---
product: Chilkat
product_version: 11.7.0
language: pascal
language_label: Lazarus Pascal
class: Stream
license: free
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/pascal_StreamRef.html
---
# Chilkat Stream — Lazarus Pascal — v11.7.0

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

## Purpose

**Read, write, pipe, monitor, and control byte or text streams.**

`Chilkat.Stream` is a general-purpose streaming object for moving data between sources and sinks without requiring the entire payload to be handled at once. A stream can read from files, byte arrays, strings, or other sources; write to files, memory, `BinData`, `StringBuilder`, or other sinks; handle binary and text data; apply character-set rules for strings; process file parts; track bytes sent and received; and support timeouts, polling, aborts, async task integration, and end-of-stream handling.

**File and memory sources**

Stream from a source file, byte array, string, or selected file part without manually loading or copying all data first.

**File and object sinks**

Write streamed data to a sink file, append to an existing file, or output to `BinData`, `StringBuilder`, bytes, or strings.

**Binary reads and writes**

Read or write raw bytes, fixed byte counts, encoded byte strings, individual bytes, or `BinData` content.

**Text streaming**

Read and write strings using `StringCharset`, optionally use a BOM, and read text until CRLF or a matching delimiter.

**Timeouts and polling**

Control read and write wait behavior, poll for immediately available data, and inspect read or write failure reasons.

**Progress and lifecycle**

Track bytes sent and received, detect end-of-stream or write-closed state, reset streams, close writing, and abort long-running operations.

**Common pattern:** Configure the stream's source and sink, set the character set or chunk size if needed, then read or write using the method that matches the data type: bytes, encoded bytes, strings, `BinData`, or `StringBuilder`. Check `EndOfStream`, `ReadFailReason`, `WriteFailReason`, `NumReceived`, `NumSent`, and `LastErrorText` to understand stream progress and failures.

**Timeout note:** For `ReadTimeoutMs`, a value of `0` means a polling read, not an infinite timeout. For `WriteTimeoutMs`, `0` means return immediately if the stream cannot be written to right away.

## Object creation, unlocking and error handling

**Create / Free**

```pascal
uses
  Chilkat.Stream;

var
  obj: TStream;
begin
  obj := TStream.Create;
  try
    if not obj.IsValid then
      raise Exception.Create('Failed to create a TStream instance.');

    // ... use obj ...

  finally
    obj.Free;
  end;
end;
```

`constructor Create;`

Allocates the underlying CkStream object and returns a new TStream instance. Simply adding **Chilkat.Stream** 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).

`destructor Destroy; override;`

Every TStream created by calling `Create` should eventually be released by calling `.Free` (inherited from `TObject`). The destructor automatically disposes the underlying CkStream handle. A native (unmanaged) memory leak occurs if the object is never freed.

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 Lazarus Pascal.

