Compression Chilkat2 Perl Reference Documentation
Chilkat2::Compression
Current Version: 11.7.0
Markdown version of this page for AI tools (v 11.7.0) · all AI docs
Chilkat.Compression
Supports
Work with byte arrays, strings,
Process data incrementally with
Return compressed bytes as text using encodings such as
Compress or decompress large files and streams with stable memory usage.
Combine compression and encryption in file workflows with integrated methods.
For an extended overview, see
Compression Class Overview.
See also
Binary Encodings
for supported encoded output formats.
Compress and decompress bytes, text, files, and streams with a flexible API.
Chilkat.Compression provides a general-purpose API for compressing
and decompressing data in memory, files, and streams. It supports multiple
algorithms, text charset conversion, encoded output, chunked processing, and
streaming operations for large data.
Multiple algorithms
deflate, zlib,
bzip2, and lzw.
Flexible data types
BinData,
StringBuilder, files, and streams.
Chunked processing
FirstChunk and
LastChunk for chunk-aware methods.
Encoded output
base64, hex, and others.
Streaming support
Compression + encryption
Charset = "utf-8" unless
another encoding is required. For encoded compressed data, set
EncodingMode to the desired output format.
Object Creation
use Chilkat2;
my $compression = Chilkat2::Compression->new;
# or set properties (and RaiseError) at creation:
# my $compression = Chilkat2::Compression->new(VerboseLogging => 1, RaiseError => 1);Creates the object. The optional pairs set writable properties (and RaiseError) in order, as if set one by one; an unknown or read-only name croaks. use Chilkat2; loads every class; the Chilkat2/Compression.pm file holds only this class's documentation (perldoc Chilkat2::Compression).
Perl frees the object when its last reference goes (undef $compression, or the variable going out of scope); there is nothing to close. Objects returned by methods are independent and freed the same way. The class may be subclassed (use parent -norequire, 'Chilkat2::Compression';): an object is a blessed hash reference whose hash is free for the subclass's own fields.
When false (the default), a method that fails returns false (or undef), and the reason is in LastErrorText. When true, it dies with a Chilkat2::Error instead, as DBI does with its RaiseError. Objects returned by a method inherit the value of the object that returned them.
Errors
A Chilkat2::Error stringifies to the failed call's full LastErrorText, and has the methods text, class ('Chilkat2::Compression'), method (the method name) and object. Methods that look something up and find nothing return undef without dying (each such method says so), methods that answer a question (HasMember, IsUnlocked, ...) return a plain boolean, and property reads and writes never fail for Chilkat reasons.
Misuse always croaks, with your file and line, whatever RaiseError is: a wrong number of arguments, a reference or undef where a string or number is expected, an object of the wrong class, an out-of-range integer, a string containing a NUL character, a wide character in a byte string, or a write to a read-only property.
Strings are Perl character strings in both directions (length, regexes and :encoding layers see characters); binary data (BinData) is a byte string. Unlocking: call Chilkat2::Global->new->UnlockBundle('...') once at startup.
Properties
Algorithm
my $strVal = $compression->Algorithm;
$compression->Algorithm($strVal);
Specifies the compression algorithm to use. Supported values are
deflate, zlib, gzip, bzip2, and lzw.
The zlib option is the deflate algorithm with a zlib header.
The gzip option (starting in v11.7.0) is the deflate algorithm in the gzip format (RFC 1952): a gzip
header, the deflate data, and a trailer with the CRC-32 and size of the uncompressed data. When decompressing in one
call, the CRC-32 and size are checked. Before v11.7.0, gzip was not recognized and was treated as
deflate.
Note: ppmd is deprecated and should not be used.
It was only available on 32-bit systems and specifically used the J variant.
New applications should use one of the supported algorithms listed above.
Charset
my $strVal = $compression->Charset;
$compression->Charset($strVal);
Specifies the character encoding used when converting text to bytes before compression, and bytes back to text after decompression.
The current default is the computer’s ANSI charset, such as Windows-1252 on many
Western Windows systems. However, most modern applications should explicitly set
this property to utf-8.
Recommendation: Set Charset = "utf-8" unless you
specifically need compatibility with another encoding.
DebugLogFilePath
my $strVal = $compression->DebugLogFilePath;
$compression->DebugLogFilePath($strVal);
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
my $intVal = $compression->DeflateLevel;
$compression->DeflateLevel($intVal);
Sets the compression level used by the deflate and zlib
algorithms.
