WebPHandler.php

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<?php
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MediaWikiServices;
use Wikimedia\XMPReader\Reader as XMPReader;
 
class WebPHandler extends BitmapHandler {
    private const BROKEN_FILE = '0';
    private const MINIMUM_CHUNK_HEADER_LENGTH = 18;
    private const MAX_METADATA_CHUNK_SIZE = 1024 * 1024 * 2;
    private const _MW_WEBP_VERSION = 2;
 
    private const VP8X_ICC = 32;
    private const VP8X_ALPHA = 16;
    private const VP8X_EXIF = 8;
    private const VP8X_XMP = 4;
    private const VP8X_ANIM = 2;
 
    public function getSizeAndMetadata( $state, $filename ) {
        $parsedWebPData = self::extractMetadata( $filename );
        if ( !$parsedWebPData ) {
            return [ 'metadata' => [ '_error' => self::BROKEN_FILE ] ];
        }
 
        $parsedWebPData['metadata']['_MW_WEBP_VERSION'] = self::_MW_WEBP_VERSION;
        $info = [
            'width' => $parsedWebPData['width'],
            'height' => $parsedWebPData['height'],
            'metadata' => $parsedWebPData
        ];
        return $info;
    }
 
    public function getMetadataType( $image ) {
        return 'parsed-webp';
    }
 
    public function isFileMetadataValid( $image ) {
        $data = $image->getMetadataArray();
        if ( $data === [ '_error' => self::BROKEN_FILE ] ) {
                // Do not repetitivly regenerate metadata on broken file.
                return self::METADATA_GOOD;
        }
 
        if ( !$data || !isset( $data['_error'] ) ) {
                wfDebug( __METHOD__ . " invalid WebP metadata" );
 
                return self::METADATA_BAD;
        }
 
        if ( !isset( $data['metadata']['_MW_WEBP_VERSION'] )
                || $data['metadata']['_MW_WEBP_VERSION'] != self::_MW_WEBP_VERSION
        ) {
                wfDebug( __METHOD__ . " old but compatible WebP metadata" );
 
                return self::METADATA_COMPATIBLE;
        }
        return self::METADATA_GOOD;
    }
 
    public static function extractMetadata( $filename ) {
        wfDebugLog( 'WebP', __METHOD__ . ": Extracting metadata from $filename" );
 
        $info = RiffExtractor::findChunksFromFile( $filename, 100 );
        if ( $info === false ) {
            wfDebugLog( 'WebP', __METHOD__ . ": Not a valid RIFF file" );
            return false;
        }
 
        if ( $info['fourCC'] !== 'WEBP' ) {
            wfDebugLog( 'WebP', __METHOD__ . ': FourCC was not WEBP: ' .
                bin2hex( $info['fourCC'] ) );
            return false;
        }
        $metadata = self::extractMetadataFromChunks( $info['chunks'], $filename );
        if ( !$metadata ) {
            wfDebugLog( 'WebP', __METHOD__ . ": No VP8 chunks found" );
            return false;
        }
 
        return $metadata;
    }
 
    public static function extractMetadataFromChunks( $chunks, $filename ) {
        $vp8Info = [];
        $exifData = null;
        $xmpData = null;
 
        foreach ( $chunks as $chunk ) {
            // Note, spec says it should be 'XMP ' but some real life files use "XMP\0"
            if ( !in_array( $chunk['fourCC'], [ 'VP8 ', 'VP8L', 'VP8X', 'EXIF', 'XMP ', "XMP\0" ] ) ) {
                // Not a chunk containing interesting metadata
                continue;
            }
 
            $chunkHeader = file_get_contents( $filename, false, null,
                $chunk['start'], self::MINIMUM_CHUNK_HEADER_LENGTH );
            wfDebugLog( 'WebP', __METHOD__ . ": {$chunk['fourCC']}" );
 
            switch ( $chunk['fourCC'] ) {
                case 'VP8 ':
                    $vp8Info = array_merge( $vp8Info,
                        self::decodeLossyChunkHeader( $chunkHeader ) );
                    break;
                case 'VP8L':
                    $vp8Info = array_merge( $vp8Info,
                        self::decodeLosslessChunkHeader( $chunkHeader ) );
                    break;
                case 'VP8X':
                    $vp8Info = array_merge( $vp8Info,
                        self::decodeExtendedChunkHeader( $chunkHeader ) );
                    // Continue looking for other chunks to improve the metadata
                    break;
                case 'EXIF':
                    // Spec says ignore all but first one
                    $exifData ??= self::extractChunk( $chunk, $filename );
                    break;
                case 'XMP ':
                case "XMP\0":
                    $xmpData ??= self::extractChunk( $chunk, $filename );
                    break;
            }
        }
        $vp8Info = array_merge( $vp8Info,
            self::decodeMediaMetadata( $exifData, $xmpData, $filename ) );
        return $vp8Info;
    }
 
    private static function decodeMediaMetadata( $exifData, $xmpData, $filename ) {
        if ( $exifData === null && $xmpData === null ) {
            // Nothing to do
            return [];
        }
        $bitmapMetadataHandler = new BitmapMetadataHandler;
 
        if ( $xmpData && XMPReader::isSupported() ) {
            $xmpReader = new XMPReader( LoggerFactory::getInstance( 'XMP' ), $filename );
            $xmpReader->parse( $xmpData );
            $res = $xmpReader->getResults();
            foreach ( $res as $type => $array ) {
                $bitmapMetadataHandler->addMetadata( $array, $type );
            }
        }
 
        if ( $exifData ) {
            // The Exif section of a webp file is basically a tiff file without an image.
            // Some files start with an Exif\0\0. This is wrong according to standard and
            // will prevent us from reading file, so remove for compatibility.
            if ( substr( $exifData, 0, 6 ) === "Exif\x00\x00" ) {
                $exifData = substr( $exifData, 6 );
            }
            $tmpFile = MediaWikiServices::getInstance()->
                getTempFSFileFactory()->
                newTempFSFile( 'webp-exif_', 'tiff' );
 
