Compression DataFlex Reference Documentation

Compression

Current Version: 11.0.0

Implements the Bzip2, Deflate, and LZW compression algorithms.

Object Creation

// (Dataflex programs use the 32-bit Chilkat ActiveX)
Handle hoCompression
Get Create(RefClass(cComChilkatCompression)) to hoCompression

Properties

Algorithm
Function ComAlgorithm Returns String
Procedure Set ComAlgorithm String value

Specifies the compression algorithm: "deflate", "zlib", "bzip2", or "lzw". Note that "ppmd" is deprecated and should not be used. It was only available for 32-bit systems and specifically used the "J" variant. Please transition to one of the recommended algorithms.

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Charset
Function ComCharset Returns String
Procedure Set ComCharset String value

Specifies the character encoding for compressing or decompressing strings. Options include utf-8 (default), windows-1252, Shift_JIS, iso-8859-2, and others.

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DebugLogFilePath
Function ComDebugLogFilePath Returns String
Procedure Set ComDebugLogFilePath String value

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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DeflateLevel
Function ComDeflateLevel Returns Integer
Procedure Set ComDeflateLevel Integer value
Introduced in version 9.5.0.73

This property allows for customization of the compression level for the "deflate" and "zlib" compression algoirthms. ("zlib" is just the deflate algorithm with a zlib header.) A value of 0 = no compression, while 9 = maximum compression. The default is 6.

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EncodingMode
Function ComEncodingMode Returns String
Procedure Set ComEncodingMode String value

Controls the encoding expected by methods ending in "ENC", such as CompressBytesENC. Valid values are "base64", "hex", "url", and "quoted-printable". Compression methods ending in ENC return the binary compressed data as an encoded string using this encoding. Decompress methods expect the input string to be this encoding.

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FirstChunk
Function ComFirstChunk Returns Boolean
Procedure Set ComFirstChunk Boolean value
Introduced in version 11.0.0

This property applies to FirstChunk and LastChunk aware compression and decompression methods. It signifies that the data being compressed is the first of multiple chunks.

The default value is True.

When both FirstChunk and LastChunk, it means the entire amount of data to be compressed or decompressed is presented in a single call.

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LastBinaryResult
Function ComLastBinaryResult Returns Variant

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 True. 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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LastChunk
Function ComLastChunk Returns Boolean
Procedure Set ComLastChunk Boolean value
Introduced in version 11.0.0

This property applies to FirstChunk and LastChunk aware compression and decompression methods. It signifies that the data being compressed is the last of multiple chunks.

The default value is True.

When both FirstChunk and LastChunk, it means the entire amount of data to be compressed or decompressed is presented in a single call.

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LastErrorHtml
Function ComLastErrorHtml Returns String

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
Function ComLastErrorText Returns String

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
Function ComLastErrorXml Returns String

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
Function ComLastMethodSuccess Returns Boolean
Procedure Set ComLastMethodSuccess Boolean value

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.

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LastStringResult
Function ComLastStringResult Returns String

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
Function ComLastStringResultLen Returns Integer

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

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UncommonOptions
Function ComUncommonOptions Returns String
Procedure Set ComUncommonOptions String value
Introduced in version 11.0.0

This is a catch-all property to be used for uncommon needs. This property defaults to the empty string and should typically remain empty.

Can be set to a list of the following comma separated keywords:

  • Crypt2CompressHdr - Duplicates the compression and decompression as implemented in the deprecated and removed Crypt2 compression functions.

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VerboseLogging
Function ComVerboseLogging Returns Boolean
Procedure Set ComVerboseLogging Boolean value

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.

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Version
Function ComVersion Returns String

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

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Methods

CompressBd
Function ComCompressBd cComChilkatBinData bd Returns Boolean
Introduced in version 9.5.0.66

Compresses the data contained in bd. This method is not FirstChunk/LastChunk aware.

Returns True for success, False for failure.

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CompressBdAsync (1)
Function ComCompressBdAsync cComChilkatBinData bd Returns cComChilkatTask
Introduced in version 9.5.0.66

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

Returns null on failure

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CompressBd2
Function ComCompressBd2 cComChilkatBinData bdIn cComChilkatBinData bdOut Returns Boolean
Introduced in version 11.0.0

This method compresses the data in bdIn without modifying it and appends the compressed data to bdOut. It is also FirstChunk/LastChunk aware.

Returns True for success, False for failure.

