includes/libs/CSSMin.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  */
  18
  19 /**
  20  * Transforms CSS data
  21  *
  22  * This class provides minification, URL remapping, URL extracting, and data-URL embedding.
  23  *
  24  * @author Trevor Parscal
  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
  38         /* Protected Static Members */
  39
  40         /** @var array List of common image files extensions and mime-types */
  41         protected static $mimeTypes = array(
  42                 'gif' => 'image/gif',
  43                 'jpe' => 'image/jpeg',
  44                 'jpeg' => 'image/jpeg',
  45                 'jpg' => 'image/jpeg',
  46                 'png' => 'image/png',
  47                 'tif' => 'image/tiff',
  48                 'tiff' => 'image/tiff',
  49                 'xbm' => 'image/x-xbitmap',
  50         );
  51
  52         /* Static Methods */
  53
  54         /**
  55          * Gets a list of local file paths which are referenced in a CSS style sheet
  56          *
  57          * @param $source string CSS data to remap
  58          * @param $path string File path where the source was read from (optional)
  59          * @return array List of local file references
  60          */
  61         public static function getLocalFileReferences( $source, $path = null ) {
  62                 $pattern = '/url\([\'"]?(?<file>[^\?\)\:]*)\??[^\)]*[\'"]?\)/';
  63                 $files = array();
  64                 if ( preg_match_all( $pattern, $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*\*\/)(?<rule>[^\;\}]*))?url\([\'"]?(?<file>[^\?\)\:]*)\??[^\)]*[\'"]?\)(?<extra>[^;]*)[\;]?/';
  86                 $offset = 0;
  87                 while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
  88                         // Shortcuts
  89                         $embed = $match['embed'][0];
  90                         $rule = $match['rule'][0];
  91                         $extra = $match['extra'][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                                         $replacement = "{$rule}url(data:{$type};base64,{$data}){$extra};{$rule}url({$url}){$extra}!ie;";
 121                                 } else {
 122                                         // Build a CSS property with a remapped and versioned URL
 123                                         $replacement = "{$embed}{$rule}url({$url}){$extra};";
 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 }