## 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: string read GetDebugLogFilePath write SetDebugLogFilePath;` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. |
| `LastErrorHtml` | `property LastErrorHtml: string read GetLastErrorHtml;` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `property LastErrorText: string read GetLastErrorText;` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `property LastErrorXml: string read GetLastErrorXml;` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `property LastMethodSuccess: Boolean read GetLastMethodSuccess write SetLastMethodSuccess;` | read/write | Indicates the success or failure of the most recent method call: `True` means success, `False` means failure. |
| `VerboseLogging` | `property VerboseLogging: Boolean read GetVerboseLogging write SetVerboseLogging;` | read/write | If set to `True`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `property Version: string read GetVersion;` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `AbortCurrent` | property, read/write | `property AbortCurrent: Boolean read GetAbortCurrent write SetAbortCurrent;` |
| `CanRead` | property, read-only | `property CanRead: Boolean read GetCanRead;` |
| `CanWrite` | property, read-only | `property CanWrite: Boolean read GetCanWrite;` |
| `DataAvailable` | property, read-only | `property DataAvailable: Boolean read GetDataAvailable;` |
| `DefaultChunkSize` | property, read/write | `property DefaultChunkSize: Integer read GetDefaultChunkSize write SetDefaultChunkSize;` |
| `EndOfStream` | property, read-only | `property EndOfStream: Boolean read GetEndOfStream;` |
| `HeartbeatMs` | property, read/write | `property HeartbeatMs: Integer read GetHeartbeatMs write SetHeartbeatMs;` |
| `IsWriteClosed` | property, read-only | `property IsWriteClosed: Boolean read GetIsWriteClosed;` |
| `Length` | property, read/write | `property Length: Int64 read GetLength write SetLength;` |
| `Length32` | property, read/write | `property Length32: Integer read GetLength32 write SetLength32;` |
| `NumReceived` | property, read-only | `property NumReceived: Int64 read GetNumReceived;` |
| `NumSent` | property, read-only | `property NumSent: Int64 read GetNumSent;` |
| `ReadFailReason` | property, read-only | `property ReadFailReason: Integer read GetReadFailReason;` |
| `ReadTimeoutMs` | property, read/write | `property ReadTimeoutMs: Integer read GetReadTimeoutMs write SetReadTimeoutMs;` |
| `SinkFile` | property, read/write | `property SinkFile: string read GetSinkFile write SetSinkFile;` |
| `SinkFileAppend` | property, read/write | `property SinkFileAppend: Boolean read GetSinkFileAppend write SetSinkFileAppend;` |
| `SourceFile` | property, read/write | `property SourceFile: string read GetSourceFile write SetSourceFile;` |
| `SourceFilePart` | property, read/write | `property SourceFilePart: Integer read GetSourceFilePart write SetSourceFilePart;` |
| `SourceFilePartSize` | property, read/write | `property SourceFilePartSize: Integer read GetSourceFilePartSize write SetSourceFilePartSize;` |
| `StringBom` | property, read/write | `property StringBom: Boolean read GetStringBom write SetStringBom;` |
| `StringCharset` | property, read/write | `property StringCharset: string read GetStringCharset write SetStringCharset;` |
| `WriteFailReason` | property, read-only | `property WriteFailReason: Integer read GetWriteFailReason;` |
| `WriteTimeoutMs` | property, read/write | `property WriteTimeoutMs: Integer read GetWriteTimeoutMs write SetWriteTimeoutMs;` |
| `LoadTaskCaller` | method | `// task is a TTask object. function LoadTaskCaller(task: TChilkatBase): Boolean;` |
| `ReadBd` | method | `// binData is a TBinData object. function ReadBd(binData: TChilkatBase): Boolean;` |
| `ReadBytesENC` | method | `function ReadBytesENC(const encoding: string): string;` |
| `ReadNBytesENC` | method | `function ReadNBytesENC(numBytes: Integer;     const encoding: string): string;` |
| `ReadSb` | method | `// sb is a TStringBuilder object. function ReadSb(sb: TChilkatBase): Boolean;` |
| `ReadString` | method | `function ReadString: string;` |
| `ReadToCRLF` | method | `function ReadToCRLF: string;` |
| `ReadUntilMatch` | method | `function ReadUntilMatch(const matchStr: string): string;` |
| `Reset` | method | `procedure Reset;` |
| `SetSourceString` | method | `function SetSourceString(const srcStr: string;     const charset: string): Boolean;` |
| `WriteBd` | method | `// binData is a TBinData object. function WriteBd(binData: TChilkatBase): Boolean;` |
| `WriteByte` | method | `function WriteByte(byteVal: Integer): Boolean;` |
| `WriteBytesENC` | method | `function WriteBytesENC(const byteData: string;     const encoding: string): Boolean;` |
| `WriteClose` | method | `function WriteClose: Boolean;` |
| `WriteSb` | method | `// sb is a TStringBuilder object. function WriteSb(sb: TChilkatBase): Boolean;` |
| `WriteString` | method | `function WriteString(const str: string): Boolean;` |

## Properties

### Stream.AbortCurrent

`Chilkat 11.7.0 · pascal · Stream · AbortCurrent · property · read/write · since 9.5.0.58`

```pascal
property AbortCurrent: Boolean read GetAbortCurrent write SetAbortCurrent;
```

When set to `True`, causes the currently running method to abort. Methods that always finish quickly (i.e.have no length file operations or network communications) are not affected. If no method is running, then this property is automatically reset to `False` when the next method is called. When the abort occurs, this property is reset to `False`. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)

### Stream.CanRead

`Chilkat 11.7.0 · pascal · Stream · CanRead · property · read-only · since 9.5.0.56`

```pascal
property CanRead: Boolean read GetCanRead;
```

`True` if the stream supports reading. Otherwise `False`.