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CompressBd2Async (1)
Function ComCompressBd2Async cComChilkatBinData bdIn cComChilkatBinData bdOut Returns cComChilkatTask
Introduced in version 11.0.0

Creates an asynchronous task to call the CompressBd2 method with the arguments provided.

Returns null on failure

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CompressBytes
Function ComCompressBytes Variant data Returns Variant

Compresses byte data.

This method is FirstChunk/LastChunk aware.

Returns null on failure

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CompressBytesAsync (1)
Function ComCompressBytesAsync Variant data Returns cComChilkatTask

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

Returns null on failure

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CompressEncryptFile
Function ComCompressEncryptFile cComChilkatJsonObject cryptParams String srcPath String destPath Returns Boolean
Introduced in version 9.5.0.99

Performs file-to-file compression and encryption. Files of any size may be compressed because the file is compressed and encrypted internally in streaming mode.

Returns True for success, False for failure.

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CompressEncryptFileAsync (1)
Function ComCompressEncryptFileAsync cComChilkatJsonObject cryptParams String srcPath String destPath Returns cComChilkatTask
Introduced in version 9.5.0.99

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

Returns null on failure

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CompressFile
Function ComCompressFile String srcPath String destPath Returns Boolean

Performs file-to-file compression. Files of any size may be compressed because the file is compressed internally in streaming mode.

Returns True for success, False for failure.

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CompressFileAsync (1)
Function ComCompressFileAsync String srcPath String destPath Returns cComChilkatTask

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

Returns null on failure

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CompressSb
Function ComCompressSb cComChilkatStringBuilder sb cComChilkatBinData binData Returns Boolean
Introduced in version 9.5.0.73

Compresses the contents of sb and appends the compressed bytes to binData.

This method is FirstChunk/LastChunk aware.

Returns True for success, False for failure.

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CompressSbAsync (1)
Function ComCompressSbAsync cComChilkatStringBuilder sb cComChilkatBinData binData Returns cComChilkatTask
Introduced in version 9.5.0.73

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

Returns null on failure

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CompressStr
Function ComCompressStr String str cComChilkatBinData bd Returns Boolean
Introduced in version 11.0.0

Compresses a string and appends to bd. The byte representation (character encoding) of the actual bytes to be compressed is determined by the Charset property. This method is FirstChunk / LastChunk aware.

Returns True for success, False for failure.

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CompressStrAsync (1)
Function ComCompressStrAsync String str cComChilkatBinData bd Returns cComChilkatTask
Introduced in version 11.0.0

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

Returns null on failure

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CompressStream
Function ComCompressStream cComChilkatStream strm Returns Boolean
Introduced in version 9.5.0.56

Compresses a stream. Internally, the strm's source is read, compressed, and the compressed data written to the strm's sink. It does this in streaming fashion. Extremely large or even infinite streams can be compressed with stable ungrowing memory usage.

Returns True for success, False for failure.

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CompressStreamAsync (1)
Function ComCompressStreamAsync cComChilkatStream strm Returns cComChilkatTask
Introduced in version 9.5.0.56

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

Returns null on failure

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CompressString
Function ComCompressString String str Returns Variant

Compresses a string.

This method is FirstChunk/LastChunk aware.

Returns null on failure

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CompressStringAsync (1)
Function ComCompressStringAsync String str Returns cComChilkatTask

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

Returns null on failure

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CompressStringENC
Function ComCompressStringENC String str Returns String

Compresses a string and returns the compressed data encoded to a string. The output encoding (hex, base64, etc.) is determined by the EncodingMode property setting.

Returns null on failure

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CompressStringENCAsync (1)
Function ComCompressStringENCAsync String str Returns cComChilkatTask

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

Returns null on failure

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DecompressBd
Function ComDecompressBd cComChilkatBinData bd Returns Boolean
Introduced in version 9.5.0.66

Decompresses the data contained in bd. This method is not FirstChunk/LastChunk aware.

Returns True for success, False for failure.

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DecompressBdAsync (1)
Function ComDecompressBdAsync cComChilkatBinData bd Returns cComChilkatTask
Introduced in version 9.5.0.66

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

Returns null on failure

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DecompressBd2
Function ComDecompressBd2 cComChilkatBinData bdIn cComChilkatBinData bdOut Returns Boolean
Introduced in version 11.0.0

This method decompresses the data in bdIn without modifying it and appends the decompressed data to bdOut. It is also FirstChunk/LastChunk aware.

Returns True for success, False for failure.

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DecompressBd2Async (1)
Function ComDecompressBd2Async cComChilkatBinData bdIn cComChilkatBinData bdOut Returns cComChilkatTask
Introduced in version 11.0.0

Creates an asynchronous task to call the DecompressBd2 method with the arguments provided.

