com.drew.imaging.jpeg
Class JpegSegmentData

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

All Implemented Interfaces:

Serializable

public class JpegSegmentData
extends Object
implements Serializable

Holds a collection of Jpeg data segments. This need not necessarily be all segments within the Jpeg. For example, it may be convenient to store only the non-image segments when analysing (or serializing) metadata. Segments are keyed via their segment marker (a byte). Where multiple segments use the same segment marker, they will all be stored and available.

See Also:

Serialized Form

Field Summary

private HashMap	_segmentDataMap A map of byte[], keyed by the segment marker
(package private) static long	serialVersionUID

Constructor Summary

JpegSegmentData()
Creates a new JpegSegmentData collection object.

Method Summary

void	addSegment(byte segmentMarker, byte[] segmentBytes) Adds segment bytes to the collection.
boolean	containsSegment(byte segmentMarker) Determines whether data is present for a given segment marker.
static JpegSegmentData	FromFile(File file) Deserialises the contents of a JpegSegmentData from a file.
private List	getOrCreateSegmentList(byte segmentMarker)
byte[]	getSegment(byte segmentMarker) Gets the first Jpeg segment data for the specified marker.
byte[]	getSegment(byte segmentMarker, int occurrence) Gets segment data for a specific occurrence and marker.
int	getSegmentCount(byte segmentMarker) Returns the count of segment data byte arrays stored for a given segment marker.
private List	getSegmentList(byte segmentMarker)
void	removeSegment(byte segmentMarker) Removes all segments from the collection having the specified marker.
void	removeSegmentOccurrence(byte segmentMarker, int occurrence) Removes a specified instance of a segment's data from the collection.
static void	ToFile(File file, JpegSegmentData segmentData) Serialises the contents of a JpegSegmentData to a file.

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

_segmentDataMap

private final HashMap _segmentDataMap

A map of byte[], keyed by the segment marker

Constructor Detail

JpegSegmentData

public JpegSegmentData()

Creates a new JpegSegmentData collection object.

Method Detail

addSegment

public void addSegment(byte segmentMarker,
                       byte[] segmentBytes)

Adds segment bytes to the collection.

Parameters:

segmentMarker -

segmentBytes -

getSegment

public byte[] getSegment(byte segmentMarker)

Gets the first Jpeg segment data for the specified marker.

Parameters:

segmentMarker - the byte identifier for the desired segment

Returns:

a byte[] containing segment data or null if no data exists for that segment

getSegment

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

Gets segment data for a specific occurrence and marker. Use this method when more than one occurrence of segment data for a given marker exists.

Parameters:

segmentMarker - identifies the required segment

occurrence - the zero-based index of the occurrence

Returns:

the segment data as a byte[], or null if no segment exists for the marker & occurrence

getSegmentCount

public int getSegmentCount(byte segmentMarker)

Returns the count of segment data byte arrays stored for a given segment marker.

Parameters:

segmentMarker - identifies the required segment

Returns:

the segment count (zero if no segments exist).

removeSegmentOccurrence

public void removeSegmentOccurrence(byte segmentMarker,
                                    int occurrence)

Removes a specified instance of a segment's data from the collection. Use this method when more than one occurrence of segment data for a given marker exists.

Parameters:

segmentMarker - identifies the required segment

occurrence - the zero-based index of the segment occurrence to remove.

removeSegment

public void removeSegment(byte segmentMarker)

Removes all segments from the collection having the specified marker.

Parameters:

segmentMarker - identifies the required segment

containsSegment

public boolean containsSegment(byte segmentMarker)

Determines whether data is present for a given segment marker.

Parameters:

segmentMarker - identifies the required segment

Returns:

true if data exists, otherwise false

ToFile

public static void ToFile(File file,
                          JpegSegmentData segmentData)
                   throws IOException

Serialises the contents of a JpegSegmentData to a file.

Parameters:

file - to file to write from

segmentData - the data to write

Throws:

IOException - if problems occur while writing

FromFile

public static JpegSegmentData FromFile(File file)
                                throws IOException,
                                       ClassNotFoundException

Deserialises the contents of a JpegSegmentData from a file.

Parameters:

file - the file to read from

Returns:

the JpegSegmentData as read

Throws:

IOException - if problems occur while reading

ClassNotFoundException - if problems occur while deserialising

getSegmentList

private List getSegmentList(byte segmentMarker)

getOrCreateSegmentList

private List getOrCreateSegmentList(byte segmentMarker)