**Note:** A stream that supports reading, which has already reached the end-of-stream, will still have a CanRead value of `True`. This property indicates the stream's inherent ability, and not whether or not the stream can be read at a particular moment in time.

### Stream.CanWrite

`Chilkat 11.7.0 · pascal · Stream · CanWrite · property · read-only · since 9.5.0.56`

```pascal
property CanWrite: Boolean read GetCanWrite;
```

`True` if the stream supports writing. Otherwise `False`.

**Note:** A stream that supports writing, which has already been closed for write, will still have a CanWrite value of `True`. This property indicates the stream's inherent ability, and not whether or not the stream can be written at a particular moment in time.

### Stream.DataAvailable

`Chilkat 11.7.0 · pascal · Stream · DataAvailable · property · read-only · since 9.5.0.56`

```pascal
property DataAvailable: Boolean read GetDataAvailable;
```

`True` if it is known for sure that data is ready and waiting to be read. `False` if it is not known for sure (it may be that data is immediately available, but reading the stream with a ReadTimeoutMs of 0, which is to poll the stream, is the way to find out).

### Stream.DefaultChunkSize

`Chilkat 11.7.0 · pascal · Stream · DefaultChunkSize · property · read/write · since 9.5.0.56`

```pascal
property DefaultChunkSize: Integer read GetDefaultChunkSize write SetDefaultChunkSize;
```

The default internal chunk size for reading or writing. The default value is 65536. If this property is set to 0, it will cause the default chunk size (65536) to be used. Note: The chunk size can have significant performance impact. If performance is an issue, be sure to experiment with different chunk sizes.

### Stream.EndOfStream

`Chilkat 11.7.0 · pascal · Stream · EndOfStream · property · read-only · since 9.5.0.56`

```pascal
property EndOfStream: Boolean read GetEndOfStream;
```

`True` if the end-of-stream has already been reached. When the stream has already ended, all calls to Read\* methods will return `False` with the ReadFailReason set to 3 (already at end-of-stream).

### Stream.HeartbeatMs

`Chilkat 11.7.0 · pascal · Stream · HeartbeatMs · property · read/write · since 9.5.0.97`

```pascal
property HeartbeatMs: Integer read GetHeartbeatMs write SetHeartbeatMs;
```

**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)

The interval in milliseconds between each `AbortCheck` event callback, which enables an application to abort certain method calls before they complete. **By default, HeartbeatMs is set to** `0`**, meaning no AbortCheck event callbacks will trigger.**

### Stream.IsWriteClosed

`Chilkat 11.7.0 · pascal · Stream · IsWriteClosed · property · read-only · since 9.5.0.56`

```pascal
property IsWriteClosed: Boolean read GetIsWriteClosed;
```

`True` if the stream is closed for writing. Once closed, no more data may be written to the stream.

### Stream.Length

`Chilkat 11.7.0 · pascal · Stream · Length · property · read/write · since 9.5.0.56`

```pascal
property Length: Int64 read GetLength write SetLength;
```

The length (in bytes) of the stream's source. If unknown, then this property will have a value of -1. This property may be set by the application if it knows in advance the length of the stream.

### Stream.Length32

`Chilkat 11.7.0 · pascal · Stream · Length32 · property · read/write · since 9.5.0.58`

```pascal
property Length32: Integer read GetLength32 write SetLength32;
```

The length (in bytes) of the stream's source. If unknown, then this property will have a value of -1. This property may be set by the application if it knows in advance the length of the stream.

Setting this property also sets the Length property (which is a 64-bit integer).

### Stream.NumReceived

`Chilkat 11.7.0 · pascal · Stream · NumReceived · property · read-only · since 9.5.0.56`

```pascal
property NumReceived: Int64 read GetNumReceived;
```

The number of bytes received by the stream.

### Stream.NumSent

`Chilkat 11.7.0 · pascal · Stream · NumSent · property · read-only · since 9.5.0.56`

```pascal
property NumSent: Int64 read GetNumSent;
```

The number of bytes sent by the stream.

