Class Deflater

This is the Deflater class. The deflater class compresses input with the deflate algorithm described in RFC 1951. It has several compression levels and three different strategies described below.

This class is not thread safe. This is inherent in the API, due to the split of deflate and setInput.

author of the original java version : Jochen Hoenicke

Inheritance

System.Object

Deflater

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.ToString()

Namespace: ICSharpCode.SharpZipLib.Zip.Compression

Assembly: ICSharpCode.SharpZipLib.dll

Syntax

public class Deflater

Constructors

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Deflater()

Creates a new deflater with default compression level.

Declaration

public Deflater()

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Deflater(Int32)

Creates a new deflater with given compression level.

Declaration

public Deflater(int level)

Parameters

Type	Name	Description
System.Int32	level	the compression level, a value between NO_COMPRESSION and BEST_COMPRESSION, or DEFAULT_COMPRESSION.

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	if lvl is out of range.

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Deflater(Int32, Boolean)

Creates a new deflater with given compression level.

Declaration

public Deflater(int level, bool noZlibHeaderOrFooter)

Parameters

Type	Name	Description
System.Int32	level	the compression level, a value between NO_COMPRESSION and BEST_COMPRESSION.
System.Boolean	noZlibHeaderOrFooter	true, if we should suppress the Zlib/RFC1950 header at the beginning and the adler checksum at the end of the output. This is useful for the GZIP/PKZIP formats.

Exceptions

Type	Condition
System.ArgumentOutOfRangeException	if lvl is out of range.

Fields

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BEST_COMPRESSION

The best and slowest compression level. This tries to find very long and distant string repetitions.

Declaration

public const int BEST_COMPRESSION = 9

Field Value

Type	Description
System.Int32

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BEST_SPEED

The worst but fastest compression level.

Declaration

public const int BEST_SPEED = 1

Field Value

Type	Description
System.Int32

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DEFAULT_COMPRESSION

The default compression level.

Declaration

public const int DEFAULT_COMPRESSION = -1

Field Value

Type	Description
System.Int32

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DEFLATED

The compression method. This is the only method supported so far. There is no need to use this constant at all.

Declaration

public const int DEFLATED = 8

Field Value

Type	Description
System.Int32

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NO_COMPRESSION

This level won't compress at all but output uncompressed blocks.

Declaration

public const int NO_COMPRESSION = 0

Field Value

Type	Description
System.Int32

Properties

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Adler

Gets the current adler checksum of the data that was processed so far.

Declaration

public int Adler { get; }

Property Value

Type	Description
System.Int32

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IsFinished

Returns true if the stream was finished and no more output bytes are available.

Declaration

public bool IsFinished { get; }

Property Value

Type	Description
System.Boolean

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IsNeedingInput

Returns true, if the input buffer is empty. You should then call setInput(). NOTE: This method can also return true when the stream was finished.

Declaration

public bool IsNeedingInput { get; }

Property Value

Type	Description
System.Boolean

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TotalIn

Gets the number of input bytes processed so far.

Declaration

public long TotalIn { get; }

Property Value

Type	Description
System.Int64

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TotalOut

Gets the number of output bytes so far.

Declaration

public long TotalOut { get; }

Property Value

Type	Description
System.Int64

Methods

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Deflate(Byte[])

Deflates the current input block with to the given array.

Declaration

public int Deflate(byte[] output)

Parameters

Type	Name	Description
System.Byte[]	output	The buffer where compressed data is stored

Returns

Type	Description
System.Int32	The number of compressed bytes added to the output, or 0 if either IsNeedingInput() or IsFinished returns true or length is zero.

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Deflate(Byte[], Int32, Int32)

Deflates the current input block to the given array.

Declaration

public int Deflate(byte[] output, int offset, int length)

Parameters

Type	Name	Description
System.Byte[]	output	Buffer to store the compressed data.
System.Int32	offset	Offset into the output array.
System.Int32	length	The maximum number of bytes that may be stored.

