includes/libs/CSSMin.php

   1 <?php
   2 /*
   3  * Copyright 2010 Wikimedia Foundation
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
   6  * the License. You may obtain a copy of the License at
   7  *
   8  *              http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
  11  * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
  12  * specific language governing permissions and limitations under the License.
  13  */
  14
  15 /**
  16  * Transforms CSS data
  17  *
  18  * This class provides minification, URL remapping, URL extracting, and data-URL embedding.
  19  *
  20  * @file
  21  * @version 0.1.0 -- 2010-09-09
  22  * @author Trevor Parscal <tparscal@wikimedia.org>
  23  * @copyright Copyright 2010 Wikimedia Foundation
  24  * @license http://www.apache.org/licenses/LICENSE-2.0
  25  */
  26 class CSSMin {
  27
  28         /* Constants */
  29
  30         /**
  31          * Maximum file size to still qualify for in-line embedding as a data-URI
  32          *
  33          * 24,576 is used because Internet Explorer has a 32,768 byte limit for data URIs, which when base64 encoded will
  34          * result in a 1/3 increase in size.
  35          */
  36         const EMBED_SIZE_LIMIT = 24576;
  37         const URL_REGEX = 'url\([\'"]?(?<file>[^\?\)\:\'"]*)\??[^\)\'"]*[\'"]?\)';
  38
  39         /* Protected Static Members */
  40
  41         /** @var array List of common image files extensions and mime-types */
  42         protected static $mimeTypes = array(
  43                 'gif' => 'image/gif',
  44                 'jpe' => 'image/jpeg',
  45                 'jpeg' => 'image/jpeg',
  46                 'jpg' => 'image/jpeg',
  47                 'png' => 'image/png',
  48                 'tif' => 'image/tiff',
  49                 'tiff' => 'image/tiff',
  50                 'xbm' => 'image/x-xbitmap',
  51         );
  52
  53         /* Static Methods */
  54
  55         /**
  56          * Gets a list of local file paths which are referenced in a CSS style sheet
  57          *
  58          * @param $source string CSS data to remap
  59          * @param $path string File path where the source was read from (optional)
  60          * @return array List of local file references
  61          */
  62         public static function getLocalFileReferences( $source, $path = null ) {
  63                 $files = array();
  64                 if ( preg_match_all( '/' . self::URL_REGEX . '/', $source, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER ) ) {
  65                         foreach ( $matches as $match ) {
  66                                 $file = ( isset( $path ) ? rtrim( $path, '/' ) . '/' : '' ) . "{$match['file'][0]}";
  67
  68                                 // Only proceed if we can access the file
  69                                 if ( file_exists( $file ) ) {
  70                                         $files[] = $file;
  71                                 }
  72                         }
  73                 }
  74                 return $files;
  75         }
  76
  77         /**
  78          * Remaps CSS URL paths and automatically embeds data URIs for URL rules preceded by an /* @embed * / comment
  79          *
  80          * @param $source string CSS data to remap
  81          * @param $path string File path where the source was read from
  82          * @return string Remapped CSS data
  83          */
  84         public static function remap( $source, $path, $embed = true ) {
  85                 $pattern = '/((?<embed>\s*\/\*\s*\@embed\s*\*\/)(?<pre>[^\;\}]*))?' . self::URL_REGEX . '(?<post>[^;]*)[\;]?/';
  86                 $offset = 0;
  87                 while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
  88                         // Shortcuts
  89                         $embed = $match['embed'][0];
  90                         $pre = $match['pre'][0];
  91                         $post = $match['post'][0];
  92                         $file = "{$path}/{$match['file'][0]}";
  93                         // Only proceed if we can access the file
  94                         if ( file_exists( $file ) ) {
  95                                 // Add version parameter as a time-stamp in ISO 8601 format, using Z for the timezone, meaning GMT
  96                                 $url = "{$file}?" . gmdate( 'Y-m-d\TH:i:s\Z', round( filemtime( $file ), -2 ) );
  97                                 // If we the mime-type can't be determined, no embedding will take place
  98                                 $type = false;
  99                                 // Try a couple of different ways to get the mime-type of a file, in order of preference
 100                                 if ( function_exists( 'finfo_file' ) && function_exists( 'finfo_open' ) ) {
 101                                         // As of PHP 5.3, this is how you get the mime-type of a file; it uses the Fileinfo PECL extension
 102                                         $type = finfo_file( finfo_open( FILEINFO_MIME_TYPE ), $file );
 103                                 } else if ( function_exists( 'mime_content_type' ) ) {
 104                                         // Before this was deprecated in PHP 5.3, this used to be how you get the mime-type of a file
 105                                         $type = mime_content_type( $file );
 106                                 } else {
 107                                         // Worst-case scenario has happend, use the file extension to infer the mime-type
 108                                         $ext = strtolower( pathinfo( $file, PATHINFO_EXTENSION ) );
 109                                         if ( isset( self::$mimeTypes[$ext] ) ) {
 110                                                 $type = self::$mimeTypes[$ext];
 111                                         }
 112                                 }
 113                                 // Detect when URLs were preceeded with embed tags, and also verify file size is below the limit
 114                                 if ( $embed && $type && $match['embed'][1] > 0 && filesize( $file ) < self::EMBED_SIZE_LIMIT ) {
 115                                         // Strip off any trailing = symbols (makes browsers freak out)
 116                                         $data = base64_encode( file_get_contents( $file ) );
 117                                         // Build 2 CSS properties; one which uses a base64 encoded data URI in place of the @embed
 118                                         // comment to try and retain line-number integrity , and the other with a remapped an versioned
 119                                         // URL and an Internet Explorer hack making it ignored in all browsers that support data URIs
 120                                         $replacement = "{$pre}url(data:{$type};base64,{$data}){$post};{$pre}url({$url}){$post}!ie;";
 121                                 } else {
 122                                         // Build a CSS property with a remapped and versioned URL, preserving comment for debug mode
 123                                         $replacement = "{$embed}{$pre}url({$url}){$post};";
 124                                 }
 125
 126                                 // Perform replacement on the source
 127                                 $source = substr_replace( $source, $replacement, $match[0][1], strlen( $match[0][0] ) );
 128                                 // Move the offset to the end of the replacement in the source
 129                                 $offset = $match[0][1] + strlen( $replacement );
 130                                 continue;
 131                         }
 132                         // Move the offset to the end of the match, leaving it alone
 133                         $offset = $match[0][1] + strlen( $match[0][0] );
 134                 }
 135                 return $source;
 136         }
 137
 138         /**
 139          * Removes whitespace from CSS data
 140          *
 141          * @param $source string CSS data to minify
 142          * @return string Minified CSS data
 143          */
 144         public static function minify( $css ) {
 145                 return trim(
 146                         str_replace(
 147                                 array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
 148                                 array( ';', ':', '{', '{', ',', '}', '}' ),
 149                                 preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
 150                         )
 151                 );
 152         }
 153 }