com.itextpdf.kernel.pdf

Class RunLengthCompressionStrategy

java.lang.Object

com.itextpdf.kernel.pdf.RunLengthCompressionStrategy

All Implemented Interfaces:

IStreamCompressionStrategy

public class RunLengthCompressionStrategy
extends Object
implements IStreamCompressionStrategy

A compression strategy that uses the RunLengthDecode filter for PDF streams.

This strategy implements the IStreamCompressionStrategy interface and provides RunLengthDecode encoding.

Run-length encoding works best, when input data has long sequences of identical bytes. This is, usually, not the case for PDF content streams, so using this strategy will often cause a marginal size increase instead.

Constructor Summary

Constructors

Constructor and Description
RunLengthCompressionStrategy() Constructs a new RunLengthCompressionStrategy instance.

Method Summary

Modifier and Type	Method and Description
OutputStream	createNewOutputStream(OutputStream original, PdfStream stream) Creates a new output stream with run length compression applied.
PdfObject	getDecodeParams() Returns the decode parameters for the RunLengthDecode filter.
PdfName	getFilterName() Returns the name of the compression filter.

Methods inherited from class java.lang.Object

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

Constructor Detail

RunLengthCompressionStrategy

public RunLengthCompressionStrategy()

Constructs a new RunLengthCompressionStrategy instance.

Method Detail

getFilterName

public PdfName getFilterName()

Returns the name of the compression filter.

Specified by:

getFilterName in interface IStreamCompressionStrategy

Returns:

PdfName.RunLengthDecode representing the RunLengthDecode filter

getDecodeParams

public PdfObject getDecodeParams()

Returns the decode parameters for the RunLengthDecode filter.

This implementation returns null as no special decode parameters are required for standard run length compression.

Specified by:

getDecodeParams in interface IStreamCompressionStrategy

Returns:

null as no decode parameters are needed

createNewOutputStream

public OutputStream createNewOutputStream(OutputStream original,
                                          PdfStream stream)

Creates a new output stream with run length compression applied.

This method wraps the original output stream in a RunLengthOutputStream that applies run length compression.

Specified by:

createNewOutputStream in interface IStreamCompressionStrategy

Parameters:

original - the original output stream to wrap

stream - the PDF stream containing compression configuration

Returns:

a new RunLengthOutputStream that compresses data using the run length algorithm