Lz4 Module

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The Lz4 module implements an LZ4 compressor and decompressor.

Syntax

IPWorksZip.Lz4

Remarks

The Lz4 module is compliant with the LZ4 Frame Format specification. Data compressed by the module can be decompressed by any standard LZ4-compatible tool or library, and the module can in turn decompress data produced by any standard LZ4 encoder, including frames using linked blocks, block checksums, or skippable frames. Note that the legacy LZ4 frame format and LZ4 dictionaries are not supported, and frames using either are rejected with an error.

The CompressionLevel property selects the compression level to use, from 1 (fastest) to 6 (most compact).

Data may be operated on in multiple ways as discussed below.

Compression and Decompression Streams

The GetDecompressionStream and GetCompressionStream methods are used to retrieve streams that read or write compressed data, as appropriate. The underlying stream should be passed to either method as a parameter.

CompressBlock and DecompressBlock

The CompressBlock and DecompressBlock methods operate on blocks (chunks) of data. The methods may be used to compress and decompress data as they become available.

Note that when using blocks of data, the OutputData property is not applicable. Instead, data are made available via the CompressedData and DecompressedData events.

If all data is available ahead of time, the CompressData and DecompressData methods may be called instead.

Compress Data

THe InputData property should be set to the current block to be compressed. Next, the CompressBlock method should be called to compress the current block. Note that this method takes a LastBlock parameter; if the block of data is the final block to be compressed, it must be set to true. For all other blocks, it must remain false.

During compression, the CompressedData event will fire with the compressed data. Note that this event may not fire for every call to CompressBlock due to the way the compression algorithm operates.

zipstream.InputDataB = MyDecompressedData; zipstream.CompressBlock(); Data are accumulated inside the CompressedData event: private static void Zipstream_OnCompressedData(object sender, ZipstreamCompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that the OutputData property is not applicable when compressing block data.

Decompress Data

The InputData property should be set to the current block to be decompressed. Next, the DecompressBlock method should be called to decompress the current block.

During decompression, the DecompressedData event will fire with the decompressed data. Note that this event may not fire for every call to DecompressBlock due to the way the decompression algorithm operates.

zipstream.InputDataB = MyCompressedData; zipstream.DecompressBlock(); Data is accumulated inside the DecompressedData event: private static void Zipstream_OnDecompressedData(object sender, ZipstreamDecompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that the OutputData property is not applicable when decompressing block data.

CompressData and DecompressData

The CompressData and DecompressData methods operate on the complete blob of data. The entire compressed or decompressed data must be set to the InputData property before calling either method.

To compress and decompress data in blocks (chunks), refer to the CompressBlock and DecompressBlock methods.

Compress Data

The InputData property should be set to the decompressed data. This should be the entire data to be compressed. Next, the CompressData method should be called, after which the OutputData property will hold the compressed data.

zipstream.InputDataB = MyDecompressedData; zipstream.CompressData(); MyCompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the CompressedData event.

Decompress Data

The InputData property should be set to the compressed data. This should be the entire data to be decompressed. Next, the DecompressData method should be called, after which the OutputData property will hold the decompressed data.

zipstream.InputDataB = MyCompressedData; zipstream.DecompressData(); MyDecompressedData = zipstream.OutputDataB;

In addition to OutputData, the decompressed data may also be accumulated within the DecompressedData event.

Property List

The following is the full list of the properties of the module with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the module with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the module with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the module with short descriptions. Click on the links for further details.

CloseBaseStream Property (Lz4 Module)

Whether or not to close the underlying stream.

Syntax

• Swift
• Objective-C

public var closeBaseStream: Bool {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=closeBaseStream,setter=setCloseBaseStream:) BOOL closeBaseStream;

- (BOOL)closeBaseStream;
- (void)setCloseBaseStream :(BOOL)newCloseBaseStream;

Default Value

True

Remarks

This property controls whether streams created via the GetCompressionStream and GetDecompressionStream methods will close their underlying streams when their Close method is invoked.

When enabled, the underlying streams are closed; otherwise, they will remain open.

CompressionLevel Property (Lz4 Module)

The compression level to use.

Syntax

• Swift
• Objective-C

public var compressionLevel: Int32 {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=compressionLevel,setter=setCompressionLevel:) int compressionLevel;

- (int)compressionLevel;
- (void)setCompressionLevel :(int)newCompressionLevel;

Default Value

4

Remarks

This property dictates the compression level to use, from 1 to 6. Higher values will cause the module to compress better; lower values will cause the module to compress faster.

