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MLineBreaker Class Reference

class MLineBreaker

Customizes the Unicode line-breaking algorithm.

Public Member Functions
IMPORT_C void *	ExtendedInterface(TUid &)
IMPORT_C TBool	GetLineBreak(const TDesC16 &, TInt, TInt, TBool, MContingentLineBreaker *, TInt &, TInt &)
IMPORT_C TBool	GetLineBreakInContext(const TDesC16 &, TInt, TInt, TBool, TInt &)
IMPORT_C TBool	GetLineBreakL(const TDesC16 &, TInt, TInt, TBool, MContingentLineBreakerL *, TInt &, TInt &)
IMPORT_C TBool	IsHangingCharacter(TUint)
IMPORT_C TUint	LineBreakClass(TUint, TUint &, TUint &)
IMPORT_C TBool	LineBreakPossible(TUint, TUint, TBool)

Public Member Enumerations
enum	anonymous { EOpLineBreakClass, EClLineBreakClass, EQuLineBreakClass, EGlLineBreakClass, ENsLineBreakClass, EExLineBreakClass, ESyLineBreakClass, EIsLineBreakClass, EPrLineBreakClass, EPoLineBreakClass, ENuLineBreakClass, EAlLineBreakClass, EIdLineBreakClass, EInLineBreakClass, EHyLineBreakClass, EBaLineBreakClass, EBbLineBreakClass, EB2LineBreakClass, EZwLineBreakClass, ECmLineBreakClass, EBkLineBreakClass, ECrLineBreakClass, ELfLineBreakClass, ESgLineBreakClass, ECbLineBreakClass, ESpLineBreakClass, ESaLineBreakClass, EAiLineBreakClass, EXxLineBreakClass, ELineBreakClasses }

Public Member Enumerations

enum

anonymous {
EOpLineBreakClass, EClLineBreakClass, EQuLineBreakClass, EGlLineBreakClass, ENsLineBreakClass, EExLineBreakClass, ESyLineBreakClass, EIsLineBreakClass, EPrLineBreakClass, EPoLineBreakClass, ENuLineBreakClass, EAlLineBreakClass, EIdLineBreakClass, EInLineBreakClass, EHyLineBreakClass, EBaLineBreakClass, EBbLineBreakClass, EB2LineBreakClass, EZwLineBreakClass, ECmLineBreakClass, EBkLineBreakClass, ECrLineBreakClass, ELfLineBreakClass, ESgLineBreakClass, ECbLineBreakClass, ESpLineBreakClass, ESaLineBreakClass, EAiLineBreakClass, EXxLineBreakClass, ELineBreakClasses
}

Member Functions Documentation

ExtendedInterface(TUid &)

IMPORT_C void *

ExtendedInterface

(

TUid &

aUid

)

const [virtual]

Returns an interface to more functions, or 0 if these are unsupported. Currently there are no other functions, so 0 is always returned. If this function is overridden, it must base call if aUid is not recognised, rather than just returning 0.

Parameters

TUid & aUid

Identifies the interface to be returned.

GetLineBreak(const TDesC16 &, TInt, TInt, TBool, MContingentLineBreaker *, TInt &, TInt &)

IMPORT_C TBool	GetLineBreak	(	const TDesC16 &	aText,
			TInt	aMinBreakPos,
			TInt	aMaxBreakPos,
			TBool	aForwards,
			MContingentLineBreaker *	aCbDelegate,
			TInt &	aBreakPos,
			TInt &	aBreakPosAfterSpaces
		)	const

Finds the line break according to the rules in the virtual functions.

Parameters

const TDesC16 & aText	The text to be broken.
TInt aMinBreakPos	The smallest allowed result.
TInt aMaxBreakPos	The position of the first character that fails to fit the measure.
TBool aForwards	ETrue to find the earliest legal break opportunity, EFalse to find the last.
MContingentLineBreaker * aCbDelegate	Object to resolve breaks around characters with the CB (cointingent break) line breaking class. Typically this class is only used for character 0xFFFD, which usually marks the position of embedded pictures. May be NULL, in which case LineBreakPossible() determines whether these breaks are legal.
TInt & aBreakPos	Returns the position of the break.
TInt & aBreakPosAfterSpaces	Returns the position of the start of the next line.

GetLineBreakInContext(const TDesC16 &, TInt, TInt, TBool, TInt &)

IMPORT_C TBool	GetLineBreakInContext	(	const TDesC16 &	aText,
			TInt	aMinBreakPos,
			TInt	aMaxBreakPos,
			TBool	aForwards,
			TInt &	aBreakPos
		)	const [virtual]

Returns whether a line break is possible within a run of characters all having the class ESaLineBreakClass (Complex content). Languages with Unicocde characters having such a class include: Thai, Lao, Myanmar and Khmer. This default implementation of the GetLineBreakInContext() method only supports the Thai script. Breaks are determined in Thai based on a simple understanding of syllable boundaries. When characters from the other unsupported Sa class languages are found the method exits with EFalse.

Parameters

const TDesC16 & aText	The text to be searched, which is a contiguous run of characters of class SA (or CM attatched to SA). The break position may be restricted further by aMinBreakPos and aMaxBreakPos, but more text is provided for extra context should it be needed.
TInt aMinBreakPos	The start of the text to be considered for line breaks.
TInt aMaxBreakPos	The end of the text to be considered for line breaks.
TBool aForwards	ETrue if aBreakPos is to be set with the first legal break position, EFalse if aBreakPos is to be set with the last legal break position.
TInt & aBreakPos	If break position found on exit its value is >= Min and <= Max positions supplied.

