com.drew.metadata.exif
Class ExifReader

java.lang.Object
  com.drew.metadata.exif.ExifReader

All Implemented Interfaces:

MetadataReader

public class ExifReader
extends Object
implements MetadataReader

Decodes Exif binary data, populating a Metadata object with tag values in ExifDirectory, GpsDirectory and one of the many camera makernote directories.

Author:

Drew Noakes http://drewnoakes.com

Field Summary

private byte[]	_data The Exif segment as an array of bytes.
private ExifDirectory	_exifDirectory The Exif directory used (loaded lazily)
private boolean	_isMotorollaByteOrder Represents the native byte ordering used in the JPEG segment.
private Metadata	_metadata Bean instance to store information about the image and camera/scanner/capture device.
private static int[]	BYTES_PER_FORMAT The number of bytes used per format descriptor.
private static int	FMT_BYTE
private static int	FMT_DOUBLE
private static int	FMT_SBYTE
private static int	FMT_SINGLE
private static int	FMT_SLONG
private static int	FMT_SRATIONAL
private static int	FMT_SSHORT
private static int	FMT_STRING
private static int	FMT_ULONG
private static int	FMT_UNDEFINED
private static int	FMT_URATIONAL
private static int	FMT_USHORT
private static int	MAX_FORMAT_CODE The number of formats known.
static int	TAG_EXIF_OFFSET
static int	TAG_GPS_INFO_OFFSET
static int	TAG_INTEROP_OFFSET
static int	TAG_MAKER_NOTE
static int	TIFF_HEADER_START_OFFSET

Constructor Summary

ExifReader(byte[] data)
Creates an ExifReader for the given Exif data segment.

ExifReader(File jpegFile)
Deprecated. Not all files will be Jpegs! Use a constructor that provides the exif segment in isolation.

ExifReader(InputStream jpegInputStream)
Deprecated. Not all files will be Jpegs! Use a constructor that provides the exif segment in isolation.

ExifReader(JpegSegmentData segmentData)
Deprecated. Not all files will be Jpegs! This overload doesn't offer much convenience to the caller.

Method Summary

private int	calculateTagOffset(int dirStartOffset, int entryNumber) Determine the offset at which a given InteropArray entry begins within the specified IFD.
private int	calculateTagValueOffset(int byteCount, int dirEntryOffset, int tiffHeaderOffset)
Metadata	extract() Performs the Exif data extraction, returning a new instance of Metadata.
Metadata	extract(Metadata metadata) Performs the Exif data extraction, adding found values to the specified instance of Metadata.
private Metadata	extractIFD(Metadata metadata, int tiffHeaderOffset)
Metadata	extractTiff(Metadata metadata) Performs the Exif data extraction on a Tiff/Raw, adding found values to the specified instance of Metadata.
private int	get16Bits(int offset) Get a 16 bit value from file's native byte order.
private int	get32Bits(int offset) Get a 32 bit value from file's native byte order.
private ExifDirectory	getExifDirectory()
private boolean	isDirectoryLengthValid(int dirStartOffset, int tiffHeaderOffset)
private void	processDirectory(Directory directory, HashMap processedDirectoryOffsets, int dirStartOffset, int tiffHeaderOffset) Process one of the nested Tiff IFD directories.
private void	processMakerNote(int subdirOffset, HashMap processedDirectoryOffsets, int tiffHeaderOffset)
private void	processTag(Directory directory, int tagType, int tagValueOffset, int componentCount, int formatCode)
private String	readString(int offset, int maxLength) Creates a String from the _data buffer starting at the specified offset, and ending where byte=='\0' or where length==maxLength.
private boolean	setByteOrder(String byteOrderIdentifier) Sets the _isMotorollaByteOrder flag to true or false, depending upon the file's byte order string.
private void	storeThumbnailBytes(ExifDirectory exifDirectory, int tiffHeaderOffset)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BYTES_PER_FORMAT

private static final int[] BYTES_PER_FORMAT

The number of bytes used per format descriptor.

MAX_FORMAT_CODE

private static final int MAX_FORMAT_CODE

The number of formats known.

See Also:

Constant Field Values

FMT_BYTE

private static final int FMT_BYTE

See Also:

Constant Field Values

FMT_STRING

private static final int FMT_STRING

See Also:

Constant Field Values

FMT_USHORT

private static final int FMT_USHORT

See Also:

Constant Field Values

FMT_ULONG

private static final int FMT_ULONG

See Also:

Constant Field Values

FMT_URATIONAL

private static final int FMT_URATIONAL

See Also:

Constant Field Values

FMT_SBYTE

private static final int FMT_SBYTE

See Also:

Constant Field Values

FMT_UNDEFINED

private static final int FMT_UNDEFINED

See Also:

Constant Field Values

FMT_SSHORT

private static final int FMT_SSHORT

See Also:

Constant Field Values

FMT_SLONG

private static final int FMT_SLONG

See Also:

Constant Field Values

FMT_SRATIONAL

private static final int FMT_SRATIONAL

See Also:

Constant Field Values

FMT_SINGLE

private static final int FMT_SINGLE

See Also:

Constant Field Values

FMT_DOUBLE

private static final int FMT_DOUBLE

See Also:

Constant Field Values

TAG_EXIF_OFFSET

public static final int TAG_EXIF_OFFSET

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Constant Field Values

TAG_INTEROP_OFFSET

public static final int TAG_INTEROP_OFFSET

See Also:

Constant Field Values

TAG_GPS_INFO_OFFSET

public static final int TAG_GPS_INFO_OFFSET

See Also:

Constant Field Values

TAG_MAKER_NOTE

public static final int TAG_MAKER_NOTE

See Also:

Constant Field Values

TIFF_HEADER_START_OFFSET

public static final int TIFF_HEADER_START_OFFSET

See Also:

Constant Field Values

_data

private final byte[] _data

The Exif segment as an array of bytes.

_isMotorollaByteOrder

private boolean _isMotorollaByteOrder

Represents the native byte ordering used in the JPEG segment. If true, then we're using Motorolla ordering (Big endian), else we're using Intel ordering (Little endian).

_metadata

private Metadata _metadata

Bean instance to store information about the image and camera/scanner/capture device.

_exifDirectory

private ExifDirectory _exifDirectory

The Exif directory used (loaded lazily)

Constructor Detail

ExifReader

public ExifReader(JpegSegmentData segmentData)

Deprecated. Not all files will be Jpegs! This overload doesn't offer much convenience to the caller.

Creates an ExifReader for a JpegSegmentData object.

Parameters:

segmentData -

ExifReader

public ExifReader(File jpegFile)
           throws JpegProcessingException

Deprecated. Not all files will be Jpegs! Use a constructor that provides the exif segment in isolation.

Creates an ExifReader for a Jpeg jpegFile.

Parameters:

jpegFile -

Throws:

JpegProcessingException

ExifReader

public ExifReader(InputStream jpegInputStream)
           throws JpegProcessingException

Deprecated. Not all files will be Jpegs! Use a constructor that provides the exif segment in isolation.

Creates an ExifReader for a Jpeg stream.

Parameters:

jpegInputStream - JPEG stream. Stream will be closed.

Throws:

JpegProcessingException

ExifReader

public ExifReader(byte[] data)

Creates an ExifReader for the given Exif data segment.

Method Detail

extract

public Metadata extract()

Performs the Exif data extraction, returning a new instance of Metadata.

Specified by:

extract in interface MetadataReader

Returns:

The populated Metadata object.

extract

public Metadata extract(Metadata metadata)

Performs the Exif data extraction, adding found values to the specified instance of Metadata.

Specified by:

extract in interface MetadataReader

Returns:

The updated Metadata object.

getExifDirectory

private ExifDirectory getExifDirectory()

extractTiff

public Metadata extractTiff(Metadata metadata)

Performs the Exif data extraction on a Tiff/Raw, adding found values to the specified instance of Metadata.

extractIFD

private Metadata extractIFD(Metadata metadata,
                            int tiffHeaderOffset)

storeThumbnailBytes

private void storeThumbnailBytes(ExifDirectory exifDirectory,
                                 int tiffHeaderOffset)

setByteOrder

private boolean setByteOrder(String byteOrderIdentifier)

Sets the _isMotorollaByteOrder flag to true or false, depending upon the file's byte order string. If the string cannot be interpreted, false is returned.

Parameters:

byteOrderIdentifier - a two-character string; either "MM" for Motorolla or "II" for Intel.

Returns:

true if successful, otherwise false.

processDirectory

private void processDirectory(Directory directory,
                              HashMap processedDirectoryOffsets,
                              int dirStartOffset,
                              int tiffHeaderOffset)

Process one of the nested Tiff IFD directories. 2 bytes: number of tags for each tag 2 bytes: tag type 2 bytes: format code 4 bytes: component count

processMakerNote

private void processMakerNote(int subdirOffset,
                              HashMap processedDirectoryOffsets,
                              int tiffHeaderOffset)

isDirectoryLengthValid

private boolean isDirectoryLengthValid(int dirStartOffset,
                                       int tiffHeaderOffset)

processTag

private void processTag(Directory directory,
                        int tagType,
                        int tagValueOffset,
                        int componentCount,
                        int formatCode)

calculateTagValueOffset

private int calculateTagValueOffset(int byteCount,
                                    int dirEntryOffset,
                                    int tiffHeaderOffset)

readString

private String readString(int offset,
                          int maxLength)

Creates a String from the _data buffer starting at the specified offset, and ending where byte=='\0' or where length==maxLength.

calculateTagOffset

private int calculateTagOffset(int dirStartOffset,
                               int entryNumber)

Determine the offset at which a given InteropArray entry begins within the specified IFD.

Parameters:

dirStartOffset - the offset at which the IFD starts

entryNumber - the zero-based entry number

get16Bits

private int get16Bits(int offset)

Get a 16 bit value from file's native byte order. Between 0x0000 and 0xFFFF.

get32Bits

private int get32Bits(int offset)

Get a 32 bit value from file's native byte order.