UnixCompress VB.NET Reference Documentation

UnixCompress

Current Version: 11.1.0

Requires Chilkat Bundle License

UNIX (.Z) compression component.

Object Creation

Dim obj As New Chilkat.UnixCompress()

Properties

AbortCurrent

AbortCurrent As Boolean

Introduced in version 9.5.0.58

When set to True, causes the currently running method to abort. Methods that always finish quickly (i.e.have no length file operations or network communications) are not affected. If no method is running, then this property is automatically reset to False when the next method is called. When the abort occurs, this property is reset to False. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)

DebugLogFilePath

DebugLogFilePath As String

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

A timeout property set to 0, indicating an infinite timeout.
A hang occurring within an event callback in the application code.
An internal bug in the Chilkat code causing the hang.

More Information and Examples

Example showing how to use DebugLogFilePath.

HeartbeatMs

HeartbeatMs As Integer

The interval in milliseconds between each AbortCheck event callback, which enables an application to abort certain method calls before they complete. By default, HeartbeatMs is set to 0, meaning no AbortCheck event callbacks will trigger.

More Information and Examples

Event Callback Examples

LastErrorHtml

LastErrorHtml As String (ReadOnly)

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

LastErrorText

LastErrorText As String (ReadOnly)

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

LastErrorXml

LastErrorXml As String (ReadOnly)

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

LastMethodSuccess

LastMethodSuccess As Boolean

Indicates the success or failure of the most recent method call: True means success, False means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.

VerboseLogging

VerboseLogging As Boolean

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

Version

Version As String (ReadOnly)

Version of the component/library, such as "10.1.0"

More Information and Examples

How to get the Chilkat version at runtime.

Methods

CompressFile

Function CompressFile(ByVal inFilename As String, ByVal destPath As String) As Boolean

Compresses a file to create a UNIX compressed file (.Z). This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.

Returns True for success, False for failure.

CompressFileAsync ⁽¹⁾

Function CompressFileAsync(ByVal inFilename As String, ByVal destPath As String) As Task

Creates an asynchronous task to call the CompressFile method with the arguments provided.

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nothing on failure

CompressFileToMem

Function CompressFileToMem(ByVal inFilename As String) As Byte()

Unix compresses a file to an in-memory image of a .Z file. (This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.)

Returns an empty byte array on failure

CompressFileToMemAsync ⁽¹⁾

Function CompressFileToMemAsync(ByVal inFilename As String) As Task

Creates an asynchronous task to call the CompressFileToMem method with the arguments provided.

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nothing on failure

CompressMemory

Function CompressMemory(ByVal inData As Byte()) As Byte()

Compresses in-memory data to an in-memory image of a .Z file. (This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.)

Returns an empty byte array on failure

CompressMemToFile

Function CompressMemToFile(ByVal inData As Byte(), ByVal destPath As String) As Boolean

Unix compresses and creates a .Z file from in-memory data. (This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.)

Returns True for success, False for failure.

CompressString

Function CompressString(ByVal inStr As String, ByVal charset As String) As Byte()

Compresses a string to an in-memory image of a .Z file. Prior to compression, the string is converted to the character encoding specified by charset. The charset can be any one of a large number of character encodings, such as utf-8, iso-8859-1, Windows-1252, ucs-2, etc.

Returns an empty byte array on failure

More Information and Examples

List of Valid Charsets

CompressStringToFile

Function CompressStringToFile(ByVal inStr As String, ByVal charset As String, ByVal destPath As String) As Boolean

Unix compresses and creates a .Z file from string data. The charset specifies the character encoding used for the byte representation of the characters when compressed. The charset can be any one of a large number of character encodings, such as utf-8, iso-8859-1, Windows-1252, ucs-2, etc.

Returns True for success, False for failure.

More Information and Examples

List of Valid Charsets

LoadTaskCaller

Function LoadTaskCaller(ByVal task As Task) As Boolean

Introduced in version 9.5.0.80

Loads the caller of the task's async method.

Returns True for success, False for failure.

UncompressFile

Function UncompressFile(ByVal inFilename As String, ByVal destPath As String) As Boolean

Uncompresses a .Z file. (This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.)

Returns True for success, False for failure.

UncompressFileAsync ⁽¹⁾

Function UncompressFileAsync(ByVal inFilename As String, ByVal destPath As String) As Task

Creates an asynchronous task to call the UncompressFile method with the arguments provided.

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nothing on failure

UncompressFileToMem

Function UncompressFileToMem(ByVal inFilename As String) As Byte()

Uncompresses a .Z file directly to memory. (This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.)

