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# ubidi.h File Reference

C API: Bidi algorithm. More...

`#include "unicode/utypes.h"`
`#include "unicode/uchar.h"`

Go to the source code of this file.

#define | UBIDI_DEFAULT_LTR 0xfe
| Paragraph level setting.
#define | UBIDI_DEFAULT_RTL 0xff
| Paragraph level setting.
#define | UBIDI_MAX_EXPLICIT_LEVEL 61
| Maximum explicit embedding level.
#define | UBIDI_LEVEL_OVERRIDE 0x80
| Bit flag for level input.
#define | UBIDI_MAP_NOWHERE (-1)
| Special value which can be returned by the mapping functions when a logical index has no corresponding visual index or vice-versa.
#define | UBIDI_KEEP_BASE_COMBINING 1
| option bit for ubidi_writeReordered(): keep combining characters after their base characters in RTL runs
#define | UBIDI_DO_MIRRORING 2
| option bit for ubidi_writeReordered(): replace characters with the "mirrored" property in RTL runs by their mirror-image mappings
#define | UBIDI_INSERT_LRM_FOR_NUMERIC 4
| option bit for ubidi_writeReordered(): surround the run with LRMs if necessary; this is part of the approximate "inverse Bidi" algorithm
#define | UBIDI_REMOVE_BIDI_CONTROLS 8
| option bit for ubidi_writeReordered(): remove Bidi control characters (this does not affect UBIDI_INSERT_LRM_FOR_NUMERIC)
#define | UBIDI_OUTPUT_REVERSE 16
| option bit for ubidi_writeReordered(): write the output in reverse order
#define | U_BIDI_CLASS_DEFAULT U_CHAR_DIRECTION_COUNT
| value returned by `UBiDiClassCallback` callbacks when there is no need to override the standard Bidi class for a given code point.
enum | UBiDiDirection { UBIDI_LTR, UBIDI_RTL, UBIDI_MIXED }
| `UBiDiDirection` values indicate the text direction. More...
enum | UBiDiReorderingMode { UBIDI_REORDER_DEFAULT = 0, UBIDI_REORDER_NUMBERS_SPECIAL, UBIDI_REORDER_GROUP_NUMBERS_WITH_R, UBIDI_REORDER_RUNS_ONLY, UBIDI_REORDER_INVERSE_NUMBERS_AS_L, UBIDI_REORDER_INVERSE_LIKE_DIRECT, UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL, UBIDI_REORDER_COUNT }
| `UBiDiReorderingMode` values indicate which variant of the Bidi algorithm to use. More...
enum | UBiDiReorderingOption { UBIDI_OPTION_DEFAULT = 0, UBIDI_OPTION_INSERT_MARKS = 1, UBIDI_OPTION_REMOVE_CONTROLS = 2, UBIDI_OPTION_STREAMING = 4 }
| `UBiDiReorderingOption` values indicate which options are specified to affect the Bidi algorithm. More...
typedef uint8_t | UBiDiLevel
| UBiDiLevel is the type of the level values in this Bidi implementation.
typedef enum UBiDiDirection | UBiDiDirection
typedef UBiDi | UBiDi
typedef UCharDirection U_CALLCONV | UBiDiClassCallback (const void *context, UChar32 c)
| Callback type declaration for overriding default Bidi class values with custom ones.
UBiDi * | ubidi_open (void)
| Allocate a `UBiDi` structure.
UBiDi * | ubidi_openSized (int32_t maxLength, int32_t maxRunCount, UErrorCode *pErrorCode)
| Allocate a `UBiDi` structure with preallocated memory for internal structures.
void | ubidi_close (UBiDi *pBiDi)
| `ubidi_close()` must be called to free the memory associated with a UBiDi object.
void | ubidi_setInverse (UBiDi *pBiDi, UBool isInverse)
| Modify the operation of the Bidi algorithm such that it approximates an "inverse Bidi" algorithm.
UBool | ubidi_isInverse (UBiDi *pBiDi)
| Is this Bidi object set to perform the inverse Bidi algorithm?
void | ubidi_orderParagraphsLTR (UBiDi *pBiDi, UBool orderParagraphsLTR)
| Specify whether block separators must be allocated level zero, so that successive paragraphs will progress from left to right.
UBool | ubidi_isOrderParagraphsLTR (UBiDi *pBiDi)
| Is this Bidi object set to allocate level 0 to block separators so that successive paragraphs progress from left to right?
void | ubidi_setReorderingMode (UBiDi *pBiDi, UBiDiReorderingMode reorderingMode)
| Modify the operation of the Bidi algorithm such that it implements some variant to the basic Bidi algorithm or approximates an "inverse Bidi" algorithm, depending on different values of the "reordering mode".
UBiDiReorderingMode | ubidi_getReorderingMode (UBiDi *pBiDi)
| What is the requested reordering mode for a given Bidi object?
void | ubidi_setReorderingOptions (UBiDi *pBiDi, uint32_t reorderingOptions)
| Specify which of the reordering options should be applied during Bidi transformations.
uint32_t | ubidi_getReorderingOptions (UBiDi *pBiDi)
| What are the reordering options applied to a given Bidi object?
