Exif.php

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<?php
class Exif {

    const BYTE = 1; 
    const ASCII = 2; 
    const SHORT = 3; 
    const LONG = 4; 
    const RATIONAL = 5; 
    const SHORT_OR_LONG = 6; 
    const UNDEFINED = 7; 
    const SLONG = 9; 
    const SRATIONAL = 10; 
    const IGNORE = -1; // A fake value for things we don't want or don't support.

    /* @var array
     * @private
     */

    var $mExifTags;

    var $mRawExifData;

    var $mFilteredExifData;

    var $mFormattedExifData;


    /* @var string
     * @private
     */

    var $file;

    var $basename;

    var $log = false;

    private $byteOrder;

    function __construct( $file, $byteOrder = '' ) {
        $this->mExifTags = array(
            # TIFF Rev. 6.0 Attribute Information (p22)
            'IFD0' => array(
                # Tags relating to image structure
                'ImageWidth' => Exif::SHORT_OR_LONG,        # Image width
                'ImageLength' => Exif::SHORT_OR_LONG,       # Image height
                'BitsPerSample' => array( Exif::SHORT, 3 ),     # Number of bits per component
                # "When a primary image is JPEG compressed, this designation is not"
                # "necessary and is omitted." (p23)
                'Compression' => Exif::SHORT,               # Compression scheme #p23
                'PhotometricInterpretation' => Exif::SHORT,     # Pixel composition #p23
                'Orientation' => Exif::SHORT,               # Orientation of image #p24
                'SamplesPerPixel' => Exif::SHORT,           # Number of components
                'PlanarConfiguration' => Exif::SHORT,           # Image data arrangement #p24
                'YCbCrSubSampling' => array( Exif::SHORT, 2 ),      # Subsampling ratio of Y to C #p24
                'YCbCrPositioning' => Exif::SHORT,          # Y and C positioning #p24-25
                'XResolution' => Exif::RATIONAL,            # Image resolution in width direction
                'YResolution' => Exif::RATIONAL,            # Image resolution in height direction
                'ResolutionUnit' => Exif::SHORT,            # Unit of X and Y resolution #(p26)

                # Tags relating to recording offset
                'StripOffsets' => Exif::SHORT_OR_LONG,          # Image data location
                'RowsPerStrip' => Exif::SHORT_OR_LONG,          # Number of rows per strip
                'StripByteCounts' => Exif::SHORT_OR_LONG,       # Bytes per compressed strip
                'JPEGInterchangeFormat' => Exif::SHORT_OR_LONG,     # Offset to JPEG SOI
                'JPEGInterchangeFormatLength' => Exif::SHORT_OR_LONG,   # Bytes of JPEG data

                # Tags relating to image data characteristics
                'TransferFunction' => Exif::IGNORE,         # Transfer function
                'WhitePoint' => array( Exif::RATIONAL, 2 ),     # White point chromaticity
                'PrimaryChromaticities' => array( Exif::RATIONAL, 6 ),  # Chromaticities of primarities
                'YCbCrCoefficients' => array( Exif::RATIONAL, 3 ),  # Color space transformation matrix coefficients #p27
                'ReferenceBlackWhite' => array( Exif::RATIONAL, 6 ),    # Pair of black and white reference values

                # Other tags
                'DateTime' => Exif::ASCII,              # File change date and time
                'ImageDescription' => Exif::ASCII,          # Image title
                'Make' => Exif::ASCII,                  # Image input equipment manufacturer
                'Model' => Exif::ASCII,                 # Image input equipment model
                'Software' => Exif::ASCII,              # Software used
                'Artist' => Exif::ASCII,                # Person who created the image
                'Copyright' => Exif::ASCII,             # Copyright holder
            ),

            # Exif IFD Attribute Information (p30-31)
            'EXIF' => array(
                # TODO: NOTE: Nonexistence of this field is taken to mean nonconformance
                # to the Exif 2.1 AND 2.2 standards
                'ExifVersion' => Exif::UNDEFINED,           # Exif version
                'FlashPixVersion' => Exif::UNDEFINED,           # Supported Flashpix version #p32

                # Tags relating to Image Data Characteristics
                'ColorSpace' => Exif::SHORT,                # Color space information #p32

                # Tags relating to image configuration
                'ComponentsConfiguration' => Exif::UNDEFINED,           # Meaning of each component #p33
                'CompressedBitsPerPixel' => Exif::RATIONAL,         # Image compression mode
                'PixelYDimension' => Exif::SHORT_OR_LONG,       # Valid image width
                'PixelXDimension' => Exif::SHORT_OR_LONG,       # Valid image height

