ZipCrc ActiveX Reference Documentation

ZipCrc

Current Version: 10.1.2

Calculate a Zip CRC checksum for a file or in-memory data.

Object Creation

Note:
For versions of Chilkat < 10.0.0, use "Chilkat_9_5_0.ZipCrc" instead of "Chilkat.ZipCrc"
For a specific major version, use "Chilkat.ZipCrc.<major_version>", such as "Chilkat.ZipCrc.10" for Chilkat v10.*.*
See Chilkat ActiveX Object Creation

(ASP)
set obj = Server.CreateObject("Chilkat.ZipCrc")

(AutoIt)
$obj = ObjCreate("Chilkat.ZipCrc")

(Visual Basic 6.0)
Dim obj As New ChilkatZipCrc

(VBScript)
set obj = CreateObject("Chilkat.ZipCrc")

(Delphi)
obj := TChilkatZipCrc.Create(Self);

(FoxPro)
loObject = CreateObject('Chilkat.ZipCrc')

(PowerBuilder)
lole_object = create oleobject
li_rc = lole_object.ConnectToNewObject("Chilkat.ZipCrc")

(SQL Server)
EXEC @hr = sp_OACreate 'Chilkat.ZipCrc', @obj OUT

(Javascript)
var obj = new ActiveXObject("Chilkat.ZipCrc");

Properties

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.

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LastBinaryResult
LastBinaryResult As Variant (read-only)

This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. It is only accessible if Chilkat.Global.KeepBinaryResult is set to 1. This feature allows for the retrieval of large varbinary results in an SQL Server environment, which has restrictions on returning large data via method calls, though temp tables can handle binary properties.

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LastErrorHtml
LastErrorHtml As String (read-only)

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.

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LastErrorText
LastErrorText As String (read-only)

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.

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LastErrorXml
LastErrorXml As String (read-only)

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.

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LastMethodSuccess
LastMethodSuccess As Long

Indicates the success or failure of the most recent method call: 1 means success, 0 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.

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LastStringResult
LastStringResult As String (read-only)

In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. It is accessible only when Chilkat.Global.KeepStringResult is set to TRUE. SQL Server has limitations on string lengths returned from methods and properties, but temp tables can be used to access large strings.

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LastStringResultLen
LastStringResultLen As Long (read-only)

The length, in characters, of the string contained in the LastStringResult property.

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VerboseLogging
VerboseLogging As Long

If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
Version As String (read-only)

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

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Methods

BeginStream
BeginStream()

Provides a way to calculate a CRC by streaming the data a chunk at a time. An application would start by calling BeginStream. Then it would add data by calling MoreData for each additional chunk. After the last chunk has been processed, the EndStream method is called to return the CRC.

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CalculateCrc
CalculateCrc(data As Variant) As Long

Calculates a 32-bit CRC for in-memory byte data. This is the 32-bit CRC that would be found in a Zip file header if a file containing the data was added to a zip archive. Returns the CRC32 of the data.

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CrcBd
CrcBd(bd As ChilkatBinData) As Long
Introduced in version 9.5.0.75

Calculates a CRC32 for the bytes contained in bd.

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CrcSb
CrcSb(sb As ChilkatStringBuilder, charset As String) As Long
Introduced in version 9.5.0.75

Calculates a CRC32 for the string contained in sb. The charset is the byte representation to be used for the sb when calculating the CRC32. It can be utf-8, utf-16, windows-1252, iso-8859-1, or any of the character encodings (charsets) listed at the link below.

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CrcString
CrcString(str As String, charset As String) As Long
Introduced in version 9.5.0.75

Calculates a CRC32 for a string. The charset is the byte representation to be used for the str when calculating the CRC32. It can be utf-8, utf-16, windows-1252, iso-8859-1, or any of the character encodings (charsets) listed at the link below.

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EndStream
EndStream() As Long

Finalizes and returns the Zip CRC value calculated by calling BeginStream followed by multiple calls to MoreData.

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FileCrc
FileCrc(path As String) As Long

Calculates the CRC32 of a file. The data contained in the file is streamed for the calculation to keep the memory footprint small and constant. Returns the CRC32 of the file.

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FileCrcAsync (1) (2) (AutoIt) (PowerBuilder) (VBScript) (Visual Basic 6.0) (Visual FoxPro)
FileCrcAsync(path As String) As ChilkatTask

Creates an asynchronous task to call the FileCrc 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

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LoadTaskCaller
LoadTaskCaller(task As ChilkatTask) As Long
Introduced in version 9.5.0.80

Loads the caller of the task's async method.

Returns 1 for success, 0 for failure.

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MoreData
MoreData(data As Variant)

Adds additional data to the CRC currently being calculated. (See BeginStream for more information.)

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ToHex
ToHex(ByVal crc As Long) As String

Converts a 32-bit integer to a hex string.

Returns Nothing on failure

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Events

AbortCheck
AbortCheck(abort As Long)

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.

VB6 Event callback implementation:

Important: Event callbacks from asynchronous method calls are generally not possible from the ActiveX. See VB6 Async Callbacks

Dim WithEvents myZipcrc As ChilkatZipCrc

Private Sub myZipcrc_AbortCheck(abort As Long)

	'Insert application code here.

End Sub
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PercentDone
PercentDone(ByVal pctDone As Long, abort As Long)

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

The abort output argument provides a means for aborting the operation. Setting it to 1 will cause the method to abort and return a failed status (or whatever return value indicates failure).

VB6 Event callback implementation:

Important: Event callbacks from asynchronous method calls are generally not possible from the ActiveX. See VB6 Async Callbacks

Dim WithEvents myZipcrc As ChilkatZipCrc

Private Sub myZipcrc_PercentDone(ByVal pctDone As Long, abort As Long)

	'Insert application code here.

End Sub
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ProgressInfo
ProgressInfo(ByVal name As String, ByVal value As String)

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

VB6 Event callback implementation:

Important: Event callbacks from asynchronous method calls are generally not possible from the ActiveX. See VB6 Async Callbacks

Dim WithEvents myZipcrc As ChilkatZipCrc

Private Sub myZipcrc_ProgressInfo(ByVal name As String, ByVal value As String)

	'Insert application code here.

End Sub
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