void | ubidi_setPara (UBiDi *pBiDi, const UChar *text, int32_t length, UBiDiLevel paraLevel, UBiDiLevel *embeddingLevels, UErrorCode *pErrorCode)
| Perform the Unicode Bidi algorithm.
void | ubidi_setLine (const UBiDi *pParaBiDi, int32_t start, int32_t limit, UBiDi *pLineBiDi, UErrorCode *pErrorCode)
| `ubidi_setLine()` sets a `UBiDi` to contain the reordering information, especially the resolved levels, for all the characters in a line of text.
UBiDiDirection | ubidi_getDirection (const UBiDi *pBiDi)
| Get the directionality of the text.
const UChar * | ubidi_getText (const UBiDi *pBiDi)
| Get the pointer to the text.
int32_t | ubidi_getLength (const UBiDi *pBiDi)
| Get the length of the text.
UBiDiLevel | ubidi_getParaLevel (const UBiDi *pBiDi)
| Get the paragraph level of the text.
int32_t | ubidi_countParagraphs (UBiDi *pBiDi)
| Get the number of paragraphs.
int32_t | ubidi_getParagraph (const UBiDi *pBiDi, int32_t charIndex, int32_t *pParaStart, int32_t *pParaLimit, UBiDiLevel *pParaLevel, UErrorCode *pErrorCode)
| Get a paragraph, given a position within the text.
void | ubidi_getParagraphByIndex (const UBiDi *pBiDi, int32_t paraIndex, int32_t *pParaStart, int32_t *pParaLimit, UBiDiLevel *pParaLevel, UErrorCode *pErrorCode)
| Get a paragraph, given the index of this paragraph.
UBiDiLevel | ubidi_getLevelAt (const UBiDi *pBiDi, int32_t charIndex)
| Get the level for one character.
const UBiDiLevel * | ubidi_getLevels (UBiDi *pBiDi, UErrorCode *pErrorCode)
| Get an array of levels for each character.
void | ubidi_getLogicalRun (const UBiDi *pBiDi, int32_t logicalPosition, int32_t *pLogicalLimit, UBiDiLevel *pLevel)
| Get a logical run.
int32_t | ubidi_countRuns (UBiDi *pBiDi, UErrorCode *pErrorCode)
| Get the number of runs.
UBiDiDirection | ubidi_getVisualRun (UBiDi *pBiDi, int32_t runIndex, int32_t *pLogicalStart, int32_t *pLength)
| Get one run's logical start, length, and directionality, which can be 0 for LTR or 1 for RTL.
int32_t | ubidi_getVisualIndex (UBiDi *pBiDi, int32_t logicalIndex, UErrorCode *pErrorCode)
| Get the visual position from a logical text position.
int32_t | ubidi_getLogicalIndex (UBiDi *pBiDi, int32_t visualIndex, UErrorCode *pErrorCode)
| Get the logical text position from a visual position.
void | ubidi_getLogicalMap (UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode)
| Get a logical-to-visual index map (array) for the characters in the UBiDi (paragraph or line) object.
void | ubidi_getVisualMap (UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode)
| Get a visual-to-logical index map (array) for the characters in the UBiDi (paragraph or line) object.
void | ubidi_reorderLogical (const UBiDiLevel *levels, int32_t length, int32_t *indexMap)
| This is a convenience function that does not use a UBiDi object.
void | ubidi_reorderVisual (const UBiDiLevel *levels, int32_t length, int32_t *indexMap)
| This is a convenience function that does not use a UBiDi object.
void | ubidi_invertMap (const int32_t *srcMap, int32_t *destMap, int32_t length)
| Invert an index map.
int32_t | ubidi_getProcessedLength (const UBiDi *pBiDi)
| Get the length of the source text processed by the last call to `ubidi_setPara()`.
int32_t | ubidi_getResultLength (const UBiDi *pBiDi)
| Get the length of the reordered text resulting from the last call to `ubidi_setPara()`.
U_CDECL_END UCharDirection | ubidi_getCustomizedClass (UBiDi *pBiDi, UChar32 c)
| Retrieve the Bidi class for a given code point.
void | ubidi_setClassCallback (UBiDi *pBiDi, UBiDiClassCallback *newFn, const void *newContext, UBiDiClassCallback **oldFn, const void **oldContext, UErrorCode *pErrorCode)
| Set the callback function and callback data used by the UBA implementation for Bidi class determination.
void | ubidi_getClassCallback (UBiDi *pBiDi, UBiDiClassCallback **fn, const void **context)
| Get the current callback function used for Bidi class determination.
int32_t | ubidi_writeReordered (UBiDi *pBiDi, UChar *dest, int32_t destSize, uint16_t options, UErrorCode *pErrorCode)
| Take a `UBiDi` object containing the reordering information for a piece of text (one or more paragraphs) set by `ubidi_setPara()` or for a line of text set by `ubidi_setLine()` and write a reordered string to the destination buffer.
int32_t | ubidi_writeReverse (const UChar *src, int32_t srcLength, UChar *dest, int32_t destSize, uint16_t options, UErrorCode *pErrorCode)
| Reverse a Right-To-Left run of Unicode text.