InputData Property (Lz4 Module)

The data to compress or decompress.

Syntax

• Swift
• Objective-C

public var inputData: String {
  get {...}
  set {...}
}

public var inputDataB: Data {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=inputData,setter=setInputData:) NSString* inputData;

- (NSString*)inputData;
- (void)setInputData :(NSString*)newInputData;

@property (nonatomic,readwrite,assign,getter=inputDataB,setter=setInputDataB:) NSData* inputDataB;

- (NSData*)inputDataB;
- (void)setInputDataB :(NSData*)newInputData;

Default Value

""

Remarks

This property specifies the data to compress or decompress.

When decompressing, this should be set to the compressed data before the DecompressData or DecompressBlock methods are called.

When compressing, this should be set to the decompressed data before the CompressData or CompressBlock methods are called.

Note that this property is not automatically cleared after each operation when performing operations on multiple chunks of data.

OutputData Property (Lz4 Module)

The output data after compression or decompression.

Syntax

• Swift
• Objective-C

public var outputData: String {
  get {...}
}

public var outputDataB: Data {
  get {...}
}

@property (nonatomic,readonly,assign,getter=outputData) NSString* outputData;

- (NSString*)outputData;

@property (nonatomic,readonly,assign,getter=outputDataB) NSData* outputDataB;

- (NSData*)outputDataB;

Default Value

""

Remarks

This property holds the compressed or decompressed data after the CompressData or DecompressData methods are called.

This property is not applicable when calling the CompressBlock or DecompressBlock methods.

This property is read-only.

CompressBlock Method (Lz4 Module)

Compresses a block of data.

Syntax

• Swift
• Objective-C

public func compressBlock(lastBlock: Bool) throws -> Void

- (void)compressBlock :(BOOL)lastBlock;

Remarks

This method compresses the block of data specified by the InputData property.

The CompressBlock and DecompressBlock methods operate on blocks (chunks) of data. The methods may be used to compress and decompress data as they become available.

Note that when using blocks of data, the OutputData property is not applicable. Instead, data are made available via the CompressedData and DecompressedData events.

If all data is available ahead of time, the CompressData and DecompressData methods may be called instead.

Compress Data

The InputData property should be set to the current block to be compressed. Next, the CompressBlock method should be called to compress the current block. Note that this method takes a LastBlock parameter; if the block of data is the final block to be compressed, it must be set to true. For all other blocks, it must remain false.

During compression, the CompressedData event will fire with the compressed data. Note that this event may not fire for every call to CompressBlock due to the way the compression algorithm operates.

zipstream.InputDataB = MyDecompressedData; zipstream.CompressBlock(); Data are accumulated inside the CompressedData event: private static void Zipstream_OnCompressedData(object sender, ZipstreamCompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that the OutputData property is not applicable when compressing block data.

Decompress Data

The InputData property should be set to the current block to be decompressed. Next, the DecompressBlock method should be called to decompress the current block.

During decompression, the DecompressedData event will fire with the decompressed data. Note that this event may not fire for every call to DecompressBlock due to the way the decompression algorithm operates.

zipstream.InputDataB = MyCompressedData; zipstream.DecompressBlock(); Data is accumulated inside the DecompressedData event: private static void Zipstream_OnDecompressedData(object sender, ZipstreamDecompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that the OutputData property is not applicable when decompressing block data.

CompressData Method (Lz4 Module)

Compresses the specified data.

Syntax

• Swift
• Objective-C

public func compressData() throws -> Void

- (void)compressData;

Remarks

This method compresses the data specified by the InputData property. After calling this method, the OutputData property holds the compressed data.

The CompressData and DecompressData methods operate on the complete blob of data. The entire compressed or decompressed data must be set to the InputData property before calling either method.

To compress and decompress data in blocks (chunks), refer to the CompressBlock and DecompressBlock methods.

Compress Data

The InputData property should be set to the decompressed data. This should be the entire data to be compressed. Next, the CompressData method should be called, after which the OutputData property will hold the compressed data.

zipstream.InputDataB = MyDecompressedData; zipstream.CompressData(); MyCompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the CompressedData event.

Decompress Data

The InputData property should be set to the compressed data. This should be the entire data to be decompressed. Next, the DecompressData method should be called, after which the OutputData property will hold the decompressed data.

zipstream.InputDataB = MyCompressedData; zipstream.DecompressData(); MyDecompressedData = zipstream.OutputDataB;

In addition to OutputData, the decompressed data may also be accumulated within the DecompressedData event.

Config Method (Lz4 Module)

Sets or retrieves a configuration setting.

