Compression Python Reference Documentation

Compression

Current Version: 9.5.0.97

Data compression component implementing the PPMD, Bzip2, Deflate, and LZW compression algorithms. .NET, ActiveX, and C++ implementations provide progress monitoring and abort capabilities. Provides a unified API for all supported compression algorithms.

Object Creation

obj = chilkat2.Compression()

Properties

Algorithm
string Algorithm

The compression algorithm to be used. Should be set to either "ppmd", "deflate", "zlib", "bzip2", or "lzw".

Note: The PPMD compression algorithm is only available for 32-bit builds. It is not available for 64-bit implementations. Also, this PPMD implementation is the "J" variant.

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Charset
string Charset

Only applies to methods that compress or decompress strings. This specifies the character encoding that the string should be converted to before compression. Many programming languages use Unicode (2 bytes per char) for representing characters. This property allows for the string to be converted to a 1-byte per char encoding prior to compression.

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DebugLogFilePath
string DebugLogFilePath

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

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DeflateLevel
int DeflateLevel
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
string EncodingMode

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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LastErrorHtml
string LastErrorHtml (read-only)

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
string LastErrorText (read-only)

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
string LastErrorXml (read-only)

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
bool LastMethodSuccess

Indicate whether the last method call succeeded or failed. A value of True indicates success, a value of False indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = True and failure = False.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to True. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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VerboseLogging
bool VerboseLogging

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
string Version (read-only)

Version of the component/library, such as "9.5.0.94"

More Information and Examples
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Methods

BeginCompressBytes
memoryview BeginCompressBytes(memoryview data)

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 None on failure

More Information and Examples
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BeginCompressBytesAsync (1)
Task BeginCompressBytesAsync(memoryview data)

Creates an asynchronous task to call the BeginCompressBytes method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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BeginCompressBytesENC
string BeginCompressBytesENC(memoryview data)

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 None on failure

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BeginCompressBytesENCAsync (1)
Task BeginCompressBytesENCAsync(memoryview data)

Creates an asynchronous task to call the BeginCompressBytesENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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BeginCompressString
memoryview BeginCompressString(string str)

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 None on failure

More Information and Examples
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BeginCompressStringAsync (1)
Task BeginCompressStringAsync(string str)

Creates an asynchronous task to call the BeginCompressString method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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BeginCompressStringENC
string BeginCompressStringENC(string str)

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 None on failure

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BeginCompressStringENCAsync (1)
Task BeginCompressStringENCAsync(string str)

Creates an asynchronous task to call the BeginCompressStringENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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BeginDecompressBytes
memoryview BeginDecompressBytes(memoryview data)

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 None on failure

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BeginDecompressBytesAsync (1)
Task BeginDecompressBytesAsync(memoryview data)

Creates an asynchronous task to call the BeginDecompressBytes method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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BeginDecompressBytesENC
memoryview BeginDecompressBytesENC(string str)

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 None on failure

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BeginDecompressBytesENCAsync (1)
Task BeginDecompressBytesENCAsync(string str)

Creates an asynchronous task to call the BeginDecompressBytesENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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BeginDecompressString
string BeginDecompressString(memoryview data)

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 None on failure

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BeginDecompressStringAsync (1)
Task BeginDecompressStringAsync(memoryview data)

Creates an asynchronous task to call the BeginDecompressString method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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BeginDecompressStringENC
string BeginDecompressStringENC(string str)

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 None on failure

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BeginDecompressStringENCAsync (1)
Task BeginDecompressStringENCAsync(string str)

Creates an asynchronous task to call the BeginDecompressStringENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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CompressBd
bool CompressBd(BinData binData)
Introduced in version 9.5.0.66

Compresses the data contained in a BinData object.

Returns True for success, False for failure.

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CompressBdAsync (1)
Task CompressBdAsync(BinData binData)
Introduced in version 9.5.0.66

Creates an asynchronous task to call the CompressBd method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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CompressBytes
memoryview CompressBytes(memoryview data)

Compresses byte data.

