effect to images, by scaling them to width, height 
		 * while maintaining the aspect ratio and filling the rest with black. 
		 * See: http://developer.wordpress.com/docs/photon/api/#lb
		 */

		$args = array(
			'lb' => $w.','.$h
		);
		 
		$src = add_query_arg($args, $src);
		
		return $src;
	}
	
	
	function resize($src, $w, $h = 0, $crop = 'default', $force_resize = false ) {
		if (empty($src)){
			return '';
		}
		
		/* 
		 * Translate the URL.
		 * Only necessary for Timber versions (0.18.0 and older) that lack the 'timber_image_src' filter.
		 */
		 
		$src = $this->photon_url($src);

		/* Set width
		 * Photon docs: Set the width of an image. Defaults to pixels, supports percentages. 
		 * See: http://developer.wordpress.com/docs/photon/api/#w
		 */
		 
		$args = array(
			'w' => $w
		);
		
		/* Use resize if height is set
		 * Photon docs: Resize and crop an image to exact width,height pixel dimensions. 
		 * Set the first number as close to the target size as possible and then crop the rest. 
		 * Which direction it’s resized and cropped depends on the aspect ratios of the original image and the target size.
		 * See: http://developer.wordpress.com/docs/photon/api/#resize
		 */
		 
		if (!empty($h)) {
			$args['resize'] = $w.','.$h;
			unset ($args['w']);
		}

		$src = add_query_arg($args, $src);
	
		return $src;
	}
	
	/**
	 * Activates hooks that add Photon support to Timber.
	 *
	 * @since	0.1
	 * @since	0.4	Added support for the renamed 'timber/twig/filters' in Timber.
	 * 
	 * @return void
	 */
	function plugins_loaded() {
		if ($this->system_ready()) {
			add_action('timber/twig/filters', array(&$this, 'twig_apply_filters'), 99);
			add_action('twig_apply_filters', array(&$this, 'twig_apply_filters'), 99);
			add_filter('timber_image_src', array($this, 'timber_image_src'));
		}		
	}
	
	/*
	 * Translate a URL to a Photon URL.
	 * Photon docs: http://i0.wp.com/$REMOTE_IMAGE_URL
	 */
	
	function photon_url($url) {
		if ($parsed = parse_url($url)) {
			if (in_array($parsed['host'], $this->photon_hosts)) {
				// $url is already a Photon URL.
				// Leave it alone.
			} else {
				// Strip http:// from $url.
				$stripped_url = $parsed['host'].$parsed['path'];

				$args = array();
				
				if (!empty($parsed['query'])) {
					$args = parse_str($parsed['query']);
				}
				
				$args = apply_filters('jetpack_photon_pre_args', $args, $url, $parsed['scheme']);

				if (!empty($args)) {
					$stripped_url.= '?'.http_build_query( $args );
				}
				
				/*
				 * Pick a Photon host based on the crc32 of the stripped_url.
				 * Photon docs: Multiple domains. In order to take advantage of parallel downloads 
				 * we support multiple sub-domains for Photon. If you tend to have many images per 
				 * page you can split them across i0.wp.com, i1.wp.com, and i2.wp.com.
				 */
				$photon_host =  $this->photon_hosts[abs(crc32($stripped_url) % 2)];

				// Create a Photon URL.
				$url = $parsed['scheme'].'://'.$photon_host.'/'.$stripped_url;		
			}
		}
		return $url;
	}
	
	/*
	 * Check if Timber and Jetpack are installed and activated.
	 * Check if Photon is activated
	 */
	
	function system_ready() {
		global $timber;
	
		// Is Timber installed and activated?
		if (!class_exists('Timber')) {
			$this->admin_notices[] = 'timber';
			add_action( 'admin_notices', array($this,'admin_notices'));
			return false;
		}
		
		// Determine if Jetpack is installed and can generate photon URLs.
		if (!class_exists( 'Jetpack' ) || !method_exists( 'Jetpack', 'get_active_modules' ) || !in_array( 'photon', Jetpack::get_active_modules() )) {
			$this->admin_notices[] = 'photon';
			add_action( 'admin_notices', array($this,'admin_notices'));
			return false;
		}
		
		return true;
	}
	
	function timber_image_src($src) {
		return $this->photon_url($src);
	}
}

new TimberPhoton();

?>