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<?php
/**
* Minification of CSS stylesheets.
*
* Copyright 2010 Wikimedia Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed
* under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
* OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*
* @file
* @version 0.1.1 -- 2010-09-11
* @author Trevor Parscal <tparscal@wikimedia.org>
* @copyright Copyright 2010 Wikimedia Foundation
* @license http://www.apache.org/licenses/LICENSE-2.0
*/
/**
* Transforms CSS data
*
* This class provides minification, URL remapping, URL extracting, and data-URL embedding.
*/
class CSSMin {
/* Constants */
/**
* Maximum file size to still qualify for in-line embedding as a data-URI
*
* 24,576 is used because Internet Explorer has a 32,768 byte limit for data URIs,
* which when base64 encoded will result in a 1/3 increase in size.
*/
const EMBED_SIZE_LIMIT = 24576;
const URL_REGEX = 'url\(\s*[\'"]?(?P<file>[^\?\)\'"]*)(?P<query>\??[^\)\'"]*)[\'"]?\s*\)';
/* Protected Static Members */
/** @var array List of common image files extensions and mime-types */
protected static $mimeTypes = array(
'gif' => 'image/gif',
'jpe' => 'image/jpeg',
'jpeg' => 'image/jpeg',
'jpg' => 'image/jpeg',
'png' => 'image/png',
'tif' => 'image/tiff',
'tiff' => 'image/tiff',
'xbm' => 'image/x-xbitmap',
);
/* Static Methods */
/**
* Gets a list of local file paths which are referenced in a CSS style sheet
*
* @param $source string CSS data to remap
* @param $path string File path where the source was read from (optional)
* @return array List of local file references
*/
public static function getLocalFileReferences( $source, $path = null ) {
$files = array();
$rFlags = PREG_OFFSET_CAPTURE | PREG_SET_ORDER;
if ( preg_match_all( '/' . self::URL_REGEX . '/', $source, $matches, $rFlags ) ) {
foreach ( $matches as $match ) {
$file = ( isset( $path )
? rtrim( $path, '/' ) . '/'
: '' ) . "{$match['file'][0]}";
// Only proceed if we can access the file
if ( !is_null( $path ) && file_exists( $file ) ) {
$files[] = $file;
}
}
}
return $files;
}
/**
* @param $file string
* @return bool|string
*/
protected static function getMimeType( $file ) {
$realpath = realpath( $file );
// Try a couple of different ways to get the mime-type of a file, in order of
// preference
if (
$realpath
&& function_exists( 'finfo_file' )
&& function_exists( 'finfo_open' )
&& defined( 'FILEINFO_MIME_TYPE' )
) {
// As of PHP 5.3, this is how you get the mime-type of a file; it uses the Fileinfo
// PECL extension
return finfo_file( finfo_open( FILEINFO_MIME_TYPE ), $realpath );
} elseif ( function_exists( 'mime_content_type' ) ) {
// Before this was deprecated in PHP 5.3, this was how you got the mime-type of a file
return mime_content_type( $file );
} else {
// Worst-case scenario has happened, use the file extension to infer the mime-type
$ext = strtolower( pathinfo( $file, PATHINFO_EXTENSION ) );
if ( isset( self::$mimeTypes[$ext] ) ) {
return self::$mimeTypes[$ext];
}
}
return false;
}
/**
* Remaps CSS URL paths and automatically embeds data URIs for URL rules
* preceded by an /* @embed * / comment
*
* @param $source string CSS data to remap
* @param $local string File path where the source was read from
* @param $remote string URL path to the file
* @param $embedData bool If false, never do any data URI embedding, even if / * @embed * / is found
* @return string Remapped CSS data
*/
public static function remap( $source, $local, $remote, $embedData = true ) {
$pattern = '/((?P<embed>\s*\/\*\s*\@embed\s*\*\/)(?P<pre>[^\;\}]*))?' .