Returns null on failure

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DecompressBytes
Function ComDecompressBytes Variant data Returns Variant

This method decompresses bytes.

This method is FirstChunk/LastChunk aware.

Returns null on failure

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DecompressBytesAsync (1)
Function ComDecompressBytesAsync Variant data Returns cComChilkatTask

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

Returns null on failure

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DecompressFile
Function ComDecompressFile String srcPath String destPath Returns Boolean

Performs file-to-file decompression (the opposite of CompressFile). Internally the file is decompressed in streaming mode which allows files of any size to be decompressed.

Returns True for success, False for failure.

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DecompressFileAsync (1)
Function ComDecompressFileAsync String srcPath String destPath Returns cComChilkatTask

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

Returns null on failure

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DecompressSb
Function ComDecompressSb cComChilkatBinData binData cComChilkatStringBuilder sb Returns Boolean
Introduced in version 9.5.0.73

Decompresses the contents of binData and appends the decompressed string to sb.

This method is FirstChunk/LastChunk aware.

Returns True for success, False for failure.

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DecompressSbAsync (1)
Function ComDecompressSbAsync cComChilkatBinData binData cComChilkatStringBuilder sb Returns cComChilkatTask
Introduced in version 9.5.0.73

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

Returns null on failure

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DecompressStream
Function ComDecompressStream cComChilkatStream strm Returns Boolean
Introduced in version 9.5.0.56

Decompresses a stream. Internally, the strm's source is read, decompressed, and the decompressed data written to the strm's sink. It does this in streaming fashion. Extremely large or even infinite streams can be decompressed with stable ungrowing memory usage.

Returns True for success, False for failure.

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DecompressStreamAsync (1)
Function ComDecompressStreamAsync cComChilkatStream strm Returns cComChilkatTask
Introduced in version 9.5.0.56

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

Returns null on failure

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DecryptDecompressFile
Function ComDecryptDecompressFile cComChilkatJsonObject cryptParams String srcPath String destPath Returns Boolean
Introduced in version 9.5.0.99

Performs file-to-file decryption and decompression.

Returns True for success, False for failure.

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DecryptDecompressFileAsync (1)
Function ComDecryptDecompressFileAsync cComChilkatJsonObject cryptParams String srcPath String destPath Returns cComChilkatTask
Introduced in version 9.5.0.99

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

Returns null on failure

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LoadTaskCaller
Function ComLoadTaskCaller cComChilkatTask task Returns Boolean
Introduced in version 9.5.0.80

Loads the caller of the task's async method.

Returns True for success, False for failure.

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Deprecated

BeginCompressBytes
Function ComBeginCompressBytes Variant data Returns Variant
This method is deprecated.

Large amounts of binary byte data may be compressed in chunks by first calling BeginCompressBytes, followed by 0 or more calls to MoreCompressedBytes, and ending with a final call to EndCompressBytes. Each call returns 0 or more bytes of compressed data which may be output to a compressed data stream (such as a file, socket, etc.).

Returns null on failure

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BeginCompressBytesENC
Function ComBeginCompressBytesENC Variant data Returns String
This method is deprecated.

Large amounts of binary byte data may be compressed in chunks by first calling BeginCompressBytesENC, followed by 0 or more calls to MoreCompressedBytesENC, and ending with a final call to EndCompressBytesENC. Each call returns 0 or more characters of compressed data (encoded as a string according to the EncodingMode property setting) which may be output to a compressed data stream (such as a file, socket, etc.).

Returns null on failure

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BeginCompressString
Function ComBeginCompressString String str Returns Variant
This method is deprecated.

Large amounts of string data may be compressed in chunks by first calling BeginCompressString, followed by 0 or more calls to MoreCompressedString, and ending with a final call to EndCompressString. Each call returns 0 or more bytes of compressed data which may be output to a compressed data stream (such as a file, socket, etc.).

Returns null on failure

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BeginCompressStringENC
Function ComBeginCompressStringENC String str Returns String
This method is deprecated.

Large amounts of string data may be compressed in chunks by first calling BeginCompressStringENC, followed by 0 or more calls to MoreCompressedStringENC, and ending with a final call to EndCompressStringENC. Each call returns 0 or more characters of compressed data (encoded as a string according to the EncodingMode property setting) which may be output to a compressed data stream (such as a file, socket, etc.).

Returns null on failure

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BeginDecompressBytes
Function ComBeginDecompressBytes Variant data Returns Variant
This method is deprecated.