GetLineBreakL(const TDesC16 &, TInt, TInt, TBool, MContingentLineBreakerL *, TInt &, TInt &)

IMPORT_C TBool	GetLineBreakL	(	const TDesC16 &	aText,
			TInt	aMinBreakPos,
			TInt	aMaxBreakPos,
			TBool	aForwards,
			MContingentLineBreakerL *	aCbDelegate,
			TInt &	aBreakPos,
			TInt &	aBreakPosAfterSpaces
		)	const

Exactly the same as GetLineBreak, but aCbDelegate's functions may leave so the whole function may leave.

Parameters

const TDesC16 & aText	The text to be broken.
TInt aMinBreakPos	The smallest allowed result.
TInt aMaxBreakPos	he position of the first character that fails to fit the measure.
TBool aForwards	ETrue to find the earliest legal break opportunity, EFalse to find the last.
MContingentLineBreakerL * aCbDelegate	Object to resolve breaks around characters with the CB (cointingent break) line breaking class. Typically this class is only used for character 0xFFFD, which usually marks the position of embedded pictures. May be NULL, in which case LineBreakPossible() determines whether these breaks are legal.
TInt & aBreakPos	Returns the position of the break.
TInt & aBreakPosAfterSpaces	Returns the position of the start of the next line.

IsHangingCharacter(TUint)

IMPORT_C TBool

IsHangingCharacter

(

TUint

aChar

)

const [virtual]

Returns ETrue if the character value may be positioned outside the margins.

Parameters

TUint aChar

Chatacter to test

LineBreakClass(TUint, TUint &, TUint &)

IMPORT_C TUint	LineBreakClass	(	TUint	aCode,
			TUint &	aRangeStart,
			TUint &	aRangeEnd
		)	const [virtual]

Converts Unicode character into line breaking class.

Parameters

TUint aCode	Input Unicode value.
TUint & aRangeStart	Returns the start of the contiguous range of characters including aCode that have the returned line breaking class.
TUint & aRangeEnd	Returns the end of the contiguous range of characters including aCode that have the returned line breaking class.

LineBreakPossible(TUint, TUint, TBool)

IMPORT_C TBool	LineBreakPossible	(	TUint	aPrevClass,
			TUint	aNextClass,
			TBool	aHaveSpaces
		)	const [virtual]

Returns whether line breaks are legal between a character of line breaking class aPrevClass and aNextClass, with intervening spaces or not as determined by aHaveSpaces.

Parameters

TUint aPrevClass	The class before the potential line break.
TUint aNextClass	The class after the potential line break.
TBool aHaveSpaces	Whether spaces separate the characters.

Member Enumerations Documentation

Enum anonymous

The Unicode line breaking classes; see Unicode Technical Report 14. Not a named enumerated type, so that overriding classes may add new line breaking classes freely. The description of each constant gives the name of the line-breaking class, an example and a brief, imprecise description of the default behaviour of characters of that class.

Enumerators

EOpLineBreakClass	Opening Punctuation (e.g. '['). Breaking after prohibited.
EClLineBreakClass	Closing Punctuation (e.g. ']'). Breaking before prohibited.
EQuLineBreakClass	Ambiguous Quotes (e.g. '"'). Breaking before and after prohibited.
EGlLineBreakClass	Glue (e.g. Non-breaking space). Breaking before and after prohibited unless spaces are present.
ENsLineBreakClass	Non-Starter (e.g. small Japanese kana). Breaking before prohibited if no spaces present.
EExLineBreakClass	Exclamation or Interrogation (e.g. '?'). Like closing punctuation except before Postfix or Non-starter.
ESyLineBreakClass	Symbol (e.g. '/'. Like Alphabetic, but allows breaking before Alphabetic.
EIsLineBreakClass	Numeric Infix Separator (e.g. ','). Forbids breaking after any and before Numeric.
EPrLineBreakClass	Numeric Prefix (e.g. '$'). Forbids breaking before Numeric.
EPoLineBreakClass	Numeric Postfix (e.g. ''). Forbids breaking after Numeric.
ENuLineBreakClass	Numeric (e.g. '1').
EAlLineBreakClass	Alphabetic (e.g. 'a').
EIdLineBreakClass	Ideographic (e.g. Japanese Kanji). Generally break before or after
EInLineBreakClass	Inseparable (e.g. ellipsis). Forbid breaks between Inseparables.
EHyLineBreakClass	Hyphen (e.g. '-'). Allows a break after except before Numeric.
EBaLineBreakClass	Break After. Generally allow a break after. Breaking between Break Afters not separated by spaces is prohibited.
EBbLineBreakClass	Break Before. Generally allow a break before. Breaking between Break Befores not separated by spaces is prohibited.
EB2LineBreakClass	Break Before and After. Generally allow a break before or after. Breaking between Break Before and Afters is prohibited, even if spaces are present.
EZwLineBreakClass	Zero-Width Space. Allow a break.
ECmLineBreakClass	Combining Mark. Takes on the class of its base class.
EBkLineBreakClass	Mandatory Break.
ECrLineBreakClass	Carriage Return. Break after unless part of a CRLF pair.
ELfLineBreakClass	Line Feed. Break after.
ESgLineBreakClass	Surrogate. Half of a surrogate pair.
ECbLineBreakClass	Contingent Break (e.g. embedded pictures). Uses external information
ESpLineBreakClass	Space. Intervening characters of class Space are indicated by aHaveSpaces in LineBreakPossible.
ESaLineBreakClass	Complex Context (e.g. Thai). Runs of Complex Context are passed to GetLineBreakInContext.
EAiLineBreakClass	Ambiguous. Characters of ambiguous East Asian width are treated as Alphabetic, unless they are resolved as being "Wide", in which case they are treated as Ideographic.
EXxLineBreakClass	The Xx class is used when the class is unknown; e.g.; outside the provided context.
ELineBreakClasses	The number of Unicode line break classes.