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<?php
/**
* DjVu image handler
*
* Copyright © 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
*
* @file
*/
/**
* 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/
*
* @ingroup Media
*/
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 );
// @todo FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
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;
}
// @todo FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
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() {
wfSuppressWarnings();
$file = fopen( $this->mFilename, 'rb' );
wfRestoreWarnings();
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 {
// @todo FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
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 {
// @todo FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
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;
}
// @todo FIXME: Would be good to replace this extract() call with something that explicitly initializes local variables.
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 );
}
/**
* Return an XML string describing the DjVu image
* @return string
*/
function retrieveMetaData() {
global $wgDjvuToXML, $wgDjvuDump, $wgDjvuTxt;
wfProfileIn( __METHOD__ );
if ( isset( $wgDjvuDump ) ) {
# djvudump is faster as of version 3.5
# http://sourceforge.net/tracker/index.php?func=detail&aid=1704049&group_id=32953&atid=406583
wfProfileIn( 'djvudump' );
$cmd = wfEscapeShellArg( $wgDjvuDump ) . ' ' . wfEscapeShellArg( $this->mFilename );
$dump = wfShellExec( $cmd );
$xml = $this->convertDumpToXML( $dump );
wfProfileOut( 'djvudump' );
} elseif ( isset( $wgDjvuToXML ) ) {
wfProfileIn( 'djvutoxml' );
$cmd = wfEscapeShellArg( $wgDjvuToXML ) . ' --without-anno --without-text ' .
wfEscapeShellArg( $this->mFilename );
$xml = wfShellExec( $cmd );
wfProfileOut( 'djvutoxml' );
} else {
$xml = null;
}
# Text layer
if ( isset( $wgDjvuTxt ) ) {
wfProfileIn( 'djvutxt' );
$cmd = wfEscapeShellArg( $wgDjvuTxt ) . ' --detail=page ' . wfEscapeShellArg( $this->mFilename ) ;
wfDebug( __METHOD__.": $cmd\n" );
$retval = '';
$txt = wfShellExec( $cmd, $retval );
wfProfileOut( 'djvutxt' );
if( $retval == 0) {
# Strip some control characters
$txt = preg_replace( "/[\013\035\037]/", "", $txt );
$reg = <<<EOR
/\(page\s[\d-]*\s[\d-]*\s[\d-]*\s[\d-]*\s*"
((?> # Text to match is composed of atoms of either:
\\\\. # - any escaped character
| # - any character different from " and \
[^"\\\\]+
)*?)
"\s*\)
| # Or page can be empty ; in this case, djvutxt dumps ()
\(\s*()\)/sx
EOR;
$txt = preg_replace_callback( $reg, array( $this, 'pageTextCallback' ), $txt );
$txt = "<DjVuTxt>\n<HEAD></HEAD>\n<BODY>\n" . $txt . "</BODY>\n</DjVuTxt>\n";
$xml = preg_replace( "/<DjVuXML>/", "<mw-djvu><DjVuXML>", $xml, 1 );
$xml = $xml . $txt. '</mw-djvu>' ;
}
}
wfProfileOut( __METHOD__ );
return $xml;
}
function pageTextCallback( $matches ) {
# Get rid of invalid UTF-8, strip control characters
return '<PAGE value="' . htmlspecialchars( UtfNormal::cleanUp( $matches[1] ) ) . '" />';
}
/**
* Hack to temporarily work around djvutoxml bug
*/
function convertDumpToXML( $dump ) {
if ( strval( $dump ) == '' ) {
return false;
}
$xml = <<<EOT
<?xml version="1.0" ?>
<!DOCTYPE DjVuXML PUBLIC "-//W3C//DTD DjVuXML 1.1//EN" "pubtext/DjVuXML-s.dtd">
<DjVuXML>
<HEAD></HEAD>
<BODY>
EOT;
$dump = str_replace( "\r", '', $dump );
$line = strtok( $dump, "\n" );
$m = false;
$good = false;
if ( preg_match( '/^( *)FORM:DJVU/', $line, $m ) ) {
# Single-page
if ( $this->parseFormDjvu( $line, $xml ) ) {
$good = true;
} else {
return false;
}
} elseif ( preg_match( '/^( *)FORM:DJVM/', $line, $m ) ) {
# Multi-page
$parentLevel = strlen( $m[1] );
# Find DIRM
$line = strtok( "\n" );
while ( $line !== false ) {
$childLevel = strspn( $line, ' ' );
if ( $childLevel <= $parentLevel ) {
# End of chunk
break;
}
if ( preg_match( '/^ *DIRM.*indirect/', $line ) ) {
wfDebug( "Indirect multi-page DjVu document, bad for server!\n" );
return false;
}
if ( preg_match( '/^ *FORM:DJVU/', $line ) ) {
# Found page
if ( $this->parseFormDjvu( $line, $xml ) ) {
$good = true;
} else {
return false;
}
}
$line = strtok( "\n" );
}
}
if ( !$good ) {
return false;
}
$xml .= "</BODY>\n</DjVuXML>\n";
return $xml;
}
function parseFormDjvu( $line, &$xml ) {
$parentLevel = strspn( $line, ' ' );
$line = strtok( "\n" );
# Find INFO
while ( $line !== false ) {
$childLevel = strspn( $line, ' ' );
if ( $childLevel <= $parentLevel ) {
# End of chunk
break;
}
if ( preg_match( '/^ *INFO *\[\d*\] *DjVu *(\d+)x(\d+), *\w*, *(\d+) *dpi, *gamma=([0-9.-]+)/', $line, $m ) ) {
$xml .= Xml::tags( 'OBJECT',
array(
#'data' => '',
#'type' => 'image/x.djvu',
'height' => $m[2],
'width' => $m[1],
#'usemap' => '',
),
"\n" .
Xml::element( 'PARAM', array( 'name' => 'DPI', 'value' => $m[3] ) ) . "\n" .
Xml::element( 'PARAM', array( 'name' => 'GAMMA', 'value' => $m[4] ) ) . "\n"
) . "\n";
return true;
}
$line = strtok( "\n" );
}
# Not found
return false;
}
}