Compression PureBasic Reference Documentation

Compression

Current Version: 10.0.0

Requires Chilkat Bundle License

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.

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.

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:

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

More Information and Examples

Example showing how to use DebugLogFilePath.

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.

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.

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.

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.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

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.

LastMethodSuccess

Declare.i ckLastMethodSuccess(obj.i)
Declare setCkLastMethodSuccess(obj.i, value.i)

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.

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.

Version

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

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

More Information and Examples

How to get the Chilkat version at runtime.

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

Compress String Feed to Base64

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

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.

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

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.

More Information and Examples

Compress and Decompress Base64 Compress and Decompress Hex String

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

CompressEncryptFile

Declare.i ckCompressEncryptFile(obj.i, cryptParams.i, srcPath.s, destPath.s)

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 1 for success, 0 for failure.

More Information and Examples

Compress and Encrypt a Large File (Low and Constant Memory Footprint)

CompressEncryptFileAsync ⁽¹⁾

Declare.i ckCompressEncryptFileAsync(obj.i, cryptParams.i, srcPath.s, destPath.s)

Introduced in version 9.5.0.99

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

Returns 0 on failure

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

Compress and Decompress a File

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

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.

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

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

Streaming Compression

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

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.

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

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.

More Information and Examples

Compress and Decompress Base64 Compress and Decompress Hex String

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

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

Compress and Decompress a File

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

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.

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

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

Streaming Compression

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

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.

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

DecryptDecompressFile

Declare.i ckDecryptDecompressFile(obj.i, cryptParams.i, srcPath.s, destPath.s)

Introduced in version 9.5.0.99

Performs file-to-file decryption and decompression.

Returns 1 for success, 0 for failure.

More Information and Examples

Compress and Encrypt a Large File (Low and Constant Memory Footprint)

DecryptDecompressFileAsync ⁽¹⁾

Declare.i ckDecryptDecompressFileAsync(obj.i, cryptParams.i, srcPath.s, destPath.s)

Introduced in version 9.5.0.99

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

Returns 0 on failure

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.

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

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

Compress String Feed to Base64

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

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.

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

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.

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

LoadTaskCaller

Declare.i ckLoadTaskCaller(obj.i, task.i)

Introduced in version 9.5.0.80

Loads the caller of the task's async method.

Returns 1 for success, 0 for failure.

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

Compress String Feed to Base64

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

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.

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