wikimedia/mediawiki-core

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includes/media/BitmapMetadataHandler.php

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<?php
/**
 * Extraction of metadata from different bitmap image types.
 *
 * 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
 * @ingroup Media
 */

use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use Wikimedia\XMPReader\Reader as XMPReader;

/**
 * Class to deal with reconciling and extracting metadata from bitmap images.
 * This is meant to comply with http://www.metadataworkinggroup.org/pdf/mwg_guidance.pdf
 *
 * This sort of acts as an intermediary between MediaHandler::getMetadata
 * and the various metadata extractors.
 *
 * @todo Other image formats.
 * @newable
 * @note marked as newable in 1.35 for lack of a better alternative,
 *       but should become a stateless service, or a handler managed
 *       registry for metadata handlers for different file types.
 * @ingroup Media
 */
class BitmapMetadataHandler {
    /** @var array */
    private $metadata = [];

    /** @var array Metadata priority */
    private $metaPriority = [
        20 => [ 'other' ],
        40 => [ 'native' ],
        60 => [ 'iptc-good-hash', 'iptc-no-hash' ],
        70 => [ 'xmp-deprecated' ],
        80 => [ 'xmp-general' ],
        90 => [ 'xmp-exif' ],
        100 => [ 'iptc-bad-hash' ],
        120 => [ 'exif' ],
    ];

    /** @var string */
    private $iptcType = 'iptc-no-hash';

    /**
     * This does the photoshop image resource app13 block
     * of interest, IPTC-IIM metadata is stored here.
     *
     * Mostly just calls doPSIR and doIPTC
     *
     * @param string $app13 String containing app13 block from jpeg file
     */
    private function doApp13( $app13 ) {
        try {
            $this->iptcType = JpegMetadataExtractor::doPSIR( $app13 );
        } catch ( InvalidPSIRException $e ) {
            // Error reading the iptc hash information.
            // This probably means the App13 segment is something other than what we expect.
            // However, still try to read it, and treat it as if the hash didn't exist.
            wfDebug( "Error parsing iptc data of file: " . $e->getMessage() );
            $this->iptcType = 'iptc-no-hash';
        }

        $iptc = IPTC::parse( $app13 );
        $this->addMetadata( $iptc, $this->iptcType );
    }

    /**
     * Get exif info using exif class.
     * Basically what used to be in BitmapHandler::getMetadata().
     * Just calls stuff in the Exif class.
     *
     * Parameters are passed to the Exif class.
     *
     * @param string $filename
     * @param string $byteOrder
     */
    public function getExif( $filename, $byteOrder ) {
        $showEXIF = MediaWikiServices::getInstance()->getMainConfig()->get( MainConfigNames::ShowEXIF );
        if ( file_exists( $filename ) && $showEXIF ) {
            $exif = new Exif( $filename, $byteOrder );
            $data = $exif->getFilteredData();
            if ( $data ) {
                $this->addMetadata( $data, 'exif' );
            }
        }
    }

    /** Add misc metadata. Warning: atm if the metadata category
     * doesn't have a priority, it will be silently discarded.
     *
     * @param array $metaArray Array of metadata values
     * @param string $type Type. defaults to other. if two things have the same type they're merged
     */
    public function addMetadata( $metaArray, $type = 'other' ) {
        if ( isset( $this->metadata[$type] ) ) {
            /* merge with old data */
            $metaArray += $this->metadata[$type];
        }

        $this->metadata[$type] = $metaArray;
    }

    /**
     * Merge together the various types of metadata
     * the different types have different priorities,
     * and are merged in order.
     *
     * This function is generally called by the media handlers' getMetadata()
     *
     * @return array
     */
    public function getMetadataArray() {
        // this seems a bit ugly... This is all so its merged in right order
        // based on the MWG recommendation.
        $temp = [];
        krsort( $this->metaPriority );
        foreach ( $this->metaPriority as $pri ) {
            foreach ( $pri as $type ) {
                if ( isset( $this->metadata[$type] ) ) {
                    // Do some special casing for multilingual values.
                    // Don't discard translations if also as a simple value.
                    foreach ( $this->metadata[$type] as $itemName => $item ) {
                        if ( is_array( $item ) && isset( $item['_type'] ) && $item['_type'] === 'lang' &&
                            isset( $temp[$itemName] ) && !is_array( $temp[$itemName] )
                        ) {
                            $default = $temp[$itemName];
                            $temp[$itemName] = $item;
                            $temp[$itemName]['x-default'] = $default;
                            unset( $this->metadata[$type][$itemName] );
                        }
                    }

                    $temp += $this->metadata[$type];
                }
            }
        }

        return $temp;
    }

    /** Main entry point for jpeg's.
     *
     * @param string $filename Filename (with full path)
     * @return array Metadata result array.
     * @throws InvalidJpegException
     */
    public static function Jpeg( $filename ) {
        $showXMP = XMPReader::isSupported();
        $meta = new self();

