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
   6  * not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *              http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software distributed
  12  * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
  13  * OF ANY KIND, either express or implied. See the License for the
  14  * specific language governing permissions and limitations under the License.
  15  */
  16
  17 /**
  18  * Transforms CSS data
  19  *
  20  * This class provides minification, URL remapping, URL extracting, and data-URL embedding.
  21  *
  22  * @file
  23  * @version 0.1.1 -- 2010-09-11
  24  * @author Trevor Parscal <tparscal@wikimedia.org>
  25  * @copyright Copyright 2010 Wikimedia Foundation
  26  * @license http://www.apache.org/licenses/LICENSE-2.0
  27  */
  28 class CSSMin {
  29
  30         /* Constants */
  31
  32         /**
  33          * Maximum file size to still qualify for in-line embedding as a data-URI
  34          *
  35          * 24,576 is used because Internet Explorer has a 32,768 byte limit for data URIs,
  36          * which when base64 encoded will result in a 1/3 increase in size.
  37          */
  38         const EMBED_SIZE_LIMIT = 24576;
  39         const URL_REGEX = 'url\(\s*[\'"]?(?P<file>[^\?\)\:\'"]*)\??[^\)\'"]*[\'"]?\s*\)';
  40
  41         /* Protected Static Members */
  42
  43         /** @var array List of common image files extensions and mime-types */
  44         protected static $mimeTypes = array(
  45                 'gif' => 'image/gif',
  46                 'jpe' => 'image/jpeg',
  47                 'jpeg' => 'image/jpeg',
  48                 'jpg' => 'image/jpeg',
  49                 'png' => 'image/png',
  50                 'tif' => 'image/tiff',
  51                 'tiff' => 'image/tiff',
  52                 'xbm' => 'image/x-xbitmap',
  53         );
  54
  55         /* Static Methods */
  56
  57         /**
  58          * Gets a list of local file paths which are referenced in a CSS style sheet
  59          *
  60          * @param $source string CSS data to remap
  61          * @param $path string File path where the source was read from (optional)
  62          * @return array List of local file references
  63          */
  64         public static function getLocalFileReferences( $source, $path = null ) {
  65                 $files = array();
  66                 $rFlags = PREG_OFFSET_CAPTURE | PREG_SET_ORDER;
  67                 if ( preg_match_all( '/' . self::URL_REGEX . '/', $source, $matches, $rFlags ) ) {
  68                         foreach ( $matches as $match ) {
  69                                 $file = ( isset( $path )
  70                                         ? rtrim( $path, '/' ) . '/'
  71                                         : '' ) . "{$match['file'][0]}";
  72
  73                                 // Only proceed if we can access the file
  74                                 if ( !is_null( $path ) && file_exists( $file ) ) {
  75                                         $files[] = $file;
  76                                 }
  77                         }
  78                 }
  79                 return $files;
  80         }
  81
  82         /**
  83          * Remaps CSS URL paths and automatically embeds data URIs for URL rules
  84          * preceded by an /* @embed * / comment
  85          *
  86          * @param $source string CSS data to remap
  87          * @param $local string File path where the source was read from
  88          * @param $remote string URL path to the file
  89          * @param $embed ???
  90          * @return string Remapped CSS data
  91          */
  92         public static function remap( $source, $local, $remote, $embed = true ) {
  93                 $pattern = '/((?P<embed>\s*\/\*\s*\@embed\s*\*\/)(?P<pre>[^\;\}]*))?' .
  94                         self::URL_REGEX . '(?P<post>[^;]*)[\;]?/';
  95                 $offset = 0;
  96                 while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
  97                         // Shortcuts
  98                         $embed = $match['embed'][0];
  99                         $pre = $match['pre'][0];
 100                         $post = $match['post'][0];
 101                         $file = "{$local}/{$match['file'][0]}";
 102                         $url = "{$remote}/{$match['file'][0]}";
 103                         // Only proceed if we can access the file
 104                         if ( file_exists( $file ) ) {
 105                                 // Add version parameter as a time-stamp in ISO 8601 format,
 106                                 // using Z for the timezone, meaning GMT
 107                                 $url .= '?' . gmdate( 'Y-m-d\TH:i:s\Z', round( filemtime( $file ), -2 ) );
 108                                 // If we the mime-type can't be determined, no embedding will take place
 109                                 $type = false;
 110                                 $realpath = realpath( $file );
 111                                 // Try a couple of different ways to get the mime-type of a file,
 112                                 // in order of preference
 113                                 if ( $realpath
 114                                         && function_exists( 'finfo_file' ) && function_exists( 'finfo_open' )
 115                                         && defined( 'FILEINFO_MIME_TYPE' ) )
 116                                 {
 117                                         // As of PHP 5.3, this is how you get the mime-type of a file;
 118                                         // it uses the Fileinfo PECL extension
 119                                         $type = finfo_file( finfo_open( FILEINFO_MIME_TYPE ), $realpath );
 120                                 } else if ( function_exists( 'mime_content_type' ) ) {
 121                                         // Before this was deprecated in PHP 5.3,
 122                                         // this used to be how you get the mime-type of a file
 123                                         $type = mime_content_type( $file );
 124                                 } else {
 125                                         // Worst-case scenario has happened,
 126                                         // use the file extension to infer the mime-type
 127                                         $ext = strtolower( pathinfo( $file, PATHINFO_EXTENSION ) );
 128                                         if ( isset( self::$mimeTypes[$ext] ) ) {
 129                                                 $type = self::$mimeTypes[$ext];
 130                                         }
 131                                 }
 132                                 // Detect when URLs were preceeded with embed tags,
 133                                 // and also verify file size is below the limit
 134                                 if ( $embed && $type && $match['embed'][1] > 0
 135                                         && filesize( $file ) < self::EMBED_SIZE_LIMIT )
 136                                 {
 137                                         // Strip off any trailing = symbols (makes browsers freak out)
 138                                         $data = base64_encode( file_get_contents( $file ) );
 139                                         // Build 2 CSS properties; one which uses a base64 encoded data URI
 140                                         // in place of the @embed comment to try and retain line-number integrity,
 141                                         // and the other with a remapped an versioned URL and an Internet Explorer
 142                                         // hack making it ignored in all browsers that support data URIs
 143                                         $replacement = "{$pre}url(data:{$type};base64,{$data}){$post};";
 144                                         $replacement .= "{$pre}url({$url}){$post}!ie;";
 145                                 } else {
 146                                         // Build a CSS property with a remapped and versioned URL,
 147                                         // preserving comment for debug mode
 148                                         $replacement = "{$embed}{$pre}url({$url}){$post};";
 149                                 }
 150
 151                                 // Perform replacement on the source
 152                                 $source = substr_replace( $source,
 153                                         $replacement, $match[0][1], strlen( $match[0][0] ) );
 154                                 // Move the offset to the end of the replacement in the source
 155                                 $offset = $match[0][1] + strlen( $replacement );
 156                                 continue;
 157                         }
 158                         // Move the offset to the end of the match, leaving it alone
 159                         $offset = $match[0][1] + strlen( $match[0][0] );
 160                 }
 161                 return $source;
 162         }
 163
 164         /**
 165          * Removes whitespace from CSS data
 166          *
 167          * @param $css string CSS data to minify
 168          * @return string Minified CSS data
 169          */
 170         public static function minify( $css ) {
 171                 return trim(
 172                         str_replace(
 173                                 array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
 174                                 array( ';', ':', '{', '{', ',', '}', '}' ),
 175                                 preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
 176                         )
 177                 );
 178         }
 179 }