exif.php

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<?php
/**
 * @package MediaWiki
 * @subpackage Metadata
 *
 * @author 脝var Arnfj枚r冒 Bjarmason <[e-mail]>
 * @copyright Copyright 漏 2005, 脝var Arnfj枚r冒 Bjarmason
 * @license http://www.gnu.org/copyleft/gpl.html GNU General Public License
 *
 * 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
 *
 * @link http://exif.org/Exif2-2.PDF The Exif 2.2 specification
 * @bug 1555, 1947
 */

/**
 * @package MediaWiki
 * @subpackage Metadata
 */
class Exif {
	//@{
	/* @var array
	 * @private
	 */

	/**#@+
	 * Exif tag type definition
	 */
	const BYTE      = 1;    # An 8-bit (1-byte) unsigned integer.
	const ASCII     = 2;    # An 8-bit byte containing one 7-bit ASCII code. The final byte is terminated with NULL.
	const SHORT     = 3;    # A 16-bit (2-byte) unsigned integer.
	const LONG      = 4;    # A 32-bit (4-byte) unsigned integer.
	const RATIONAL  = 5;    # Two LONGs. The first LONG is the numerator and the second LONG expresses the denominator
	const UNDEFINED = 7;    # An 8-bit byte that can take any value depending on the field definition
	const SLONG     = 9;    # A 32-bit (4-byte) signed integer (2's complement notation),
	const SRATIONAL = 10;   # Two SLONGs. The first SLONG is the numerator and the second SLONG is the denominator.

	/**
	 * Exif tags grouped by category, the tagname itself is the key and the type
	 * is the value, in the case of more than one possible value type they are
	 * seperated by commas.
	 */
	var $mExifTags;

	/**
	 * A one dimentional array of all Exif tags
	 */
	var $mFlatExifTags;

	/**
	 * The raw Exif data returned by exif_read_data()
	 */
	var $mRawExifData;

	/**
	 * A Filtered version of $mRawExifData that has been pruned of invalid
	 * tags and tags that contain content they shouldn't contain according
	 * to the Exif specification
	 */
	var $mFilteredExifData;

	/**
	 * Filtered and formatted Exif data, see FormatExif::getFormattedData()
	 */
	var $mFormattedExifData;

	//@}

	//@{
	/* @var string
	 * @private
	 */

	/**
	 * The file being processed
	 */
	var $file;

	/**
	 * The basename of the file being processed
	 */
	var $basename;

	/**
	 * The private log to log to
	 */
	var $log = 'exif';

	//@}

	/**
	 * Constructor
	 *
	 * @param $file String: filename.
	 */
	function Exif( $file ) {
		/**
		 * Page numbers here refer to pages in the EXIF 2.2 standard
		 *
		 * @link http://exif.org/Exif2-2.PDF The Exif 2.2 specification
		 */
		$this->mExifTags = array(
			# TIFF Rev. 6.0 Attribute Information (p22)
			'tiff' => array(
				# Tags relating to image structure
				'structure' => array(
					'ImageWidth' => Exif::SHORT.','.Exif::LONG,		# Image width
					'ImageLength' => Exif::SHORT.','.Exif::LONG,	# Image height
					'BitsPerSample' => Exif::SHORT,			# 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' => Exif::SHORT,			# 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
				'offset' => array(
					'StripOffsets' => Exif::SHORT.','.Exif::LONG,			# Image data location
					'RowsPerStrip' => Exif::SHORT.','.Exif::LONG,			# Number of rows per strip
					'StripByteCounts' => Exif::SHORT.','.Exif::LONG,			# Bytes per compressed strip
					'JPEGInterchangeFormat' => Exif::SHORT.','.Exif::LONG,		# Offset to JPEG SOI
					'JPEGInterchangeFormatLength' => Exif::SHORT.','.Exif::LONG,	# Bytes of JPEG data
				),

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

				# Other tags
				'other' => array(
					'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(
				# Tags relating to version
				'version' => 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
				'characteristics' => array(
					'ColorSpace' => Exif::SHORT,		# Color space information #p32
				),

				# Tags relating to image configuration
				'configuration' => array(
					'ComponentsConfiguration' => Exif::UNDEFINED,		# Meaning of each component #p33
					'CompressedBitsPerPixel' => Exif::RATIONAL,		# Image compression mode
					'PixelYDimension' => Exif::SHORT.','.Exif::LONG,	# Valid image width
					'PixelXDimension' => Exif::SHORT.','.Exif::LONG,	# Valind image height
				),

