<?php
/**
- * PNG frame counter.
+ * PNG frame counter and metadata extractor.
* Slightly derived from GIFMetadataExtractor.php
* Deliberately not using MWExceptions to avoid external dependencies, encouraging
* redistribution.
class PNGMetadataExtractor {
static $png_sig;
static $CRC_size;
+ static $text_chunks;
+
+ const VERSION = 1;
+ const MAX_CHUNK_SIZE = 3145728; // 3 megabytes
static function getMetadata( $filename ) {
self::$png_sig = pack( "C8", 137, 80, 78, 71, 13, 10, 26, 10 );
self::$CRC_size = 4;
-
+ /* based on list at http://owl.phy.queensu.ca/~phil/exiftool/TagNames/PNG.html#TextualData
+ * and http://www.w3.org/TR/PNG/#11keywords
+ */
+ self::$text_chunks = array(
+ 'xml:com.adobe.xmp' => 'xmp',
+ # Artist is unofficial. Author is the recommended
+ # keyword in the PNG spec. However some people output
+ # Artist so support both.
+ 'artist' => 'Artist',
+ 'model' => 'Model',
+ 'make' => 'Make',
+ 'author' => 'Artist',
+ 'comment' => 'PNGFileComment',
+ 'description' => 'ImageDescription',
+ 'title' => 'ObjectName',
+ 'copyright' => 'Copyright',
+ # Source as in original device used to make image
+ # not as in who gave you the image
+ 'source' => 'Model',
+ 'software' => 'Software',
+ 'disclaimer' => 'Disclaimer',
+ 'warning' => 'ContentWarning',
+ 'url' => 'Identifier', # Not sure if this is best mapping. Maybe WebStatement.
+ 'label' => 'Label',
+ 'creation time' => 'DateTimeDigitized',
+ /* Other potentially useful things - Document */
+ );
+
$frameCount = 0;
$loopCount = 1;
+ $text = array();
$duration = 0.0;
+ $bitDepth = 0;
+ $colorType = 'unknown';
- if (!$filename)
+ if ( !$filename ) {
throw new Exception( __METHOD__ . ": No file name specified" );
- elseif ( !file_exists($filename) || is_dir($filename) )
+ } elseif ( !file_exists( $filename ) || is_dir( $filename ) ) {
throw new Exception( __METHOD__ . ": File $filename does not exist" );
-
+ }
+
$fh = fopen( $filename, 'r' );
-
- if (!$fh)
+
+ if ( !$fh ) {
throw new Exception( __METHOD__ . ": Unable to open file $filename" );
-
+ }
+
// Check for the PNG header
$buf = fread( $fh, 8 );
- if ( !($buf == self::$png_sig) ) {
+ if ( $buf != self::$png_sig ) {
throw new Exception( __METHOD__ . ": Not a valid PNG file; header: $buf" );
}
// Read chunks
- while( !feof( $fh ) ) {
+ while ( !feof( $fh ) ) {
$buf = fread( $fh, 4 );
- if( !$buf ) {
- throw new Exception( __METHOD__ . ": Read error" );
- }
- $chunk_size = unpack( "N", $buf);
+ if ( !$buf ) {
+ throw new Exception( __METHOD__ . ": Read error" );
+ }
+ $chunk_size = unpack( "N", $buf );
$chunk_size = $chunk_size[1];
$chunk_type = fread( $fh, 4 );
- if( !$chunk_type ) {
- throw new Exception( __METHOD__ . ": Read error" );
- }
+ if ( !$chunk_type ) {
+ throw new Exception( __METHOD__ . ": Read error" );
+ }
- if ( $chunk_type == "acTL" ) {
+ if ( $chunk_type == "IHDR" ) {
+ $buf = self::read( $fh, $chunk_size );
+ if ( !$buf ) {
+ throw new Exception( __METHOD__ . ": Read error" );
+ }
+ $bitDepth = ord( substr( $buf, 8, 1 ) );
+ // Detect the color type in British English as per the spec
+ // http://www.w3.org/TR/PNG/#11IHDR
+ switch ( ord( substr( $buf, 9, 1 ) ) ) {
+ case 0:
+ $colorType = 'greyscale';
+ break;
+ case 2:
+ $colorType = 'truecolour';
+ break;
+ case 3:
+ $colorType = 'index-coloured';
+ break;
+ case 4:
+ $colorType = 'greyscale-alpha';
+ break;
+ case 6:
+ $colorType = 'truecolour-alpha';
+ break;
+ default:
+ $colorType = 'unknown';
+ break;
+ }
+ } elseif ( $chunk_type == "acTL" ) {
$buf = fread( $fh, $chunk_size );
if( !$buf ) {
- throw new Exception( __METHOD__ . ": Read error" );
- }
+ throw new Exception( __METHOD__ . ": Read error" );
+ }
$actl = unpack( "Nframes/Nplays", $buf );
$frameCount = $actl['frames'];
$loopCount = $actl['plays'];
} elseif ( $chunk_type == "fcTL" ) {
- $buf = fread( $fh, $chunk_size );
- if( !$buf ) {
- throw new Exception( __METHOD__ . ": Read error" );
- }
- $buf = substr( $buf, 20 );
+ $buf = self::read( $fh, $chunk_size );
+ if ( !$buf ) {
+ throw new Exception( __METHOD__ . ": Read error" );
+ }
+ $buf = substr( $buf, 20 );
$fctldur = unpack( "ndelay_num/ndelay_den", $buf );
- if( $fctldur['delay_den'] == 0 ) $fctldur['delay_den'] = 100;
- if( $fctldur['delay_num'] ) {
+ if ( $fctldur['delay_den'] == 0 ) {
+ $fctldur['delay_den'] = 100;
+ }
+ if ( $fctldur['delay_num'] ) {
$duration += $fctldur['delay_num'] / $fctldur['delay_den'];
}
- } elseif ( ( $chunk_type == "IDAT" || $chunk_type == "IEND" ) && $frameCount == 0 ) {
- // Not a valid animated image. No point in continuing.
- break;
+ } elseif ( $chunk_type == "iTXt" ) {
+ // Extracts iTXt chunks, uncompressing if necessary.
+ $buf = self::read( $fh, $chunk_size );
+ $items = array();
+ if ( preg_match(
+ '/^([^\x00]{1,79})\x00(\x00|\x01)\x00([^\x00]*)(.)[^\x00]*\x00(.*)$/Ds',
+ $buf, $items )
+ ) {
+ /* $items[1] = text chunk name, $items[2] = compressed flag,
+ * $items[3] = lang code (or ""), $items[4]= compression type.
+ * $items[5] = content
+ */
+
+ // Theoretically should be case-sensitive, but in practise...
+ $items[1] = strtolower( $items[1] );
+ if ( !isset( self::$text_chunks[$items[1]] ) ) {
+ // Only extract textual chunks on our list.
+ fseek( $fh, self::$CRC_size, SEEK_CUR );
+ continue;
+ }
+
+ $items[3] = strtolower( $items[3] );
+ if ( $items[3] == '' ) {
+ // if no lang specified use x-default like in xmp.
+ $items[3] = 'x-default';
+ }
+
+ // if compressed
+ if ( $items[2] == "\x01" ) {
+ if ( function_exists( 'gzuncompress' ) && $items[4] === "\x00" ) {
+ wfSuppressWarnings();
+ $items[5] = gzuncompress( $items[5] );
+ wfRestoreWarnings();
+
+ if ( $items[5] === false ) {
+ // decompression failed
+ wfDebug( __METHOD__ . ' Error decompressing iTxt chunk - ' . $items[1] );
+ fseek( $fh, self::$CRC_size, SEEK_CUR );
+ continue;
+ }
+
+ } else {
+ wfDebug( __METHOD__ . ' Skipping compressed png iTXt chunk due to lack of zlib,'
+ . ' or potentially invalid compression method' );
+ fseek( $fh, self::$CRC_size, SEEK_CUR );
+ continue;
+ }
+ }
+ $finalKeyword = self::$text_chunks[ $items[1] ];
+ $text[ $finalKeyword ][ $items[3] ] = $items[5];
+ $text[ $finalKeyword ]['_type'] = 'lang';
+
+ } else {
+ // Error reading iTXt chunk
+ throw new Exception( __METHOD__ . ": Read error on iTXt chunk" );
+ }
+
+ } elseif ( $chunk_type == 'tEXt' ) {
+ $buf = self::read( $fh, $chunk_size );
+
+ // In case there is no \x00 which will make explode fail.
