includes/media/XCF.php

   1 <?php
   2 /**
   3  * Handler for the Gimp's native file format (XCF)
   4  *
   5  * Overview:
   6  *   https://en.wikipedia.org/wiki/XCF_(file_format)
   7  * Specification in Gnome repository:
   8  *   http://svn.gnome.org/viewvc/gimp/trunk/devel-docs/xcf.txt?view=markup
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License along
  21  * with this program; if not, write to the Free Software Foundation, Inc.,
  22  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  23  * http://www.gnu.org/copyleft/gpl.html
  24  *
  25  * @file
  26  * @ingroup Media
  27  */
  28
  29 /**
  30  * Handler for the Gimp's native file format; getimagesize() doesn't
  31  * support these files
  32  *
  33  * @ingroup Media
  34  */
  35 class XCFHandler extends BitmapHandler {
  36         /**
  37          * @param File $file
  38          * @return bool
  39          */
  40         function mustRender( $file ) {
  41                 return true;
  42         }
  43
  44         /**
  45          * Render files as PNG
  46          *
  47          * @param string $ext
  48          * @param string $mime
  49          * @param array $params
  50          * @return array
  51          */
  52         function getThumbType( $ext, $mime, $params = null ) {
  53                 return array( 'png', 'image/png' );
  54         }
  55
  56         /**
  57          * Get width and height from the XCF header.
  58          *
  59          * @param File $image
  60          * @param string $filename
  61          * @return array
  62          */
  63         function getImageSize( $image, $filename ) {
  64                 $header = self::getXCFMetaData( $filename );
  65                 if ( !$header ) {
  66                         return false;
  67                 }
  68
  69                 # Forge a return array containing metadata information just like getimagesize()
  70                 # See PHP documentation at: http://www.php.net/getimagesize
  71                 $metadata = array();
  72                 $metadata[0] = $header['width'];
  73                 $metadata[1] = $header['height'];
  74                 $metadata[2] = null; # IMAGETYPE constant, none exist for XCF.
  75                 $metadata[3] = sprintf(
  76                         'height="%s" width="%s"', $header['height'], $header['width']
  77                 );
  78                 $metadata['mime'] = 'image/x-xcf';
  79                 $metadata['channels'] = null;
  80                 $metadata['bits'] = 8; # Always 8-bits per color
  81
  82                 assert( '7 == count($metadata); ' .
  83                         '# return array must contains 7 elements just like getimagesize() return' );
  84
  85                 return $metadata;
  86         }
  87
  88         /**
  89          * Metadata for a given XCF file
  90          *
  91          * Will return false if file magic signature is not recognized
  92          * @author Hexmode
  93          * @author Hashar
  94          *
  95          * @param string $filename Full path to a XCF file
  96          * @return bool|array Metadata Array just like PHP getimagesize()
  97          */
  98         static function getXCFMetaData( $filename ) {
  99                 # Decode master structure
 100                 $f = fopen( $filename, 'rb' );
 101                 if ( !$f ) {
 102                         return false;
 103                 }
 104                 # The image structure always starts at offset 0 in the XCF file.
 105                 # So we just read it :-)
 106                 $binaryHeader = fread( $f, 26 );
 107                 fclose( $f );
 108
 109                 # Master image structure:
 110                 #
 111                 # byte[9] "gimp xcf "  File type magic
 112                 # byte[4] version      XCF version
 113                 #                        "file" - version 0
 114                 #                        "v001" - version 1
 115                 #                        "v002" - version 2
 116                 # byte    0            Zero-terminator for version tag
 117                 # uint32  width        With of canvas
 118                 # uint32  height       Height of canvas
 119                 # uint32  base_type    Color mode of the image; one of
 120                 #                         0: RGB color
 121                 #                         1: Grayscale
 122                 #                         2: Indexed color
 123                 #        (enum GimpImageBaseType in libgimpbase/gimpbaseenums.h)
 124                 try {
 125                         $header = wfUnpack(
 126                                 "A9magic" . # A: space padded
 127                                         "/a5version" . # a: zero padded
 128                                         "/Nwidth" . # \
 129                                         "/Nheight" . # N: unsigned long 32bit big endian
 130                                         "/Nbase_type", # /
 131                                 $binaryHeader
 132                         );
 133                 } catch ( Exception $mwe ) {
 134                         return false;
 135                 }
 136
 137                 # Check values
 138                 if ( $header['magic'] !== 'gimp xcf' ) {
 139                         wfDebug( __METHOD__ . " '$filename' has invalid magic signature.\n" );
 140
 141                         return false;
 142                 }
 143                 # TODO: we might want to check for sane values of width and height
 144
 145                 wfDebug( __METHOD__ .
 146                         ": canvas size of '$filename' is {$header['width']} x {$header['height']} px\n" );
 147
 148                 return $header;
 149         }
 150
 151         /**
 152          * Store the channel type
 153          *
 154          * Greyscale files need different command line options.
 155          *
 156          * @param File $file The image object, or false if there isn't one.
 157          *   Warning, FSFile::getPropsFromPath might pass an (object)array() instead (!)
 158          * @param string $filename The filename
 159          * @return string
 160          */
 161         public function getMetadata( $file, $filename ) {
 162                 $header = self::getXCFMetadata( $filename );
 163                 $metadata = array();
 164                 if ( $header ) {
 165                         // Try to be consistent with the names used by PNG files.
 166                         // Unclear from base media type if it has an alpha layer,
 167                         // so just assume that it does since it "potentially" could.
 168                         switch ( $header['base_type'] ) {
 169                         case 0:
 170                                 $metadata['colorType'] = 'truecolour-alpha';
 171                                 break;
 172                         case 1:
 173                                 $metadata['colorType'] = 'greyscale-alpha';
 174                                 break;
 175                         case 2:
 176                                 $metadata['colorType'] = 'index-coloured';
 177                                 break;
 178                         default:
 179                                 $metadata['colorType'] = 'unknown';
 180
 181                         }
 182                 } else {
 183                         // Marker to prevent repeated attempted extraction
 184                         $metadata['error'] = true;
 185                 }
 186                 return serialize( $metadata );
 187         }
 188
 189         /**
 190          * Should we refresh the metadata
 191          *
 192          * @param File $file The file object for the file in question
 193          * @param string $metadata Serialized metadata
 194          * @return bool One of the self::METADATA_(BAD|GOOD|COMPATIBLE) constants
 195          */
 196         public function isMetadataValid( $file, $metadata ) {
 197                 if ( !$metadata ) {
 198                         // Old metadata when we just put an empty string in there
 199                         return self::METADATA_BAD;
 200                 } else {
 201                         return self::METADATA_GOOD;
 202                 }
 203         }
 204
 205         /**
 206          * Must use "im" for XCF
 207          *
 208          * @param string $dstPath
 209          * @param bool $checkDstPath
 210          * @return string
 211          */
 212         protected function getScalerType( $dstPath, $checkDstPath = true ) {
 213                 return "im";
 214         }
 215
 216         /**
 217          * Can we render this file?
 218          *
 219          * Image magick doesn't support indexed xcf files as of current
 220          * writing (as of 6.8.9-3)
 221          * @param File $file
 222          * @return bool
 223          */
 224         public function canRender( $file ) {
 225                 MediaWiki\suppressWarnings();
 226                 $xcfMeta = unserialize( $file->getMetadata() );
 227                 MediaWiki\restoreWarnings();
 228                 if ( isset( $xcfMeta['colorType'] ) && $xcfMeta['colorType'] === 'index-coloured' ) {
 229                         return false;
 230                 }
 231                 return parent::canRender( $file );
 232         }
 233 }