Class CFaxT4

CFaxT4

Support

Supported from 5.0

Description

Fax line coding/decoding

Provides utility functions for encoding and decoding fax scan lines. The lines can be encoded/decoded as 1 dimensional modified Huffman or 2 dimensional modified Read.

Users must first create a CFaxT4 object using NewL() or NewLC(). Specific functions are provided to encode/decode scan lines using the two coding schemes. In addition, general functions are provided which determine the coding type from the values specified when the object is initialised — using PageInitialise().

In pre-v5.1 releases of Symbian OS, this class was defined in faxstore.h and its import library was faxst2.lib.

Derivation

Defined in CFaxT4:
DecodeScanLine(), DecodeScanLine1D(), DecodeScanLine2D(), EncodeScanLine(), EncodeScanLine1D(), EncodeScanLine2D(), NewL(), NewLC(), PageInitialize()

Inherited from CBase:
operator new()

static CFaxT4* NewL();

Description

Constructs a CFaxT4 object, which provides utility functions to encode and decode fax scan lines.

The function is exactly the same as NewLC() except that the new object is popped from the cleanup stack.

The new object is constructed with the default compression and resolution: EModifiedHuffman and EFaxNormal respectively.

Return value

Leave codes

static CFaxT4* NewLC();

Description

Constructs a CFaxT4 object, which provides utility functions to encode and decode fax scan lines.

As is usual in Symbian OS, the only difference between this function and NewL() is that this variant pushes the object to the cleanup stack.

The new object is constructed with the default compression and resolution: EModifiedHuffman and EFaxNormal respectively.

Return value

Leave codes

void PageInitialize(TFaxResolution aResolution, TFaxCompression aCompression, TInt aFlag2 = 0);

Description

Initialises the CFaxT4 object with a specific resolution and compression.

Parameters

void EncodeScanLine(const TDesC8& aScanLine,TDes8& anEncodedScanLine);

Description

Encodes a scan line using either one dimensional Modified Huffman (MH) or two dimensional Modified Read (MR) encoding.

The type of encoding used depends on the compression type specified when the object was initialised — using PageInitialize(). If the object was not initialised, then the default compression is MH.

Parameters

TInt DecodeScanLine(TDes8& aScanLine,const TDesC8& anEncodedScanLine);

Description

Decodes a scan line.

The decoding method depends on the compression type specified when the object was initialised — using PageInitialize(). If the object was not initialised, then the scan line is decoded as Modified Huffman.

Parameters

Return value

Notes:

• The fax client can determine the type of compression used in a fax from its header, and can hence use PageInitialize() to set the correct decoding method. KErrUnderflow is returned if the wrong type of compression is specified.

void EncodeScanLine1D(const TDesC8& aScanLine,TDes8& anEncodedScanLine);

Description

Encodes a scan line using Modified Huffman compression.

Parameters

TInt DecodeScanLine1D(TDes8& aScanLine,const TDesC8& anEncodedScanLine);

Description

Decodes a Modified Huffman encoded scan line.

Parameters

Return value

void EncodeScanLine2D(const TDesC8& aScanLine,TDes8& anEncodedScanLine);

Description

Encodes a scan line using Modified Read compression.

Parameters

TInt DecodeScanLine2D(TDes8& aScanLine,const TDesC8& anEncodedScanLine);

Description

Decodes a Modified Read encoded scan line.

Parameters

Return value