                # Tags relating to related user information
                'MakerNote' => Exif::IGNORE,                # Manufacturer notes
                'UserComment' => Exif::UNDEFINED,           # User comments #p34

                # Tags relating to related file information
                'RelatedSoundFile' => Exif::ASCII,          # Related audio file

                # Tags relating to date and time
                'DateTimeOriginal' => Exif::ASCII,          # Date and time of original data generation #p36
                'DateTimeDigitized' => Exif::ASCII,         # Date and time of original data generation
                'SubSecTime' => Exif::ASCII,                # DateTime subseconds
                'SubSecTimeOriginal' => Exif::ASCII,            # DateTimeOriginal subseconds
                'SubSecTimeDigitized' => Exif::ASCII,           # DateTimeDigitized subseconds

                # Tags relating to picture-taking conditions (p31)
                'ExposureTime' => Exif::RATIONAL,           # Exposure time
                'FNumber' => Exif::RATIONAL,                # F Number
                'ExposureProgram' => Exif::SHORT,           # Exposure Program #p38
                'SpectralSensitivity' => Exif::ASCII,           # Spectral sensitivity
                'ISOSpeedRatings' => Exif::SHORT,           # ISO speed rating
                'OECF' => Exif::IGNORE,
                # Optoelectronic conversion factor. Note: We don't have support for this atm.
                'ShutterSpeedValue' => Exif::SRATIONAL,         # Shutter speed
                'ApertureValue' => Exif::RATIONAL,          # Aperture
                'BrightnessValue' => Exif::SRATIONAL,           # Brightness
                'ExposureBiasValue' => Exif::SRATIONAL,         # Exposure bias
                'MaxApertureValue' => Exif::RATIONAL,           # Maximum land aperture
                'SubjectDistance' => Exif::RATIONAL,            # Subject distance
                'MeteringMode' => Exif::SHORT,              # Metering mode #p40
                'LightSource' => Exif::SHORT,               # Light source #p40-41
                'Flash' => Exif::SHORT,                 # Flash #p41-42
                'FocalLength' => Exif::RATIONAL,            # Lens focal length
                'SubjectArea' => array( Exif::SHORT, 4 ),       # Subject area
                'FlashEnergy' => Exif::RATIONAL,            # Flash energy
                'SpatialFrequencyResponse' => Exif::IGNORE,     # Spatial frequency response. Not supported atm.
                'FocalPlaneXResolution' => Exif::RATIONAL,      # Focal plane X resolution
                'FocalPlaneYResolution' => Exif::RATIONAL,      # Focal plane Y resolution
                'FocalPlaneResolutionUnit' => Exif::SHORT,      # Focal plane resolution unit #p46
                'SubjectLocation' => array( Exif::SHORT, 2 ),       # Subject location
                'ExposureIndex' => Exif::RATIONAL,          # Exposure index
                'SensingMethod' => Exif::SHORT,             # Sensing method #p46
                'FileSource' => Exif::UNDEFINED,            # File source #p47
                'SceneType' => Exif::UNDEFINED,             # Scene type #p47
                'CFAPattern' => Exif::IGNORE,               # CFA pattern. not supported atm.
                'CustomRendered' => Exif::SHORT,            # Custom image processing #p48
                'ExposureMode' => Exif::SHORT,              # Exposure mode #p48
                'WhiteBalance' => Exif::SHORT,              # White Balance #p49
                'DigitalZoomRatio' => Exif::RATIONAL,           # Digital zoom ration
                'FocalLengthIn35mmFilm' => Exif::SHORT,         # Focal length in 35 mm film
                'SceneCaptureType' => Exif::SHORT,          # Scene capture type #p49
                'GainControl' => Exif::SHORT,               # Scene control #p49-50
                'Contrast' => Exif::SHORT,              # Contrast #p50
                'Saturation' => Exif::SHORT,                # Saturation #p50
                'Sharpness' => Exif::SHORT,             # Sharpness #p50
                'DeviceSettingDescription' => Exif::IGNORE,
                # Device settings description. This could maybe be supported. Need to find an
                # example file that uses this to see if it has stuff of interest in it.
                'SubjectDistanceRange' => Exif::SHORT,          # Subject distance range #p51

