Compression PureBasic Reference Documentation

Compression

Current Version: 11.0.0

Requires Chilkat Bundle License

Implements the Bzip2, Deflate, and LZW 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)

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.

Charset

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

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

More Information and Examples

Full List of Character Encodings Supported by Chilkat

DebugLogFilePath

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

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.

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.

FirstChunk

Declare.i ckFirstChunk(obj.i)
Declare setCkFirstChunk(obj.i, value.i)

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 1.

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

LastChunk

Declare.i ckLastChunk(obj.i)
Declare setCkLastChunk(obj.i, value.i)

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 1.

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

LastErrorHtml

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

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

LastErrorText

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

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

LastErrorXml

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

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

LastMethodSuccess

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

Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.

UncommonOptions

Declare.s ckUncommonOptions(obj.i)
Declare setCkUncommonOptions(obj.i, value.s)

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.

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 "10.1.0"

More Information and Examples

How to get the Chilkat version at runtime.

Methods

CompressBd

Declare.i ckCompressBd(obj.i, bd.i)

Introduced in version 9.5.0.66

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

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, bd.i)

Introduced in version 9.5.0.66

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

Returns 0 on failure

CompressBd2

Declare.i ckCompressBd2(obj.i, bdIn.i, bdOut.i)

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 1 for success, 0 for failure.

CompressBd2Async ⁽¹⁾

Declare.i ckCompressBd2Async(obj.i, bdIn.i, bdOut.i)

Introduced in version 11.0.0

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

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.

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.

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.

This method is FirstChunk/LastChunk aware.

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.

Returns 0 on failure

CompressStr

Declare.i ckCompressStr(obj.i, str.s, bd.i)

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 1 for success, 0 for failure.

CompressStrAsync ⁽¹⁾

Declare.i ckCompressStrAsync(obj.i, str.s, bd.i)

Introduced in version 11.0.0

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

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.

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.

Returns 0 on failure

DecompressBd

Declare.i ckDecompressBd(obj.i, bd.i)

Introduced in version 9.5.0.66

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

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, bd.i)

Introduced in version 9.5.0.66

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

Returns 0 on failure

DecompressBd2

Declare.i ckDecompressBd2(obj.i, bdIn.i, bdOut.i)

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 1 for success, 0 for failure.

DecompressBd2Async ⁽¹⁾

Declare.i ckDecompressBd2Async(obj.i, bdIn.i, bdOut.i)

Introduced in version 11.0.0

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

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.

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.

This method is FirstChunk/LastChunk aware.

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.

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.

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.

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.

Deprecated

BeginCompressStringENC

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

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

More Information and Examples

Compress String Feed to Base64

BeginDecompressStringENC

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

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

EndCompressBytesENC

Declare.s ckEndCompressBytesENC(obj.i)

This method is deprecated.

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.

EndCompressStringENC

Declare.s ckEndCompressStringENC(obj.i)

This method is deprecated.

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

EndDecompressString

Declare.s ckEndDecompressString(obj.i)

This method is deprecated.

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.

EndDecompressStringENC

Declare.s ckEndDecompressStringENC(obj.i)

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

MoreCompressStringENC

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

This method is deprecated.

(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

MoreDecompressStringENC

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

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