+ if ( strpos( $buf, "\x00" ) === false ) {
+ throw new Exception( __METHOD__ . ": Read error on tEXt chunk" );
+ }
+
+ list( $keyword, $content ) = explode( "\x00", $buf, 2 );
+ if ( $keyword === '' || $content === '' ) {
+ throw new Exception( __METHOD__ . ": Read error on tEXt chunk" );
+ }
+
+ // Theoretically should be case-sensitive, but in practise...
+ $keyword = strtolower( $keyword );
+ if ( !isset( self::$text_chunks[ $keyword ] ) ) {
+ // Don't recognize chunk, so skip.
+ fseek( $fh, self::$CRC_size, SEEK_CUR );
+ continue;
+ }
+ wfSuppressWarnings();
+ $content = iconv( 'ISO-8859-1', 'UTF-8', $content );
+ wfRestoreWarnings();
+
+ if ( $content === false ) {
+ throw new Exception( __METHOD__ . ": Read error (error with iconv)" );
+ }
+
+ $finalKeyword = self::$text_chunks[ $keyword ];
+ $text[ $finalKeyword ][ 'x-default' ] = $content;
+ $text[ $finalKeyword ]['_type'] = 'lang';
+
+ } elseif ( $chunk_type == 'zTXt' ) {
+ if ( function_exists( 'gzuncompress' ) ) {
+ $buf = self::read( $fh, $chunk_size );
+
+ // In case there is no \x00 which will make explode fail.
+ if ( strpos( $buf, "\x00" ) === false ) {
+ throw new Exception( __METHOD__ . ": Read error on zTXt chunk" );
+ }
+
+ list( $keyword, $postKeyword ) = explode( "\x00", $buf, 2 );
+ if ( $keyword === '' || $postKeyword === '' ) {
+ throw new Exception( __METHOD__ . ": Read error on zTXt chunk" );
+ }
+ // Theoretically should be case-sensitive, but in practise...
+ $keyword = strtolower( $keyword );
+
+ if ( !isset( self::$text_chunks[ $keyword ] ) ) {
+ // Don't recognize chunk, so skip.
+ fseek( $fh, self::$CRC_size, SEEK_CUR );
+ continue;
+ }
+ $compression = substr( $postKeyword, 0, 1 );
+ $content = substr( $postKeyword, 1 );
+ if ( $compression !== "\x00" ) {
+ wfDebug( __METHOD__ . " Unrecognized compression method in zTXt ($keyword). Skipping." );
+ fseek( $fh, self::$CRC_size, SEEK_CUR );
+ continue;
+ }
+
+ wfSuppressWarnings();
+ $content = gzuncompress( $content );
+ wfRestoreWarnings();
+
+ if ( $content === false ) {
+ // decompression failed
+ wfDebug( __METHOD__ . ' Error decompressing zTXt chunk - ' . $keyword );
+ fseek( $fh, self::$CRC_size, SEEK_CUR );
+ continue;
+ }
+
+ wfSuppressWarnings();
+ $content = iconv( 'ISO-8859-1', 'UTF-8', $content );
+ wfRestoreWarnings();
+
+ if ( $content === false ) {
+ throw new Exception( __METHOD__ . ": Read error (error with iconv)" );
+ }
+
+ $finalKeyword = self::$text_chunks[ $keyword ];
+ $text[ $finalKeyword ][ 'x-default' ] = $content;
+ $text[ $finalKeyword ]['_type'] = 'lang';
+
+ } else {
+ wfDebug( __METHOD__ . " Cannot decompress zTXt chunk due to lack of zlib. Skipping." );
+ fseek( $fh, $chunk_size, SEEK_CUR );
+ }
+ } elseif ( $chunk_type == 'tIME' ) {
+ // last mod timestamp.
