JpegSegmentReader Class Reference

Collaboration diagram for JpegSegmentReader:

[legend]

List of all members.

Public Member Functions
final int	getSegmentCount (byte segmentMarker)
	JpegSegmentReader (InputStream in) throws JpegProcessingException
	JpegSegmentReader (byte[] fileContents) throws JpegProcessingException
	JpegSegmentReader (File file) throws JpegProcessingException
byte[]	readSegment (byte segmentMarker, int occurrence)
byte[]	readSegment (byte segmentMarker) throws JpegProcessingException
Static Public Attributes
static final byte	SEGMENT_APP0 = (byte)0xE0
static final byte	SEGMENT_APP1 = (byte)0xE1
static final byte	SEGMENT_APP2 = (byte)0xE2
static final byte	SEGMENT_APP3 = (byte)0xE3
static final byte	SEGMENT_APP4 = (byte)0xE4
static final byte	SEGMENT_APP5 = (byte)0xE5
static final byte	SEGMENT_APP6 = (byte)0xE6
static final byte	SEGMENT_APP7 = (byte)0xE7
static final byte	SEGMENT_APP8 = (byte)0xE8
static final byte	SEGMENT_APP9 = (byte)0xE9
static final byte	SEGMENT_APPA = (byte)0xEA
static final byte	SEGMENT_APPB = (byte)0xEB
static final byte	SEGMENT_APPC = (byte)0xEC
static final byte	SEGMENT_APPD = (byte)0xED
static final byte	SEGMENT_APPE = (byte)0xEE
static final byte	SEGMENT_APPF = (byte)0xEF
static final byte	SEGMENT_COM = (byte)0xFE
static final byte	SEGMENT_DHT = (byte)0xC4
static final byte	SEGMENT_DQT = (byte)0xDB
static final byte	SEGMENT_SOF0 = (byte)0xC0
static final byte	SEGMENT_SOI = (byte)0xD8
Private Member Functions
BufferedInputStream	getJpegInputStream () throws JpegProcessingException
boolean	isValidJpegHeaderBytes (InputStream fileStream) throws IOException
void	readSegments () throws JpegProcessingException
Private Attributes
final byte[]	_data
final File	_file
HashMap	_segmentDataMap
InputStream	_stream
Static Private Attributes
static final byte	MARKER_EOI = (byte)0xD9
static final byte	SEGMENT_SOS = (byte)0xDA

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Detailed Description

Performs read functions of Jpeg files, returning specific file segments. TODO add a findAvailableSegments() method TODO add more segment identifiers TODO add a getSegmentDescription() method, returning for example 'App1 application data segment, commonly containing Exif data'

Author:

Drew Noakes http://drewnoakes.com

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Constructor & Destructor Documentation

JpegSegmentReader

(

File

file

)

throws JpegProcessingException

Creates a JpegSegmentReader for a specific file.

Parameters:

file

the Jpeg file to read segments from

JpegSegmentReader

(

byte[]

fileContents

)

throws JpegProcessingException

Creates a JpegSegmentReader for a byte array.

Parameters:

fileContents

the byte array containing Jpeg data

JpegSegmentReader

(

InputStream

in

)

throws JpegProcessingException

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Member Function Documentation

BufferedInputStream getJpegInputStream

(

)

throws JpegProcessingException [private]

Private helper method to create a BufferedInputStream of Jpeg data from whichever data source was specified upon construction of this instance.

Returns:

a a BufferedInputStream of Jpeg data

Exceptions:

JpegProcessingException

for any problems obtaining the stream

final int getSegmentCount

(

byte

segmentMarker

)

boolean isValidJpegHeaderBytes

(

InputStream

fileStream

)

throws IOException [private]

Helper method that validates the Jpeg file's magic number.