## Detailed Description

C API: Bidi algorithm.

## Bidi algorithm for ICU

This is an implementation of the Unicode Bidirectional algorithm. The algorithm is defined in the Unicode Standard Annex #9, version 13, also described in The Unicode Standard, Version 4.0 .

Note: Libraries that perform a bidirectional algorithm and reorder strings accordingly are sometimes called "Storage Layout Engines". ICU's Bidi and shaping (u_shapeArabic()) APIs can be used at the core of such "Storage Layout Engines".

### General remarks about the API:

In functions with an error code parameter, the `pErrorCode` pointer must be valid and the value that it points to must not indicate a failure before the function call. Otherwise, the function returns immediately. After the function call, the value indicates success or failure.

The "limit" of a sequence of characters is the position just after their last character, i.e., one more than that position.

Some of the API functions provide access to "runs". Such a "run" is defined as a sequence of characters that are at the same embedding level after performing the Bidi algorithm.

Author:
  Markus W. Scherer

Version:
  1.0

#### Sample code for the ICU Bidi API

##### Rendering a paragraph with the ICU Bidi API

This is (hypothetical) sample code that illustrates how the ICU Bidi API could be used to render a paragraph of text. Rendering code depends highly on the graphics system, therefore this sample code must make a lot of assumptions, which may or may not match any existing graphics system's properties.

The basic assumptions are:

- Rendering is done from left to right on a horizontal line.
- A run of single-style, unidirectional text can be rendered at once.
- Such a run of text is passed to the graphics system with characters (code units) in logical order.
- The line-breaking algorithm is very complicated and Locale-dependent - and therefore its implementation omitted from this sample code.

     *#include "unicode/ubidi.h"

     *typedef enum {
         styleNormal=0, styleSelected=1,
         styleBold=2, styleItalics=4,
         styleSuper=8, styleSub=16
     *} Style;

     *typedef struct { int32_t limit; Style style; } StyleRun;

     *int getTextWidth(const UChar *text, int32_t start, int32_t limit,
                      const StyleRun *styleRuns, int styleRunCount);

     // set *pLimit and *pStyleRunLimit for a line
     // from text[start] and from styleRuns[styleRunStart]
     // using ubidi_getLogicalRun(para, ...)
     *void getLineBreak(const UChar *text, int32_t start, int32_t *pLimit,
                      UBiDi *para,
                      const StyleRun *styleRuns, int styleRunStart, int *pStyleRunLimit,
                      int *pLineWidth);

     // render runs on a line sequentially, always from left to right

     // prepare rendering a new line
     void startLine(UBiDiDirection textDirection, int lineWidth);

     // render a run of text and advance to the right by the run width
     // the text[start..limit-1] is always in logical order
     void renderRun(const UChar *text, int32_t start, int32_t limit,
                   UBiDiDirection textDirection, Style style);

     // We could compute a cross-product
     // from the style runs with the directional runs
     // and then reorder it.
     // Instead, here we iterate over each run type
     // and render the intersections -
     // with shortcuts in simple (and common) cases.
     // renderParagraph() is the main function.

     // render a directional run with
     // (possibly) multiple style runs intersecting with it
     void renderDirectionalRun(const UChar *text,
                               int32_t start, int32_t limit,
                               UBiDiDirection direction,
                               const StyleRun *styleRuns, int styleRunCount) {
         int i;

         // iterate over style runs
         if(direction==UBIDI_LTR) {
             int styleLimit;

             for(i=0; i<styleRunCount; ++i) {
                 styleLimit=styleRun[i].limit;
                 if(start<styleLimit) {
                     if(styleLimit>limit) { styleLimit=limit; }
                     renderRun(text, start, styleLimit,
                               direction, styleRun[i].style);
                     if(styleLimit==limit) { break; }
                     start=styleLimit;
                 }
             }
         } else {
             int styleStart;

             for(i=styleRunCount-1; i>=0; --i) {
                 if(i>0) {
                     styleStart=styleRun[i-1].limit;
                 } else {
                     styleStart=0;
                 }
                 if(limit>=styleStart) {
                     if(styleStart<start) { styleStart=start; }
                     renderRun(text, styleStart, limit,
                               direction, styleRun[i].style);
                     if(styleStart==start) { break; }
                     limit=styleStart;
                 }
             }
         }
     }