Returns None on failure

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CompressBytesAsync (1)
Task CompressBytesAsync(memoryview data)

Creates an asynchronous task to call the CompressBytes method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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CompressBytesENC
string CompressBytesENC(memoryview data)

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

Returns None on failure

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CompressBytesENCAsync (1)
Task CompressBytesENCAsync(memoryview data)

Creates an asynchronous task to call the CompressBytesENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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CompressFile
bool CompressFile(string srcPath, string destPath)

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)
Task CompressFileAsync(string srcPath, string destPath)

Creates an asynchronous task to call the CompressFile method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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CompressSb
bool CompressSb(StringBuilder sb, BinData binData)
Introduced in version 9.5.0.73

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

Returns True for success, False for failure.

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CompressSbAsync (1)
Task CompressSbAsync(StringBuilder sb, BinData binData)
Introduced in version 9.5.0.73

Creates an asynchronous task to call the CompressSb method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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CompressStream
bool CompressStream(Stream strm)
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)
Task CompressStreamAsync(Stream strm)
Introduced in version 9.5.0.56

Creates an asynchronous task to call the CompressStream method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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CompressString
memoryview CompressString(string str)

Compresses a string.

Returns None on failure

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CompressStringAsync (1)
Task CompressStringAsync(string str)

Creates an asynchronous task to call the CompressString method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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CompressStringENC
string CompressStringENC(string str)

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 None on failure

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CompressStringENCAsync (1)
Task CompressStringENCAsync(string str)

Creates an asynchronous task to call the CompressStringENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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DecompressBd
bool DecompressBd(BinData binData)
Introduced in version 9.5.0.66

Decompresses the data contained in a BinData object.

Returns True for success, False for failure.

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DecompressBdAsync (1)
Task DecompressBdAsync(BinData binData)
Introduced in version 9.5.0.66

Creates an asynchronous task to call the DecompressBd method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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DecompressBytes
memoryview DecompressBytes(memoryview data)

The opposite of CompressBytes.

Returns None on failure

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DecompressBytesAsync (1)
Task DecompressBytesAsync(memoryview data)

Creates an asynchronous task to call the DecompressBytes method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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DecompressBytesENC
memoryview DecompressBytesENC(string encodedCompressedData)

The opposite of CompressBytesENC. encodedCompressedData contains the compressed data as an encoded string (hex, base64, etc) as specified by the EncodingMode property setting.

Returns None on failure

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DecompressBytesENCAsync (1)
Task DecompressBytesENCAsync(string encodedCompressedData)

Creates an asynchronous task to call the DecompressBytesENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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DecompressFile
bool DecompressFile(string srcPath, string destPath)

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)
Task DecompressFileAsync(string srcPath, string destPath)

Creates an asynchronous task to call the DecompressFile method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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DecompressSb
bool DecompressSb(BinData binData, StringBuilder sb)
Introduced in version 9.5.0.73

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

Returns True for success, False for failure.

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DecompressSbAsync (1)
Task DecompressSbAsync(BinData binData, StringBuilder sb)
Introduced in version 9.5.0.73

Creates an asynchronous task to call the DecompressSb method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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DecompressStream
bool DecompressStream(Stream strm)
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)
Task DecompressStreamAsync(Stream strm)
Introduced in version 9.5.0.56

Creates an asynchronous task to call the DecompressStream method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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DecompressString
string DecompressString(memoryview data)

Takes compressed bytes, decompresses, and returns the resulting string.

Returns None on failure

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DecompressStringAsync (1)
Task DecompressStringAsync(memoryview data)

Creates an asynchronous task to call the DecompressString method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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DecompressStringENC
string DecompressStringENC(string encodedCompressedData)

The opposite of CompressStringENC. encodedCompressedData contains the compressed data as an encoded string (hex, base64, etc) as specified by the EncodingMode property setting.