+ if ( $chunk_size !== 7 ) {
+ throw new Exception( __METHOD__ . ": tIME wrong size" );
+ }
+ $buf = self::read( $fh, $chunk_size );
+ if ( !$buf ) {
+ throw new Exception( __METHOD__ . ": Read error" );
+ }
+
+ // Note: spec says this should be UTC.
+ $t = unpack( "ny/Cm/Cd/Ch/Cmin/Cs", $buf );
+ $strTime = sprintf( "%04d%02d%02d%02d%02d%02d",
+ $t['y'], $t['m'], $t['d'], $t['h'],
+ $t['min'], $t['s'] );
+
+ $exifTime = wfTimestamp( TS_EXIF, $strTime );
+
+ if ( $exifTime ) {
+ $text['DateTime'] = $exifTime;
+ }
+
+ } elseif ( $chunk_type == 'pHYs' ) {
+ // how big pixels are (dots per meter).
+ if ( $chunk_size !== 9 ) {
+ throw new Exception( __METHOD__ . ": pHYs wrong size" );
+ }
+
+ $buf = self::read( $fh, $chunk_size );
+ if ( !$buf ) {
+ throw new Exception( __METHOD__ . ": Read error" );
+ }
+
+ $dim = unpack( "Nwidth/Nheight/Cunit", $buf );
+ if ( $dim['unit'] == 1 ) {
+ // unit is meters
+ // (as opposed to 0 = undefined )
+ $text['XResolution'] = $dim['width']
+ . '/100';
+ $text['YResolution'] = $dim['height']
+ . '/100';
+ $text['ResolutionUnit'] = 3;
+ // 3 = dots per cm (from Exif).
+ }
+
} elseif ( $chunk_type == "IEND" ) {
break;
} else {
}
fclose( $fh );
- if( $loopCount > 1 ) {
+ if ( $loopCount > 1 ) {
$duration *= $loopCount;
}
+ if ( isset( $text['DateTimeDigitized'] ) ) {
+ // Convert date format from rfc2822 to exif.
+ foreach ( $text['DateTimeDigitized'] as $name => &$value ) {
+ if ( $name === '_type' ) {
+ continue;
+ }
+
+ // @todo FIXME: Currently timezones are ignored.
+ // possibly should be wfTimestamp's
+ // responsibility. (at least for numeric TZ)
+ $formatted = wfTimestamp( TS_EXIF, $value );
+ if ( $formatted ) {
+ // Only change if we could convert the
+ // date.
+ // The png standard says it should be
+ // in rfc2822 format, but not required.
+ // In general for the exif stuff we
+ // prettify the date if we can, but we
+ // display as-is if we cannot or if
+ // it is invalid.
+ // So do the same here.
+
+ $value = $formatted;
+ }
+ }
+ }
return array(
'frameCount' => $frameCount,
'loopCount' => $loopCount,
- 'duration' => $duration
+ 'duration' => $duration,
+ 'text' => $text,
+ 'bitDepth' => $bitDepth,
+ 'colorType' => $colorType,
);
-
+
+ }
+ /**
+ * Read a chunk, checking to make sure its not too big.
+ *
+ * @param $fh resource The file handle
+ * @param $size Integer size in bytes.
+ * @throws Exception if too big.
+ * @return String The chunk.
+ */
+ static private function read( $fh, $size ) {
+ if ( $size > self::MAX_CHUNK_SIZE ) {
+ throw new Exception( __METHOD__ . ': Chunk size of ' . $size .
+ ' too big. Max size is: ' . self::MAX_CHUNK_SIZE );
+ }
+ return fread( $fh, $size );
}
}
dépôts / lhc / web / wiklou.git / blobdiff