     // the line object represents text[start..limit-1]
     void renderLine(UBiDi *line, const UChar *text,
                     int32_t start, int32_t limit,
                     const StyleRun *styleRuns, int styleRunCount) {
         UBiDiDirection direction=ubidi_getDirection(line);
         if(direction!=UBIDI_MIXED) {
             // unidirectional
             if(styleRunCount<=1) {
                 renderRun(text, start, limit, direction, styleRuns[0].style);
             } else {
                 renderDirectionalRun(text, start, limit,
                                      direction, styleRuns, styleRunCount);
             }
         } else {
             // mixed-directional
             int32_t count, i, length;
             UBiDiLevel level;

             count=ubidi_countRuns(para, pErrorCode);
             if(U_SUCCESS(*pErrorCode)) {
                 if(styleRunCount<=1) {
                     Style style=styleRuns[0].style;

                     // iterate over directional runs
                    for(i=0; i<count; ++i) {
                        direction=ubidi_getVisualRun(para, i, &start, &length);
                         renderRun(text, start, start+length, direction, style);
                    }
                 } else {
                     int32_t j;

                     // iterate over both directional and style runs
                     for(i=0; i<count; ++i) {
                         direction=ubidi_getVisualRun(line, i, &start, &length);
                         renderDirectionalRun(text, start, start+length,
                                              direction, styleRuns, styleRunCount);
                     }
                 }
             }
         }
     }

     *void renderParagraph(const UChar *text, int32_t length,
                         UBiDiDirection textDirection,
                          const StyleRun *styleRuns, int styleRunCount,
                          int lineWidth,
                          UErrorCode *pErrorCode) {
         UBiDi *para;

         if(pErrorCode==NULL || U_FAILURE(*pErrorCode) || length<=0) {
             return;
         }

         para=ubidi_openSized(length, 0, pErrorCode);
         if(para==NULL) { return; }

         ubidi_setPara(para, text, length,
                       textDirection ? UBIDI_DEFAULT_RTL : UBIDI_DEFAULT_LTR,
                       NULL, pErrorCode);
         if(U_SUCCESS(*pErrorCode)) {
             UBiDiLevel paraLevel=1&ubidi_getParaLevel(para);
             StyleRun styleRun={ length, styleNormal };
             int width;

             if(styleRuns==NULL || styleRunCount<=0) {
                styleRunCount=1;
                 styleRuns=&styleRun;
             }

            // assume styleRuns[styleRunCount-1].limit>=length

             width=getTextWidth(text, 0, length, styleRuns, styleRunCount);
             if(width<=lineWidth) {
                 // everything fits onto one line

                // prepare rendering a new line from either left or right
                 startLine(paraLevel, width);

                 renderLine(para, text, 0, length,
                            styleRuns, styleRunCount);
             } else {
                 UBiDi *line;

                 // we need to render several lines
                 line=ubidi_openSized(length, 0, pErrorCode);
                 if(line!=NULL) {
                     int32_t start=0, limit;
                     int styleRunStart=0, styleRunLimit;

                     for(;;) {
                         limit=length;
                         styleRunLimit=styleRunCount;
                         getLineBreak(text, start, &limit, para,
                                      styleRuns, styleRunStart, &styleRunLimit,
                                     &width);
                         ubidi_setLine(para, start, limit, line, pErrorCode);
                         if(U_SUCCESS(*pErrorCode)) {
                             // prepare rendering a new line
                             // from either left or right
                             startLine(paraLevel, width);

                             renderLine(line, text, start, limit,
                                        styleRuns+styleRunStart,
                                        styleRunLimit-styleRunStart);
                         }
                         if(limit==length) { break; }
                         start=limit;
                         styleRunStart=styleRunLimit-1;
                         if(start>=styleRuns[styleRunStart].limit) {
                             ++styleRunStart;
                         }
                     }

                     ubidi_close(line);
                 }
            }
        }

         ubidi_close(para);
     *}
     *

Definition in file ubidi.h.

## Define Documentation

#define U_BIDI_CLASS_DEFAULT U_CHAR_DIRECTION_COUNT

value returned by `UBiDiClassCallback` callbacks when there is no need to override the standard Bidi class for a given code point.

See also:
  UBiDiClassCallback

Stable:
  ICU 3.6

Definition at line 1781 of file ubidi.h.

#define UBIDI_DEFAULT_LTR 0xfe

Paragraph level setting.

Constant indicating that the base direction depends on the first strong directional character in the text according to the Unicode Bidirectional Algorithm. If no strong directional character is present, then set the paragraph level to 0 (left-to-right).

If this value is used in conjunction with reordering modes `UBIDI_REORDER_INVERSE_LIKE_DIRECT` or `UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL`, the text to reorder is assumed to be visual LTR, and the text after reordering is required to be the corresponding logical string with appropriate contextual direction. The direction of the result string will be RTL if either the righmost or leftmost strong character of the source text is RTL or Arabic Letter, the direction will be LTR otherwise.

