CFormatLayer Class Reference

#include <txtfmlyr.h>

class CFormatLayer : public CBase

Inherits from

CFormatLayer

Protected Attributes
	__DECLARE_TEST
const CFormatLayer *	iBasedOn
RFormatStream	iStore

Public Member Functions
IMPORT_C TInt	ChainCount()
IMPORT_C void	ExternalizeChainL(RWriteStream &, TInt)
pure virtual void	ExternalizeL(RWriteStream &)
IMPORT_C void	InternalizeChainL(RReadStream &, const CFormatLayer *)
pure virtual void	InternalizeL(RReadStream &, const CFormatLayer *)
IMPORT_C TBool	IsEmpty()
pure virtual TBool	IsIdentical(CFormatLayer *, TBool)
IMPORT_C void	Reset()
IMPORT_C const CFormatLayer *	SenseBase()
IMPORT_C void	SetBase(const CFormatLayer *)
void	Swap(CFormatLayer &)

Protected Member Functions
	CFormatLayer()
	~CFormatLayer()
void	CloneLayerL(CFormatLayer *)
void	ExternalizeLayersRecurseL(RWriteStream &, TInt)
TBool	IsIdentical(const TUint8 *, TInt)
const TUint8 *	Ptr(TInt &)
pure virtual CFormatLayer *	RestoreNewL(RReadStream &)

Inherited Functions
	CBase::CBase()
	CBase::Delete(CBase *)
	CBase::Extension_(TUint,TAny &,TAny )
	CBase::operator new(TUint)
	CBase::operator new(TUint,TAny *)
	CBase::operator new(TUint,TLeave)
	CBase::operator new(TUint,TLeave,TUint)
	CBase::operator new(TUint,TUint)
	CBase::~CBase()

Detailed Description

Abstract base class for the paragraph and character format layers.

A format layer is a set of character or paragraph format attributes which may own a pointer to another format layer. This pointer is called a based-on link. The effective formatting of a text object may be built up from a chain of format layers - the final layer in the chain has a NULL based-on link. In case of conflict, attribute values set in upper layers (layers furthest from the layer with the NULL based-on link) override those set in lower layers. In rich text, additional formatting may be applied on top of these format layers.

The system of based-on links is implemented by the CFormatLayer class. It also implements persistence for chains of format layers.

When setting or sensing the attributes of a CParaFormatLayer or CCharFormatLayer, a format mask and container are specified as parameters. The container has data members for every format attribute, which may be set independently. When setting the layer, the mask indicates the attributes which will be taken from the container. Any attributes not specified in the mask will be taken from the system-provided default values.

When sensing a layer, on return, the mask indicates which attributes have been explicitly set in the layer, (i.e. not taken from the default values). In addition, a layer's effective format may be sensed. In this case, no mask is used because the format container will, on return, contain a value for every attribute.

Member Attribute Documentation

__DECLARE_TEST

[protected]

iBasedOn

const CFormatLayer *

iBasedOn

[protected]

iStore

RFormatStream

iStore

[protected]

Constructor & Destructor Documentation

CFormatLayer ( )

CFormatLayer

(

)

[protected]

~CFormatLayer ( )

~CFormatLayer

(

)

[protected]

Member Function Documentation

ChainCount ( )

IMPORT_C TInt

ChainCount

(

)

const

Gets the number of format layers in the chain, inclusive of itself. Assumes that the format layer chain has been correctly set up to terminate with a NULL based-on link.

Returns: The number of format layers in the chain, counting from the current layer.

CloneLayerL ( CFormatLayer * )

void

CloneLayerL

(

CFormatLayer *

aClone

)

const [protected]

ExternalizeChainL ( RWriteStream &, TInt )

IMPORT_C void	ExternalizeChainL	(	RWriteStream &	aStream,
			TInt	aExcludeCount = 0
		)	const

Stores a chain of format layers. By default an entire chain is stored unless an exclude count is provided. In this case, the length of the chain stored is the ChainCount() minus the exclude count. The excluded layers are the ones starting with the layer with the NULL based-on link.

Note

The exclude count must be zero or greater but must be less than the total number of layers in the chain, otherwise a panic occurs.

Parameter	Description
aStream	Stream to which the format layer chain should be externalised.
aExcludeCount	The number of layers to be excluded. By default, zero.

