---
product: Chilkat
product_version: 11.7.0
language: delphix
language_label: Delphi ActiveX
class: Bz2
class_name: TChilkatBz2
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/delphiBz2Ref.html
---
# Chilkat Bz2 — Delphi ActiveX — v11.7.0

> Chilkat 11.7.0 · language=delphix · class=Bz2 (TChilkatBz2)
> Other versions: replace `11.7.0` in this URL. Other languages: `https://www.chilkatsoft.com/ai-docs/v/11.7.0/<lang>/classes/Bz2.md`.
> Language-wide rules (install, unlock, error model, strings/bytes): `https://www.chilkatsoft.com/ai-docs/v/11.7.0/delphix/guide.md`.

## Purpose

`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](https://www.chilkatsoft.com/bz2_class_overview.asp)

## Object creation, unlocking and error handling

**Object Creation**

```pascal
var
obj: TChilkatBz2;
...
begin
obj := TChilkatBz2.Create(Self);
...
// When finished, free the object instance.
obj.Free();
```

Call `Global.UnlockBundle` once at the start of the program, before using this or any other Chilkat class. Any string unlocks a fully functional 30-day trial; a purchased unlock code is used in production. See `guide.md` for the exact code in Delphi ActiveX.

How failure is reported depends on the method's return type and is stated in the note under each method below. In every case the diagnostic text is in the `LastErrorText` property of the object whose method was called.

## Members common to every Chilkat class

Documented once per language in `common-members.md`; listed here so this page is self-contained.

| Property | Signature | Access | Meaning |
|---|---|---|---|
| `DebugLogFilePath` | `property DebugLogFilePath: WideString` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. |
| `LastBinaryResult` | `property LastBinaryResult: OleVariant readonly` | read-only | This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. |
| `LastErrorHtml` | `property LastErrorHtml: WideString readonly` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `property LastErrorText: WideString readonly` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `property LastErrorXml: WideString readonly` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `property LastMethodSuccess: Integer` | read/write | Indicates the success or failure of the most recent method call: `1` means success, `0` means failure. |
| `LastStringResult` | `property LastStringResult: WideString readonly` | read-only | In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. |
| `LastStringResultLen` | `property LastStringResultLen: Integer readonly` | read-only | The length, in characters, of the string contained in the LastStringResult property. |
| `VerboseLogging` | `property VerboseLogging: Integer` | read/write | If set to `1`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `property Version: WideString readonly` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `AbortCurrent` | property, read/write | `property AbortCurrent: Integer` |
| `HeartbeatMs` | property, read/write | `property HeartbeatMs: Integer` |
| `CompressBd` | method | `function CompressBd(bd: IChilkatBinData): Integer;` |
| `CompressFile` | method | `function CompressFile(inFilename: WideString; toPath: WideString): Integer;` |
| `CompressFileToMem` | method | `function CompressFileToMem(inFilename: WideString): OleVariant;` |
| `CompressMemory` | method | `function CompressMemory(inData: OleVariant): OleVariant;` |
| `CompressMemToFile` | method | `function CompressMemToFile(inData: OleVariant; toPath: WideString): Integer;` |
| `LoadTaskCaller` | method | `function LoadTaskCaller(task: IChilkatTask): Integer;` |
| `UncompressBd` | method | `function UncompressBd(bd: IChilkatBinData): Integer;` |
| `UncompressFile` | method | `function UncompressFile(inFilename: WideString; toPath: WideString): Integer;` |
| `UncompressFileToMem` | method | `function UncompressFileToMem(inFilename: WideString): OleVariant;` |
| `UncompressMemory` | method | `function UncompressMemory(inData: OleVariant): OleVariant;` |
| `UncompressMemToFile` | method | `function UncompressMemToFile(inData: OleVariant; toPath: WideString): Integer;` |

## Properties

### Bz2.AbortCurrent

`Chilkat 11.7.0 · delphix · Bz2 · AbortCurrent · property · read/write · since 9.5.0.58`

```pascal
property AbortCurrent: Integer
```

Set this property to `1` to request cancellation of the compression or decompression operation currently executing on this object. Long-running operations check the request periodically; an operation that finishes quickly may complete before the request is observed.

A synchronous call can be cancelled by setting this property from another thread. After cancellation is processed, Chilkat resets the property to `0`. If no operation is running, a previously set value is cleared when the next method begins.

**Cancellation is cooperative:** Setting this property requests an abort; it does not guarantee immediate termination. Check the method's return value and `LastErrorText` to determine the final outcome.

### Bz2.HeartbeatMs

`Chilkat 11.7.0 · delphix · Bz2 · HeartbeatMs · property · read/write`

```pascal
property HeartbeatMs: Integer
```

**Full documentation for this property (same in every language):** [Event Callback Examples](https://www.chilkatsoft.com/ai-docs/v/11.7.0/articles/event_callback_examples.md)

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.