If reordering option `UBIDI_OPTION_INSERT_MARKS` is set, an RLM may be added at the beginning of the result string to ensure round trip (that the result string, when reordered back to visual, will produce the original source text).

See also:
  UBIDI_REORDER_INVERSE_LIKE_DIRECT

  UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL

Stable:
  ICU 2.0

Definition at line 356 of file ubidi.h.

#define UBIDI_DEFAULT_RTL 0xff

Paragraph level setting.

Constant indicating that the base direction depends on the first strong directional character in the text according to the Unicode Bidirectional Algorithm. If no strong directional character is present, then set the paragraph level to 1 (right-to-left).

If this value is used in conjunction with reordering modes `UBIDI_REORDER_INVERSE_LIKE_DIRECT` or `UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL`, the text to reorder is assumed to be visual LTR, and the text after reordering is required to be the corresponding logical string with appropriate contextual direction. The direction of the result string will be RTL if either the righmost or leftmost strong character of the source text is RTL or Arabic Letter, or if the text contains no strong character; the direction will be LTR otherwise.

If reordering option `UBIDI_OPTION_INSERT_MARKS` is set, an RLM may be added at the beginning of the result string to ensure round trip (that the result string, when reordered back to visual, will produce the original source text).

See also:
  UBIDI_REORDER_INVERSE_LIKE_DIRECT

  UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL

Stable:
  ICU 2.0

Definition at line 383 of file ubidi.h.

#define UBIDI_DO_MIRRORING 2

option bit for ubidi_writeReordered(): replace characters with the "mirrored" property in RTL runs by their mirror-image mappings

See also:
  ubidi_writeReordered

Stable:
  ICU 2.0

Definition at line 1658 of file ubidi.h.

#define UBIDI_INSERT_LRM_FOR_NUMERIC 4

option bit for ubidi_writeReordered(): surround the run with LRMs if necessary; this is part of the approximate "inverse Bidi" algorithm

This option does not imply corresponding adjustment of the index mappings.

See also:
  ubidi_setInverse

  ubidi_writeReordered

Stable:
  ICU 2.0

Definition at line 1672 of file ubidi.h.

#define UBIDI_KEEP_BASE_COMBINING 1

option bit for ubidi_writeReordered(): keep combining characters after their base characters in RTL runs

See also:
  ubidi_writeReordered

Stable:
  ICU 2.0

Definition at line 1648 of file ubidi.h.

#define UBIDI_LEVEL_OVERRIDE 0x80

Bit flag for level input.

Overrides directional properties.

Stable:
  ICU 2.0

Definition at line 396 of file ubidi.h.

#define UBIDI_MAP_NOWHERE (-1)

Special value which can be returned by the mapping functions when a logical index has no corresponding visual index or vice-versa.

This may happen for the logical-to-visual mapping of a Bidi control when option `UBIDI_OPTION_REMOVE_CONTROLS` is specified. This can also happen for the visual-to-logical mapping of a Bidi mark (LRM or RLM) inserted by option `UBIDI_OPTION_INSERT_MARKS`.

See also:
  ubidi_getVisualIndex

  ubidi_getVisualMap

  ubidi_getLogicalIndex

  ubidi_getLogicalMap

Stable:
  ICU 3.6

Definition at line 411 of file ubidi.h.

#define UBIDI_MAX_EXPLICIT_LEVEL 61

Maximum explicit embedding level.

(The maximum resolved level can be up to `UBIDI_MAX_EXPLICIT_LEVEL+1`).

Stable:
  ICU 2.0

Definition at line 390 of file ubidi.h.

#define UBIDI_OUTPUT_REVERSE 16

option bit for ubidi_writeReordered(): write the output in reverse order

This has the same effect as calling `ubidi_writeReordered()` first without this option, and then calling `ubidi_writeReverse()` without mirroring. Doing this in the same step is faster and avoids a temporary buffer. An example for using this option is output to a character terminal that is designed for RTL scripts and stores text in reverse order.

See also:
  ubidi_writeReordered

Stable:
  ICU 2.0

Definition at line 1701 of file ubidi.h.

#define UBIDI_REMOVE_BIDI_CONTROLS 8

option bit for ubidi_writeReordered(): remove Bidi control characters (this does not affect UBIDI_INSERT_LRM_FOR_NUMERIC)

This option does not imply corresponding adjustment of the index mappings.

See also:
  ubidi_writeReordered

Stable:
  ICU 2.0

Definition at line 1685 of file ubidi.h.

## Typedef Documentation

typedef struct UBiDi UBiDi

Stable:
  ICU 2.0

Definition at line 442 of file ubidi.h.

typedef UCharDirection U_CALLCONV UBiDiClassCallback(const void *context, UChar32 c)

Callback type declaration for overriding default Bidi class values with custom ones.

