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Forward declaration of theUBiDiTransform structure that stores information used by the layout transformation engine.

Stable:

ICU 58

Definition at line1 of fileubiditransform.h.

UBiDiMirroring indicates whether or not characters with the "mirrored" property in RTL runs should be replaced with their mirror-image counterparts.

See also

UBIDI_DO_MIRRORING

ubidi_setReorderingOptions

ubidi_writeReordered

ubidi_writeReverse

Stable:

ICU 58

Definition at line94 of fileubiditransform.h.

UBiDiOrder indicates the order of text.

This bidi transformation engine supports all possible combinations (4 in total) of input and output text order:

• <logical input, visual output>: unless the output direction is RTL, this corresponds to a normal operation of the Bidi algorithm as described in the Unicode Technical Report and implemented byUBiDi when the reordering mode is set toUBIDI_REORDER_DEFAULT. Visual RTL mode is not supported byUBiDi and is accomplished through reversing a visual LTR string,
• <visual input, logical output>: unless the input direction is RTL, this corresponds to an "inverse bidi algorithm" inUBiDi with the reordering mode set toUBIDI_REORDER_INVERSE_LIKE_DIRECT. Visual RTL mode is not not supported byUBiDi and is accomplished through reversing a visual LTR string,
• <logical input, logical output>: if the input and output base directions mismatch, this corresponds to theUBiDi implementation with the reordering mode set toUBIDI_REORDER_RUNS_ONLY; and if the input and output base directions are identical, the transformation engine will only handle character mirroring and Arabic shaping operations without reordering,
• <visual input, visual output>: this reordering mode is not supported by theUBiDi engine; it implies character mirroring, Arabic shaping, and - if the input/output base directions mismatch - string reverse operations.

  See also

  ubidi_setInverse

  ubidi_setReorderingMode

  UBIDI_REORDER_DEFAULT

  UBIDI_REORDER_INVERSE_LIKE_DIRECT

  UBIDI_REORDER_RUNS_ONLY

  Stable:

  ICU 58

Definition at line71 of fileubiditransform.h.

Deallocates the givenUBiDiTransform object.

Stable:

ICU 58

Allocates aUBiDiTransform object.

This object can be reused, e.g. with different ordering schemes, mirroring or shaping options.

Note:The object can only be reused in the same thread. All other threads should allocate a newUBiDiTransform object before using it.

Example of usage:

UErrorCode errorCode =U_ZERO_ERROR;
// Open a new UBiDiTransform.
UBiDiTransform* transform =ubiditransform_open(&errorCode);
// Run a transformation.
ubiditransform_transform(transform,
           text1, -1, text2, -1,
UBIDI_RTL,UBIDI_LOGICAL,
UBIDI_LTR,UBIDI_VISUAL,
UBIDI_MIRRORING_ON,
U_SHAPE_DIGITS_EN2AN,
           &errorCode);
// Do something with the output text and invoke another transformation using
//   that text as input.
ubiditransform_transform(transform,
           text2, -1, text3, -1,
UBIDI_LTR,UBIDI_VISUAL,
UBIDI_RTL,UBIDI_VISUAL,
UBIDI_MIRRORING_ON,
           0, &errorCode);
*
UBIDI_LTR
@ UBIDI_LTR
Left-to-right text.
Definition:ubidi.h:441
UBIDI_RTL
@ UBIDI_RTL
Right-to-left text.
Definition:ubidi.h:453
ubiditransform_transform
U_CAPI uint32_t ubiditransform_transform(UBiDiTransform *pBiDiTransform, const UChar *src, int32_t srcLength, UChar *dest, int32_t destSize, UBiDiLevel inParaLevel, UBiDiOrder inOrder, UBiDiLevel outParaLevel, UBiDiOrder outOrder, UBiDiMirroring doMirroring, uint32_t shapingOptions, UErrorCode *pErrorCode)
Performs transformation of text from the bidi layout defined by the input ordering scheme to the bidi...
UBiDiTransform
struct UBiDiTransform UBiDiTransform
Forward declaration of the UBiDiTransform structure that stores information used by the layout transf...
Definition:ubiditransform.h:115
ubiditransform_open
U_CAPI UBiDiTransform * ubiditransform_open(UErrorCode *pErrorCode)
Allocates a UBiDiTransform object.
UBIDI_LOGICAL
@ UBIDI_LOGICAL
0: Constant indicating a logical order.
Definition:ubiditransform.h:76
UBIDI_VISUAL
@ UBIDI_VISUAL
1: Constant indicating a visual order.
Definition:ubiditransform.h:81
UBIDI_MIRRORING_ON
@ UBIDI_MIRRORING_ON
1: Constant indicating that character mirroring should be performed.
Definition:ubiditransform.h:107
U_SHAPE_DIGITS_EN2AN
#define U_SHAPE_DIGITS_EN2AN
Digit shaping option: Replace European digits (U+0030...) by Arabic-Indic digits.
Definition:ushape.h:251
UErrorCode
UErrorCode
Standard ICU4C error code type, a substitute for exceptions.
Definition:utypes.h:509
U_ZERO_ERROR
@ U_ZERO_ERROR
No error, no warning.
Definition:utypes.h:544

TheUBiDiTransform object must be deallocated by callingubiditransform_close().

Returns

An emptyUBiDiTransform object.

Stable:

ICU 58

Performs transformation of text from the bidi layout defined by the input ordering scheme to the bidi layout defined by the output ordering scheme, and applies character mirroring and Arabic shaping operations.