0means no compression.9means maximum compression.- The default value is
6.
Higher values may produce smaller output but can require more processing time.
topEncodingMode
my $strVal = $compression->EncodingMode;
$compression->EncodingMode($strVal);
Specifies the text encoding used by methods whose names end in ENC,
such as CompressBytesENC and DecompressStringENC.
Compression methods ending in ENC return compressed binary data as
an encoded string. Decompression methods ending in ENC expect the
input string to use this same encoding.
Valid values include:
base64hexurlquoted-printable
FirstChunk
my $boolVal = $compression->FirstChunk;
$compression->FirstChunk($boolVal);
Indicates that the next chunk-aware compression or decompression call is the first chunk in a sequence.
The default value is 1
When both FirstChunk and LastChunk are
1
HeartbeatMs
my $intVal = $compression->HeartbeatMs;
$compression->HeartbeatMs($intVal);
Specifies the interval, in milliseconds, between AbortCheck event
callbacks.
This allows an application to periodically check whether a long-running operation should be aborted.
The default value is 0, which disables AbortCheck
callbacks.
LastChunk
my $boolVal = $compression->LastChunk;
$compression->LastChunk($boolVal);
Indicates that the next chunk-aware compression or decompression call is the final chunk in a sequence.
The default value is 1
When both FirstChunk and LastChunk are
1
LastErrorHtml
my $strVal = $compression->LastErrorHtml;
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
my $strVal = $compression->LastErrorText;
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
my $strVal = $compression->LastErrorXml;
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
my $boolVal = $compression->LastMethodSuccess;
$compression->LastMethodSuccess($boolVal);
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. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
UncommonOptions
my $strVal = $compression->UncommonOptions;
$compression->UncommonOptions($strVal);
Provides a way to enable specialized or uncommon behavior. This property normally remains empty.
It may be set to a comma-separated list of keywords.
Supported option:
-
Crypt2CompressHdr— Duplicates the compression/decompression header behavior used by the deprecated and removed Crypt2 compression functions.
VerboseLogging
my $boolVal = $compression->VerboseLogging;
$compression->VerboseLogging($boolVal);
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
my $strVal = $compression->Version;
Methods
CompressBd
# $success is true or false
my $success = $compression->CompressBd($bd);
Compresses the data contained in a BinData object.
The BinData object is modified to contain the compressed result.
This method is not FirstChunk / LastChunk aware.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
CompressBd2
# $bdOut is a Chilkat2::BinData
# $success is true or false
my $success = $compression->CompressBd2($bdIn, $bdOut);
Compresses the data in one BinData object and appends the
compressed output to another BinData object.
The input BinData is not modified.
This method is FirstChunk / LastChunk aware.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
CompressEncryptFile
# $srcPath is a string
# $destPath is a string
# $success is true or false
my $success = $compression->CompressEncryptFile($cryptParams, $srcPath, $destPath);
Compresses and encrypts a file, writing the result to a destination file.
The compression and encryption are performed internally in streaming mode, so files of any size can be processed without loading the entire file into memory.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
CompressFile
# $destPath is a string
# $success is true or false
my $success = $compression->CompressFile($srcPath, $destPath);
Compresses a source file and writes the compressed data to a destination file.
The file is processed internally in streaming mode, allowing files of any size to be compressed with stable memory usage.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
CompressSb
# $binData is a Chilkat2::BinData
# $success is true or false
my $success = $compression->CompressSb($sb, $binData);
Compresses the text contained in a StringBuilder and appends the
compressed bytes to a BinData object.
Text is converted to bytes according to the Charset property.
This method is FirstChunk / LastChunk aware.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
CompressStream
# $success is true or false
my $success = $compression->CompressStream($strm);
Compresses data from a stream source and writes the compressed data to the stream sink.
The operation is performed in streaming mode, making it suitable for very large or even continuous streams while maintaining stable memory usage.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
CompressStringENC
# $str is a string or undef
my $str = $compression->CompressStringENC($str);
Compresses a string and returns the compressed result as an encoded string.
The string is first converted to bytes using Charset, then
compressed, and finally encoded according to EncodingMode.
This method is not FirstChunk / LastChunk aware.