Usually, the function pointer will be propagated to a `UBiDi` object by calling the `ubidi_setClassCallback()` function; then the callback will be invoked by the UBA implementation any time the class of a character is to be determined.

Parameters:

  | context | is a pointer to the callback private data.
  | c | is the code point to get a Bidi class for.

Returns:
  The directional property / Bidi class for the given code point `c` if the default class has been overridden, or `U_BIDI_CLASS_DEFAULT` if the standard Bidi class value for `c` is to be used.

See also:
  ubidi_setClassCallback

  ubidi_getClassCallback

Stable:
  ICU 3.6

Definition at line 1804 of file ubidi.h.

typedef enum UBiDiDirection UBiDiDirection

Stable:
  ICU 2.0

Definition at line 427 of file ubidi.h.

typedef uint8_t UBiDiLevel

UBiDiLevel is the type of the level values in this Bidi implementation.

It holds an embedding level and indicates the visual direction by its bit 0 (even/odd value).

It can also hold non-level values for the `paraLevel` and `embeddingLevels` arguments of `ubidi_setPara()`; there:

- bit 7 of an `embeddingLevels[]` value indicates whether the using application is specifying the level of a character to override whatever the Bidi implementation would resolve it to.
- `paraLevel` can be set to the pseudo-level values `UBIDI_DEFAULT_LTR` and `UBIDI_DEFAULT_RTL`.

See also:
  ubidi_setPara

The related constants are not real, valid level values. `UBIDI_DEFAULT_XXX` can be used to specify a default for the paragraph level for when the `ubidi_setPara()` function shall determine it but there is no strongly typed character in the input.

Note that the value for `UBIDI_DEFAULT_LTR` is even and the one for `UBIDI_DEFAULT_RTL` is odd, just like with normal LTR and RTL level values - these special values are designed that way. Also, the implementation assumes that UBIDI_MAX_EXPLICIT_LEVEL is odd.

See also:
  UBIDI_DEFAULT_LTR

  UBIDI_DEFAULT_RTL

  UBIDI_LEVEL_OVERRIDE

  UBIDI_MAX_EXPLICIT_LEVEL

Stable:
  ICU 2.0

Definition at line 330 of file ubidi.h.

## Enumeration Type Documentation

enum UBiDiDirection

`UBiDiDirection` values indicate the text direction.

Stable:
  ICU 2.0

Enumerator:

  UBIDI_LTR | All left-to-right text. This is a 0 value. Stable: ICU 2.0
  UBIDI_RTL | All right-to-left text. This is a 1 value. Stable: ICU 2.0
  UBIDI_MIXED | Mixed-directional text. Stable: ICU 2.0

Definition at line 417 of file ubidi.h.

enum UBiDiReorderingMode

`UBiDiReorderingMode` values indicate which variant of the Bidi algorithm to use.

See also:
  ubidi_setReorderingMode

Stable:
  ICU 3.6

Enumerator:

  UBIDI_REORDER_DEFAULT | Regular Logical to Visual Bidi algorithm according to Unicode. This is a 0 value. Stable: ICU 3.6
  UBIDI_REORDER_NUMBERS_SPECIAL | Logical to Visual algorithm which handles numbers in a way which mimicks the behavior of Windows XP. Stable: ICU 3.6
  UBIDI_REORDER_GROUP_NUMBERS_WITH_R | Logical to Visual algorithm grouping numbers with adjacent R characters (reversible algorithm). Stable: ICU 3.6
  UBIDI_REORDER_RUNS_ONLY | Reorder runs only to transform a Logical LTR string to the Logical RTL string with the same display, or vice-versa. If this mode is set together with option `UBIDI_OPTION_INSERT_MARKS`, some Bidi controls in the source text may be removed and other controls may be added to produce the minimum combination which has the required display. Stable: ICU 3.6
  UBIDI_REORDER_INVERSE_NUMBERS_AS_L | Visual to Logical algorithm which handles numbers like L (same algorithm as selected by `ubidi_setInverse(TRUE)`. See also: ubidi_setInverse Stable: ICU 3.6
  UBIDI_REORDER_INVERSE_LIKE_DIRECT | Visual to Logical algorithm equivalent to the regular Logical to Visual algorithm. Stable: ICU 3.6
  UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL | Inverse Bidi (Visual to Logical) algorithm for the `UBIDI_REORDER_NUMBERS_SPECIAL` Bidi algorithm. Stable: ICU 3.6
  UBIDI_REORDER_COUNT | Number of values for reordering mode. Stable: ICU 3.6

Definition at line 636 of file ubidi.h.

enum UBiDiReorderingOption

`UBiDiReorderingOption` values indicate which options are specified to affect the Bidi algorithm.