            $exifDataFile = $tmpFile->getPath();
            file_put_contents( $exifDataFile, $exifData );
            $byteOrder = BitmapMetadataHandler::getTiffByteOrder( $exifDataFile );
            $bitmapMetadataHandler->getExif( $exifDataFile, $byteOrder );
        }
        return [ 'media-metadata' => $bitmapMetadataHandler->getMetadataArray() ];
    }
 
    private static function extractChunk( $chunk, $filename ) {
        if ( $chunk['size'] > self::MAX_METADATA_CHUNK_SIZE || $chunk['size'] < 1 ) {
            return null;
        }
 
        // Skip first 8 bytes as that is the fourCC header followed by size of chunk.
        return file_get_contents( $filename, false, null, $chunk['start'] + 8, $chunk['size'] );
    }
 
    protected static function decodeLossyChunkHeader( $header ) {
        // Bytes 0-3 are 'VP8 '
        // Bytes 4-7 are the VP8 stream size
        // Bytes 8-10 are the frame tag
        // Bytes 11-13 are 0x9D 0x01 0x2A called the sync code
        $syncCode = substr( $header, 11, 3 );
        if ( $syncCode !== "\x9D\x01\x2A" ) {
            wfDebugLog( 'WebP', __METHOD__ . ': Invalid sync code: ' .
                bin2hex( $syncCode ) );
            return [];
        }
        // Bytes 14-17 are image size
        $imageSize = unpack( 'v2', substr( $header, 14, 4 ) );
        // Image sizes are 14 bit, 2 MSB are scaling parameters which are ignored here
        return [
            'compression' => 'lossy',
            'width' => $imageSize[1] & 0x3FFF,
            'height' => $imageSize[2] & 0x3FFF
        ];
    }
 
    public static function decodeLosslessChunkHeader( $header ) {
        // Bytes 0-3 are 'VP8L'
        // Bytes 4-7 are chunk stream size
        // Byte 8 is 0x2F called the signature
        if ( $header[8] !== "\x2F" ) {
            wfDebugLog( 'WebP', __METHOD__ . ': Invalid signature: ' .
                bin2hex( $header[8] ) );
            return [];
        }
        // Bytes 9-12 contain the image size
        // Bits 0-13 are width-1; bits 15-27 are height-1
        $imageSize = unpack( 'C4', substr( $header, 9, 4 ) );
        return [
                'compression' => 'lossless',
                'width' => ( $imageSize[1] | ( ( $imageSize[2] & 0x3F ) << 8 ) ) + 1,
                'height' => ( ( ( $imageSize[2] & 0xC0 ) >> 6 ) |
                        ( $imageSize[3] << 2 ) | ( ( $imageSize[4] & 0x03 ) << 10 ) ) + 1
        ];
    }
 
    public static function decodeExtendedChunkHeader( $header ) {
        // Bytes 0-3 are 'VP8X'
        // Byte 4-7 are chunk length
        // Byte 8-11 are a flag bytes
        $flags = unpack( 'c', substr( $header, 8, 1 ) );
 
        // Byte 12-17 are image size (24 bits)
        $width = unpack( 'V', substr( $header, 12, 3 ) . "\x00" );
        $height = unpack( 'V', substr( $header, 15, 3 ) . "\x00" );
 
        return [
            'compression' => 'unknown',
            'animated' => ( $flags[1] & self::VP8X_ANIM ) === self::VP8X_ANIM,
            'transparency' => ( $flags[1] & self::VP8X_ALPHA ) === self::VP8X_ALPHA,
            'width' => ( $width[1] & 0xFFFFFF ) + 1,
            'height' => ( $height[1] & 0xFFFFFF ) + 1
        ];
    }
 
    public function mustRender( $file ) {
        return true;
    }
 
    public function canRender( $file ) {
        if ( $this->isAnimatedImage( $file ) ) {
            return false;
        }
        return true;
    }
 
    public function isAnimatedImage( $image ) {
        $metadata = $image->getMetadataArray();
        if ( isset( $metadata['animated'] ) && $metadata['animated'] === true ) {
            return true;
        }
 
        return false;
    }
 
    public function canAnimateThumbnail( $file ) {
        return false;
    }
 
    public function getThumbType( $ext, $mime, $params = null ) {
        return [ 'png', 'image/png' ];
    }
 
    protected function hasGDSupport() {
        return function_exists( 'gd_info' ) && ( gd_info()['WebP Support'] ?? false );
    }
 
    public function getCommonMetaArray( File $image ) {
        $meta = $image->getMetadataArray();
        return $meta['media-metadata'] ?? [];
    }
 
    public function formatMetadata( $image, $context = false ) {
        $meta = $this->getCommonMetaArray( $image );
        if ( !$meta ) {
            return false;
        }
 
        return $this->formatMetadataHelper( $meta, $context );
    }
}