self::URL_REGEX . '(?P<post>[^;]*)[\;]?/';
$offset = 0;
while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
// Skip fully-qualified URLs and data URIs
$urlScheme = parse_url( $match['file'][0], PHP_URL_SCHEME );
if ( $urlScheme ) {
// Move the offset to the end of the match, leaving it alone
$offset = $match[0][1] + strlen( $match[0][0] );
continue;
}
// URLs with absolute paths like /w/index.php need to be expanded
// to absolute URLs but otherwise left alone
if ( $match['file'][0] !== '' && $match['file'][0][0] === '/' ) {
// Replace the file path with an expanded (possibly protocol-relative) URL
// ...but only if wfExpandUrl() is even available.
// This will not be the case if we're running outside of MW
$lengthIncrease = 0;
if ( function_exists( 'wfExpandUrl' ) ) {
$expanded = wfExpandUrl( $match['file'][0], PROTO_RELATIVE );
$origLength = strlen( $match['file'][0] );
$lengthIncrease = strlen( $expanded ) - $origLength;
$source = substr_replace( $source, $expanded,
$match['file'][1], $origLength
);
}
// Move the offset to the end of the match, leaving it alone
$offset = $match[0][1] + strlen( $match[0][0] ) + $lengthIncrease;
continue;
}
// Guard against double slashes, because "some/remote/../foo.png"
// resolves to "some/remote/foo.png" on (some?) clients (bug 27052).
if ( substr( $remote, -1 ) == '/' ) {
$remote = substr( $remote, 0, -1 );
}
// Shortcuts
$embed = $match['embed'][0];
$pre = $match['pre'][0];
$post = $match['post'][0];
$query = $match['query'][0];
$url = "{$remote}/{$match['file'][0]}";
$file = "{$local}/{$match['file'][0]}";
$replacement = false;
if ( $local !== false && file_exists( $file ) ) {
// Add version parameter as a time-stamp in ISO 8601 format,
// using Z for the timezone, meaning GMT
$url .= '?' . gmdate( 'Y-m-d\TH:i:s\Z', round( filemtime( $file ), -2 ) );
// Embedding requires a bit of extra processing, so let's skip that if we can
if ( $embedData && $embed ) {
$type = self::getMimeType( $file );
// Detect when URLs were preceeded with embed tags, and also verify file size is
// below the limit
if (
$type
&& $match['embed'][1] > 0
&& filesize( $file ) < self::EMBED_SIZE_LIMIT
) {
// Strip off any trailing = symbols (makes browsers freak out)
$data = base64_encode( file_get_contents( $file ) );
// Build 2 CSS properties; one which uses a base64 encoded data URI in place
// of the @embed comment to try and retain line-number integrity, and the
// other with a remapped an versioned URL and an Internet Explorer hack
// making it ignored in all browsers that support data URIs
$replacement = "{$pre}url(data:{$type};base64,{$data}){$post};";
$replacement .= "{$pre}url({$url}){$post}!ie;";
}
}
if ( $replacement === false ) {
// Assume that all paths are relative to $remote, and make them absolute
$replacement = "{$embed}{$pre}url({$url}){$post};";
}
} elseif ( $local === false ) {
// Assume that all paths are relative to $remote, and make them absolute
$replacement = "{$embed}{$pre}url({$url}{$query}){$post};";
}
if ( $replacement !== false ) {
// Perform replacement on the source
$source = substr_replace(
$source, $replacement, $match[0][1], strlen( $match[0][0] )
);
// Move the offset to the end of the replacement in the source
$offset = $match[0][1] + strlen( $replacement );
continue;
}
// Move the offset to the end of the match, leaving it alone
$offset = $match[0][1] + strlen( $match[0][0] );
}
return $source;
}
/**
* Removes whitespace from CSS data
*
* @param $css string CSS data to minify
* @return string Minified CSS data
*/
public static function minify( $css ) {
return trim(
str_replace(
array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
array( ';', ':', '{', '{', ',', '}', '}' ),
preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
)
);
}
}
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