### Stream.ReadFailReason

`Chilkat 11.7.0 · pascal · Stream · ReadFailReason · property · read-only · since 9.5.0.56`

```pascal
property ReadFailReason: Integer read GetReadFailReason;
```

This property is automatically set when a Read\* method is called. It indicates the reason for failure. Possible values are:

0>
0. No failure (success)
1. Timeout, or no data is immediately available for a polling read.
2. Aborted by an application callback.
3. Already at end-of-stream.
4. Fatal stream error.
5. Out-of-memory error (this is very unlikely).

### Stream.ReadTimeoutMs

`Chilkat 11.7.0 · pascal · Stream · ReadTimeoutMs · property · read/write · since 9.5.0.56`

```pascal
property ReadTimeoutMs: Integer read GetReadTimeoutMs write SetReadTimeoutMs;
```

The maximum number of seconds to wait while reading. The default value is 30 seconds (i.e. 30000ms). A value of 0 indicates a poll. (A polling read is to return with a timeout if no data is immediately available.)

**Important:** For most Chilkat timeout related properties, a value of 0 indicates an infinite timeout. For this property, a value of 0 indicates a poll. If setting a timeout related property (or method argument) to zero, be sure to understand if 0 means `wait forever` or `poll`.

The timeout value is not a total timeout. It is the maximum time to wait while no additional data is forthcoming.

### Stream.SinkFile

`Chilkat 11.7.0 · pascal · Stream · SinkFile · property · read/write · since 9.5.0.56`

```pascal
property SinkFile: string read GetSinkFile write SetSinkFile;
```

Sets the sink to the path of a file. The file does not need to exist at the time of setting this property. The sink file will be automatically opened on demand, when the stream is first written.

**Note:** This property takes priority over other potential sinks. Make sure this property is set to an empty string if the stream's sink is to be something else.

### Stream.SinkFileAppend

`Chilkat 11.7.0 · pascal · Stream · SinkFileAppend · property · read/write · since 9.5.0.83`

```pascal
property SinkFileAppend: Boolean read GetSinkFileAppend write SetSinkFileAppend;
```

If `True`, the stream appends to the SinkFile rather than truncating and re-writing the sink file. The default value is `False`.

### Stream.SourceFile

`Chilkat 11.7.0 · pascal · Stream · SourceFile · property · read/write · since 9.5.0.56`

```pascal
property SourceFile: string read GetSourceFile write SetSourceFile;
```

Sets the source to the path of a file. The file does not need to exist at the time of setting this property. The source file will be automatically opened on demand, when the stream is first read.

**Note:** This property takes priority over other potential sources. Make sure this property is set to an empty string if the stream's source is to be something else.

### Stream.SourceFilePart

`Chilkat 11.7.0 · pascal · Stream · SourceFilePart · property · read/write · since 9.5.0.59`

```pascal
property SourceFilePart: Integer read GetSourceFilePart write SetSourceFilePart;
```

If the source is a file, then this property can be used to stream one part of the file. The SourceFilePartSize property defines the size (in bytes) of each part. The SourceFilePart and SourceFilePartSize have default values of 0, which means the entire SourceFile is streamed.

This property is a 0-based index. For example, if the SourceFilePartSize is 1000, then part 0 is for bytes 0 to 999, part 1 is for bytes 1000 to 1999, etc.

### Stream.SourceFilePartSize

`Chilkat 11.7.0 · pascal · Stream · SourceFilePartSize · property · read/write · since 9.5.0.59`

```pascal
property SourceFilePartSize: Integer read GetSourceFilePartSize write SetSourceFilePartSize;
```

If the source is a file, then this property, in conjunction with the SourceFilePart property, can be used to stream a single part of the file. This property defines the size (in bytes) of each part. The SourceFilePart and SourceFilePartSize have default values of 0, which means that by default, the entire SourceFile is streamed.

### Stream.StringBom

`Chilkat 11.7.0 · pascal · Stream · StringBom · property · read/write · since 9.5.0.56`

```pascal
property StringBom: Boolean read GetStringBom write SetStringBom;
```

If `True`, then include the BOM when creating a string source via SetSourceString where the charset is utf-8, utf-16, etc. (The term `BOM` stands for Byte Order Mark, also known as the preamble.) Also, if `True`, then include the BOM when writing a string via the WriteString method. The default value of this property is `False`.

