Compression PureBasic Reference Documentation

Compression

Current Version: 9.5.0.75

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.i = CkCompression::ckCreate()

; Make sure to dispose of the object when finished like this:
CkCompression::ckDispose(obj);

Properties

Algorithm
Declare.s ckAlgorithm(obj.i)
Declare setCkAlgorithm(obj.i, value.s)

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
Declare.s ckCharset(obj.i)
Declare setCkCharset(obj.i, value.s)

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
Declare.s ckDebugLogFilePath(obj.i)
Declare setCkDebugLogFilePath(obj.i, value.s)

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
Declare.i ckDeflateLevel(obj.i)
Declare setCkDeflateLevel(obj.i, value.i)
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
Declare.s ckEncodingMode(obj.i)
Declare setCkEncodingMode(obj.i, value.s)

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
Declare.s ckLastErrorHtml(obj.i) ; (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
Declare.s ckLastErrorText(obj.i) ; (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
Declare.s ckLastErrorXml(obj.i) ; (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
Declare.i ckLastMethodSuccess(obj.i)
Declare setCkLastMethodSuccess(obj.i, value.i)
Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of 1 indicates success, a value of 0 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 = 1 and failure = 0.
  • 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 1. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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VerboseLogging
Declare.i ckVerboseLogging(obj.i)
Declare setCkVerboseLogging(obj.i, value.i)

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
Declare.s ckVersion(obj.i) ; (read-only)

Version of the component/library, such as "9.5.0.63"

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Methods

BeginCompressStringENC
Declare.s ckBeginCompressStringENC(obj.i, str.s)

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 an empty string on failure. Use the LastMethodSuccess property to check for success.

More Information and Examples
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BeginCompressStringENCAsync (1)
Declare.i ckBeginCompressStringENCAsync(obj.i, str.s)

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 0 on failure

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BeginDecompressStringENC
Declare.s ckBeginDecompressStringENC(obj.i, str.s)

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 an empty string on failure. Use the LastMethodSuccess property to check for success.

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BeginDecompressStringENCAsync (1)
Declare.i ckBeginDecompressStringENCAsync(obj.i, str.s)

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 0 on failure

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CompressBd
Declare.i ckCompressBd(obj.i, binData.i)
Introduced in version 9.5.0.66

Compresses the data contained in a BinData object.

Returns 1 for success, 0 for failure.

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CompressBdAsync (1)
Declare.i ckCompressBdAsync(obj.i, binData.i)
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 0 on failure

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CompressFile
Declare.i ckCompressFile(obj.i, srcPath.s, destPath.s)

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

Returns 1 for success, 0 for failure.

More Information and Examples
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CompressFileAsync (1)
Declare.i ckCompressFileAsync(obj.i, srcPath.s, destPath.s)

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 0 on failure

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CompressSb
Declare.i ckCompressSb(obj.i, sb.i, binData.i)
Introduced in version 9.5.0.73

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

Returns 1 for success, 0 for failure.

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CompressSbAsync (1)
Declare.i ckCompressSbAsync(obj.i, sb.i, binData.i)
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 0 on failure

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CompressStream
Declare.i ckCompressStream(obj.i, strm.i)
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 1 for success, 0 for failure.

More Information and Examples
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CompressStreamAsync (1)
Declare.i ckCompressStreamAsync(obj.i, strm.i)
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 0 on failure

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CompressStringENC
Declare.s ckCompressStringENC(obj.i, str.s)

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 an empty string on failure. Use the LastMethodSuccess property to check for success.

More Information and Examples
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CompressStringENCAsync (1)
Declare.i ckCompressStringENCAsync(obj.i, str.s)

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 0 on failure

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DecompressBd
Declare.i ckDecompressBd(obj.i, binData.i)
Introduced in version 9.5.0.66

Decompresses the data contained in a BinData object.

Returns 1 for success, 0 for failure.