                'ImageUniqueID' => Exif::ASCII,             # Unique image ID
            ),

            # GPS Attribute Information (p52)
            'GPS' => array(
                'GPSVersion' => Exif::UNDEFINED,
                # Should be an array of 4 Exif::BYTE's. However php treats it as an undefined
                # Note exif standard calls this GPSVersionID, but php doesn't like the id suffix
                'GPSLatitudeRef' => Exif::ASCII,            # North or South Latitude #p52-53
                'GPSLatitude' => array( Exif::RATIONAL, 3 ),        # Latitude
                'GPSLongitudeRef' => Exif::ASCII,           # East or West Longitude #p53
                'GPSLongitude' => array( Exif::RATIONAL, 3 ),       # Longitude
                'GPSAltitudeRef' => Exif::UNDEFINED,
                # Altitude reference. Note, the exif standard says this should be an EXIF::Byte,
                # but php seems to disagree.
                'GPSAltitude' => Exif::RATIONAL,            # Altitude
                'GPSTimeStamp' => array( Exif::RATIONAL, 3 ),       # GPS time (atomic clock)
                'GPSSatellites' => Exif::ASCII,             # Satellites used for measurement
                'GPSStatus' => Exif::ASCII,             # Receiver status #p54
                'GPSMeasureMode' => Exif::ASCII,            # Measurement mode #p54-55
                'GPSDOP' => Exif::RATIONAL,             # Measurement precision
                'GPSSpeedRef' => Exif::ASCII,               # Speed unit #p55
                'GPSSpeed' => Exif::RATIONAL,               # Speed of GPS receiver
                'GPSTrackRef' => Exif::ASCII,               # Reference for direction of movement #p55
                'GPSTrack' => Exif::RATIONAL,               # Direction of movement
                'GPSImgDirectionRef' => Exif::ASCII,            # Reference for direction of image #p56
                'GPSImgDirection' => Exif::RATIONAL,            # Direction of image
                'GPSMapDatum' => Exif::ASCII,               # Geodetic survey data used
                'GPSDestLatitudeRef' => Exif::ASCII,            # Reference for latitude of destination #p56
                'GPSDestLatitude' => array( Exif::RATIONAL, 3 ),    # Latitude destination
                'GPSDestLongitudeRef' => Exif::ASCII,           # Reference for longitude of destination #p57
                'GPSDestLongitude' => array( Exif::RATIONAL, 3 ),   # Longitude of destination
                'GPSDestBearingRef' => Exif::ASCII,         # Reference for bearing of destination #p57
                'GPSDestBearing' => Exif::RATIONAL,         # Bearing of destination
                'GPSDestDistanceRef' => Exif::ASCII,            # Reference for distance to destination #p57-58
                'GPSDestDistance' => Exif::RATIONAL,            # Distance to destination
                'GPSProcessingMethod' => Exif::UNDEFINED,       # Name of GPS processing method
                'GPSAreaInformation' => Exif::UNDEFINED,        # Name of GPS area
                'GPSDateStamp' => Exif::ASCII,              # GPS date
                'GPSDifferential' => Exif::SHORT,           # GPS differential correction
            ),
        );

        $this->file = $file;
        $this->basename = wfBaseName( $this->file );
        if ( $byteOrder === 'BE' || $byteOrder === 'LE' ) {
            $this->byteOrder = $byteOrder;
        } else {
            // Only give a warning for b/c, since originally we didn't
            // require this. The number of things affected by this is
            // rather small.
            wfWarn( 'Exif class did not have byte order specified. ' .
                'Some properties may be decoded incorrectly.' );
            $this->byteOrder = 'BE'; // BE seems about twice as popular as LE in jpg's.
        }

        $this->debugFile( $this->basename, __FUNCTION__, true );
        if ( function_exists( 'exif_read_data' ) ) {
            wfSuppressWarnings();
            $data = exif_read_data( $this->file, 0, true );
            wfRestoreWarnings();
        } else {
            throw new MWException( "Internal error: exif_read_data not present. \$wgShowEXIF may be incorrectly set or not checked by an extension." );
        }
        $this->mRawExifData = $data ? $data : array();
        $this->makeFilteredData();
        $this->collapseData();
        $this->debugFile( __FUNCTION__, false );
    }

    function makeFilteredData() {
        $this->mFilteredExifData = Array();

        foreach ( array_keys( $this->mRawExifData ) as $section ) {
            if ( !in_array( $section, array_keys( $this->mExifTags ) ) ) {
                $this->debug( $section, __FUNCTION__, "'$section' is not a valid Exif section" );
                continue;
            }

            foreach ( array_keys( $this->mRawExifData[$section] ) as $tag ) {
                if ( !in_array( $tag, array_keys( $this->mExifTags[$section] ) ) ) {
                    $this->debug( $tag, __FUNCTION__, "'$tag' is not a valid tag in '$section'" );
                    continue;
                }

                $this->mFilteredExifData[$tag] = $this->mRawExifData[$section][$tag];
                // This is ok, as the tags in the different sections do not conflict.
                // except in computed and thumbnail section, which we don't use.

