Package org.tukaani.xz

Class DeltaOptions

java.lang.Object

org.tukaani.xz.FilterOptions

org.tukaani.xz.DeltaOptions

All Implemented Interfaces:

java.lang.Cloneable

public class DeltaOptions
extends FilterOptions

Delta filter options. The Delta filter can be used only as a non-last filter in the chain, for example Delta + LZMA2.

Currently only simple byte-wise delta is supported. The only option is the delta distance, which you should set to match your data. It's not possible to provide a generic default value for it.

For example, with distance = 2 and eight-byte input A1 B1 A2 B3 A3 B5 A4 B7, the output will be A1 B1 01 02 01 02 01 02.

The Delta filter can be good with uncompressed bitmap images. It can also help with PCM audio, although special-purpose compressors like FLAC will give much smaller result at much better compression speed.

Field Summary

Fields

Modifier and Type	Field	Description
static int	DISTANCE_MAX	Largest supported delta calculation distance.
static int	DISTANCE_MIN	Smallest supported delta calculation distance.

Constructor Summary

Constructors

Constructor	Description
DeltaOptions()	Creates new Delta options and sets the delta distance to 1 byte.
DeltaOptions(int distance)	Creates new Delta options and sets the distance to the given value.

Method Summary

Modifier and Type	Method	Description
java.lang.Object	clone()
int	getDecoderMemoryUsage()	Gets how much memory the decoder will need to decompress the data that was encoded with these options.
int	getDistance()	Gets the delta distance.
int	getEncoderMemoryUsage()	Gets how much memory the encoder will need with these options.
java.io.InputStream	getInputStream(java.io.InputStream in, ArrayCache arrayCache)	Gets a raw (no XZ headers) decoder input stream using these options and the given ArrayCache.
FinishableOutputStream	getOutputStream(FinishableOutputStream out, ArrayCache arrayCache)	Gets a raw (no XZ headers) encoder output stream using these options and the given ArrayCache.
void	setDistance(int distance)	Sets the delta distance in bytes.

Methods inherited from class org.tukaani.xz.FilterOptions

getDecoderMemoryUsage, getEncoderMemoryUsage, getInputStream, getOutputStream

Methods inherited from class java.lang.Object

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

Field Detail

DISTANCE_MIN

public static final int DISTANCE_MIN

Smallest supported delta calculation distance.

See Also:

Constant Field Values

DISTANCE_MAX

public static final int DISTANCE_MAX

Largest supported delta calculation distance.

See Also:

Constant Field Values

Constructor Detail

DeltaOptions

public DeltaOptions()

Creates new Delta options and sets the delta distance to 1 byte.

DeltaOptions

public DeltaOptions(int distance)
             throws UnsupportedOptionsException

Creates new Delta options and sets the distance to the given value.

Throws:

UnsupportedOptionsException

Method Detail

setDistance

public void setDistance(int distance)
                 throws UnsupportedOptionsException

Sets the delta distance in bytes. The new distance must be in the range [DISTANCE_MIN, DISTANCE_MAX].

Throws:

UnsupportedOptionsException

getDistance

public int getDistance()

Gets the delta distance.

getEncoderMemoryUsage

public int getEncoderMemoryUsage()

Description copied from class: FilterOptions

Gets how much memory the encoder will need with these options.

Specified by:

getEncoderMemoryUsage in class FilterOptions

getOutputStream

public FinishableOutputStream getOutputStream(FinishableOutputStream out,
                                              ArrayCache arrayCache)

Description copied from class: FilterOptions

Gets a raw (no XZ headers) encoder output stream using these options and the given ArrayCache. Raw streams are an advanced feature. In most cases you want to store the compressed data in the .xz container format instead of using a raw stream. To use this filter in a .xz file, pass this object to XZOutputStream.

Specified by:

getOutputStream in class FilterOptions

getDecoderMemoryUsage

public int getDecoderMemoryUsage()

Description copied from class: FilterOptions

Gets how much memory the decoder will need to decompress the data that was encoded with these options.

Specified by:

getDecoderMemoryUsage in class FilterOptions

getInputStream

public java.io.InputStream getInputStream(java.io.InputStream in,
                                          ArrayCache arrayCache)

Description copied from class: FilterOptions

Gets a raw (no XZ headers) decoder input stream using these options and the given ArrayCache.

Specified by:

getInputStream in class FilterOptions

clone

public java.lang.Object clone()

Overrides:

clone in class java.lang.Object