com.drew.imaging.jpeg
Class JpegSegmentReader

java.lang.Object
  com.drew.imaging.jpeg.JpegSegmentReader

public class JpegSegmentReader
extends Object

Performs read functions of Jpeg files, returning specific file segments.

Author:

Drew Noakes http://drewnoakes.com

Field Summary

static byte	SEGMENT_APP0 APP0 Jpeg segment identifier -- JFIF data (also JFXX apparently).
static byte	SEGMENT_APP1 APP1 Jpeg segment identifier -- where Exif data is kept.
static byte	SEGMENT_APP2 APP2 Jpeg segment identifier.
static byte	SEGMENT_APP3 APP3 Jpeg segment identifier.
static byte	SEGMENT_APP4 APP4 Jpeg segment identifier.
static byte	SEGMENT_APP5 APP5 Jpeg segment identifier.
static byte	SEGMENT_APP6 APP6 Jpeg segment identifier.
static byte	SEGMENT_APP7 APP7 Jpeg segment identifier.
static byte	SEGMENT_APP8 APP8 Jpeg segment identifier.
static byte	SEGMENT_APP9 APP9 Jpeg segment identifier.
static byte	SEGMENT_APPA APPA (App10) Jpeg segment identifier -- can hold Unicode comments.
static byte	SEGMENT_APPB APPB (App11) Jpeg segment identifier.
static byte	SEGMENT_APPC APPC (App12) Jpeg segment identifier.
static byte	SEGMENT_APPD APPD (App13) Jpeg segment identifier -- IPTC data in here.
static byte	SEGMENT_APPE APPE (App14) Jpeg segment identifier.
static byte	SEGMENT_APPF APPF (App15) Jpeg segment identifier.
static byte	SEGMENT_COM Jpeg comment segment identifier.
static byte	SEGMENT_DHT Define Huffman Table segment identifier.
static byte	SEGMENT_DQT Define Quantization Table segment identifier.
static byte	SEGMENT_SOF0 Start-of-Frame Zero segment identifier.
static byte	SEGMENT_SOI Start Of Image segment identifier.

Constructor Summary

JpegSegmentReader(byte[] fileContents)
Creates a JpegSegmentReader for a byte array.

JpegSegmentReader(File file)
Creates a JpegSegmentReader for a specific file.

JpegSegmentReader(InputStream inputStream, boolean waitForBytes)
Creates a JpegSegmentReader for an InputStream.

Method Summary

int	getSegmentCount(byte segmentMarker) Returns the number of segments having the specified JPEG segment marker.
JpegSegmentData	getSegmentData() Returns the JpegSegmentData object used by this reader.
byte[]	readSegment(byte segmentMarker) Reads the first instance of a given Jpeg segment, returning the contents as a byte array.
byte[]	readSegment(byte segmentMarker, int occurrence) Reads the Nth instance of a given Jpeg segment, returning the contents as a byte array.
Iterable<byte[]>	readSegments(byte segmentMarker) Returns all instances of a given Jpeg segment.

Methods inherited from class java.lang.Object

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

Field Detail

SEGMENT_APP0

public static final byte SEGMENT_APP0

APP0 Jpeg segment identifier -- JFIF data (also JFXX apparently).

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Constant Field Values

SEGMENT_APP1

public static final byte SEGMENT_APP1

APP1 Jpeg segment identifier -- where Exif data is kept. XMP data is also kept in here, though usually in a second instance.

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Constant Field Values

SEGMENT_APP2

public static final byte SEGMENT_APP2

APP2 Jpeg segment identifier.

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Constant Field Values

SEGMENT_APP3

public static final byte SEGMENT_APP3

APP3 Jpeg segment identifier.

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Constant Field Values

SEGMENT_APP4

public static final byte SEGMENT_APP4

APP4 Jpeg segment identifier.