See also:
  ubidi_setReorderingOptions

Stable:
  ICU 3.6

Enumerator:

  UBIDI_OPTION_DEFAULT | option value for `ubidi_setReorderingOptions`: disable all the options which can be set with this function See also: ubidi_setReorderingOptions Stable: ICU 3.6
  UBIDI_OPTION_INSERT_MARKS | option bit for `ubidi_setReorderingOptions`: insert Bidi marks (LRM or RLM) when needed to ensure correct result of a reordering to a Logical order This option must be set or reset before calling `ubidi_setPara`. This option is significant only with reordering modes which generate a result with Logical order, specifically: `UBIDI_REORDER_RUNS_ONLY` `UBIDI_REORDER_INVERSE_NUMBERS_AS_L` `UBIDI_REORDER_INVERSE_LIKE_DIRECT` `UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL` If this option is set in conjunction with reordering mode `UBIDI_REORDER_INVERSE_NUMBERS_AS_L` or with calling `ubidi_setInverse(TRUE)`, it implies option `UBIDI_INSERT_LRM_FOR_NUMERIC` in calls to function `ubidi_writeReordered()`. For other reordering modes, a minimum number of LRM or RLM characters will be added to the source text after reordering it so as to ensure round trip, i.e. when applying the inverse reordering mode on the resulting logical text with removal of Bidi marks (option `UBIDI_OPTION_REMOVE_CONTROLS` set before calling `ubidi_setPara()` or option `UBIDI_REMOVE_BIDI_CONTROLS` in `ubidi_writeReordered`), the result will be identical to the source text in the first transformation. This option will be ignored if specified together with option `UBIDI_OPTION_REMOVE_CONTROLS`. It inhibits option `UBIDI_REMOVE_BIDI_CONTROLS` in calls to function `ubidi_writeReordered()` and it implies option `UBIDI_INSERT_LRM_FOR_NUMERIC` in calls to function `ubidi_writeReordered()` if the reordering mode is `UBIDI_REORDER_INVERSE_NUMBERS_AS_L`. See also: ubidi_setReorderingMode ubidi_setReorderingOptions Stable: ICU 3.6
  UBIDI_OPTION_REMOVE_CONTROLS | option bit for `ubidi_setReorderingOptions`: remove Bidi control characters This option must be set or reset before calling `ubidi_setPara`. This option nullifies option `UBIDI_OPTION_INSERT_MARKS`. It inhibits option `UBIDI_INSERT_LRM_FOR_NUMERIC` in calls to function `ubidi_writeReordered()` and it implies option `UBIDI_REMOVE_BIDI_CONTROLS` in calls to that function. See also: ubidi_setReorderingMode ubidi_setReorderingOptions Stable: ICU 3.6
  UBIDI_OPTION_STREAMING | option bit for `ubidi_setReorderingOptions`: process the output as part of a stream to be continued This option must be set or reset before calling `ubidi_setPara`. This option specifies that the caller is interested in processing large text object in parts. The results of the successive calls are expected to be concatenated by the caller. Only the call for the last part will have this option bit off. When this option bit is on, `ubidi_setPara()` may process less than the full source text in order to truncate the text at a meaningful boundary. The caller should call `ubidi_getProcessedLength()` immediately after calling `ubidi_setPara()` in order to determine how much of the source text has been processed. Source text beyond that length should be resubmitted in following calls to `ubidi_setPara`. The processed length may be less than the length of the source text if a character preceding the last character of the source text constitutes a reasonable boundary (like a block separator) for text to be continued. If the last character of the source text constitutes a reasonable boundary, the whole text will be processed at once. If nowhere in the source text there exists such a reasonable boundary, the processed length will be zero. The caller should check for such an occurrence and do one of the following: submit a larger amount of text with a better chance to include a reasonable boundary. resubmit the same text after turning off option `UBIDI_OPTION_STREAMING`. In all cases, this option should be turned off before processing the last part of the text. When the `UBIDI_OPTION_STREAMING` option is used, it is recommended to call `ubidi_orderParagraphsLTR()` with argument `orderParagraphsLTR` set to `TRUE` before calling `ubidi_setPara` so that later paragraphs may be concatenated to previous paragraphs on the right. See also: ubidi_setReorderingMode ubidi_setReorderingOptions ubidi_getProcessedLength ubidi_orderParagraphsLTR Stable: ICU 3.6

Definition at line 849 of file ubidi.h.

## Function Documentation

void ubidi_close | ( | UBiDi * | pBiDi | ) |

`ubidi_close()` must be called to free the memory associated with a UBiDi object.

Important: A parent `UBiDi` object must not be destroyed or reused if it still has children. If a `UBiDi` object has become the child of another one (its parent) by calling `ubidi_setLine()`, then the child object must be destroyed (closed) or reused (by calling `ubidi_setPara()` or `ubidi_setLine()`) before the parent object.

Parameters:

  | pBiDi | is a `UBiDi` object.

See also:
  ubidi_setPara

  ubidi_setLine

Stable:
  ICU 2.0

int32_t ubidi_countParagraphs | ( | UBiDi * | pBiDi | ) |

Get the number of paragraphs.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.