ExternalizeL ( RWriteStream & )

void

ExternalizeL

(

RWriteStream &

aStream

)

const [pure virtual]

Implementations of this function externalise the format layer but not its based-on link to a write stream. The presence of this function means that the standard templatedoperator<<() (defined in s32strm.h) is available to externalise objects of the derived class.

Parameter	Description
aStream	Stream to which the format layer should be externalised.

ExternalizeLayersRecurseL ( RWriteStream &, TInt )

void	ExternalizeLayersRecurseL	(	RWriteStream &	aStream,
			TInt	aDescendantCount
		)	const [protected]

Stores a format layer chain with *aLength* number of layers in a stack-like fashion. This necessitates navigating to the end of the chain and storing the layers as we unwind back to the top of the chain.

InternalizeChainL ( RReadStream &, const CFormatLayer * )

IMPORT_C void	InternalizeChainL	(	RReadStream &	aStream,
			const CFormatLayer *	aBase = NULL
		)

Restores a chain of format layers from a read stream. The layer at the end of the chain (the one furthest from this layer) is set to be based on the specified layer aBase, which may be NULL. This layer is set to be at the head of the restored chain (i.e. no other layers are based on it).

Parameter	Description
aStream	Stream from which the format layer chain should be internalised.
aBase	The format layer at the end of the chain (furthest from this layer). May be NULL.

InternalizeL ( RReadStream &, const CFormatLayer * )

void	InternalizeL	(	RReadStream &	aStream,
			const CFormatLayer *	aBase = NULL
		)	[pure virtual]

Implementations of this function internalise the format layer but not its based-on link from a read stream. The presence of this function means that the standard templated operator>>() (defined in s32strm.h) is available to internalise objects of the derived class. The internalised layer is set to be based on the layer specified.

Parameter	Description
aStream	Stream from which the format layer should be internalised.
aBase	The based-on link to assign to the layer. By default, NULL.

IsEmpty ( )

IMPORT_C TBool

IsEmpty

(

)

const

Tests whether any formatting is stored in the format layer.

Returns: ETrue if no formatting is stored in the format layer, otherwise returns EFalse.

IsIdentical ( CFormatLayer *, TBool )

TBool	IsIdentical	(	CFormatLayer *	aLayer,
			TBool	aCheckBasedOnLink = ETrue
		)	const [pure virtual]

Implementations of this function compare another format layer with the current object. For the two layers to be equal, they must have the same contents and (if the second parameter is ETrue), their based-on links must point to the same format layer.

Parameter	Description
aLayer	The layer to compare to this format layer.
aCheckBasedOnLink	If ETrue, both layers' based-on links must point to the same format layer. If EFalse, the based-on links are not used in the comparison. By default, ETrue.

Returns: ETrue if the two layers are identical, otherwise EFalse.

IsIdentical ( const TUint8 *, TInt )

TBool	IsIdentical	(	const TUint8 *	aPtr,
			TInt	aSize
		)	const [protected]

Implementations of this function compare another format layer with the current object. For the two layers to be equal, they must have the same contents and (if the second parameter is ETrue),their based-on links must point to the same format layer.

Returns: ETrue if the two layers are identical, otherwise EFalse.

Ptr ( TInt & )

const TUint8 *

Ptr

(

TInt &

aSize

)

const [protected]

Return a pointer to the stored bytecode.

Reset ( )

IMPORT_C void

Reset

(

)

Deletes the contents of the format layer. The based-on link is not affected.

RestoreNewL ( RReadStream & )

CFormatLayer *

RestoreNewL

(

RReadStream &

aStream

)

[protected, pure virtual]

SenseBase ( )

IMPORT_C const CFormatLayer *

SenseBase

(

)

const

Gets the format layer which this layer's based-on link points to. If NULL, this layer is the final layer in the chain.

Returns: The format layer on which this layer is based.

SetBase ( const CFormatLayer * )

IMPORT_C void

SetBase

(

const CFormatLayer *

aBaseFormatLayer

)

Sets the format layer which this layer's based-on link points to.

Parameter	Description
aBaseFormatLayer	The format layer which this layer's based-on link points to. Specify NULL if this is the final layer in the chain (the layer on which all other layers are based).

Swap ( CFormatLayer & )

void

Swap

(

CFormatLayer &

aLayer

)

Swaps the contents of this with aLayer.

Parameter	Description
aLayer	The layer to swap contents with.