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Diffstat (limited to 'includes/DjVuImage.php')
| -rw-r--r-- | includes/DjVuImage.php | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/includes/DjVuImage.php b/includes/DjVuImage.php new file mode 100644 index 00000000..b857fa66 --- /dev/null +++ b/includes/DjVuImage.php @@ -0,0 +1,214 @@ +<?php +/** + * Support for detecting/validating DjVu image files and getting + * some basic file metadata (resolution etc) + * + * File format docs are available in source package for DjVuLibre: + * http://djvulibre.djvuzone.org/ + * + * + * Copyright (C) 2006 Brion Vibber <brion@pobox.com> + * http://www.mediawiki.org/ + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * http://www.gnu.org/copyleft/gpl.html + * + * @package MediaWiki + */ + +class DjVuImage { + function __construct( $filename ) { + $this->mFilename = $filename; + } + + /** + * Check if the given file is indeed a valid DjVu image file + * @return bool + */ + public function isValid() { + $info = $this->getInfo(); + return $info !== false; + } + + + /** + * Return data in the style of getimagesize() + * @return array or false on failure + */ + public function getImageSize() { + $data = $this->getInfo(); + + if( $data !== false ) { + $width = $data['width']; + $height = $data['height']; + + return array( $width, $height, 'DjVu', + "width=\"$width\" height=\"$height\"" ); + } + return false; + } + + // --------- + + /** + * For debugging; dump the IFF chunk structure + */ + function dump() { + $file = fopen( $this->mFilename, 'rb' ); + $header = fread( $file, 12 ); + extract( unpack( 'a4magic/a4chunk/NchunkLength', $header ) ); + echo "$chunk $chunkLength\n"; + $this->dumpForm( $file, $chunkLength, 1 ); + fclose( $file ); + } + + private function dumpForm( $file, $length, $indent ) { + $start = ftell( $file ); + $secondary = fread( $file, 4 ); + echo str_repeat( ' ', $indent * 4 ) . "($secondary)\n"; + while( ftell( $file ) - $start < $length ) { + $chunkHeader = fread( $file, 8 ); + if( $chunkHeader == '' ) { + break; + } + extract( unpack( 'a4chunk/NchunkLength', $chunkHeader ) ); + echo str_repeat( ' ', $indent * 4 ) . "$chunk $chunkLength\n"; + + if( $chunk == 'FORM' ) { + $this->dumpForm( $file, $chunkLength, $indent + 1 ); + } else { + fseek( $file, $chunkLength, SEEK_CUR ); + if( $chunkLength & 1 == 1 ) { + // Padding byte between chunks + fseek( $file, 1, SEEK_CUR ); + } + } + } + } + + function getInfo() { + $file = fopen( $this->mFilename, 'rb' ); + if( $file === false ) { + wfDebug( __METHOD__ . ": missing or failed file read\n" ); + return false; + } + + $header = fread( $file, 16 ); + $info = false; + + if( strlen( $header ) < 16 ) { + wfDebug( __METHOD__ . ": too short file header\n" ); + } else { + extract( unpack( 'a4magic/a4form/NformLength/a4subtype', $header ) ); + + if( $magic != 'AT&T' ) { + wfDebug( __METHOD__ . ": not a DjVu file\n" ); + } elseif( $subtype == 'DJVU' ) { + // Single-page document + $info = $this->getPageInfo( $file, $formLength ); + } elseif( $subtype == 'DJVM' ) { + // Multi-page document + $info = $this->getMultiPageInfo( $file, $formLength ); + } else { + wfDebug( __METHOD__ . ": unrecognized DJVU file type '$formType'\n" ); + } + } + fclose( $file ); + return $info; + } + + private function readChunk( $file ) { + $header = fread( $file, 8 ); + if( strlen( $header ) < 8 ) { + return array( false, 0 ); + } else { + extract( unpack( 'a4chunk/Nlength', $header ) ); + return array( $chunk, $length ); + } + } + + private function skipChunk( $file, $chunkLength ) { + fseek( $file, $chunkLength, SEEK_CUR ); + + if( $chunkLength & 0x01 == 1 && !feof( $file ) ) { + // padding byte + fseek( $file, 1, SEEK_CUR ); + } + } + + private function getMultiPageInfo( $file, $formLength ) { + // For now, we'll just look for the first page in the file + // and report its information, hoping others are the same size. + $start = ftell( $file ); + do { + list( $chunk, $length ) = $this->readChunk( $file ); + if( !$chunk ) { + break; + } + + if( $chunk == 'FORM' ) { + $subtype = fread( $file, 4 ); + if( $subtype == 'DJVU' ) { + wfDebug( __METHOD__ . ": found first subpage\n" ); + return $this->getPageInfo( $file, $length ); + } + $this->skipChunk( $file, $length - 4 ); + } else { + wfDebug( __METHOD__ . ": skipping '$chunk' chunk\n" ); + $this->skipChunk( $file, $length ); + } + } while( $length != 0 && !feof( $file ) && ftell( $file ) - $start < $formLength ); + + wfDebug( __METHOD__ . ": multi-page DJVU file contained no pages\n" ); + return false; + } + + private function getPageInfo( $file, $formLength ) { + list( $chunk, $length ) = $this->readChunk( $file ); + if( $chunk != 'INFO' ) { + wfDebug( __METHOD__ . ": expected INFO chunk, got '$chunk'\n" ); + return false; + } + + if( $length < 9 ) { + wfDebug( __METHOD__ . ": INFO should be 9 or 10 bytes, found $length\n" ); + return false; + } + $data = fread( $file, $length ); + if( strlen( $data ) < $length ) { + wfDebug( __METHOD__ . ": INFO chunk cut off\n" ); + return false; + } + + extract( unpack( + 'nwidth/' . + 'nheight/' . + 'Cminor/' . + 'Cmajor/' . + 'vresolution/' . + 'Cgamma', $data ) ); + # Newer files have rotation info in byte 10, but we don't use it yet. + + return array( + 'width' => $width, + 'height' => $height, + 'version' => "$major.$minor", + 'resolution' => $resolution, + 'gamma' => $gamma / 10.0 ); + } +} + + +?>
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