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Constant Field Values

SEGMENT_APP5

public static final byte SEGMENT_APP5

APP5 Jpeg segment identifier.

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Constant Field Values

SEGMENT_APP6

public static final byte SEGMENT_APP6

APP6 Jpeg segment identifier.

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Constant Field Values

SEGMENT_APP7

public static final byte SEGMENT_APP7

APP7 Jpeg segment identifier.

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Constant Field Values

SEGMENT_APP8

public static final byte SEGMENT_APP8

APP8 Jpeg segment identifier.

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Constant Field Values

SEGMENT_APP9

public static final byte SEGMENT_APP9

APP9 Jpeg segment identifier.

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Constant Field Values

SEGMENT_APPA

public static final byte SEGMENT_APPA

APPA (App10) Jpeg segment identifier -- can hold Unicode comments.

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Constant Field Values

SEGMENT_APPB

public static final byte SEGMENT_APPB

APPB (App11) Jpeg segment identifier.

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Constant Field Values

SEGMENT_APPC

public static final byte SEGMENT_APPC

APPC (App12) Jpeg segment identifier.

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Constant Field Values

SEGMENT_APPD

public static final byte SEGMENT_APPD

APPD (App13) Jpeg segment identifier -- IPTC data in here.

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Constant Field Values

SEGMENT_APPE

public static final byte SEGMENT_APPE

APPE (App14) Jpeg segment identifier.

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Constant Field Values

SEGMENT_APPF

public static final byte SEGMENT_APPF

APPF (App15) Jpeg segment identifier.

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Constant Field Values

SEGMENT_SOI

public static final byte SEGMENT_SOI

Start Of Image segment identifier.

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Constant Field Values

SEGMENT_DQT

public static final byte SEGMENT_DQT

Define Quantization Table segment identifier.

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Constant Field Values

SEGMENT_DHT

public static final byte SEGMENT_DHT

Define Huffman Table segment identifier.

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Constant Field Values

SEGMENT_SOF0

public static final byte SEGMENT_SOF0

Start-of-Frame Zero segment identifier.

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Constant Field Values

SEGMENT_COM

public static final byte SEGMENT_COM

Jpeg comment segment identifier.

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Constant Field Values

Constructor Detail

JpegSegmentReader

public JpegSegmentReader(File file)
                  throws JpegProcessingException,
                         IOException

Creates a JpegSegmentReader for a specific file.

Parameters:

file - the Jpeg file to read segments from

Throws:

JpegProcessingException

IOException

JpegSegmentReader

public JpegSegmentReader(byte[] fileContents)
                  throws JpegProcessingException

Creates a JpegSegmentReader for a byte array.

Parameters:

fileContents - the byte array containing Jpeg data

Throws:

JpegProcessingException

JpegSegmentReader

public JpegSegmentReader(InputStream inputStream,
                         boolean waitForBytes)
                  throws JpegProcessingException

Creates a JpegSegmentReader for an InputStream.

Parameters:

inputStream - the InputStream containing Jpeg data

Throws:

JpegProcessingException

Method Detail

readSegment

public byte[] readSegment(byte segmentMarker)

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

readSegment

public byte[] readSegment(byte segmentMarker,
                          int occurrence)

Reads the Nth 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

readSegments

public Iterable<byte[]> readSegments(byte segmentMarker)

Returns all instances of a given Jpeg segment. If no instances exist, an empty sequence is returned.

Parameters:

segmentMarker - a number which identifies the type of Jpeg segment being queried

Returns:

zero or more byte arrays, each holding the data of a Jpeg segment

getSegmentCount

public final int getSegmentCount(byte segmentMarker)

Returns the number of segments having the specified JPEG segment marker.

Parameters:

segmentMarker - the JPEG segment identifying marker.

Returns:

the count of matching segments.

getSegmentData

public final JpegSegmentData getSegmentData()

Returns the JpegSegmentData object used by this reader.

Returns:

the JpegSegmentData object.