Compression C Reference Documentation
Compression
Current Version: 11.0.0
Implements the Bzip2, Deflate, and LZW compression algorithms.
Create/Dispose
HCkCompression instance = CkCompression_Create(); // ... CkCompression_Dispose(instance);
Creates an instance of the HCkCompression object and returns a handle ("void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.
Objects created by calling CkCompression_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkCompression_Dispose.
Callback Functions
Provides the opportunity for a method call to be aborted. If TRUE is returned, the operation in progress is aborted.
Return FALSE to allow the current method call to continue.
This callback function is called periodically based on the value of the HeartbeatMs property.
(If HeartbeatMs is 0, then no callbacks are made.) As an example, to make 5 AbortCheck callbacks per second, set the HeartbeatMs property equal to 200.
See Also:C Example using Callback Functions
Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This callback is only called when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For methods that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).
This callback counts as an AbortCheck callback, and takes the place of the AbortCheck event when it fires.
The return value indicates whether the method call should be aborted, or whether it should proceed. Return TRUE to abort, and FALSE to proceed.
This is a general callback that provides name/value information about what is happening at certain points during a method call. To see the information provided in ProgressInfo callbacks, if any, write code to handle this event and log the name/value pairs. Most are self-explanatory.
Called in the background thread when an asynchronous task completes. (Note: When an async method is running, all callbacks are in the background thread.)
Properties
Algorithm
void CkCompression_putAlgorithm(HCkCompression cHandle, const char *newVal);
const char *CkCompression_algorithm(HCkCompression cHandle);
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.
topCharset
void CkCompression_putCharset(HCkCompression cHandle, const char *newVal);
const char *CkCompression_charset(HCkCompression cHandle);
Specifies the character encoding for compressing or decompressing strings. Options include utf-8 (default), windows-1252, Shift_JIS, iso-8859-2, and others.
DebugLogFilePath
void CkCompression_putDebugLogFilePath(HCkCompression cHandle, const char *newVal);
const char *CkCompression_debugLogFilePath(HCkCompression cHandle);
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.
DeflateLevel
void CkCompression_putDeflateLevel(HCkCompression cHandle, int newVal);
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.
topEncodingMode
void CkCompression_putEncodingMode(HCkCompression cHandle, const char *newVal);
const char *CkCompression_encodingMode(HCkCompression cHandle);
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.
topFirstChunk
void CkCompression_putFirstChunk(HCkCompression cHandle, BOOL newVal);
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 TRUE.
When both FirstChunk and LastChunk, it means the entire amount of data to be compressed or decompressed is presented in a single call.
HeartbeatMs
void CkCompression_putHeartbeatMs(HCkCompression cHandle, int newVal);
The number of milliseconds between each AbortCheck event callback. The AbortCheck callback allows an application to abort any method call prior to completion. If HeartbeatMs is 0 (the default), no AbortCheck event callbacks will fire.
topLastChunk
void CkCompression_putLastChunk(HCkCompression cHandle, BOOL newVal);
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 TRUE.
When both FirstChunk and LastChunk, it means the entire amount of data to be compressed or decompressed is presented in a single call.
LastErrorHtml
const char *CkCompression_lastErrorHtml(HCkCompression cHandle);
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.
topLastErrorText
const char *CkCompression_lastErrorText(HCkCompression cHandle);
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.
LastErrorXml
const char *CkCompression_lastErrorXml(HCkCompression cHandle);
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.
topLastMethodSuccess
void CkCompression_putLastMethodSuccess(HCkCompression cHandle, BOOL newVal);
Indicates the success or failure of the most recent method call: TRUE means success, FALSE 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
void CkCompression_putUncommonOptions(HCkCompression cHandle, const char *newVal);
const char *CkCompression_uncommonOptions(HCkCompression cHandle);
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.
Utf8
void CkCompression_putUtf8(HCkCompression cHandle, BOOL newVal);
When set to TRUE, all const char * arguments and return values are interpreted as UTF-8 strings. When set to FALSE, they are interpreted as ANSI strings.
In Chilkat v11.0.0 and later, the default value is TRUE. Before v11.0.0, it was FALSE.
VerboseLogging
void CkCompression_putVerboseLogging(HCkCompression cHandle, BOOL newVal);
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.
Version
const char *CkCompression_version(HCkCompression cHandle);
Methods
CompressBd
Compresses the data contained in bd. This method is not FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
CompressBdAsync (1)
Creates an asynchronous task to call the CompressBd method with the arguments provided.
Returns NULL on failure
CompressBd2
This method compresses the data in bdIn without modifying it and appends the compressed data to bdOut. It is also FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topCompressBd2Async (1)
Creates an asynchronous task to call the CompressBd2 method with the arguments provided.
Returns NULL on failure
CompressBytes Deprecated
Compresses byte data.
This method is FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topCompressBytesAsync Deprecated (1)
Creates an asynchronous task to call the CompressBytes method with the arguments provided.
Returns NULL on failure
CompressBytes2 Deprecated
Compresses byte data.
This method is FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topCompressEncryptFile
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 TRUE for success, FALSE for failure.
CompressEncryptFileAsync (1)
Creates an asynchronous task to call the CompressEncryptFile method with the arguments provided.
Returns NULL on failure
CompressFile
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.
CompressFileAsync (1)
Creates an asynchronous task to call the CompressFile method with the arguments provided.
Returns NULL on failure
CompressSb
Compresses the contents of sb and appends the compressed bytes to binData.
This method is FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topCompressSbAsync (1)
Creates an asynchronous task to call the CompressSb method with the arguments provided.
Returns NULL on failure
CompressStr Deprecated
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 TRUE for success, FALSE for failure.
topCompressStrAsync Deprecated (1)
Creates an asynchronous task to call the CompressStr method with the arguments provided.