### Stream.StringCharset

`Chilkat 11.7.0 · pascal · Stream · StringCharset · property · read/write · since 9.5.0.56`

```pascal
property StringCharset: string read GetStringCharset write SetStringCharset;
```

Indicates the expected character encoding, such as utf-8, windows-1256, utf-16, etc. for methods that read text such as: ReadString, ReadToCRLF, ReadUntilMatch. Also controls the character encoding when writing strings with the WriteString method. The supported charsets are indicated at the link below.

The default value is `utf-8`.

See also:

- [Charsets Supported by Chilkat](http://www.cknotes.com/chilkat-charsets-character-encodings-supported/)

### Stream.WriteFailReason

`Chilkat 11.7.0 · pascal · Stream · WriteFailReason · property · read-only · since 9.5.0.56`

```pascal
property WriteFailReason: Integer read GetWriteFailReason;
```

This property is automatically set when a Write\* method is called. It indicates the reason for failure. Possible values are:

0>
0. No failure (success)
1. Timeout, or unable to immediately write when the WriteTimeoutMs is 0.
2. Aborted by an application callback.
3. The stream has already ended.
4. Fatal stream error.
5. Out-of-memory error (this is very unlikely).

### Stream.WriteTimeoutMs

`Chilkat 11.7.0 · pascal · Stream · WriteTimeoutMs · property · read/write · since 9.5.0.56`

```pascal
property WriteTimeoutMs: Integer read GetWriteTimeoutMs write SetWriteTimeoutMs;
```

The maximum number of seconds to wait while writing. The default value is 30 seconds (i.e. 30000ms). A value of 0 indicates to return immediately if it is not possible to write to the sink immediately.

## Methods

### Stream.LoadTaskCaller

`Chilkat 11.7.0 · pascal · Stream · LoadTaskCaller · method · since 9.5.0.80`

```pascal
// task is a TTask object.

function  LoadTaskCaller(task: TChilkatBase): Boolean;
```

Loads the caller of the task's async method.

Returns True for success, False for failure.

### Stream.ReadBd

`Chilkat 11.7.0 · pascal · Stream · ReadBd · method · since 9.5.0.67`

```pascal
// binData is a TBinData object.

function  ReadBd(binData: TChilkatBase): Boolean;
```

Read as much data as is immediately available on the stream. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The incoming data is appended to `binData`.

Returns True for success, False for failure.

### Stream.ReadBytesENC

`Chilkat 11.7.0 · pascal · Stream · ReadBytesENC · method · since 9.5.0.56`

```pascal
function  ReadBytesENC(const encoding: string): string;
```

**Full documentation for this method (same in every language):** [Binary Encodings Supported by Chilkat](https://www.chilkatsoft.com/ai-docs/v/11.7.0/articles/binary_encodings.md)

The same as ReadBytes, except returns the received bytes in encoded string form. The `encoding` argument indicates the encoding, which can be `base64`, `hex`, or any of the multitude of encodings indicated in the link below.

Returns True for success, False for failure.

### Stream.ReadNBytesENC

`Chilkat 11.7.0 · pascal · Stream · ReadNBytesENC · method · since 9.5.0.56`

```pascal
function  ReadNBytesENC(numBytes: Integer;
    const encoding: string): string;
```

**Full documentation for this method (same in every language):** [Binary Encodings Supported by Chilkat](https://www.chilkatsoft.com/ai-docs/v/11.7.0/articles/binary_encodings.md)

The same as ReadNBytes, except returns the received bytes in encoded string form. The `encoding` argument indicates the encoding, which can be `base64`, `hex`, or any of the multitude of encodings indicated in the link below.

Returns True for success, False for failure.

### Stream.ReadSb

`Chilkat 11.7.0 · pascal · Stream · ReadSb · method · since 9.5.0.67`

```pascal
// sb is a TStringBuilder object.

function  ReadSb(sb: TChilkatBase): Boolean;
```

Read as much data as is immediately available on the stream. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The data is appended to `sb`. The incoming bytes are interpreted according to the StringCharset property. For example, if utf-8 bytes are expected, then StringCharset should be set to `utf-8` prior to calling ReadSb.

Returns True for success, False for failure.