In terms ofUBiDi, such a transformation implies:

• callingubidi_setReorderingMode as needed (when the reordering mode is other than normal),
• callingubidi_setInverse as needed (when text should be transformed from a visual to a logical form),
• resolving embedding levels of each character in the input text by callingubidi_setPara,
• reordering the characters based on the computed embedding levels, also performing character mirroring as needed, and streaming the result to the output, by callingubidi_writeReordered,
• performing Arabic digit and letter shaping on the output text by callingu_shapeArabic.

An "ordering scheme" encompasses the base direction and the order of text, and these characteristics must be defined by the caller for both input and output explicitly .

There are 36 possible combinations of <input, output> ordering schemes, which are partially supported byUBiDi already. Examples of the currently supported combinations:

• <Logical LTR, Visual LTR>: this is equivalent to callingubidi_setPara withparaLevel == UBIDI_LTR,
• <Logical RTL, Visual LTR>: this is equivalent to callingubidi_setPara withparaLevel == UBIDI_RTL,
• <Logical Default ("Auto") LTR, Visual LTR>: this is equivalent to callingubidi_setPara withparaLevel == UBIDI_DEFAULT_LTR,
• <Logical Default ("Auto") RTL, Visual LTR>: this is equivalent to callingubidi_setPara withparaLevel == UBIDI_DEFAULT_RTL,
• <Visual LTR, Logical LTR>: this is equivalent to callingubidi_setInverse(UBiDi*, true) and thenubidi_setPara withparaLevel == UBIDI_LTR,
• <Visual LTR, Logical RTL>: this is equivalent to callingubidi_setInverse(UBiDi*, true) and thenubidi_setPara withparaLevel == UBIDI_RTL.

All combinations that involve the Visual RTL scheme are unsupported byUBiDi, for instance:

• <Logical LTR, Visual RTL>,
• <Visual RTL, Logical RTL>.

Example of usage of the transformation engine:

UChar text1[] = {'a','b','c', 0x0625,'1', 0};
UChar text2[] = {'a','b','c', 0x0625,'1', 0};
UErrorCode errorCode =U_ZERO_ERROR;
// Run a transformation.
ubiditransform_transform(pBidiTransform,
           text1, -1, text2, -1,
UBIDI_LTR,UBIDI_VISUAL,
UBIDI_RTL,UBIDI_LOGICAL,
UBIDI_MIRRORING_OFF,
U_SHAPE_DIGITS_AN2EN |U_SHAPE_DIGIT_TYPE_AN_EXTENDED,
           &errorCode);
// Do something with text2.
   text2[4] ='2';
// Run a reverse transformation.
ubiditransform_transform(pBidiTransform,
           text2, -1, text1, -1,
UBIDI_RTL,UBIDI_LOGICAL,
UBIDI_LTR,UBIDI_VISUAL,
UBIDI_MIRRORING_OFF,
U_SHAPE_DIGITS_EN2AN |U_SHAPE_DIGIT_TYPE_AN_EXTENDED,
           &errorCode);
*
UBIDI_MIRRORING_OFF
@ UBIDI_MIRRORING_OFF
0: Constant indicating that character mirroring should not be performed.
Definition:ubiditransform.h:100
UChar
char16_t UChar
The base type for UTF-16 code units and pointers.
Definition:umachine.h:400
U_SHAPE_DIGITS_AN2EN
#define U_SHAPE_DIGITS_AN2EN
Digit shaping option: Replace Arabic-Indic digits by European digits (U+0030...).
Definition:ushape.h:258
U_SHAPE_DIGIT_TYPE_AN_EXTENDED
#define U_SHAPE_DIGIT_TYPE_AN_EXTENDED
Digit type option: Use Eastern (Extended) Arabic-Indic digits (U+06f0...U+06f9).
Definition:ushape.h:296

Parameters

pBiDiTransform

A pointer to aUBiDiTransform object allocated withubiditransform_open() orNULL.

This object serves for one-time setup to amortize initialization overheads. Use of this object is not thread-safe. All other threads should allocate a newUBiDiTransform object by callingubiditransform_open() before using it. Alternatively, a caller can set this parameter toNULL, in which case the object will be allocated by the engine on the fly.

Parameters

src	A pointer to the text that the Bidi layout transformations will be performed on.

Note: the text must be (at least)srcLength long.

Parameters

srcLength	The length of the text, in number of UChars. Iflength == -1 then the text must be zero-terminated.
dest	A pointer to where the processed text is to be copied.
destSize	The size of thedest buffer, in number of UChars. If theU_SHAPE_LETTERS_UNSHAPE option is set, then the destination length could be as large assrcLength * 2. Otherwise, the destination length will not exceedsrcLength. If the caller reserves the last position for zero-termination, it should be excluded fromdestSize.

destSize == -1 is allowed and makes sense whendest was holds some meaningful value, e.g. that ofsrc. In this casedest must be zero-terminated.

Parameters

inParaLevel	A base embedding level of the input as defined inubidi_setPara documentation for theparaLevel parameter.
inOrder	An order of the input, which can be one of theUBiDiOrder values.
outParaLevel	A base embedding level of the output as defined inubidi_setPara documentation for theparaLevel parameter.
outOrder	An order of the output, which can be one of theUBiDiOrder values.
doMirroring	Indicates whether or not to perform character mirroring, and can accept one of theUBiDiMirroring values.
shapingOptions	Arabic digit and letter shaping options defined in theushape.h documentation.

Note: Direction indicator options are computed by the transformation engine based on the effective ordering schemes, so user-defined direction indicators will be ignored.

Parameters

pErrorCode

A pointer to an error code value.

Returns

The destination length, i.e. the number of UChars written todest. If the transformation fails, the return value will be 0 (and the error code will be written topErrorCode).

See also

UBiDiLevel

UBiDiOrder

UBiDiMirroring

ubidi_setPara

u_shapeArabic

Stable:

ICU 58