        $seg = JpegMetadataExtractor::segmentSplitter( $filename );

        if ( isset( $seg['SOF'] ) ) {
            $meta->addMetadata( [ 'SOF' => $seg['SOF'] ] );
        }
        if ( isset( $seg['COM'] ) && isset( $seg['COM'][0] ) ) {
            $meta->addMetadata( [ 'JPEGFileComment' => $seg['COM'] ], 'native' );
        }
        if ( isset( $seg['PSIR'] ) && count( $seg['PSIR'] ) > 0 ) {
            foreach ( $seg['PSIR'] as $curPSIRValue ) {
                $meta->doApp13( $curPSIRValue );
            }
        }
        if ( isset( $seg['XMP'] ) && $showXMP ) {
            $xmp = new XMPReader( LoggerFactory::getInstance( 'XMP' ), $filename );
            $xmp->parse( $seg['XMP'] );
            foreach ( $seg['XMP_ext'] as $xmpExt ) {
                /* Support for extended xmp in jpeg files
                 * is not well tested and a bit fragile.
                 */
                $xmp->parseExtended( $xmpExt );
            }
            $res = $xmp->getResults();
            foreach ( $res as $type => $array ) {
                $meta->addMetadata( $array, $type );
            }
        }

        $meta->getExif( $filename, $seg['byteOrder'] ?? 'BE' );

        return $meta->getMetadataArray();
    }

    /** Entry point for png
     * At some point in the future this might
     * merge the png various tEXt chunks to that
     * are interesting, but for now it only does XMP
     *
     * @param string $filename Full path to file
     * @return array Array for storage in img_metadata.
     */
    public static function PNG( $filename ) {
        $showXMP = XMPReader::isSupported();

        $meta = new self();
        $array = PNGMetadataExtractor::getMetadata( $filename );
        if ( isset( $array['text']['xmp']['x-default'] )
            && $array['text']['xmp']['x-default'] !== '' && $showXMP
        ) {
            $xmp = new XMPReader( LoggerFactory::getInstance( 'XMP' ), $filename );
            $xmp->parse( $array['text']['xmp']['x-default'] );
            $xmpRes = $xmp->getResults();
            foreach ( $xmpRes as $type => $xmpSection ) {
                $meta->addMetadata( $xmpSection, $type );
            }
        }
        unset( $array['text']['xmp'] );
        // @phan-suppress-next-line PhanTypePossiblyInvalidDimOffset xmp is not alone in text, makes text always set
        $meta->addMetadata( $array['text'], 'native' );
        unset( $array['text'] );
        $array['metadata'] = $meta->getMetadataArray();
        $array['metadata']['_MW_PNG_VERSION'] = PNGMetadataExtractor::VERSION;

        return $array;
    }

    /** function for gif images.
     *
     * They don't really have native metadata, so just merges together
     * XMP and image comment.
     *
     * @param string $filename Full path to file
     * @return array Metadata array
     */
    public static function GIF( $filename ) {
        $meta = new self();
        $baseArray = GIFMetadataExtractor::getMetadata( $filename );

        if ( count( $baseArray['comment'] ) > 0 ) {
            $meta->addMetadata( [ 'GIFFileComment' => $baseArray['comment'] ], 'native' );
        }

        if ( $baseArray['xmp'] !== '' && XMPReader::isSupported() ) {
            $xmp = new XMPReader( LoggerFactory::getInstance( 'XMP' ), $filename );
            $xmp->parse( $baseArray['xmp'] );
            $xmpRes = $xmp->getResults();
            foreach ( $xmpRes as $type => $xmpSection ) {
                $meta->addMetadata( $xmpSection, $type );
            }
        }

        unset( $baseArray['comment'] );
        unset( $baseArray['xmp'] );

        $baseArray['metadata'] = $meta->getMetadataArray();
        $baseArray['metadata']['_MW_GIF_VERSION'] = GIFMetadataExtractor::VERSION;

        return $baseArray;
    }

    /**
     * This doesn't do much yet, but eventually I plan to add
     * XMP support for Tiff. (PHP's exif support already extracts
     * but needs some further processing because PHP's exif support
     * is stupid...)
     *
     * @todo Add XMP support, so this function actually makes sense to put here.
     *
     * The various exceptions this throws are caught later.
     * @param string $filename
     * @throws InvalidTiffException
     * @return array The metadata.
     */
    public static function Tiff( $filename ) {
        if ( file_exists( $filename ) ) {
            $byteOrder = self::getTiffByteOrder( $filename );
            if ( !$byteOrder ) {
                throw new InvalidTiffException( "Error determining byte order of $filename" );
            }
            $exif = new Exif( $filename, $byteOrder );
            $data = $exif->getFilteredData();
            if ( $data ) {
                $data['MEDIAWIKI_EXIF_VERSION'] = Exif::version();

                return $data;
            } else {
                throw new InvalidTiffException( "Could not extract data from tiff file $filename" );
            }
        } else {
            throw new InvalidTiffException( "File doesn't exist - $filename" );
        }
    }

    /**
     * Read the first 2 bytes of a tiff file to figure out
     * Little Endian or Big Endian. Needed for exif stuff.
     *
     * @param string $filename
     * @return string|false 'BE' or 'LE' or false
     */
    public static function getTiffByteOrder( $filename ) {
        $fh = fopen( $filename, 'rb' );
        if ( !$fh ) {
            return false;
        }
        $head = fread( $fh, 2 );
        fclose( $fh );

        switch ( $head ) {
            case 'II':
                return 'LE'; // II for intel.
            case 'MM':
                return 'BE'; // MM for motorla.
            default:
                return false; // Something went wrong.

        }
    }
}