### Stream.ReadString

`Chilkat 11.7.0 · pascal · Stream · ReadString · method · since 9.5.0.56`

```pascal
function  ReadString: string;
```

Read as much data as is immediately available on the stream. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The data is returned as a string. The incoming bytes are interpreted according to the StringCharset property. For example, if utf-8 bytes are expected, then StringCharset should be set to `utf-8` prior to calling ReadString.

Returns True for success, False for failure.

### Stream.ReadToCRLF

`Chilkat 11.7.0 · pascal · Stream · ReadToCRLF · method · since 9.5.0.56`

```pascal
function  ReadToCRLF: string;
```

Reads the stream until a CRLF is received. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The data is returned as a string. The incoming bytes are interpreted according to the StringCharset property. For example, if utf-8 bytes are expected, then StringCharset should be set to `utf-8` prior to calling ReadString.

Note: If the end-of-stream is reached prior to receiving the CRLF, then the remaining data is returned, and the ReadFailReason property will be set to 3 (to indicate end-of-file). This is the only case where as string would be returned that does not end with CRLF.

Returns True for success, False for failure.

### Stream.ReadUntilMatch

`Chilkat 11.7.0 · pascal · Stream · ReadUntilMatch · method · since 9.5.0.56`

```pascal
function  ReadUntilMatch(const matchStr: string): string;
```

Reads the stream until the string indicated by `matchStr` is received. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The data is returned as a string. The incoming bytes are interpreted according to the StringCharset property. For example, if utf-8 bytes are expected, then StringCharset should be set to `utf-8` prior to calling ReadString.

Note: If the end-of-stream is reached prior to receiving the match string, then the remaining data is returned, and the ReadFailReason property will be set to 3 (to indicate end-of-file). This is the only case where as string would be returned that does not end with the desired match string.

Returns True for success, False for failure.

### Stream.Reset

`Chilkat 11.7.0 · pascal · Stream · Reset · method · since 9.5.0.56`

```pascal
procedure Reset;
```

Resets the stream. If a source or sink is open, then it is closed. Properties such as EndOfStream and IsWriteClose are reset to default values.

### Stream.SetSourceString

`Chilkat 11.7.0 · pascal · Stream · SetSourceString · method · since 9.5.0.56`

```pascal
function  SetSourceString(const srcStr: string;
    const charset: string): Boolean;
```

Sets the stream's source to the contents of `srcStr`. The `charset` indicates the character encoding to be used for the byte representation of the `srcStr`.

Returns True for success, False for failure.

### Stream.WriteBd

`Chilkat 11.7.0 · pascal · Stream · WriteBd · method · since 9.5.0.67`

```pascal
// binData is a TBinData object.

function  WriteBd(binData: TChilkatBase): Boolean;
```

Writes the contents of `binData` to the stream.

Returns True for success, False for failure.

### Stream.WriteByte

`Chilkat 11.7.0 · pascal · Stream · WriteByte · method · since 9.5.0.56`

```pascal
function  WriteByte(byteVal: Integer): Boolean;
```

Writes a single byte to the stream. The `byteVal` must have a value from 0 to 255.

Returns True for success, False for failure.

### Stream.WriteBytesENC

`Chilkat 11.7.0 · pascal · Stream · WriteBytesENC · method · since 9.5.0.56`

```pascal
function  WriteBytesENC(const byteData: string;
    const encoding: string): Boolean;
```

**Full documentation for this method (same in every language):** [Binary Encodings Supported by Chilkat](https://www.chilkatsoft.com/ai-docs/v/11.7.0/articles/binary_encodings.md)

Writes binary bytes to a stream. The byte data is passed in encoded string form, where the `encoding` can be `base64`, `hex`, or any of the supported binary encodings listed at the link below.

Returns True for success, False for failure.

### Stream.WriteClose

`Chilkat 11.7.0 · pascal · Stream · WriteClose · method · since 9.5.0.56`

```pascal
function  WriteClose: Boolean;
```

Indicates that no more data will be written to the stream.

Returns True for success, False for failure.

### Stream.WriteSb

`Chilkat 11.7.0 · pascal · Stream · WriteSb · method · since 9.5.0.67`

```pascal
// sb is a TStringBuilder object.

function  WriteSb(sb: TChilkatBase): Boolean;
```

Writes the contents of `sb` to the stream. The actual bytes written are the byte representation of the string as indicated by the StringCharset property. For example, to write utf-8 bytes, first set StringCharset equal to `utf-8` and then call WriteSb.