Returns

Type	Description
System.Int32	The number of compressed bytes added to the output, or 0 if either needsInput() or finished() returns true or length is zero.

Exceptions

Type	Condition
System.InvalidOperationException	If Finish() was previously called.
System.ArgumentOutOfRangeException	If offset or length don't match the array length.

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Finish()

Finishes the deflater with the current input block. It is an error to give more input after this method was called. This method must be called to force all bytes to be flushed.

Declaration

public void Finish()

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Flush()

Flushes the current input block. Further calls to deflate() will produce enough output to inflate everything in the current input block. This is not part of Sun's JDK so I have made it package private. It is used by DeflaterOutputStream to implement flush().

Declaration

public void Flush()

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GetLevel()

Get current compression level

Declaration

public int GetLevel()

Returns

Type	Description
System.Int32	Returns the current compression level

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Reset()

Resets the deflater. The deflater acts afterwards as if it was just created with the same compression level and strategy as it had before.

Declaration

public void Reset()

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SetDictionary(Byte[])

Sets the dictionary which should be used in the deflate process. This call is equivalent to

setDictionary(dict, 0, dict.Length)

Declaration

public void SetDictionary(byte[] dictionary)

Parameters

Type	Name	Description
System.Byte[]	dictionary	the dictionary.

Exceptions

Type	Condition
System.InvalidOperationException	if SetInput () or Deflate () were already called or another dictionary was already set.

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SetDictionary(Byte[], Int32, Int32)

Sets the dictionary which should be used in the deflate process. The dictionary is a byte array containing strings that are likely to occur in the data which should be compressed. The dictionary is not stored in the compressed output, only a checksum. To decompress the output you need to supply the same dictionary again.

Declaration

public void SetDictionary(byte[] dictionary, int index, int count)

Parameters

Type	Name	Description
System.Byte[]	dictionary	The dictionary data
System.Int32	index	The index where dictionary information commences.
System.Int32	count	The number of bytes in the dictionary.

Exceptions

Type	Condition
System.InvalidOperationException	If SetInput () or Deflate() were already called or another dictionary was already set.

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SetInput(Byte[])

Sets the data which should be compressed next. This should be only called when needsInput indicates that more input is needed. If you call setInput when needsInput() returns false, the previous input that is still pending will be thrown away. The given byte array should not be changed, before needsInput() returns true again. This call is equivalent to

setInput(input, 0, input.length)

Declaration

public void SetInput(byte[] input)

Parameters

Type	Name	Description
System.Byte[]	input	the buffer containing the input data.

Exceptions

Type	Condition
System.InvalidOperationException	if the buffer was finished() or ended().

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SetInput(Byte[], Int32, Int32)

Sets the data which should be compressed next. This should be only called when needsInput indicates that more input is needed. The given byte array should not be changed, before needsInput() returns true again.

Declaration

public void SetInput(byte[] input, int offset, int count)

Parameters

Type	Name	Description
System.Byte[]	input	the buffer containing the input data.
System.Int32	offset	the start of the data.
System.Int32	count	the number of data bytes of input.

Exceptions

Type	Condition
System.InvalidOperationException	if the buffer was Finish()ed or if previous input is still pending.

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SetLevel(Int32)

Sets the compression level. There is no guarantee of the exact position of the change, but if you call this when needsInput is true the change of compression level will occur somewhere near before the end of the so far given input.

Declaration

public void SetLevel(int level)

Parameters

Type	Name	Description
System.Int32	level	the new compression level.

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SetStrategy(DeflateStrategy)

Sets the compression strategy. Strategy is one of DEFAULT_STRATEGY, HUFFMAN_ONLY and FILTERED. For the exact position where the strategy is changed, the same as for SetLevel() applies.

Declaration

public void SetStrategy(DeflateStrategy strategy)

Parameters

Type	Name	Description
DeflateStrategy	strategy	The new compression strategy.