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DecompressBdAsync (1)
Declare.i ckDecompressBdAsync(obj.i, binData.i)
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 0 on failure

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DecompressFile
Declare.i ckDecompressFile(obj.i, srcPath.s, destPath.s)

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 1 for success, 0 for failure.

More Information and Examples
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DecompressFileAsync (1)
Declare.i ckDecompressFileAsync(obj.i, srcPath.s, destPath.s)

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 0 on failure

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DecompressSb
Declare.i ckDecompressSb(obj.i, binData.i, sb.i)
Introduced in version 9.5.0.73

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

Returns 1 for success, 0 for failure.

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DecompressSbAsync (1)
Declare.i ckDecompressSbAsync(obj.i, binData.i, sb.i)
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 0 on failure

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DecompressStream
Declare.i ckDecompressStream(obj.i, strm.i)
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 1 for success, 0 for failure.

More Information and Examples
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DecompressStreamAsync (1)
Declare.i ckDecompressStreamAsync(obj.i, strm.i)
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 0 on failure

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DecompressStringENC
Declare.s ckDecompressStringENC(obj.i, encodedCompressedData.s)

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

Returns an empty string on failure. Use the LastMethodSuccess property to check for success.

More Information and Examples
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DecompressStringENCAsync (1)
Declare.i ckDecompressStringENCAsync(obj.i, encodedCompressedData.s)

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 0 on failure

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EndCompressBytesENC
Declare.s ckEndCompressBytesENC(obj.i)

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

(See BeginCompressBytesENC)

Returns an empty string on failure. Use the LastMethodSuccess property to check for success.

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EndCompressBytesENCAsync (1)
Declare.i ckEndCompressBytesENCAsync(obj.i)

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 0 on failure

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EndCompressStringENC
Declare.s ckEndCompressStringENC(obj.i)

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

(See BeginCompressStringENC)

Returns an empty string on failure. Use the LastMethodSuccess property to check for success.

More Information and Examples
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EndCompressStringENCAsync (1)
Declare.i ckEndCompressStringENCAsync(obj.i)

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 0 on failure

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EndDecompressString
Declare.s ckEndDecompressString(obj.i)

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

(See BeginDecompressString)

Returns an empty string on failure. Use the LastMethodSuccess property to check for success.

More Information and Examples
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EndDecompressStringAsync (1)
Declare.i ckEndDecompressStringAsync(obj.i)

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 0 on failure

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EndDecompressStringENC
Declare.s ckEndDecompressStringENC(obj.i)

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 an empty string on failure. Use the LastMethodSuccess property to check for success.

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EndDecompressStringENCAsync (1)
Declare.i ckEndDecompressStringENCAsync(obj.i)

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 0 on failure

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MoreCompressStringENC
Declare.s ckMoreCompressStringENC(obj.i, str.s)

(See BeginCompressStringENC)

Returns an empty string on failure. Use the LastMethodSuccess property to check for success.

More Information and Examples
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MoreCompressStringENCAsync (1)
Declare.i ckMoreCompressStringENCAsync(obj.i, str.s)

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 0 on failure

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MoreDecompressStringENC
Declare.s ckMoreDecompressStringENC(obj.i, str.s)

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 an empty string on failure. Use the LastMethodSuccess property to check for success.

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MoreDecompressStringENCAsync (1)
Declare.i ckMoreDecompressStringENCAsync(obj.i, str.s)

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 0 on failure

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SaveLastError
Declare.i ckSaveLastError(obj.i, path.s)

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns 1 for success, 0 for failure.

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UnlockComponent
Declare.i ckUnlockComponent(obj.i, unlockCode.s)

Unlocks the component allowing for the full functionality to be used. The component may be used fully-functional for the 1st 30-days after download by passing an arbitrary string to this method. If for some reason you do not receive the full 30-day trial, send email to support@chilkatsoft.com for a temporary unlock code w/ an explicit expiration date. Upon purchase, a purchased unlock code is provided which should replace the temporary/arbitrary string passed to this method.

Returns 1 for success, 0 for failure.

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