PngModule (JHOVE - JSTOR/Harvard Object Validation Environment 1.16.0 API)

java.lang.Object
- edu.harvard.hul.ois.jhove.ModuleBase
- - com.mcgath.jhove.module.PngModule

All Implemented Interfaces:

Module
```
public class PngModule
extends ModuleBase
```
Module for validation and metadata extraction on PNG files.

Author:

Gary McGath An earlier PNG module was submitted by Gian Uberto Lauri. A few bits of code are copied from it. It validates files but doesn't do much metadata extraction. I noticed it only after making a significant start on my own version. -- GDM

Field Summary

Fields
Modifier and Type	Field and Description
`protected Checksummer`	`_ckSummer`
`protected int`	`_colorType`
`protected ChecksumInputStream`	`_cstream`
`protected DataInputStream`	`_dstream`
`protected List<Property>`	`_keywordPropList`
`protected Property`	`_metadata`
`protected List<Property>`	`_propList`
`protected List<Property>`	`_spltList`

Fields inherited from class edu.harvard.hul.ois.jhove.ModuleBase
_app, _bigEndian, _checksumFinished, _countStream, _coverage, _crc32, _date, _defaultParams, _features, _format, _init, _isRandomAccess, _je, _logger, _md5, _mimeType, _name, _nByte, _note, _param, _release, _repInfoNote, _rights, _sha1, _signature, _specification, _validityNote, _vendor, _verbosity, _wellFormedNote

Fields inherited from interface edu.harvard.hul.ois.jhove.Module
MAXIMUM_VERBOSITY, MINIMUM_VERBOSITY

Constructor Summary

Constructors
Constructor and Description

PngModule()
Instantiate a PngModule object.

Constructors
Constructor and Description
`PngModule()` Instantiate a `PngModule` object.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addKeyword(String keywd, String val)` Add a keyword and value.
`void`	`addKeyword(String keywd, String translatedKeywd, String val, String language)` Add a keyword, value, and language.
`void`	`addSplt(String name, int sampleDepth, int numSamples)` Add a suggested palette
`void`	`checkSignatures(File file, InputStream stream, RepInfo info)` Check if the digital object conforms to this Module's internal signature information.
`void`	`eatChunk(PNGChunk chnk)` This lets the module skip over the remainder of a chunk, not including the name, length,and CRC.
`int`	`getColorType()` Get the color type that was recorded from the IHDR chunk.
`protected void`	`initParse()` Initializes the state of the module for parsing.
`boolean`	`isChunkSeen(int chunkType)`
`boolean`	`isIdatFinished()` Return true if a non-IDAT chunk has been seen after an IDAT chunk
`boolean`	`isIdatSeen()` Return true if IDAT chunk has been seen
`boolean`	`isIhdrSeen()` Returns true if IHDR chunk has been seen
`boolean`	`isPlteSeen()` Return true if PLTE chunk has been seen
`int`	`parse(InputStream stream, RepInfo info, int parseIndex)` Parse the content of a purported JPEG stream digital object and store the results in RepInfo.
`void`	`setChunkSeen(int chunkType)`
`void`	`setColorType(int ct)` Set the color type.
`void`	`setIdatSeen(boolean b)` Note that an IDAT chunk has been seen
`void`	`setIendSeen(boolean b)` Note that an IEND chunk has been seen
`void`	`setIhdrSeen(boolean b)` Note that an IHDR chunk has been seen
`void`	`setPlteSeen(boolean b)` Note that a PLTE chunk has been seen

Methods inherited from class edu.harvard.hul.ois.jhove.ModuleBase
addIntegerProperty, addIntegerProperty, applyDefaultParams, calcRAChecksum, checkSignatures, getApp, getBase, getBufferedDataStream, getCoverage, getCRC32, getDate, getDefaultParams, getFeatures, getFormat, getMimeType, getName, getNByte, getNote, getRelease, getRepInfoNote, getRights, getSignature, getSpecification, getValidityNote, getVendor, getWellFormedNote, hasFeature, init, initFeatures, isBigEndian, isRandomAccess, param, parse, readByteBuf, readDouble, readDouble, readDouble, readFloat, readFloat, readSignedByte, readSignedByte, readSignedByte, readSignedInt, readSignedInt, readSignedInt, readSignedLong, readSignedRational, readSignedRational, readSignedShort, readSignedShort, readSignedShort, readUnsignedByte, readUnsignedByte, readUnsignedByte, readUnsignedInt, readUnsignedInt, readUnsignedInt, readUnsignedRational, readUnsignedRational, readUnsignedRational, readUnsignedShort, readUnsignedShort, readUnsignedShort, resetParams, setApp, setBase, setChecksums, setCRC32, setDefaultParams, setMD5, setNByte, setSHA1, setValidityNote, setVerbosity, show, skipBytes, skipBytes, vectorToPropArray