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

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

				# Tags relating to date and time
				'dateandtime' => array(
					'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)
				'conditions' => array(
					'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::UNDEFINED,				# Optoelectronic conversion factor
					'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' => Exif::SHORT,				# Subject area
					'FlashEnergy' => Exif::RATIONAL,			# Flash energy
					'SpatialFrequencyResponse' => Exif::UNDEFINED,	# Spatial frequency response
					'FocalPlaneXResolution' => Exif::RATIONAL,		# Focal plane X resolution
					'FocalPlaneYResolution' => Exif::RATIONAL,		# Focal plane Y resolution
					'FocalPlaneResolutionUnit' => Exif::SHORT,		# Focal plane resolution unit #p46
					'SubjectLocation' => Exif::SHORT,			# 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::UNDEFINED,			# CFA pattern
					'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::RATIONAL,			# Scene control #p49-50
					'Contrast' => Exif::SHORT,				# Contrast #p50
					'Saturation' => Exif::SHORT,				# Saturation #p50
					'Sharpness' => Exif::SHORT,				# Sharpness #p50
					'DeviceSettingDescription' => Exif::UNDEFINED,	# Desice settings description
					'SubjectDistanceRange' => Exif::SHORT,		# Subject distance range #p51
				),

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

			# GPS Attribute Information (p52)
			'gps' => array(
				'GPSVersionID' => Exif::BYTE,			# GPS tag version
				'GPSLatitudeRef' => Exif::ASCII,		# North or South Latitude #p52-53
				'GPSLatitude' => Exif::RATIONAL,		# Latitude
				'GPSLongitudeRef' => Exif::ASCII,		# East or West Longitude #p53
				'GPSLongitude' => Exif::RATIONAL,		# Longitude
				'GPSAltitudeRef' => Exif::BYTE,		# Altitude reference
				'GPSAltitude' => Exif::RATIONAL,		# Altitude
				'GPSTimeStamp' => Exif::RATIONAL,		# 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' => Exif::RATIONAL,		# Latitude destination
				'GPSDestLongitudeRef' => Exif::ASCII,		# Reference for longitude of destination #p57
				'GPSDestLongitude' => Exif::RATIONAL,		# 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 = basename( $this->file );

		$this->makeFlatExifTags();

		$this->debugFile( $this->basename, __FUNCTION__, true );
		wfSuppressWarnings();
		$data = exif_read_data( $this->file );
		wfRestoreWarnings();
		/**
		 * exif_read_data() will return false on invalid input, such as
		 * when somebody uploads a file called something.jpeg
		 * containing random gibberish.
		 */
		$this->mRawExifData = $data ? $data : array();

		$this->makeFilteredData();
		$this->makeFormattedData();

		$this->debugFile( __FUNCTION__, false );
	}

	/**#@+
	 * @private
	 */
	/**
	 * Generate a flat list of the exif tags
	 */
	function makeFlatExifTags() {
		$this->extractTags( $this->mExifTags );
	}

	/**
	 * A recursing extractor function used by makeFlatExifTags()
	 *
	 * Note: This used to use an array_walk function, but it made PHP5
	 * segfault, see `cvs diff -u -r 1.4 -r 1.5 Exif.php`
	 */
	function extractTags( &$tagset ) {
		foreach( $tagset as $key => $val ) {
			if( is_array( $val ) ) {
				$this->extractTags( $val );
			} else {
				$this->mFlatExifTags[$key] = $val;
			}
		}
	}

	/**
	 * Make $this->mFilteredExifData
	 */
	function makeFilteredData() {
		$this->mFilteredExifData = $this->mRawExifData;

		foreach( $this->mFilteredExifData as $k => $v ) {
			if ( !in_array( $k, array_keys( $this->mFlatExifTags ) ) ) {
				$this->debug( $v, __FUNCTION__, "'$k' is not a valid Exif tag" );
				unset( $this->mFilteredExifData[$k] );
			}
		}

		foreach( $this->mFilteredExifData as $k => $v ) {
			if ( !$this->validate($k, $v) ) {
				$this->debug( $v, __FUNCTION__, "'$k' contained invalid data" );
				unset( $this->mFilteredExifData[$k] );
			}
		}
	}

	/**
	 * @todo document
	 */
	function makeFormattedData( ) {
		$format = new FormatExif( $this->getFilteredData() );
		$this->mFormattedExifData = $format->getFormattedData();
	}
	/**#@-*/

	/**#@+
	 * @return array
	 */