includes/DjVuImage.php

   1 <?php
   2
   3 /**
   4  *
   5  * Copyright (C) 2006 Brion Vibber <brion@pobox.com>
   6  * http://www.mediawiki.org/
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  */
  24
  25 /**
  26  * Support for detecting/validating DjVu image files and getting
  27  * some basic file metadata (resolution etc)
  28  *
  29  * File format docs are available in source package for DjVuLibre:
  30  * http://djvulibre.djvuzone.org/
  31  *
  32  * @addtogroup Media
  33  */
  34 class DjVuImage {
  35         function __construct( $filename ) {
  36                 $this->mFilename = $filename;
  37         }
  38
  39         /**
  40          * Check if the given file is indeed a valid DjVu image file
  41          * @return bool
  42          */
  43         public function isValid() {
  44                 $info = $this->getInfo();
  45                 return $info !== false;
  46         }
  47
  48
  49         /**
  50          * Return data in the style of getimagesize()
  51          * @return array or false on failure
  52          */
  53         public function getImageSize() {
  54                 $data = $this->getInfo();
  55
  56                 if( $data !== false ) {
  57                         $width  = $data['width'];
  58                         $height = $data['height'];
  59
  60                         return array( $width, $height, 'DjVu',
  61                                 "width=\"$width\" height=\"$height\"" );
  62                 }
  63                 return false;
  64         }
  65
  66         // ---------
  67
  68         /**
  69          * For debugging; dump the IFF chunk structure
  70          */
  71         function dump() {
  72                 $file = fopen( $this->mFilename, 'rb' );
  73                 $header = fread( $file, 12 );
  74                 // FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
  75                 extract( unpack( 'a4magic/a4chunk/NchunkLength', $header ) );
  76                 echo "$chunk $chunkLength\n";
  77                 $this->dumpForm( $file, $chunkLength, 1 );
  78                 fclose( $file );
  79         }
  80
  81         private function dumpForm( $file, $length, $indent ) {
  82                 $start = ftell( $file );
  83                 $secondary = fread( $file, 4 );
  84                 echo str_repeat( ' ', $indent * 4 ) . "($secondary)\n";
  85                 while( ftell( $file ) - $start < $length ) {
  86                         $chunkHeader = fread( $file, 8 );
  87                         if( $chunkHeader == '' ) {
  88                                 break;
  89                         }
  90                         // FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
  91                         extract( unpack( 'a4chunk/NchunkLength', $chunkHeader ) );
  92                         echo str_repeat( ' ', $indent * 4 ) . "$chunk $chunkLength\n";
  93
  94                         if( $chunk == 'FORM' ) {
  95                                 $this->dumpForm( $file, $chunkLength, $indent + 1 );
  96                         } else {
  97                                 fseek( $file, $chunkLength, SEEK_CUR );
  98                                 if( $chunkLength & 1 == 1 ) {
  99                                         // Padding byte between chunks
 100                                         fseek( $file, 1, SEEK_CUR );
 101                                 }
 102                         }
 103                 }
 104         }
 105
 106         function getInfo() {
 107                 $file = fopen( $this->mFilename, 'rb' );
 108                 if( $file === false ) {
 109                         wfDebug( __METHOD__ . ": missing or failed file read\n" );
 110                         return false;
 111                 }
 112
 113                 $header = fread( $file, 16 );
 114                 $info = false;
 115
 116                 if( strlen( $header ) < 16 ) {
 117                         wfDebug( __METHOD__ . ": too short file header\n" );
 118                 } else {
 119                         // FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
 120                         extract( unpack( 'a4magic/a4form/NformLength/a4subtype', $header ) );
 121
 122                         if( $magic != 'AT&T' ) {
 123                                 wfDebug( __METHOD__ . ": not a DjVu file\n" );
 124                         } elseif( $subtype == 'DJVU' ) {
 125                                 // Single-page document
 126                                 $info = $this->getPageInfo( $file, $formLength );
 127                         } elseif( $subtype == 'DJVM' ) {
 128                                 // Multi-page document
 129                                 $info = $this->getMultiPageInfo( $file, $formLength );
 130                         } else  {
 131                                 wfDebug( __METHOD__ . ": unrecognized DJVU file type '$formType'\n" );
 132                         }
 133                 }
 134                 fclose( $file );
 135                 return $info;
 136         }
 137
 138         private function readChunk( $file ) {
 139                 $header = fread( $file, 8 );
 140                 if( strlen( $header ) < 8 ) {
 141                         return array( false, 0 );
 142                 } else {
 143                         // FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
 144                         extract( unpack( 'a4chunk/Nlength', $header ) );
 145                         return array( $chunk, $length );
 146                 }
 147         }
 148
 149         private function skipChunk( $file, $chunkLength ) {
 150                 fseek( $file, $chunkLength, SEEK_CUR );
 151
 152                 if( $chunkLength & 0x01 == 1 && !feof( $file ) ) {
 153                         // padding byte
 154                         fseek( $file, 1, SEEK_CUR );
 155                 }
 156         }
 157
 158         private function getMultiPageInfo( $file, $formLength ) {
 159                 // For now, we'll just look for the first page in the file
 160                 // and report its information, hoping others are the same size.