A compressed data stream may be decompressed in chunks by first calling BeginDecompressBytes, followed by 0 or more calls to MoreDecompressedBytes, and ending with a final call to EndDecompressBytes. Each call returns 0 or more bytes of decompressed data.

Returns null on failure

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BeginDecompressBytesENC
Function ComBeginDecompressBytesENC String str Returns Variant
This method is deprecated.

The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.

A compressed data stream may be decompressed in chunks by first calling BeginDecompressBytesENC, followed by 0 or more calls to MoreDecompressedBytesENC, and ending with a final call to EndDecompressBytesENC. Each call returns 0 or more bytes of decompressed data.

Returns null on failure

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BeginDecompressString
Function ComBeginDecompressString Variant data Returns String
This method is deprecated.

A compressed data stream may be decompressed in chunks by first calling BeginDecompressString, followed by 0 or more calls to MoreDecompressedString, and ending with a final call to EndDecompressString. Each call returns 0 or more characters of decompressed text.

Returns null on failure

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BeginDecompressStringENC
Function ComBeginDecompressStringENC String str Returns String
This method is deprecated.

The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.

A compressed data stream may be decompressed in chunks by first calling BeginDecompressStringENC, followed by 0 or more calls to MoreDecompressedStringENC, and ending with a final call to EndDecompressStringENC. Each call returns 0 or more characters of decompressed text.

Returns null on failure

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EndCompressBytes
Function ComEndCompressBytes Returns Variant
This method is deprecated.

Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.

(See BeginCompressBytes)

Returns null on failure

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EndCompressBytesENC
Function ComEndCompressBytesENC Returns String
This method is deprecated.

Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.

(See BeginCompressBytesENC)

Returns null on failure

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EndCompressString
Function ComEndCompressString Returns Variant
This method is deprecated.

Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.

(See BeginCompressString)

Returns null on failure

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EndCompressStringENC
Function ComEndCompressStringENC Returns String
This method is deprecated.

Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.

(See BeginCompressStringENC)

Returns null on failure

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EndDecompressBytes
Function ComEndDecompressBytes Returns Variant
This method is deprecated.

Called to finalize the decompression stream and return any remaining (buffered) decompressed data.

(See BeginDecompressBytes)

Returns null on failure

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EndDecompressBytesENC
Function ComEndDecompressBytesENC Returns Variant
This method is deprecated.

Called to finalize the decompression stream and return any remaining (buffered) decompressed data.

The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.

(See BeginDecompressBytesENC)

Returns null on failure

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EndDecompressString
Function ComEndDecompressString Returns String
This method is deprecated.

Called to finalize the decompression stream and return any remaining (buffered) decompressed data.

(See BeginDecompressString)

Returns null on failure

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EndDecompressStringENC
Function ComEndDecompressStringENC Returns String
This method is deprecated.

Called to finalize the decompression stream and return any remaining (buffered) decompressed data.

The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.

(See BeginDecompressStringENC)

Returns null on failure

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MoreCompressBytes
Function ComMoreCompressBytes Variant data Returns Variant
This method is deprecated.

(See BeginCompressBytes)

Returns null on failure

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MoreCompressBytesENC
Function ComMoreCompressBytesENC Variant data Returns String
This method is deprecated.

(See BeginCompressBytesENC)

Returns null on failure

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MoreCompressString
Function ComMoreCompressString String str Returns Variant
This method is deprecated.

(See BeginCompressString)

Returns null on failure

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MoreCompressStringENC
Function ComMoreCompressStringENC String str Returns String
This method is deprecated.

(See BeginCompressStringENC)

Returns null on failure

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MoreDecompressBytes
Function ComMoreDecompressBytes Variant data Returns Variant
This method is deprecated.

(See BeginDecompressBytes)

Returns null on failure

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MoreDecompressBytesENC
Function ComMoreDecompressBytesENC String str Returns Variant
This method is deprecated.

The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.

(See BeginDecompressBytesENC)

Returns null on failure

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MoreDecompressString
Function ComMoreDecompressString Variant data Returns String
This method is deprecated.

(See BeginDecompressString)

Returns null on failure

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MoreDecompressStringENC
Function ComMoreDecompressStringENC String str Returns String
This method is deprecated.

The input to this method is an encoded string containing compressed data. The EncodingMode property should be set prior to calling this method. The input string is decoded according to the EncodingMode (hex, base64, etc.) and then decompressed.

(See BeginDecompressStringENC)

Returns null on failure

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