includes/CSSMin.php

   1 <?php
   2
   3 class CSSMin {
   4         /* Constants */
   5
   6         /**
   7          * Maximum file size to still qualify for in-line embedding as a data-URI
   8          *
   9          * 24,576 is used because Internet Explorer has a 32,768 byte limit for data URIs, which when base64 encoded will
  10          * result in a 1/3 increase in size.
  11          */
  12         const EMBED_SIZE_LIMIT = 24576;
  13
  14         /* Static Methods */
  15
  16         /**
  17          * Gets a list of local file paths which are referenced in a CSS style sheet
  18          *
  19          * @param $source string CSS data to remap
  20          * @param $path string File path where the source was read from (optional)
  21          * @return array List of local file references
  22          */
  23         public static function getLocalFileReferences( $source, $path = null ) {
  24                 $pattern = '/url\([\'"]?(?<file>[^\?\)\:]*)\??[^\)]*[\'"]?\)/';
  25                 $files = array();
  26
  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
  31                                 // Only proceed if we can access the file
  32                                 if ( file_exists( $file ) ) {
  33                                         $files[] = $file;
  34                                 }
  35                         }
  36                 }
  37
  38                 return $files;
  39         }
  40
  41         /**
  42          * Remaps CSS URL paths and automatically embeds data URIs for URL rules preceded by an /* @embed * / comment
  43          *
  44          * @param $source string CSS data to remap
  45          * @param $path string File path where the source was read from
  46          * @return string Remapped CSS data
  47          */
  48         public static function remap( $source, $path ) {
  49                 global $wgUseDataURLs;
  50
  51                 $pattern = '/((?<embed>\s*\/\*\s*\@embed\s*\*\/)(?<rule>[^\;\}]*))?url\([\'"]?(?<file>[^\?\)\:]*)\??[^\)]*[\'"]?\)(?<extra>[^;]*)[\;]?/';
  52                 $offset = 0;
  53
  54                 while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
  55                         // Shortcuts
  56                         $embed = $match['embed'][0];
  57                         $rule = $match['rule'][0];
  58                         $extra = $match['extra'][0];
  59                         $file = "{$path}/{$match['file'][0]}";
  60
  61                         // Only proceed if we can access the file
  62                         if ( file_exists( $file ) ) {
  63                                 // Add version parameter as a time-stamp in ISO 8601 format, using Z for the timezone, meaning GMT
  64                                 $url = "{$file}?" . gmdate( 'Y-m-d\TH:i:s\Z', round( filemtime( $file ), -2 ) );
  65
  66                                 // Detect when URLs were preceeded with embed tags, and also verify file size is below the limit
  67                                 if ( $wgUseDataURLs && $match['embed'][1] > 0 && filesize( $file ) < self::EMBED_SIZE_LIMIT ) {
  68                                         // If we ever get to PHP 5.3, we should use the Fileinfo extension instead of mime_content_type
  69                                         $type = mime_content_type( $file );
  70                                         // Strip off any trailing = symbols (makes browsers freak out)
  71                                         $data = base64_encode( file_get_contents( $file ) );
  72                                         // Build 2 CSS properties; one which uses a base64 encoded data URI in place of the @embed
  73                                         // comment to try and retain line-number integrity , and the other with a remapped an versioned
  74                                         // URL and an Internet Explorer hack making it ignored in all browsers that support data URIs
  75                                         $replacement = "{$rule}url(data:{$type};base64,{$data}){$extra};{$rule}url({$url}){$extra}!ie;";
  76                                 } else {
  77                                         // Build a CSS property with a remapped and versioned URL
  78                                         $replacement = "{$embed}{$rule}url({$url}){$extra};";
  79                                 }
  80
  81                                 // Perform replacement on the source
  82                                 $source = substr_replace( $source, $replacement, $match[0][1], strlen( $match[0][0] ) );
  83                                 // Move the offset to the end of the replacement in the source
  84                                 $offset = $match[0][1] + strlen( $replacement );
  85                                 continue;
  86                         }
  87                         // Move the offset to the end of the match, leaving it alone
  88                         $offset = $match[0][1] + strlen( $match[0][0] );
  89                 }
  90
  91                 return $source;
  92         }
  93
  94         /**
  95          * Removes whitespace from CSS data
  96          *
  97          * @param $source string CSS data to minify
  98          * @return string Minified CSS data
  99          */
 100         public static function minify( $css ) {
 101                 return trim(
 102                         str_replace(
 103                                 array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
 104                                 array( ';', ':', '{', '{', ',', '}', '}' ),
 105                                 preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
 106                         )
 107                 );
 108         }
 109 }