**Cancellation workflow:** In an `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 `1`.

## Methods

### Bz2.CompressBd

`Chilkat 11.7.0 · delphix · Bz2 · CompressBd · method · since 11.0.0`

```pascal
function CompressBd(bd: IChilkatBinData): Integer;
```

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.

**In-place transformation:** Preserve a copy of the original data if it is still needed after this call. A BZip2 stream contains a stream header, one or more compressed blocks with integrity checks, and an end-of-stream marker. It does not contain archive filenames or directory entries.

Returns 1 for success, 0 for failure.

Async variant: `CompressBdAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.CompressFile

`Chilkat 11.7.0 · delphix · Bz2 · CompressFile · method`

```pascal
function CompressFile(inFilename: WideString; toPath: WideString): Integer;
```

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`.

**BZip2 is a compressor, not an archive format:** A `.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 1 for success, 0 for failure.

Async variant: `CompressFileAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.CompressFileToMem

`Chilkat 11.7.0 · delphix · Bz2 · CompressFileToMem · method`

```pascal
function CompressFileToMem(inFilename: WideString): OleVariant;
```

Reads the file at `inFilename`, compresses it with BZip2, and returns the complete `.bz2` byte stream in memory.

Returns a zero-length byte array (as an OleVariant) on failure.  
An empty array will have a VarArrayHighBound of -1 meaning 0 elements.

Async variant: `CompressFileToMemAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.CompressMemory

`Chilkat 11.7.0 · delphix · Bz2 · CompressMemory · method`

```pascal
function CompressMemory(inData: OleVariant): OleVariant;
```

Compresses the bytes in `inData` and returns the complete standard BZip2 stream as an in-memory byte array.

Returns a zero-length byte array (as an OleVariant) on failure.  
An empty array will have a VarArrayHighBound of -1 meaning 0 elements.

Async variant: `CompressMemoryAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.CompressMemToFile

`Chilkat 11.7.0 · delphix · Bz2 · CompressMemToFile · method`

```pascal
function CompressMemToFile(inData: OleVariant; toPath: WideString): Integer;
```

Compresses the bytes in `inData` and writes the resulting standard BZip2 stream to the file at `toPath`.

Returns 1 for success, 0 for failure.

Async variant: `CompressMemToFileAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.LoadTaskCaller

`Chilkat 11.7.0 · delphix · Bz2 · LoadTaskCaller · method · since 9.5.0.80`

```pascal
function LoadTaskCaller(task: IChilkatTask): Integer;
```

Loads this `Bz2` object with the caller state associated with the asynchronous operation represented by `task`.

**Advanced async infrastructure:** This method is used to recover the original caller object associated with a completed task. It is not normally needed by application code. Pass a `Task` created by a compatible `Bz2` asynchronous method; an unrelated task cannot be loaded.

Returns 1 for success, 0 for failure.

### Bz2.UncompressBd

`Chilkat 11.7.0 · delphix · Bz2 · UncompressBd · method · since 11.0.0`

```pascal
function UncompressBd(bd: IChilkatBinData): Integer;
```

Decompresses the BZip2 stream currently contained in `bd` in place. On success, the `BinData` is replaced with the original uncompressed bytes.

**Input requirement:** `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 1 for success, 0 for failure.

Async variant: `UncompressBdAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.UncompressFile

`Chilkat 11.7.0 · delphix · Bz2 · UncompressFile · method`

```pascal
function UncompressFile(inFilename: WideString; toPath: WideString): Integer;
```

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.

**Terminology:** This method decompresses BZip2 data; it does not “unzip” a ZIP archive. A `.bz2` file normally contains a single compressed byte stream rather than a collection of named files.

Returns 1 for success, 0 for failure.

Async variant: `UncompressFileAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.UncompressFileToMem

`Chilkat 11.7.0 · delphix · Bz2 · UncompressFileToMem · method`

```pascal
function UncompressFileToMem(inFilename: WideString): OleVariant;
```

Reads and decompresses the BZip2 stream in the file at `inFilename`, returning the original uncompressed bytes in memory.

Returns a zero-length byte array (as an OleVariant) on failure.  
An empty array will have a VarArrayHighBound of -1 meaning 0 elements.

Async variant: `UncompressFileToMemAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.UncompressMemory

`Chilkat 11.7.0 · delphix · Bz2 · UncompressMemory · method`

```pascal
function UncompressMemory(inData: OleVariant): OleVariant;
```

Interprets `inData` as a complete BZip2 stream and returns the decompressed bytes in memory.

Returns a zero-length byte array (as an OleVariant) on failure.  
An empty array will have a VarArrayHighBound of -1 meaning 0 elements.

Async variant: `UncompressMemoryAsync` — same arguments, returns a `Task` (see Async variants below).

### Bz2.UncompressMemToFile

`Chilkat 11.7.0 · delphix · Bz2 · UncompressMemToFile · method`

```pascal
function UncompressMemToFile(inData: OleVariant; toPath: WideString): Integer;
```

Interprets `inData` as a complete BZip2 stream, decompresses it, and writes the original bytes to the file at `toPath`.