Returns undef on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
DecompressBd
# $success is true or false
my $success = $compression->DecompressBd($bd);
Decompresses the compressed data contained in a BinData object.
The BinData object is modified to contain the decompressed result.
This method is not FirstChunk / LastChunk aware.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
DecompressBd2
# $bdOut is a Chilkat2::BinData
# $success is true or false
my $success = $compression->DecompressBd2($bdIn, $bdOut);
Decompresses the data in one BinData object and appends the
decompressed output to another BinData object.
The input BinData is not modified.
This method is FirstChunk / LastChunk aware.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
DecompressFile
# $destPath is a string
# $success is true or false
my $success = $compression->DecompressFile($srcPath, $destPath);
Decompresses a source file and writes the decompressed data to a destination file.
The file is processed internally in streaming mode, allowing files of any size to be decompressed without loading the entire file into memory.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
DecompressSb
# $sb is a Chilkat2::StringBuilder
# $success is true or false
my $success = $compression->DecompressSb($binData, $sb);
Decompresses compressed data from a BinData object and appends the
resulting text to a StringBuilder.
The decompressed bytes are converted to text using the Charset
property.
This method is FirstChunk / LastChunk aware.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
DecompressStream
# $success is true or false
my $success = $compression->DecompressStream($strm);
Decompresses data from a stream source and writes the decompressed data to the stream sink.
The operation is performed in streaming mode, making it suitable for very large or continuous streams while maintaining stable memory usage.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
DecompressStringENC
# $str is a string or undef
my $str = $compression->DecompressStringENC($encodedCompressedData);
Decompresses compressed data supplied as an encoded string and returns the resulting text.
The input string is decoded according to EncodingMode, then
decompressed. The resulting bytes are converted to text using
Charset.
This method is not FirstChunk / LastChunk aware.
Returns undef on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
DecryptDecompressFile
# $srcPath is a string
# $destPath is a string
# $success is true or false
my $success = $compression->DecryptDecompressFile($cryptParams, $srcPath, $destPath);
Decrypts and decompresses a file, writing the restored data to a destination file.
This is the reverse operation of CompressEncryptFile.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
Events
All Chilkat methods are synchronous: the call returns when the work is done. During a long-running call, Chilkat2::Compression reports progress to handlers installed with on, which takes Event => CODE pairs (closures, so a handler can use the variables around it):
$compression->on(
PercentDone => sub { my ($pctDone) = @_; print "$pctDone%\n"; return 0 }, # a true return aborts
ProgressInfo => sub { my ($name, $value) = @_; print "$name: $value\n" },
);
$compression->HeartbeatMs(250); # the AbortCheck handler is called 4 times per secondInstalls the handlers given, replacing those installed before for the same events; undef instead of a CODE reference removes one, and $compression->on() with no arguments returns the installed handlers as a list of pairs. The event names are checked: a misspelled one croaks, and nothing is installed.
The AbortCheck handler is called at the interval set by the HeartbeatMs property (0, the default, disables it); PercentDone is called when an operation's completion percentage is known; ProgressInfo delivers named progress values. A true return from the AbortCheck or PercentDone handler aborts the running method, which then fails in the usual way (false or undef, or a Chilkat2::Error under RaiseError).
Handlers run during the method call, on the thread that called it. Inside a handler, other objects may be used, but calling a method of the same object (or its on) croaks. A die in a handler aborts the running method and is re-thrown from the method call; the object remains usable. A handler that uses $compression itself makes a reference cycle: weaken the captured copy (Scalar::Util) or remove the handler when done.
AbortCheck
$compression->on(AbortCheck => sub { ... });
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
Example
my $deadline = time() + 30; # give up after 30 seconds
$compression->HeartbeatMs(250); # call the handler 4 times per second
$compression->on(AbortCheck => sub { return time() > $deadline });PercentDone
$compression->on(PercentDone => sub { ... });
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to 1. This will cause the method to terminate and return a failure status or corresponding failure value.
Example
$compression->on(PercentDone => sub {
my ($pctDone) = @_; # 0 to 100
print "Percent done: $pctDone\n";
return 0; # return a true value to abort the method in progress
});ProgressInfo
$compression->on(ProgressInfo => sub { ... });
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example
$compression->on(ProgressInfo => sub {
my ($name, $value) = @_;
print "$name: $value\n";
});