Bz2 Pascal Reference Documentation
Bz2
Current Version: 11.5.0
Chilkat.Bz2 provides BZip2 compression and decompression for files, memory buffers, and BinData. It can create standard .bz2 file images, decompress .bz2 content back to its original bytes, and support abortable long-running operations.
For an extended overview, see Bz2 Class Overview
Create / Free
uses
Chilkat.Bz2;
var
obj: TBz2;
begin
obj := TBz2.Create;
try
if not obj.IsValid then
raise Exception.Create('Failed to create a TBz2 instance.');
// ... use obj ...
finally
obj.Free;
end;
end;
Allocates the underlying CkBz2 object and returns a new TBz2 instance. Simply adding Chilkat.Bz2 to the unit's uses clause is enough to locate and bind to the Chilkat shared library (DLL / .so / .dylib) at runtime — no separate load step is required. Check obj.IsValid after calling Create; it is False if the underlying library could not be found/loaded or the object could not be allocated (for example, when unlicensed).
Every TBz2 created by calling Create should eventually be released by calling .Free (inherited from TObject). The destructor automatically disposes the underlying CkBz2 handle. A native (unmanaged) memory leak occurs if the object is never freed.
Properties
AbortCurrent
Set this property to True
A synchronous call can be cancelled by setting this property from another thread. After cancellation is processed, Chilkat resets the property to False
LastErrorText to determine the final outcome.DebugLogFilePath
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.
HeartbeatMs
Specifies the interval, in milliseconds, between AbortCheck event callbacks during supported long-running compression and decompression operations. The default is 0, which disables AbortCheck callbacks.
Set a positive value, such as 200, when the application needs periodic opportunities to request cancellation. The interval is approximate; callbacks occur only while an operation is at a point where progress events can be delivered.
AbortCheck handler, set the callback's abort value to request termination. A synchronous method may also be cancelled from another thread by setting AbortCurrent to TrueLastErrorHtml
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
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
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
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. 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.
VerboseLogging
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
Methods
CompressBd
function CompressBd(bd: TChilkatBase): Boolean;
Compresses the current contents of bd in place. On success, the BinData no longer contains the original bytes; it contains the complete standard BZip2 stream that may be saved with a .bz2 extension.
Returns True for success, False for failure.
topCompressBdAsync (1)
// Return value is a TTask object.
function CompressBdAsync(bd: TChilkatBase): TChilkatBase;
Creates an asynchronous task to call the CompressBd method with the arguments provided.
Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.
Returns nil on failure
CompressFile
const toPath: string): Boolean;
Reads the file at inFilename and writes its compressed bytes as a standard BZip2 stream to the file at toPath. The output is conventionally given a .bz2 extension.
Both arguments must identify files, not directories. They may be absolute or relative paths, for example data/report.txt and data/report.txt.bz2.
.bz2 file represents one compressed byte stream. It does not store the original filename, directory path, timestamps, permissions, or multiple archive entries. Formats such as .tar.bz2 first combine files in a TAR archive and then compress that TAR stream with BZip2.Returns True for success, False for failure.
CompressFileAsync (1)
function CompressFileAsync(const inFilename: string;
const toPath: string): TChilkatBase;
Creates an asynchronous task to call the CompressFile method with the arguments provided.
Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.
Returns nil on failure
LoadTaskCaller
function LoadTaskCaller(task: TChilkatBase): Boolean;
Loads this Bz2 object with the caller state associated with the asynchronous operation represented by task.
Task created by a compatible Bz2 asynchronous method; an unrelated task cannot be loaded.Returns True for success, False for failure.
topUncompressBd
function UncompressBd(bd: TChilkatBase): Boolean;
Decompresses the BZip2 stream currently contained in bd in place. On success, the BinData is replaced with the original uncompressed bytes.
bd must contain a complete, valid BZip2 stream, such as the bytes of a .bz2 file or the output of CompressBd. This method operates on binary data and does not perform character-set conversion.Returns True for success, False for failure.
topUncompressBdAsync (1)
// Return value is a TTask object.
function UncompressBdAsync(bd: TChilkatBase): TChilkatBase;
Creates an asynchronous task to call the UncompressBd method with the arguments provided.
Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.
Returns nil on failure
UncompressFile
const toPath: string): Boolean;
Reads the BZip2 stream from the file at inFilename, decompresses it, and writes the original uncompressed bytes to the file at toPath.
Both arguments must identify files, not directories. Chilkat does not derive the destination name from the .bz2 filename because the BZip2 stream does not contain the original filename.
.bz2 file normally contains a single compressed byte stream rather than a collection of named files.Returns True for success, False for failure.
topUncompressFileAsync (1)
function UncompressFileAsync(const inFilename: string;
const toPath: string): TChilkatBase;
Creates an asynchronous task to call the UncompressFile method with the arguments provided.
Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.
Returns nil on failure