                $value = $this->mRawExifData[$section][$tag];
                if ( !$this->validate( $section, $tag, $value ) ) {
                    $this->debug( $value, __FUNCTION__, "'$tag' contained invalid data" );
                    unset( $this->mFilteredExifData[$tag] );
                }
            }
        }
    }

    function collapseData() {

        $this->exifGPStoNumber( 'GPSLatitude' );
        $this->exifGPStoNumber( 'GPSDestLatitude' );
        $this->exifGPStoNumber( 'GPSLongitude' );
        $this->exifGPStoNumber( 'GPSDestLongitude' );

        if ( isset( $this->mFilteredExifData['GPSAltitude'] ) && isset( $this->mFilteredExifData['GPSAltitudeRef'] ) ) {

            // We know altitude data is a <num>/<denom> from the validation functions ran earlier.
            // But multiplying such a string by -1 doesn't work well, so convert.
            list( $num, $denom ) = explode( '/', $this->mFilteredExifData['GPSAltitude'] );
            $this->mFilteredExifData['GPSAltitude'] = $num / $denom;

            if ( $this->mFilteredExifData['GPSAltitudeRef'] === "\1" ) {
                $this->mFilteredExifData['GPSAltitude'] *= - 1;
            }
            unset( $this->mFilteredExifData['GPSAltitudeRef'] );
        }

        $this->exifPropToOrd( 'FileSource' );
        $this->exifPropToOrd( 'SceneType' );

        $this->charCodeString( 'UserComment' );
        $this->charCodeString( 'GPSProcessingMethod' );
        $this->charCodeString( 'GPSAreaInformation' );

        //ComponentsConfiguration should really be an array instead of a string...
        //This turns a string of binary numbers into an array of numbers.

        if ( isset( $this->mFilteredExifData['ComponentsConfiguration'] ) ) {
            $val = $this->mFilteredExifData['ComponentsConfiguration'];
            $ccVals = array();
            for ( $i = 0; $i < strlen( $val ); $i++ ) {
                $ccVals[$i] = ord( substr( $val, $i, 1 ) );
            }
            $ccVals['_type'] = 'ol'; //this is for formatting later.
            $this->mFilteredExifData['ComponentsConfiguration'] = $ccVals;
        }

        //GPSVersion(ID) is treated as the wrong type by php exif support.
        //Go through each byte turning it into a version string.
        //For example: "\x02\x02\x00\x00" -> "2.2.0.0"

        //Also change exif tag name from GPSVersion (what php exif thinks it is)
        //to GPSVersionID (what the exif standard thinks it is).

        if ( isset( $this->mFilteredExifData['GPSVersion'] ) ) {
            $val = $this->mFilteredExifData['GPSVersion'];
            $newVal = '';
            for ( $i = 0; $i < strlen( $val ); $i++ ) {
                if ( $i !== 0 ) {
                    $newVal .= '.';
                }
                $newVal .= ord( substr( $val, $i, 1 ) );
            }
            if ( $this->byteOrder === 'LE' ) {
                // Need to reverse the string
                $newVal2 = '';
                for ( $i = strlen( $newVal ) - 1; $i >= 0; $i-- ) {
                    $newVal2 .= substr( $newVal, $i, 1 );
                }
                $this->mFilteredExifData['GPSVersionID'] = $newVal2;
            } else {
                $this->mFilteredExifData['GPSVersionID'] = $newVal;
            }
            unset( $this->mFilteredExifData['GPSVersion'] );
        }

    }
    private function charCodeString( $prop ) {
        if ( isset( $this->mFilteredExifData[$prop] ) ) {

            if ( strlen( $this->mFilteredExifData[$prop] ) <= 8 ) {
                //invalid. Must be at least 9 bytes long.

