ExifReader Class Reference

Inherits com::drew::metadata::MetadataReader.

Collaboration diagram for ExifReader:

[legend]

List of all members.

Public Member Functions
	ExifReader (byte[] data)
	ExifReader (File file) throws JpegProcessingException
Metadata	extract (Metadata metadata)
Metadata	extract ()
Static Public Attributes
static final int	TAG_EXIF_OFFSET = 0x8769
static final int	TAG_GPS_INFO_OFFSET = 0x8825
static final int	TAG_INTEROP_OFFSET = 0xA005
static final int	TAG_MAKER_NOTE = 0x927C
static int	TIFF_HEADER_START_OFFSET = 6
Static Package Attributes
static final int[]	BYTES_PER_FORMAT = {0, 1, 1, 2, 4, 8, 1, 1, 2, 4, 8, 4, 8}
Private Member Functions
int	calculateDirectoryEntryOffset (int ifdStartOffset, int entryNumber)
int	calculateTagValueOffset (int byteCount, int dirEntryOffset)
void	extractThumbnail (Directory exifDirectory)
int	get16Bits (int offset)
int	get32Bits (int offset)
boolean	isDirectoryLengthValid (int dirStartOffset)
void	processDirectory (Directory directory, int dirStartOffset)
void	processMakerNote (int subdirOffset)
void	processTag (Directory directory, int tagType, int tagValueOffset, int componentCount, int formatCode)
String	readCommentString (int tagValueOffset, int componentCount, int formatCode)
String	readString (int offset, int maxLength)
boolean	setByteOrder (String byteOrderIdentifier)
Private Attributes
final byte[]	_data
boolean	_isMotorollaByteOrder
Metadata	_metadata
Static Private Attributes
static final int	FMT_BYTE = 1
static final int	FMT_DOUBLE = 12
static final int	FMT_SBYTE = 6
static final int	FMT_SINGLE = 11
static final int	FMT_SLONG = 9
static final int	FMT_SRATIONAL = 10
static final int	FMT_SSHORT = 8
static final int	FMT_STRING = 2
static final int	FMT_ULONG = 4
static final int	FMT_UNDEFINED = 7
static final int	FMT_URATIONAL = 5
static final int	FMT_USHORT = 3
static final int	MAX_FORMAT_CODE = 12

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Detailed Description

Extracts Exif data from a JPEG header segment, providing information about the camera/scanner/capture device (if available). Information is encapsulated in an Metadata object.

Author:

Drew Noakes http://drewnoakes.com

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Constructor & Destructor Documentation

ExifReader

(

File

file

)

throws JpegProcessingException

Parameters:

file

Exceptions:

JpegProcessingException

ExifReader

(

byte[]

data

)

Creates an ExifReader for the given JPEG header segment.

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Member Function Documentation

int calculateDirectoryEntryOffset	(	int	ifdStartOffset,
		int	entryNumber
	)			[private]

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

Parameters:

	ifdStartOffset	the offset at which the IFD starts
	entryNumber	the zero-based entry number

int calculateTagValueOffset	(	int	byteCount,
		int	dirEntryOffset
	)			[private]

Metadata extract

(

Metadata

metadata

)

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

Implements MetadataReader.

Metadata extract

(

)

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

Implements MetadataReader.

void extractThumbnail

(

Directory

exifDirectory

)

[private]

int get16Bits

(

int

offset

)

[private]

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

int get32Bits

(

int

offset

)

[private]

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

boolean isDirectoryLengthValid

(

int

dirStartOffset

)

[private]

void processDirectory	(	Directory	directory,
		int	dirStartOffset
	)			[private]

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

void processMakerNote

(

int

subdirOffset

)

[private]

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

String readCommentString	(	int	tagValueOffset,
		int	componentCount,
		int	formatCode
	)			[private]

A special case of readString that handle Exif UserComment reading. This method is necessary as certain camere models prefix the comment string with "ASCII\0", which is all that would be returned by readString(...).

String readString	(	int	offset,
		int	maxLength
	)			[private]

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

boolean setByteOrder

(

String

byteOrderIdentifier

)

[private]

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Member Data Documentation

final byte [] _data [private]

The JPEG segment as an array of bytes.

boolean _isMotorollaByteOrder [private]

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 _metadata [private]

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

final int [] BYTES_PER_FORMAT = {0, 1, 1, 2, 4, 8, 1, 1, 2, 4, 8, 4, 8} [static, package]

The number of bytes used per format descriptor.

final int FMT_BYTE = 1 [static, private]

final int FMT_DOUBLE = 12 [static, private]

final int FMT_SBYTE = 6 [static, private]

final int FMT_SINGLE = 11 [static, private]

final int FMT_SLONG = 9 [static, private]

final int FMT_SRATIONAL = 10 [static, private]

final int FMT_SSHORT = 8 [static, private]

final int FMT_STRING = 2 [static, private]

final int FMT_ULONG = 4 [static, private]

final int FMT_UNDEFINED = 7 [static, private]

final int FMT_URATIONAL = 5 [static, private]

final int FMT_USHORT = 3 [static, private]

final int MAX_FORMAT_CODE = 12 [static, private]

The number of formats known.

final int TAG_EXIF_OFFSET = 0x8769 [static]

final int TAG_GPS_INFO_OFFSET = 0x8825 [static]

final int TAG_INTEROP_OFFSET = 0xA005 [static]

final int TAG_MAKER_NOTE = 0x927C [static]

int TIFF_HEADER_START_OFFSET = 6 [static]

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The documentation for this class was generated from the following file:

• /opt/source/Wonder/Frameworks/BusinessLogic/ERAttachment/Sources/com/drew/metadata/exif/ExifReader.java