Syntax

• Swift
• Objective-C

public func config(configurationString: String) throws -> String

- (NSString*)config :(NSString*)configurationString;

Remarks

Config is a generic method available in every module. It is used to set and retrieve configuration settings for the module.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the module, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

DecompressBlock Method (Lz4 Module)

Decompresses a block of data.

Syntax

• Swift
• Objective-C

public func decompressBlock() throws -> Void

- (void)decompressBlock;

Remarks

This method decompresses the block of data specified by the InputData property.

The CompressBlock and DecompressBlock methods operate on blocks (chunks) of data. The methods may be used to compress and decompress data as they become available.

Note that when using blocks of data, the OutputData property is not applicable. Instead, data are made available via the CompressedData and DecompressedData events.

If all data is available ahead of time, the CompressData and DecompressData methods may be called instead.

Compress Data

The InputData property should be set to the current block to be compressed. Next, the CompressBlock method should be called to compress the current block. Note that this method takes a LastBlock parameter; if the block of data is the final block to be compressed, it must be set to true. For all other blocks, it must remain false.

During compression, the CompressedData event will fire with the compressed data. Note that this event may not fire for every call to CompressBlock due to the way the compression algorithm operates.

zipstream.InputDataB = MyDecompressedData; zipstream.CompressBlock(); Data are accumulated inside the CompressedData event: private static void Zipstream_OnCompressedData(object sender, ZipstreamCompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that the OutputData property is not applicable when compressing block data.

Decompress Data

The InputData property should be set to the current block to be decompressed. Next, the DecompressBlock method should be called to decompress the current block.

During decompression, the DecompressedData event will fire with the decompressed data. Note that this event may not fire for every call to DecompressBlock due to the way the decompression algorithm operates.

zipstream.InputDataB = MyCompressedData; zipstream.DecompressBlock(); Data is accumulated inside the DecompressedData event: private static void Zipstream_OnDecompressedData(object sender, ZipstreamDecompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that the OutputData property is not applicable when decompressing block data.

DecompressData Method (Lz4 Module)

Decompresses the specified data.

Syntax

• Swift
• Objective-C

public func decompressData() throws -> Void

- (void)decompressData;

Remarks

This method decompresses the data specified by the InputData property. After calling this method, the OutputData property holds the decompressed data.

The CompressData and DecompressData methods operate on the complete blob of data. The entire compressed or decompressed data must be set to the InputData property before calling either method.

To compress and decompress data in blocks (chunks), refer to the CompressBlock and DecompressBlock methods.

Compress Data

The InputData property should be set to the decompressed data. This should be the entire data to be compressed. Next, the CompressData method should be called, after which the OutputData property will hold the compressed data.

zipstream.InputDataB = MyDecompressedData; zipstream.CompressData(); MyCompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the CompressedData event.

Decompress Data

The InputData property should be set to the compressed data. This should be the entire data to be decompressed. Next, the DecompressData method should be called, after which the OutputData property will hold the decompressed data.

zipstream.InputDataB = MyCompressedData; zipstream.DecompressData(); MyDecompressedData = zipstream.OutputDataB;

In addition to OutputData, the decompressed data may also be accumulated within the DecompressedData event.

Reset Method (Lz4 Module)

Resets the module.

Syntax

• Swift
• Objective-C

public func reset() throws -> Void

- (void)reset;

Remarks

This method is used to reset the state of the module. All properties are set to their default values, and any open files are closed.

CompressedData Event (Lz4 Module)

Fires with compressed data.

Syntax

• Swift
• Objective-C

func onCompressedData(data: Data)

- (void)onCompressedData :(NSData*)data;

Remarks

This event is fired one or more times as compressed data become available when the CompressData or CompressBlock methods are called.

Data holds the current block of compressed data.

DecompressedData Event (Lz4 Module)

Fires with decompressed data.

Syntax

• Swift
• Objective-C

func onDecompressedData(data: Data)

- (void)onDecompressedData :(NSData*)data;

Remarks

This event is fired one or more times as decompressed data become available when the DecompressData or DecompressBlock methods are called.

Data holds the current block of decompressed data.

Error Event (Lz4 Module)

Fires with information about errors during data delivery.

Syntax

• Swift
• Objective-C

func onError(errorCode: Int32, description: String)

- (void)onError :(int)errorCode :(NSString*)description;

Remarks

This event is fired in case of exceptional conditions during message processing. Normally, the module .

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Config Settings (Lz4 Module)

No configuration settings defined.

Base Config Settings

Trappable Errors (Lz4 Module)

ZipStream Errors