                $this->debug( $this->mFilteredExifData[$prop], __FUNCTION__, false );
                unset( $this->mFilteredExifData[$prop] );
                return;
            }
            $charCode = substr( $this->mFilteredExifData[$prop], 0, 8 );
            $val = substr( $this->mFilteredExifData[$prop], 8 );

            switch ( $charCode ) {
                case "\x4A\x49\x53\x00\x00\x00\x00\x00":
                    //JIS
                    $charset = "Shift-JIS";
                    break;
                case "UNICODE\x00":
                    $charset = "UTF-16" . $this->byteOrder;
                    break;
                default: //ascii or undefined.
                    $charset = "";
                    break;
            }
            // This could possibly check to see if iconv is really installed
            // or if we're using the compatibility wrapper in globalFunctions.php
            if ( $charset ) {
                wfSuppressWarnings();
                $val = iconv( $charset, 'UTF-8//IGNORE', $val );
                wfRestoreWarnings();
            } else {
                // if valid utf-8, assume that, otherwise assume windows-1252
                $valCopy = $val;
                UtfNormal::quickIsNFCVerify( $valCopy ); //validates $valCopy.
                if ( $valCopy !== $val ) {
                    wfSuppressWarnings();
                    $val = iconv( 'Windows-1252', 'UTF-8//IGNORE', $val );
                    wfRestoreWarnings();
                }
            }

            //trim and check to make sure not only whitespace.
            $val = trim( $val );
            if ( strlen( $val ) === 0 ) {
                //only whitespace.
                $this->debug( $this->mFilteredExifData[$prop], __FUNCTION__, "$prop: Is only whitespace" );
                unset( $this->mFilteredExifData[$prop] );
                return;
            }

            //all's good.
            $this->mFilteredExifData[$prop] = $val;
        }
    }
    private function exifPropToOrd( $prop ) {
        if ( isset( $this->mFilteredExifData[$prop] ) ) {
            $this->mFilteredExifData[$prop] = ord( $this->mFilteredExifData[$prop] );
        }
    }
    private function exifGPStoNumber( $prop ) {
        $loc =& $this->mFilteredExifData[$prop];
        $dir =& $this->mFilteredExifData[$prop . 'Ref'];
        $res = false;

        if ( isset( $loc ) && isset( $dir ) && ( $dir === 'N' || $dir === 'S' || $dir === 'E' || $dir === 'W' ) ) {
            list( $num, $denom ) = explode( '/', $loc[0] );
            $res = $num / $denom;
            list( $num, $denom ) = explode( '/', $loc[1] );
            $res += ( $num / $denom ) * ( 1 / 60 );
            list( $num, $denom ) = explode( '/', $loc[2] );
            $res += ( $num / $denom ) * ( 1 / 3600 );

            if ( $dir === 'S' || $dir === 'W' ) {
                $res *= - 1; // make negative
            }
        }

        // update the exif records.

        if ( $res !== false ) { // using !== as $res could potentially be 0
            $this->mFilteredExifData[$prop] = $res;
            unset( $this->mFilteredExifData[$prop . 'Ref'] );
        } else { // if invalid
            unset( $this->mFilteredExifData[$prop] );
            unset( $this->mFilteredExifData[$prop . 'Ref'] );
        }
    }

    function makeFormattedData() {
        wfDeprecated( __METHOD__, '1.18' );
        $this->mFormattedExifData = FormatMetadata::getFormattedData(
            $this->mFilteredExifData );
    }
    function getData() {
        return $this->mRawExifData;
    }

    function getFilteredData() {
        return $this->mFilteredExifData;
    }

    function getFormattedData() {
        wfDeprecated( __METHOD__, '1.18' );
        if ( !$this->mFormattedExifData ) {
            $this->makeFormattedData();
        }
        return $this->mFormattedExifData;
    }
    public static function version() {
        return 2; // We don't need no bloddy constants!
    }

    private function isByte( $in ) {
        if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 255 ) {
            $this->debug( $in, __FUNCTION__, true );
            return true;
        } else {
            $this->debug( $in, __FUNCTION__, false );
            return false;
        }
    }

    private function isASCII( $in ) {
        if ( is_array( $in ) ) {
            return false;
        }

        if ( preg_match( "/[^\x0a\x20-\x7e]/", $in ) ) {
            $this->debug( $in, __FUNCTION__, 'found a character not in our whitelist' );
            return false;
        }

        if ( preg_match( '/^\s*$/', $in ) ) {
            $this->debug( $in, __FUNCTION__, 'input consisted solely of whitespace' );
            return false;
        }

        return true;
    }

    private function isShort( $in ) {
        if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 65536 ) {
            $this->debug( $in, __FUNCTION__, true );
            return true;
        } else {
            $this->debug( $in, __FUNCTION__, false );
            return false;
        }
    }

