Package org.apache.pdfbox.pdfwriter.compress

Class COSWriterCompressionPool

java.lang.Object

org.apache.pdfbox.pdfwriter.compress.COSWriterCompressionPool

public class COSWriterCompressionPool
extends java.lang.Object

An instance of this class compresses the contents of a given PDDocument.

Field Summary

Fields

Modifier and Type	Field	Description
private java.util.Set<COSBase>	allDirectObjects
private PDDocument	document
static float	MINIMUM_SUPPORTED_VERSION
private COSObjectPool	objectPool
private java.util.List<COSObjectKey>	objectStreamObjects
private CompressParameters	parameters
private java.util.List<COSObjectKey>	topLevelObjects

Constructor Summary

Constructors

Constructor	Description
COSWriterCompressionPool(PDDocument document, CompressParameters parameters)	Constructs an object that can be used to compress the contents of a given PDDocument.

Method Summary

Modifier and Type	Method	Description
private void	addElements(java.util.Iterator<COSBase> elements)
private COSBase	addObjectToPool(COSObjectKey key, COSBase base)	Adds the given COSBase to this pool, using the given COSObjectKey as it's referencable ID.
private void	addStructure(COSBase current)	Attempts to find yet unregistered streams and dictionaries in the given structure.
boolean	contains(COSBase object)	Returns true, if the given COSBase is a registered object of this compression pool.
java.util.List<COSWriterObjectStream>	createObjectStreams()	Creates COSWriterObjectStreams for all currently registered objects of this pool, that have been marked as fit for being compressed in this manner.
long	getHighestXRefObjectNumber()	Returns the highest object number, that is registered in this compression pool.
COSObjectKey	getKey(COSBase object)	Returns the COSObjectKey, that is registered for the given COSBase in this compression pool.
COSBase	getObject(COSObjectKey key)	Returns the COSBase, that is registered for the given COSObjectKey in this compression pool.
java.util.List<COSObjectKey>	getObjectStreamObjects()	Returns all COSBases that can be appended to an object stream.
java.util.List<COSObjectKey>	getTopLevelObjects()	Returns all COSBases, that must be added to the document's top level container.

Methods inherited from class java.lang.Object

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

Field Detail

MINIMUM_SUPPORTED_VERSION

public static final float MINIMUM_SUPPORTED_VERSION

See Also:

Constant Field Values

document

private final PDDocument document

parameters

private final CompressParameters parameters

objectPool

private final COSObjectPool objectPool

topLevelObjects

private final java.util.List<COSObjectKey> topLevelObjects

objectStreamObjects

private final java.util.List<COSObjectKey> objectStreamObjects

allDirectObjects

private final java.util.Set<COSBase> allDirectObjects

Constructor Detail

COSWriterCompressionPool

public COSWriterCompressionPool(PDDocument document,
                                CompressParameters parameters)
                         throws java.io.IOException

Constructs an object that can be used to compress the contents of a given PDDocument. It provides the means to:

• Compress the COSStructure of the document, by streaming COSBases to compressed COSWriterObjectStreams

Parameters:

document - The document, that shall be compressed.

parameters - The configuration of the compression operations, that shall be applied.

Throws:

java.io.IOException - Shall be thrown if a compression operation failed.

Method Detail

addObjectToPool

private COSBase addObjectToPool(COSObjectKey key,
                                COSBase base)

Adds the given COSBase to this pool, using the given COSObjectKey as it's referencable ID. This method shall determine an appropriate key, for yet unregistered objects, to register them. Depending on the type of object, it shall either be appended as-is or shall be appended to a compressed COSWriterObjectStream.

Parameters:

key - The COSObjectKey that shall be used as the COSBases ID, if possible.

base - The COSBase, that shall be registered in this pool.

addStructure

private void addStructure(COSBase current)
                   throws java.io.IOException

Attempts to find yet unregistered streams and dictionaries in the given structure.

Parameters:

current - The object to be added for compressing.

Throws:

java.io.IOException - Shall be thrown, if compressing the object failed.

addElements

private void addElements(java.util.Iterator<COSBase> elements)
                  throws java.io.IOException

Throws:

java.io.IOException

getTopLevelObjects

public java.util.List<COSObjectKey> getTopLevelObjects()

Returns all COSBases, that must be added to the document's top level container. Those objects are not valid to be added to an object stream.

Returns:

A list of all top level COSBases.

getObjectStreamObjects

public java.util.List<COSObjectKey> getObjectStreamObjects()

Returns all COSBases that can be appended to an object stream. This list is only provided to enable reflections. Contained objects should indeed be added to a compressed document via an object stream, as can be created via calling: createObjectStreams()

Returns:

A list of all COSBases, that can be added to an object stream.

contains

public boolean contains(COSBase object)

Returns true, if the given COSBase is a registered object of this compression pool.

Parameters:

object - The object, that shall be checked.

Returns:

True, if the given COSBase is a registered object of this compression pool.

getKey

public COSObjectKey getKey(COSBase object)

Returns the COSObjectKey, that is registered for the given COSBase in this compression pool.

Parameters:

object - The COSBase a COSObjectKey is registered for in this compression pool.

Returns:

The COSObjectKey, that is registered for the given COSBase in this compression pool, if such an object is contained.

getObject

public COSBase getObject(COSObjectKey key)

Returns the COSBase, that is registered for the given COSObjectKey in this compression pool.

Parameters:

key - The COSObjectKey a COSBase is registered for in this compression pool.

Returns:

The COSBase, that is registered for the given COSObjectKey in this compression pool, if such an object is contained.

getHighestXRefObjectNumber

public long getHighestXRefObjectNumber()

Returns the highest object number, that is registered in this compression pool.

Returns:

The highest object number, that is registered in this compression pool.

createObjectStreams

public java.util.List<COSWriterObjectStream> createObjectStreams()

Creates COSWriterObjectStreams for all currently registered objects of this pool, that have been marked as fit for being compressed in this manner. Such object streams may be added to a PDF document and shall be declared in a document's PDFXRefStream accordingly. The objects contained in such a stream must not be added to the document separately.

Returns:

The created COSWriterObjectStreams for all currently registered compressible objects.