edu.harvard.hul.ois.jhove.module

Class GifModule

java.lang.Object

ModuleBase

edu.harvard.hul.ois.jhove.module.GifModule

public class GifModule
extends ModuleBase

Module for identification and validation of GIF files.

Author:

Gary McGath

Field Summary

Fields

Modifier and Type	Field and Description
protected List	_blocksList
protected Checksummer	_ckSummer
protected ChecksumInputStream	_cstream
protected DataInputStream	_dstream
protected int	_gceCounter
protected boolean	_globalColorTableFlag
protected int	_globalColorTableSize
protected Property	_metadata
protected int	_numGraphicBlocks
protected byte[]	_sig PRIVATE INSTANCE FIELDS.
protected Property	_xmpProp

Constructor Summary

Constructors

Constructor and Description
GifModule() Instantiate a GifModule object.

Method Summary

Modifier and Type	Method and Description
protected Property	addByteProperty(String name, int value, String[] labels)
void	checkSignatures(File file, InputStream stream, RepInfo info) Check if the digital object conforms to this Module's internal signature information.
protected void	initParse() Initializes the state of the module for parsing.
int	parse(InputStream stream, RepInfo info, int parseIndex) Parse the content of a purported GIF stream digital object and store the results in RepInfo.
protected boolean	readAppExtension(RepInfo info)
protected boolean	readBlock(RepInfo info)
protected boolean	readCommentExtension(RepInfo info)
protected boolean	readExtBlock(RepInfo info)
protected boolean	readGraphicsCtlBlock(RepInfo info)
protected boolean	readImage(RepInfo info)
protected boolean	readLSD(RepInfo info)
protected boolean	readPlainTextExtension(RepInfo info)
protected boolean	readSig(RepInfo info)
protected int	readUnsignedShort(DataInputStream stream)
protected int	readXMP()

Methods inherited from class java.lang.Object

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

Field Detail

_sig

protected byte[] _sig

PRIVATE INSTANCE FIELDS.

_ckSummer

protected Checksummer _ckSummer

_xmpProp

protected Property _xmpProp

_cstream

protected ChecksumInputStream _cstream

_dstream

protected DataInputStream _dstream

_globalColorTableFlag

protected boolean _globalColorTableFlag

_globalColorTableSize

protected int _globalColorTableSize

_gceCounter

protected int _gceCounter

_metadata

protected Property _metadata

_blocksList

protected List _blocksList

_numGraphicBlocks

protected int _numGraphicBlocks

Constructor Detail

GifModule

public GifModule()

Instantiate a GifModule object.

Method Detail

checkSignatures

public void checkSignatures(File file,
                            InputStream stream,
                            RepInfo info)
                     throws IOException

Check if the digital object conforms to this Module's internal signature information.

Parameters:

file - A File object for the object being parsed

stream - An InputStream, positioned at its beginning, which is generated from the object to be parsed

info - A fresh RepInfo object which will be modified to reflect the results of the test

Throws:

IOException

parse

public int parse(InputStream stream,
                 RepInfo info,
                 int parseIndex)
          throws IOException

Parse the content of a purported GIF stream digital object and store the results in RepInfo.

Parameters:

stream - An InputStream, positioned at its beginning, which is generated from the object to be parsed

info - A fresh RepInfo object which will be modified to reflect the results of the parsing

parseIndex - Must be 0 in first call to parse. If parse returns a nonzero value, it must be called again with parseIndex equal to that return value.

Throws:

IOException

initParse

protected void initParse()

Initializes the state of the module for parsing.

readSig

protected boolean readSig(RepInfo info)
                   throws IOException

Throws:

IOException

readLSD

protected boolean readLSD(RepInfo info)
                   throws IOException

Throws:

IOException

readBlock

protected boolean readBlock(RepInfo info)
                     throws IOException

Throws:

IOException

readExtBlock

protected boolean readExtBlock(RepInfo info)
                        throws IOException

Throws:

IOException

readImage

protected boolean readImage(RepInfo info)
                     throws IOException

Throws:

IOException

readAppExtension

protected boolean readAppExtension(RepInfo info)
                            throws IOException

Throws:

IOException

readCommentExtension

protected boolean readCommentExtension(RepInfo info)
                                throws IOException

Throws:

IOException

readPlainTextExtension

protected boolean readPlainTextExtension(RepInfo info)
                                  throws IOException

Throws:

IOException

readGraphicsCtlBlock

protected boolean readGraphicsCtlBlock(RepInfo info)
                                throws IOException

Throws:

IOException

readXMP

protected int readXMP()
               throws IOException

Throws:

IOException

addByteProperty

protected Property addByteProperty(String name,
                                   int value,
                                   String[] labels)

readUnsignedShort

protected int readUnsignedShort(DataInputStream stream)
                         throws IOException

Throws:

IOException