Returns True for success, False for failure.

### Stream.WriteString

`Chilkat 11.7.0 · pascal · Stream · WriteString · method · since 9.5.0.56`

```pascal
function  WriteString(const str: string): Boolean;
```

Writes a string to a stream. The actual bytes written are the byte representation of the string as indicated by the StringCharset property. For example, to write utf-8 bytes, first set StringCharset equal to `utf-8` and then call WriteString.

Returns True for success, False for failure.

## Events and callbacks

Chilkat for Pascal supports three synchronous event callbacks: `OnAbortCheck`, `OnPercentDone`, and `OnProgressInfo`. Each is a property of the class; assign a method of one of your own objects (an *of object* handler) to receive the callbacks, or assign `nil` to unhook. The handler types are declared in the `Chilkat.Base` unit:

```pascal
TChilkatAbortCheckEvent   = function(Sender: TChilkatBase): Boolean of object;
TChilkatPercentDoneEvent  = function(Sender: TChilkatBase; PctDone: Integer): Boolean of object;
TChilkatProgressInfoEvent = procedure(Sender: TChilkatBase; const Name, Value: string) of object;
```

All Chilkat methods are synchronous, so callbacks are invoked on the thread that called the method -- if the method was called from the main thread, it is safe to access UI elements from the handler. The `HeartbeatMs` property controls the frequency of `OnAbortCheck` callbacks (the default of 0 means no AbortCheck events fire). Returning `True` from an `OnAbortCheck` or `OnPercentDone` handler aborts the running method.

### Stream.AbortCheck (event)

`Chilkat 11.7.0 · pascal · Stream · AbortCheck · event`

```pascal
// TChilkatAbortCheckEvent = function(Sender: TChilkatBase): Boolean of object;

property OnAbortCheck: TChilkatAbortCheckEvent;
```

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.

**Event callback implementation:**

```pascal
// A handler is a method of one of your own classes, e.g. a form:
function TMyObject.StreamAbortCheck(Sender: TChilkatBase): Boolean;
begin
  // Called every HeartbeatMs milliseconds while a method is running.
  // Return True to abort the method; return False to continue.
  Result := False;
end;
```

**To add an event handler:**

```pascal
stream := TStream.Create;
stream.HeartbeatMs := 250;   // fire OnAbortCheck 4 times per second
stream.OnAbortCheck := MyObject.StreamAbortCheck;
```

### Stream.PercentDone (event)

`Chilkat 11.7.0 · pascal · Stream · PercentDone · event`

```pascal
// TChilkatPercentDoneEvent = function(Sender: TChilkatBase; PctDone: Integer): Boolean of object;

property OnPercentDone: TChilkatPercentDoneEvent;
```

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 `True`. This will cause the method to terminate and return a failure status or corresponding failure value.

**Event callback implementation:**

```pascal
// A handler is a method of one of your own classes, e.g. a form:
function TMyObject.StreamPercentDone(Sender: TChilkatBase; PctDone: Integer): Boolean;
begin
  // PctDone ranges from 1 to 100.
  WriteLn('Percent done: ', PctDone);
  // Return True to abort the method; return False to continue.
  Result := False;
end;
```

**To add an event handler:**

```pascal
stream := TStream.Create;
stream.OnPercentDone := MyObject.StreamPercentDone;
```

### Stream.ProgressInfo (event)

`Chilkat 11.7.0 · pascal · Stream · ProgressInfo · event`

```pascal
// TChilkatProgressInfoEvent = procedure(Sender: TChilkatBase; const Name, Value: string) of object;

property OnProgressInfo: TChilkatProgressInfoEvent;
```

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.

**Event callback implementation:**

```pascal
// A handler is a method of one of your own classes, e.g. a form:
procedure TMyObject.StreamProgressInfo(Sender: TChilkatBase; const Name, Value: string);
begin
  WriteLn(Name, ': ', Value);
end;
```

**To add an event handler:**

```pascal
stream := TStream.Create;
stream.OnProgressInfo := MyObject.StreamProgressInfo;
```

## Related classes

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