 161                 $start = ftell( $file );
 162                 do {
 163                         list( $chunk, $length ) = $this->readChunk( $file );
 164                         if( !$chunk ) {
 165                                 break;
 166                         }
 167
 168                         if( $chunk == 'FORM' ) {
 169                                 $subtype = fread( $file, 4 );
 170                                 if( $subtype == 'DJVU' ) {
 171                                         wfDebug( __METHOD__ . ": found first subpage\n" );
 172                                         return $this->getPageInfo( $file, $length );
 173                                 }
 174                                 $this->skipChunk( $file, $length - 4 );
 175                         } else {
 176                                 wfDebug( __METHOD__ . ": skipping '$chunk' chunk\n" );
 177                                 $this->skipChunk( $file, $length );
 178                         }
 179                 } while( $length != 0 && !feof( $file ) && ftell( $file ) - $start < $formLength );
 180
 181                 wfDebug( __METHOD__ . ": multi-page DJVU file contained no pages\n" );
 182                 return false;
 183         }
 184
 185         private function getPageInfo( $file, $formLength ) {
 186                 list( $chunk, $length ) = $this->readChunk( $file );
 187                 if( $chunk != 'INFO' ) {
 188                         wfDebug( __METHOD__ . ": expected INFO chunk, got '$chunk'\n" );
 189                         return false;
 190                 }
 191
 192                 if( $length < 9 ) {
 193                         wfDebug( __METHOD__ . ": INFO should be 9 or 10 bytes, found $length\n" );
 194                         return false;
 195                 }
 196                 $data = fread( $file, $length );
 197                 if( strlen( $data ) < $length ) {
 198                         wfDebug( __METHOD__ . ": INFO chunk cut off\n" );
 199                         return false;
 200                 }
 201
 202                 // FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
 203                 extract( unpack(
 204                         'nwidth/' .
 205                         'nheight/' .
 206                         'Cminor/' .
 207                         'Cmajor/' .
 208                         'vresolution/' .
 209                         'Cgamma', $data ) );
 210                 # Newer files have rotation info in byte 10, but we don't use it yet.
 211
 212                 return array(
 213                         'width' => $width,
 214                         'height' => $height,
 215                         'version' => "$major.$minor",
 216                         'resolution' => $resolution,
 217                         'gamma' => $gamma / 10.0 );
 218         }
 219
 220         /**
 221          * Return an XML string describing the DjVu image
 222          * @return string
 223          */
 224         function retrieveMetaData() {
 225                 global $wgDjvuToXML, $wgDjvuDump;
 226                 if ( isset( $wgDjvuDump ) ) {
 227                         # djvudump is faster as of version 3.5
 228                         # http://sourceforge.net/tracker/index.php?func=detail&aid=1704049&group_id=32953&atid=406583
 229                         wfProfileIn( 'djvudump' );
 230                         $cmd = wfEscapeShellArg( $wgDjvuDump ) . ' ' . wfEscapeShellArg( $this->mFilename );
 231                         $dump = wfShellExec( $cmd );
 232                         $xml = $this->convertDumpToXML( $dump );
 233                         wfProfileOut( 'djvudump' );
 234                 } elseif ( isset( $wgDjvuToXML ) ) {
 235                         wfProfileIn( 'djvutoxml' );
 236                         $cmd = wfEscapeShellArg( $wgDjvuToXML ) . ' --without-anno --without-text ' .