Returns None on failure

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DecompressStringENCAsync (1)
Task DecompressStringENCAsync(string encodedCompressedData)

Creates an asynchronous task to call the DecompressStringENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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EndCompressBytes
memoryview EndCompressBytes()

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

(See BeginCompressBytes)

Returns None on failure

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EndCompressBytesAsync (1)
Task EndCompressBytesAsync()

Creates an asynchronous task to call the EndCompressBytes method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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EndCompressBytesENC
string EndCompressBytesENC()

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

(See BeginCompressBytesENC)

Returns None on failure

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EndCompressBytesENCAsync (1)
Task EndCompressBytesENCAsync()

Creates an asynchronous task to call the EndCompressBytesENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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EndCompressString
memoryview EndCompressString()

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

(See BeginCompressString)

Returns None on failure

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EndCompressStringAsync (1)
Task EndCompressStringAsync()

Creates an asynchronous task to call the EndCompressString method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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EndCompressStringENC
string EndCompressStringENC()

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

(See BeginCompressStringENC)

Returns None on failure

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EndCompressStringENCAsync (1)
Task EndCompressStringENCAsync()

Creates an asynchronous task to call the EndCompressStringENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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EndDecompressBytes
memoryview EndDecompressBytes()

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

(See BeginDecompressBytes)

Returns None on failure

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EndDecompressBytesAsync (1)
Task EndDecompressBytesAsync()

Creates an asynchronous task to call the EndDecompressBytes method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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EndDecompressBytesENC
memoryview EndDecompressBytesENC()

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 None on failure

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EndDecompressBytesENCAsync (1)
Task EndDecompressBytesENCAsync()

Creates an asynchronous task to call the EndDecompressBytesENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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EndDecompressString
string EndDecompressString()

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

(See BeginDecompressString)

Returns None on failure

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EndDecompressStringAsync (1)
Task EndDecompressStringAsync()

Creates an asynchronous task to call the EndDecompressString method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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EndDecompressStringENC
string EndDecompressStringENC()

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 None on failure

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EndDecompressStringENCAsync (1)
Task EndDecompressStringENCAsync()

Creates an asynchronous task to call the EndDecompressStringENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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LoadTaskCaller
bool LoadTaskCaller(Task task)
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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MoreCompressBytes
memoryview MoreCompressBytes(memoryview data)

(See BeginCompressBytes)

Returns None on failure

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MoreCompressBytesAsync (1)
Task MoreCompressBytesAsync(memoryview data)

Creates an asynchronous task to call the MoreCompressBytes method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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MoreCompressBytesENC
string MoreCompressBytesENC(memoryview data)

(See BeginCompressBytesENC)

Returns None on failure

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MoreCompressBytesENCAsync (1)
Task MoreCompressBytesENCAsync(memoryview data)

Creates an asynchronous task to call the MoreCompressBytesENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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MoreCompressString
memoryview MoreCompressString(string str)

(See BeginCompressString)

Returns None on failure

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MoreCompressStringAsync (1)
Task MoreCompressStringAsync(string str)

Creates an asynchronous task to call the MoreCompressString method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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MoreCompressStringENC
string MoreCompressStringENC(string str)

(See BeginCompressStringENC)

Returns None on failure

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MoreCompressStringENCAsync (1)
Task MoreCompressStringENCAsync(string str)

Creates an asynchronous task to call the MoreCompressStringENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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MoreDecompressBytes
memoryview MoreDecompressBytes(memoryview data)

(See BeginDecompressBytes)

Returns None on failure

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MoreDecompressBytesAsync (1)
Task MoreDecompressBytesAsync(memoryview data)

Creates an asynchronous task to call the MoreDecompressBytes method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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MoreDecompressBytesENC
memoryview MoreDecompressBytesENC(string str)

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 None on failure

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MoreDecompressBytesENCAsync (1)
Task MoreDecompressBytesENCAsync(string str)

Creates an asynchronous task to call the MoreDecompressBytesENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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MoreDecompressString
string MoreDecompressString(memoryview data)

(See BeginDecompressString)

Returns None on failure

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MoreDecompressStringAsync (1)
Task MoreDecompressStringAsync(memoryview data)

Creates an asynchronous task to call the MoreDecompressString method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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MoreDecompressStringENC
string MoreDecompressStringENC(string str)

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 None on failure

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MoreDecompressStringENCAsync (1)
Task MoreDecompressStringENCAsync(string str)

Creates an asynchronous task to call the MoreDecompressStringENC method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns None on failure

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