Returns an empty byte array on failure

UncompressFileToMemAsync ⁽¹⁾

Function UncompressFileToMemAsync(ByVal inFilename As String) As Task

Creates an asynchronous task to call the UncompressFileToMem method with the arguments provided.

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nothing on failure

UncompressFileToString

Function UncompressFileToString(ByVal zFilename As String, ByVal charset As String) As String

Uncompresses a .Z file that contains a text file. The contents of the text file are returned as a string. The character encoding of the text file is specified by charset. Typical charsets are iso-8859-1, utf-8, windows-1252, shift_JIS, big5, etc.

Returns Nothing on failure

More Information and Examples

List of Valid Charsets

UncompressFileToStringAsync ⁽¹⁾

Function UncompressFileToStringAsync(ByVal zFilename As String, ByVal charset As String) As Task

Creates an asynchronous task to call the UncompressFileToString method with the arguments provided.

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nothing on failure

UncompressMemory

Function UncompressMemory(ByVal inData As Byte()) As Byte()

Uncompresses from an in-memory image of a .Z file directly into memory. (This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.)

Returns an empty byte array on failure

UncompressMemToFile

Function UncompressMemToFile(ByVal inData As Byte(), ByVal destPath As String) As Boolean

Uncompresses from an in-memory image of a .Z file to a file. (This compression uses the LZW (Lempel-Ziv-Welch) compression algorithm.)

Returns True for success, False for failure.

UncompressString

Function UncompressString(ByVal inCompressedData As Byte(), ByVal charset As String) As String

Uncompresses from an in-memory image of a .Z file directly to a string. The charset specifies the character encoding used to interpret the bytes resulting from the decompression. The charset can be any one of a large number of character encodings, such as utf-8, iso-8859-1, Windows-1252, ucs-2, etc.

Returns Nothing on failure

More Information and Examples

List of Valid Charsets

UnTarZ

Function UnTarZ(ByVal zFilename As String, ByVal destDir As String, ByVal bNoAbsolute As Boolean) As Boolean

Unpacks a .tar.Z file. The decompress and untar occur in streaming mode. There are no temporary files and the memory footprint is constant (and small) while untarring.

Returns True for success, False for failure.

UnTarZAsync ⁽¹⁾

Function UnTarZAsync(ByVal zFilename As String, ByVal destDir As String, ByVal bNoAbsolute As Boolean) As Task

Creates an asynchronous task to call the UnTarZ method with the arguments provided.

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nothing on failure

Events

AbortCheck

Event OnAbortCheck

Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.

More Information and Examples

Chilkat Event Callback Examples

Args are passed using Chilkat.AbortCheckEventArgs

Event callback implementation:

Dim WithEvents unixcompress As Chilkat.UnixCompress

Private Sub unixcompress_OnAbortCheck(sender As Object, args As Chilkat.AbortCheckEventArgs) Handles unixcompress.OnAbortCheck

    ...

End Sub

PercentDone

Event OnPercentDone

This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).

The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.

To abort the operation, set the abort output argument to True. This will cause the method to terminate and return a failure status or corresponding failure value.

More Information and Examples

Chilkat Event Callback Examples

Args are passed using Chilkat.PercentDoneEventArgs

Event callback implementation:

Dim WithEvents unixcompress As Chilkat.UnixCompress

Private Sub unixcompress_OnPercentDone(sender As Object, args As Chilkat.PercentDoneEventArgs) Handles unixcompress.OnPercentDone

    ...

End Sub

ProgressInfo

Event OnProgressInfo

This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.

More Information and Examples

Chilkat Event Callback Examples

Args are passed using Chilkat.ProgressInfoEventArgs

Event callback implementation:

Dim WithEvents unixcompress As Chilkat.UnixCompress

Private Sub unixcompress_OnProgressInfo(sender As Object, args As Chilkat.ProgressInfoEventArgs) Handles unixcompress.OnProgressInfo

    ...

End Sub

TaskCompleted

Event OnTaskCompleted

Called from the background thread when an asynchronous task completes.

More Information and Examples

VB.NET TaskCompleted Event Callback Example

Args are passed using Chilkat.TaskCompletedEventArgs

Event callback implementation:

Dim WithEvents unixcompress As Chilkat.UnixCompress

Private Sub unixcompress_OnTaskCompleted(sender As Object, args As Chilkat.TaskCompletedEventArgs) Handles unixcompress.OnTaskCompleted

    ...

End Sub

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