    private function isLong( $in ) {
        if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 4294967296 ) {
            $this->debug( $in, __FUNCTION__, true );
            return true;
        } else {
            $this->debug( $in, __FUNCTION__, false );
            return false;
        }
    }

    private function isRational( $in ) {
        $m = array();
        if ( !is_array( $in ) && preg_match( '/^(\d+)\/(\d+[1-9]|[1-9]\d*)$/', $in, $m ) ) { # Avoid division by zero
            return $this->isLong( $m[1] ) && $this->isLong( $m[2] );
        } else {
            $this->debug( $in, __FUNCTION__, 'fed a non-fraction value' );
            return false;
        }
    }

    private function isUndefined( $in ) {
        $this->debug( $in, __FUNCTION__, true );
        return true;
    }

    private function isSlong( $in ) {
        if ( $this->isLong( abs( $in ) ) ) {
            $this->debug( $in, __FUNCTION__, true );
            return true;
        } else {
            $this->debug( $in, __FUNCTION__, false );
            return false;
        }
    }

    private function isSrational( $in ) {
        $m = array();
        if ( !is_array( $in ) && preg_match( '/^(-?\d+)\/(\d+[1-9]|[1-9]\d*)$/', $in, $m ) ) { # Avoid division by zero
            return $this->isSlong( $m[0] ) && $this->isSlong( $m[1] );
        } else {
            $this->debug( $in, __FUNCTION__, 'fed a non-fraction value' );
            return false;
        }
    }
    private function validate( $section, $tag, $val, $recursive = false ) {
        $debug = "tag is '$tag'";
        $etype = $this->mExifTags[$section][$tag];
        $ecount = 1;
        if ( is_array( $etype ) ) {
            list( $etype, $ecount ) = $etype;
            if ( $recursive ) {
                $ecount = 1; // checking individual elements
            }
        }
        $count = count( $val );
        if ( $ecount != $count ) {
            $this->debug( $val, __FUNCTION__, "Expected $ecount elements for $tag but got $count" );
            return false;
        }
        if ( $count > 1 ) {
            foreach ( $val as $v ) {
                if ( !$this->validate( $section, $tag, $v, true ) ) {
                    return false;
                }
            }
            return true;
        }
        // Does not work if not typecast
        switch ( (string)$etype ) {
            case (string)Exif::BYTE:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isByte( $val );
            case (string)Exif::ASCII:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isASCII( $val );
            case (string)Exif::SHORT:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isShort( $val );
            case (string)Exif::LONG:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isLong( $val );
            case (string)Exif::RATIONAL:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isRational( $val );
            case (string)Exif::SHORT_OR_LONG:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isShort( $val ) || $this->isLong( $val );
            case (string)Exif::UNDEFINED:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isUndefined( $val );
            case (string)Exif::SLONG:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isSlong( $val );
            case (string)Exif::SRATIONAL:
                $this->debug( $val, __FUNCTION__, $debug );
                return $this->isSrational( $val );
            case (string)Exif::IGNORE:
                $this->debug( $val, __FUNCTION__, $debug );
                return false;
            default:
                $this->debug( $val, __FUNCTION__, "The tag '$tag' is unknown" );
                return false;
        }
    }

    private function debug( $in, $fname, $action = null ) {
        if ( !$this->log ) {
            return;
        }
        $type = gettype( $in );
        $class = ucfirst( __CLASS__ );
        if ( is_array( $in ) ) {
            $in = print_r( $in, true );
        }

        if ( $action === true ) {
            wfDebugLog( $this->log, "$class::$fname: accepted: '$in' (type: $type)\n" );
        } elseif ( $action === false ) {
            wfDebugLog( $this->log, "$class::$fname: rejected: '$in' (type: $type)\n" );
        } elseif ( $action === null ) {
            wfDebugLog( $this->log, "$class::$fname: input was: '$in' (type: $type)\n" );
        } else {
            wfDebugLog( $this->log, "$class::$fname: $action (type: $type; content: '$in')\n" );
        }
    }

    private function debugFile( $fname, $io ) {
        if ( !$this->log ) {
            return;
        }
        $class = ucfirst( __CLASS__ );
        if ( $io ) {
            wfDebugLog( $this->log, "$class::$fname: begin processing: '{$this->basename}'\n" );
        } else {
            wfDebugLog( $this->log, "$class::$fname: end processing: '{$this->basename}'\n" );
        }
    }
}