Compression PureBasic Reference Documentation

Compression

Current Version: 10.1.2

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)

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, 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.

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.

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

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.

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.

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.

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.

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

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, 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.

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.

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

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.

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

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.

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.

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.

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.

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.

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.

Returns 0 on failure