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         /* Static Methods */
  39
  40         /**
  41          * Gets a list of local file paths which are referenced in a CSS style sheet
  42          *
  43          * @param $source string CSS data to remap
  44          * @param $path string File path where the source was read from (optional)
  45          * @return array List of local file references
  46          */
  47         public static function getLocalFileReferences( $source, $path = null ) {
  48                 $pattern = '/url\([\'"]?(?<file>[^\?\)\:]*)\??[^\)]*[\'"]?\)/';
  49                 $files = array();
  50
  51                 if ( preg_match_all( $pattern, $source, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER ) ) {
  52                         foreach ( $matches as $match ) {
  53                                 $file = ( isset( $path ) ? rtrim( $path, '/' ) . '/' : '' ) . "{$match['file'][0]}";
  54
  55                                 // Only proceed if we can access the file
  56                                 if ( file_exists( $file ) ) {
  57                                         $files[] = $file;
  58                                 }
  59                         }
  60                 }
  61
  62                 return $files;
  63         }
  64
  65         /**
  66          * Remaps CSS URL paths and automatically embeds data URIs for URL rules preceded by an /* @embed * / comment
  67          *
  68          * @param $source string CSS data to remap
  69          * @param $path string File path where the source was read from
  70          * @return string Remapped CSS data
  71          */
  72         public static function remap( $source, $path, $embed = true ) {
  73
  74                 $pattern = '/((?<embed>\s*\/\*\s*\@embed\s*\*\/)(?<rule>[^\;\}]*))?url\([\'"]?(?<file>[^\?\)\:]*)\??[^\)]*[\'"]?\)(?<extra>[^;]*)[\;]?/';
  75                 $offset = 0;
  76
  77                 while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
  78                         // Shortcuts
  79                         $embed = $match['embed'][0];
  80                         $rule = $match['rule'][0];
  81                         $extra = $match['extra'][0];
  82                         $file = "{$path}/{$match['file'][0]}";
  83
  84                         // Only proceed if we can access the file
  85                         if ( file_exists( $file ) ) {
  86                                 // Add version parameter as a time-stamp in ISO 8601 format, using Z for the timezone, meaning GMT
  87                                 $url = "{$file}?" . gmdate( 'Y-m-d\TH:i:s\Z', round( filemtime( $file ), -2 ) );
  88
  89                                 // Detect when URLs were preceeded with embed tags, and also verify file size is below the limit
  90                                 if ( $embed && $match['embed'][1] > 0 && filesize( $file ) < self::EMBED_SIZE_LIMIT ) {
  91                                         // If we ever get to PHP 5.3, we should use the Fileinfo extension instead of mime_content_type
  92                                         $type = mime_content_type( $file );
  93                                         // Strip off any trailing = symbols (makes browsers freak out)
  94                                         $data = base64_encode( file_get_contents( $file ) );
  95                                         // Build 2 CSS properties; one which uses a base64 encoded data URI in place of the @embed
  96                                         // comment to try and retain line-number integrity , and the other with a remapped an versioned
  97                                         // URL and an Internet Explorer hack making it ignored in all browsers that support data URIs
  98                                         $replacement = "{$rule}url(data:{$type};base64,{$data}){$extra};{$rule}url({$url}){$extra}!ie;";
  99                                 } else {
 100                                         // Build a CSS property with a remapped and versioned URL
 101                                         $replacement = "{$embed}{$rule}url({$url}){$extra};";
 102                                 }
 103
 104                                 // Perform replacement on the source
 105                                 $source = substr_replace( $source, $replacement, $match[0][1], strlen( $match[0][0] ) );
 106                                 // Move the offset to the end of the replacement in the source
 107                                 $offset = $match[0][1] + strlen( $replacement );
 108                                 continue;
 109                         }
 110                         // Move the offset to the end of the match, leaving it alone
 111                         $offset = $match[0][1] + strlen( $match[0][0] );
 112                 }
 113
 114                 return $source;
 115         }
 116
 117         /**
 118          * Removes whitespace from CSS data
 119          *
 120          * @param $source string CSS data to minify
 121          * @return string Minified CSS data
 122          */
 123         public static function minify( $css ) {
 124                 return trim(
 125                         str_replace(
 126                                 array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
 127                                 array( ';', ':', '{', '{', ',', '}', '}' ),
 128                                 preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
 129                         )
 130                 );
 131         }
 132 }