 237                                 wfEscapeShellArg( $this->mFilename );
 238                         $xml = wfShellExec( $cmd );
 239                         wfProfileOut( 'djvutoxml' );
 240                 } else {
 241                         $xml = null;
 242                 }
 243                 return $xml;
 244         }
 245
 246         /**
 247          * Hack to temporarily work around djvutoxml bug
 248          */
 249         function convertDumpToXML( $dump ) {
 250                 if ( strval( $dump ) == '' ) {
 251                         return false;
 252                 }
 253
 254                 $xml = <<<EOT
 255 <?xml version="1.0" ?>
 256 <!DOCTYPE DjVuXML PUBLIC "-//W3C//DTD DjVuXML 1.1//EN" "pubtext/DjVuXML-s.dtd">
 257 <DjVuXML>
 258 <HEAD></HEAD>
 259 <BODY>
 260 EOT;
 261
 262                 $dump = str_replace( "\r", '', $dump );
 263                 $line = strtok( $dump, "\n" );
 264                 $m = false;
 265                 $good = false;
 266                 if ( preg_match( '/^( *)FORM:DJVU/', $line, $m ) ) {
 267                         # Single-page
 268                         if ( $this->parseFormDjvu( $line, $xml ) ) {
 269                                 $good = true;
 270                         } else {
 271                                 return false;
 272                         }
 273                 } elseif ( preg_match( '/^( *)FORM:DJVM/', $line, $m ) ) {
 274                         # Multi-page
 275                         $parentLevel = strlen( $m[1] );
 276                         # Find DIRM
 277                         $line = strtok( "\n" );
 278                         while ( $line !== false ) {
 279                                 $childLevel = strspn( $line, ' ' );
 280                                 if ( $childLevel <= $parentLevel ) {
 281                                         # End of chunk
 282                                         break;
 283                                 }
 284
 285                                 if ( preg_match( '/^ *DIRM.*indirect/', $line ) ) {
 286                                         wfDebug( "Indirect multi-page DjVu document, bad for server!\n" );
 287                                         return false;
 288                                 }
 289                                 if ( preg_match( '/^ *FORM:DJVU/', $line ) ) {
 290                                         # Found page
 291                                         if ( $this->parseFormDjvu( $line, $xml ) ) {
 292                                                 $good = true;
 293                                         } else {
 294                                                 return false;
 295                                         }
 296                                 }
 297                                 $line = strtok( "\n" );
 298                         }
 299                 }
 300                 if ( !$good ) {
 301                         return false;
 302                 }
 303
 304                 $xml .= "</BODY>\n</DjVuXML>\n";
 305                 return $xml;
 306         }
 307
 308         function parseFormDjvu( $line, &$xml ) {
 309                 $parentLevel = strspn( $line, ' ' );
 310                 $line = strtok( "\n" );
 311
 312                 # Find INFO
 313                 while ( $line !== false ) {
 314                         $childLevel = strspn( $line, ' ' );
 315                         if ( $childLevel <= $parentLevel ) {
 316                                 # End of chunk
 317                                 break;
 318                         }
 319
 320                         if ( preg_match( '/^ *INFO *\[\d*\] *DjVu *(\d+)x(\d+), *\w*, *(\d+) *dpi, *gamma=([0-9.-]+)/', $line, $m ) ) {
 321                                 $xml .= Xml::tags( 'OBJECT',
 322                                         array(
 323                                                 #'data' => '',
 324                                                 #'type' => 'image/x.djvu',
 325                                                 'height' => $m[2],
 326                                                 'width' => $m[1],
 327                                                 #'usemap' => '',
 328                                         ),
 329                                         "\n" .
 330                                         Xml::element( 'PARAM', array( 'name' => 'DPI', 'value' => $m[3] ) ) . "\n" .
 331                                         Xml::element( 'PARAM', array( 'name' => 'GAMMA', 'value' => $m[4] ) ) . "\n"
 332                                 ) . "\n";
 333                                 return true;
 334                         }
 335                         $line = strtok( "\n" );
 336                 }
 337                 # Not found
 338                 return false;
 339         }
 340 }
 341
 342
 343 ?>