Returns 1 for success, 0 for failure.

Async variant: `UncompressMemToFileAsync` — same arguments, returns a `Task` (see Async variants below).

## Events and callbacks

### Bz2.AbortCheck (event)

`Chilkat 11.7.0 · delphix · Bz2 · AbortCheck · event`

```pascal
procedure AbortCheck(ASender: TObject;  out abort: Integer);
```

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.

**Delphi ActiveX event callback implementation:**

To handle this event, implement a procedure with the signature shown below and assign it to the object's AbortCheck event. If you dropped the component onto a form, double-clicking the event in the Object Inspector creates the empty procedure for you.

```pascal
procedure TForm1.bzAbortCheck(ASender: TObject;  out abort: Integer);
begin
    // Application code goes here...
end;


procedure TForm1.Button1Click(Sender: TObject);
var
  bz: TChilkatBz2;

begin
  bz := TChilkatBz2.Create(Self);
  bz.OnAbortCheck := bzAbortCheck;
  // ...
```

### Bz2.PercentDone (event)

`Chilkat 11.7.0 · delphix · Bz2 · PercentDone · event`

```pascal
procedure PercentDone(ASender: TObject;  pctDone: Integer; out abort: Integer);
```

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.

**Delphi ActiveX event callback implementation:**

To handle this event, implement a procedure with the signature shown below and assign it to the object's PercentDone event. If you dropped the component onto a form, double-clicking the event in the Object Inspector creates the empty procedure for you.

```pascal
procedure TForm1.bzPercentDone(ASender: TObject;  pctDone: Integer; out abort: Integer);
begin
    // Application code goes here...
end;


procedure TForm1.Button1Click(Sender: TObject);
var
  bz: TChilkatBz2;

begin
  bz := TChilkatBz2.Create(Self);
  bz.OnPercentDone := bzPercentDone;
  // ...
```

### Bz2.ProgressInfo (event)

`Chilkat 11.7.0 · delphix · Bz2 · ProgressInfo · event`

```pascal
procedure ProgressInfo(ASender: TObject;  const name: WideString; const value: WideString);
```

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.

**Delphi ActiveX event callback implementation:**

To handle this event, implement a procedure with the signature shown below and assign it to the object's ProgressInfo event. If you dropped the component onto a form, double-clicking the event in the Object Inspector creates the empty procedure for you.

```pascal
procedure TForm1.bzProgressInfo(ASender: TObject;  const name: WideString; const value: WideString);
begin
    // Application code goes here...
end;


procedure TForm1.Button1Click(Sender: TObject);
var
  bz: TChilkatBz2;

begin
  bz := TChilkatBz2.Create(Self);
  bz.OnProgressInfo := bzProgressInfo;
  // ...
```

### Bz2.TaskCompleted (event)

`Chilkat 11.7.0 · delphix · Bz2 · TaskCompleted · event`

```pascal
procedure TaskCompleted(ASender: TObject;  const task: IChilkatTask);
```

Called from the background thread when an asynchronous task completes.

**Delphi ActiveX event callback implementation:**

To handle this event, implement a procedure with the signature shown below and assign it to the object's TaskCompleted event. If you dropped the component onto a form, double-clicking the event in the Object Inspector creates the empty procedure for you.

```pascal
procedure TForm1.bzTaskCompleted(ASender: TObject;  const task: IChilkatTask);
begin
    // Application code goes here...
end;


procedure TForm1.Button1Click(Sender: TObject);
var
  bz: TChilkatBz2;

begin
  bz := TChilkatBz2.Create(Self);
  bz.OnTaskCompleted := bzTaskCompleted;
  // ...
```

## Async variants

Each returns a `Task` instead of the result and takes the same arguments as the synchronous method; run the task, wait for `Finished`, then read the result from the task. No new Async methods are added from 11.7.0 on.

```pascal
function CompressBdAsync(bd: IChilkatBinData): IChilkatTask;
function CompressFileAsync(inFilename: WideString; toPath: WideString): IChilkatTask;
function CompressFileToMemAsync(inFilename: WideString): IChilkatTask;
function CompressMemoryAsync(inData: OleVariant): IChilkatTask;
function CompressMemToFileAsync(inData: OleVariant; toPath: WideString): IChilkatTask;
function UncompressBdAsync(bd: IChilkatBinData): IChilkatTask;
function UncompressFileAsync(inFilename: WideString; toPath: WideString): IChilkatTask;
function UncompressFileToMemAsync(inFilename: WideString): IChilkatTask;
function UncompressMemoryAsync(inData: OleVariant): IChilkatTask;
function UncompressMemToFileAsync(inData: OleVariant; toPath: WideString): IChilkatTask;
```

## Related classes

[`BinData`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/delphix/classes/BinData.md), [`Task`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/delphix/classes/Task.md)