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - _ckSummer
```
protected Checksummer _ckSummer
```
  - _propList
```
protected List<Property> _propList
```
  - _keywordPropList
```
protected List<Property> _keywordPropList
```
  - _spltList
```
protected List<Property> _spltList
```
  - _cstream
```
protected ChecksumInputStream _cstream
```
  - _dstream
```
protected DataInputStream _dstream
```
  - _metadata
```
protected Property _metadata
```
  - _colorType
```
protected int _colorType
```
- Constructor Detail
  - PngModule
```
public PngModule()
```
    Instantiate a PngModule 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.
    
    Specified by:
    
    checkSignatures in interface Module
    
    Overrides:
    
    checkSignatures in class ModuleBase
    
    Parameters:
    
    file - A RandomAccessFile, positioned at its beginning, which is generated from the object to be 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 JPEG stream digital object and store the results in RepInfo. This function uses the JPEG-L method of detecting a marker following a data stream, checking for a 0 high bit rather than an entire 0 byte. So long at no JPEG markers are defined with a value from 0 through 7F, this is valid for all JPEG files.
    
    Specified by:
    
    parse in interface Module
    
    Overrides:
    
    parse in class ModuleBase
    
    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
  - eatChunk
```
public void eatChunk(PNGChunk chnk)
              throws IOException
```
    This lets the module skip over the remainder of a chunk, not including the name, length,and CRC. It updates the CRC.
    
    Throws:
    
    IOException
  - addKeyword
```
public void addKeyword(String keywd,
                       String val)
```
    Add a keyword and value. Creating arbitrary properties on the fly doesn't go well with JHOVE's approach, so we make each property a Map, with keys Keyword, Value, and optionally Language.
  - addKeyword
```
public void addKeyword(String keywd,
                       String translatedKeywd,
                       String val,
                       String language)
```
    Add a keyword, value, and language.
  - addSplt
```
public void addSplt(String name,
                    int sampleDepth,
                    int numSamples)
```
    Add a suggested palette
  - initParse
```
protected void initParse()
```
    Initializes the state of the module for parsing.
    
    Overrides:
    
    initParse in class ModuleBase
  - setIhdrSeen
```
public void setIhdrSeen(boolean b)
```
    Note that an IHDR chunk has been seen
  - isIhdrSeen
```
public boolean isIhdrSeen()
```
    Returns true if IHDR chunk has been seen
  - setIdatSeen
```
public void setIdatSeen(boolean b)
```
    Note that an IDAT chunk has been seen
  - setPlteSeen
```
public void setPlteSeen(boolean b)
```
    Note that a PLTE chunk has been seen
  - setIendSeen
```
public void setIendSeen(boolean b)
```
    Note that an IEND chunk has been seen
  - isIdatSeen
```
public boolean isIdatSeen()
```
    Return true if IDAT chunk has been seen
  - isIdatFinished
```
public boolean isIdatFinished()
```
    Return true if a non-IDAT chunk has been seen after an IDAT chunk
  - isPlteSeen
```
public boolean isPlteSeen()
```
    Return true if PLTE chunk has been seen
  - setChunkSeen
```
public void setChunkSeen(int chunkType)
```
  - isChunkSeen
```
public boolean isChunkSeen(int chunkType)
```
  - setColorType
```
public void setColorType(int ct)
```
    Set the color type. The IHDR processing will set this for the benefit of chunks that need it.
  - getColorType
```
public int getColorType()
```
    Get the color type that was recorded from the IHDR chunk.

Class PngModule

Field Summary

Fields inherited from class edu.harvard.hul.ois.jhove.ModuleBase

Fields inherited from interface edu.harvard.hul.ois.jhove.Module

Constructor Summary

Method Summary

Methods inherited from class edu.harvard.hul.ois.jhove.ModuleBase

Methods inherited from class java.lang.Object

Field Detail

_ckSummer

_propList

_keywordPropList

_spltList

_cstream

_dstream

_metadata

_colorType

Constructor Detail

PngModule

Method Detail

checkSignatures

parse

eatChunk

addKeyword

addKeyword

addSplt

initParse

setIhdrSeen

isIhdrSeen

setIdatSeen

setPlteSeen

setIendSeen

isIdatSeen

isIdatFinished

isPlteSeen

setChunkSeen

isChunkSeen

setColorType

getColorType