Returns NULL on failure
CompressStream
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.
CompressStreamAsync (1)
Creates an asynchronous task to call the CompressStream method with the arguments provided.
Returns NULL on failure
CompressString Deprecated
Compresses a string.
This method is FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topCompressStringAsync Deprecated (1)
Creates an asynchronous task to call the CompressString method with the arguments provided.
Returns NULL on failure
CompressStringENC
const char *CkCompression_compressStringENC(HCkCompression cHandle, const char *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 TRUE for success, FALSE for failure.
CompressStringENCAsync (1)
Creates an asynchronous task to call the CompressStringENC method with the arguments provided.
Returns NULL on failure
DecompressBd
Decompresses the data contained in bd. This method is not FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
DecompressBdAsync (1)
Creates an asynchronous task to call the DecompressBd method with the arguments provided.
Returns NULL on failure
DecompressBd2
This method decompresses the data in bdIn without modifying it and appends the decompressed data to bdOut. It is also FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topDecompressBd2Async (1)
Creates an asynchronous task to call the DecompressBd2 method with the arguments provided.
Returns NULL on failure
DecompressBytes Deprecated
This method decompresses bytes.
This method is FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topDecompressBytesAsync Deprecated (1)
Creates an asynchronous task to call the DecompressBytes method with the arguments provided.
Returns NULL on failure
DecompressBytes2 Deprecated
This method decompresses bytes.
This method is FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topDecompressFile
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.
DecompressFileAsync (1)
Creates an asynchronous task to call the DecompressFile method with the arguments provided.
Returns NULL on failure
DecompressSb
Decompresses the contents of binData and appends the decompressed string to sb.
This method is FirstChunk/LastChunk aware.
Returns TRUE for success, FALSE for failure.
topDecompressSbAsync (1)
Creates an asynchronous task to call the DecompressSb method with the arguments provided.
Returns NULL on failure
DecompressStream
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.
DecompressStreamAsync (1)
Creates an asynchronous task to call the DecompressStream method with the arguments provided.
Returns NULL on failure
DecryptDecompressFile
Performs file-to-file decryption and decompression.
Returns TRUE for success, FALSE for failure.
DecryptDecompressFileAsync (1)
Creates an asynchronous task to call the DecryptDecompressFile method with the arguments provided.
Returns NULL on failure
LoadTaskCaller
Deprecated
BeginCompressBytes
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 TRUE for success, FALSE for failure.
topBeginCompressBytes2
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 TRUE for success, FALSE for failure.
topBeginCompressBytesENC
const char *CkCompression_beginCompressBytesENC(HCkCompression cHandle, HCkByteData 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 TRUE for success, FALSE for failure.
topBeginCompressString
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 TRUE for success, FALSE for failure.
topBeginCompressStringENC
const char *CkCompression_beginCompressStringENC(HCkCompression cHandle, const char *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 TRUE for success, FALSE for failure.
BeginDecompressBytes
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 TRUE for success, FALSE for failure.
topBeginDecompressBytes2
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 TRUE for success, FALSE for failure.
topBeginDecompressBytesENC
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 TRUE for success, FALSE for failure.
topBeginDecompressString
const char *CkCompression_beginDecompressString(HCkCompression cHandle, HCkByteData 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 TRUE for success, FALSE for failure.
topBeginDecompressStringENC
const char *CkCompression_beginDecompressStringENC(HCkCompression cHandle, const char *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 TRUE for success, FALSE for failure.
topEndCompressBytes
Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.
(See BeginCompressBytes)
Returns TRUE for success, FALSE for failure.
topEndCompressBytesENC
const char *CkCompression_endCompressBytesENC(HCkCompression cHandle);
Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.
(See BeginCompressBytesENC)
Returns TRUE for success, FALSE for failure.
topEndCompressString
Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.
(See BeginCompressString)
Returns TRUE for success, FALSE for failure.
topEndCompressStringENC
const char *CkCompression_endCompressStringENC(HCkCompression cHandle);
Must be callled to finalize a compression stream. Returns any remaining (buffered) compressed data.
(See BeginCompressStringENC)
Returns TRUE for success, FALSE for failure.
EndDecompressBytes
Called to finalize the decompression stream and return any remaining (buffered) decompressed data.
(See BeginDecompressBytes)
Returns TRUE for success, FALSE for failure.
topEndDecompressBytesENC
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 TRUE for success, FALSE for failure.
topEndDecompressString
const char *CkCompression_endDecompressString(HCkCompression cHandle);
Called to finalize the decompression stream and return any remaining (buffered) decompressed data.
(See BeginDecompressString)
Returns TRUE for success, FALSE for failure.
EndDecompressStringENC
const char *CkCompression_endDecompressStringENC(HCkCompression cHandle);
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 TRUE for success, FALSE for failure.
topMoreCompressBytes
MoreCompressBytes2
MoreCompressBytesENC
const char *CkCompression_moreCompressBytesENC(HCkCompression cHandle, HCkByteData data);
MoreCompressString
MoreCompressStringENC
const char *CkCompression_moreCompressStringENC(HCkCompression cHandle, const char *str);
(See BeginCompressStringENC)
Returns TRUE for success, FALSE for failure.
MoreDecompressBytes
MoreDecompressBytes2
MoreDecompressBytesENC
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 TRUE for success, FALSE for failure.
topMoreDecompressString
const char *CkCompression_moreDecompressString(HCkCompression cHandle, HCkByteData data);
MoreDecompressStringENC
const char *CkCompression_moreDecompressStringENC(HCkCompression cHandle, const char *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 TRUE for success, FALSE for failure.
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