includes/CSSMin.php

   1 <?php
   2
   3 class CSSMin {
   4
   5         /* Constants */
   6
   7         /**
   8          * Maximum file size to still qualify for in-line embedding as a data-URI
   9          *
  10          * 24,576 is used because Internet Explorer has a 32,768 byte limit for data URIs, which when base64 encoded will
  11          * result in a 1/3 increase in size.
  12          */
  13         const EMBED_SIZE_LIMIT = 24576;
  14
  15         /* Static Methods */
  16
  17         /**
  18          * Gets a list of local file paths which are referenced in a CSS style sheet
  19          *
  20          * @param $source string CSS data to remap
  21          * @param $path string File path where the source was read from (optional)
  22          * @return array List of local file references
  23          */
  24         public static function getLocalFileReferences( $source, $path = null ) {
  25                 $pattern = '/url\([\'"]?(?<file>[^\?\)\:]*)\??[^\)]*[\'"]?\)/';
  26                 $files = array();
  27                 if ( preg_match_all( $pattern, $source, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER ) ) {
  28                         foreach ( $matches as $match ) {
  29                                 $file = ( isset( $path ) ? rtrim( $path, '/' ) . '/' : '' ) . "{$match['file'][0]}";
  30                                 // Only proceed if we can access the file
  31                                 if ( file_exists( $file ) ) {
  32                                         $files[] = $file;
  33                                 }
  34                         }
  35                 }
  36                 return $files;
  37         }
  38
  39         /**
  40          * Remaps CSS URL paths and automatically embeds data URIs for URL rules preceded by an /* @embed * / comment
  41          *
  42          * @param $source string CSS data to remap
  43          * @param $path string File path where the source was read from
  44          * @return string Remapped CSS data
  45          */
  46         public static function remap( $source, $path ) {
  47                 $pattern = '/((?<embed>\s*\/\*\s*\@embed\s*\*\/)(?<rule>[^\;\}]*))?url\([\'"]?(?<file>[^\?\)\:]*)\??[^\)]*[\'"]?\)(?<extra>[^;]*)[\;]?/';
  48                 $offset = 0;
  49                 while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
  50                         // Shortcuts
  51                         $embed = $match['embed'][0];
  52                         $rule = $match['rule'][0];
  53                         $extra = $match['extra'][0];
  54                         $file = "{$path}/{$match['file'][0]}";
  55                         // Only proceed if we can access the file
  56                         if ( file_exists( $file ) ) {
  57                                 // Add version parameter as a time-stamp in ISO 8601 format, using Z for the timezone, meaning GMT
  58                                 $url = "{$file}?" . gmdate( 'Y-m-d\TH:i:s\Z', round( filemtime( $file ), -2 ) );
  59                                 // Detect when URLs were preceeded with embed tags, and also verify file size is below the limit
  60                                 if ( $match['embed'][1] > 0 && filesize( $file ) < self::EMBED_SIZE_LIMIT ) {
  61                                         // If we ever get to PHP 5.3, we should use the Fileinfo extension instead of mime_content_type
  62                                         $type = mime_content_type( $file );
  63                                         // Strip off any trailing = symbols (makes browsers freak out)
  64                                         $data = rtrim( base64_encode( file_get_contents( $file ) ), '=' );
  65                                         // Build 2 CSS properties; one which uses a base64 encoded data URI in place of the @embed
  66                                         // comment to try and retain line-number integrity , and the other with a remapped an versioned
  67                                         // URL and an Internet Explorer hack making it ignored in all browsers that support data URIs
  68                                         $replacement = "{$rule}url(data:{$type};base64,{$data}){$extra};{$rule}url({$url}){$extra}!ie;";
  69                                 } else {
  70                                         // Build a CSS property with a remapped and versioned URL
  71                                         $replacement = "{$embed}{$rule}url({$url}){$extra};";
  72                                 }
  73                                 // Perform replacement on the source
  74                                 $source = substr_replace( $source, $replacement, $match[0][1], strlen( $match[0][0] ) );
  75                                 // Move the offset to the end of the replacement in the source
  76                                 $offset = $match[0][1] + strlen( $replacement );
  77                                 continue;
  78                         }
  79                         // Move the offset to the end of the match, leaving it alone
  80                         $offset = $match[0][1] + strlen( $match[0][0] );
  81                 }
  82                 return $source;
  83         }
  84
  85         /**
  86          * Removes whitespace from CSS data
  87          *
  88          * @param $source string CSS data to minify
  89          * @return string Minified CSS data
  90          */
  91         public static function minify( $css ) {
  92                 return trim(
  93                         str_replace(
  94                                 array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
  95                                 array( ';', ':', '{', '{', ',', '}', '}' ),
  96                                 preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
  97                         )
  98                 );
  99         }
 100 }