Parameters:

fileStream

the InputStream to read bytes from, which must be positioned at its start (i.e. no bytes read yet)

Returns:

true if the magic number is Jpeg (0xFFD8)

Exceptions:

IOException

for any problem in reading the file

byte [] readSegment	(	byte	segmentMarker,
		int	occurrence
	)

Reads the first instance of a given Jpeg segment, returning the contents as a byte array.

Parameters:

	segmentMarker	the byte identifier for the desired segment
	occurrence	the occurrence of the specified segment within the jpeg file

Returns:

the byte array if found, else null

Exceptions:

JpegProcessingException

for any problems processing the Jpeg data, including inner IOExceptions

byte [] readSegment

(

byte

segmentMarker

)

throws JpegProcessingException

Reads the first instance of a given Jpeg segment, returning the contents as a byte array.

Parameters:

segmentMarker

the byte identifier for the desired segment

Returns:

the byte array if found, else null

Exceptions:

JpegProcessingException

for any problems processing the Jpeg data, including inner IOExceptions

void readSegments

(

)

throws JpegProcessingException [private]

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Member Data Documentation

final byte [] _data [private]

Jpeg data as byte array.

final File _file [private]

Jpeg file.

HashMap _segmentDataMap [private]

InputStream _stream [private]

Jpeg data as an InputStream.

final byte MARKER_EOI = (byte)0xD9 [static, private]

Private, because one wouldn't search for it.

final byte SEGMENT_APP0 = (byte)0xE0 [static]

APP0 Jpeg segment identifier -- Jfif data.

final byte SEGMENT_APP1 = (byte)0xE1 [static]

APP1 Jpeg segment identifier -- where Exif data is kept.

final byte SEGMENT_APP2 = (byte)0xE2 [static]

APP2 Jpeg segment identifier.

final byte SEGMENT_APP3 = (byte)0xE3 [static]

APP3 Jpeg segment identifier.

final byte SEGMENT_APP4 = (byte)0xE4 [static]

APP4 Jpeg segment identifier.

final byte SEGMENT_APP5 = (byte)0xE5 [static]

APP5 Jpeg segment identifier.

final byte SEGMENT_APP6 = (byte)0xE6 [static]

APP6 Jpeg segment identifier.

final byte SEGMENT_APP7 = (byte)0xE7 [static]

APP7 Jpeg segment identifier.

final byte SEGMENT_APP8 = (byte)0xE8 [static]

APP8 Jpeg segment identifier.

final byte SEGMENT_APP9 = (byte)0xE9 [static]

APP9 Jpeg segment identifier.

final byte SEGMENT_APPA = (byte)0xEA [static]

APPA Jpeg segment identifier.

final byte SEGMENT_APPB = (byte)0xEB [static]

APPB Jpeg segment identifier.

final byte SEGMENT_APPC = (byte)0xEC [static]

APPC Jpeg segment identifier.

final byte SEGMENT_APPD = (byte)0xED [static]

APPD Jpeg segment identifier -- IPTC data in here.

final byte SEGMENT_APPE = (byte)0xEE [static]

APPE Jpeg segment identifier.

final byte SEGMENT_APPF = (byte)0xEF [static]

APPF Jpeg segment identifier.

final byte SEGMENT_COM = (byte)0xFE [static]

Comment segment identifier

final byte SEGMENT_DHT = (byte)0xC4 [static]

Define Huffman Table segment identifier.

final byte SEGMENT_DQT = (byte)0xDB [static]

Define Quantization Table segment identifier.

final byte SEGMENT_SOF0 = (byte)0xC0 [static]

Start-of-Frame Zero segment identifier.

final byte SEGMENT_SOI = (byte)0xD8 [static]

Start Of Image segment identifier.

final byte SEGMENT_SOS = (byte)0xDA [static, private]

Private, because this segment crashes my algorithm, and searching for it doesn't work (yet).

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

• /opt/source/Wonder/Frameworks/BusinessLogic/ERAttachment/Sources/com/drew/imaging/jpeg/JpegSegmentReader.java