Returns:
  The number of paragraphs.

Stable:
  ICU 3.4

int32_t ubidi_countRuns | ( | UBiDi * | pBiDi,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Get the number of runs.

This function may invoke the actual reordering on the `UBiDi` object, after `ubidi_setPara()` may have resolved only the levels of the text. Therefore, `ubidi_countRuns()` may have to allocate memory, and may fail doing so.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | pErrorCode | must be a valid pointer to an error code value.

Returns:
  The number of runs.

Stable:
  ICU 2.0

void ubidi_getClassCallback | ( | UBiDi * | pBiDi,
|  | UBiDiClassCallback ** | fn,
|  | const void ** | context |
| ) |  |  |

Get the current callback function used for Bidi class determination.

Parameters:

  | pBiDi | is the paragraph `UBiDi` object.
  | fn | fillin: Returns the callback function pointer.
  | context | fillin: Returns the callback's private context.

See also:
  ubidi_setClassCallback

Stable:
  ICU 3.6

U_CDECL_END UCharDirection ubidi_getCustomizedClass | ( | UBiDi * | pBiDi,
|  | UChar32 | c |
| ) |  |  |

Retrieve the Bidi class for a given code point.

If a `UBiDiClassCallback` callback is defined and returns a value other than `U_BIDI_CLASS_DEFAULT`, that value is used; otherwise the default class determination mechanism is invoked.

Parameters:

  | pBiDi | is the paragraph `UBiDi` object.
  | c | is the code point whose Bidi class must be retrieved.

Returns:
  The Bidi class for character `c` based on the given `pBiDi` instance.

See also:
  UBiDiClassCallback

Stable:
  ICU 3.6

UBiDiDirection ubidi_getDirection | ( | const UBiDi * | pBiDi | ) |

Get the directionality of the text.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.

Returns:
  a value of `UBIDI_LTR`, `UBIDI_RTL` or `UBIDI_MIXED` that indicates if the entire text represented by this object is unidirectional, and which direction, or if it is mixed-directional.

See also:
  UBiDiDirection

Stable:
  ICU 2.0

Referenced by ParagraphLayout::getTextDirection().

int32_t ubidi_getLength | ( | const UBiDi * | pBiDi | ) |

Get the length of the text.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.

Returns:
  The length of the text that the UBiDi object was created for.

Stable:
  ICU 2.0

UBiDiLevel ubidi_getLevelAt | ( | const UBiDi * | pBiDi,
|  | int32_t | charIndex |
| ) |  |  |

Get the level for one character.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | charIndex | the index of a character. It must be in the range [0..ubidi_getProcessedLength(pBiDi)].

Returns:
  The level for the character at charIndex (0 if charIndex is not in the valid range).

See also:
  UBiDiLevel

  ubidi_getProcessedLength

Stable:
  ICU 2.0

const UBiDiLevel* ubidi_getLevels | ( | UBiDi * | pBiDi,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Get an array of levels for each character.

Note that this function may allocate memory under some circumstances, unlike `ubidi_getLevelAt()`.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object, whose text length must be strictly positive.
  | pErrorCode | must be a valid pointer to an error code value.

Returns:
  The levels array for the text, or `NULL` if an error occurs.

See also:
  UBiDiLevel

  ubidi_getProcessedLength

Stable:
  ICU 2.0

int32_t ubidi_getLogicalIndex | ( | UBiDi * | pBiDi,
|  | int32_t | visualIndex,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Get the logical text position from a visual position.

If such a mapping is used many times on the same `UBiDi` object, then calling `ubidi_getVisualMap()` is more efficient.

The value returned may be `UBIDI_MAP_NOWHERE` if there is no logical position because the corresponding text character is a Bidi mark inserted in the output by option `UBIDI_OPTION_INSERT_MARKS`.

This is the inverse function to `ubidi_getVisualIndex()`.

When the visual output is altered by using options of `ubidi_writeReordered()` such as `UBIDI_INSERT_LRM_FOR_NUMERIC`, `UBIDI_KEEP_BASE_COMBINING`, `UBIDI_OUTPUT_REVERSE`, `UBIDI_REMOVE_BIDI_CONTROLS`, the logical position returned may not be correct. It is advised to use, when possible, reordering options such as `UBIDI_OPTION_INSERT_MARKS` and `UBIDI_OPTION_REMOVE_CONTROLS`.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | visualIndex | is the visual position of a character.
  | pErrorCode | must be a valid pointer to an error code value.

Returns:
  The index of this character in the text.

See also:
  ubidi_getVisualMap

  ubidi_getVisualIndex

  ubidi_getResultLength

Stable:
  ICU 2.0

void ubidi_getLogicalMap | ( | UBiDi * | pBiDi,
|  | int32_t * | indexMap,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Get a logical-to-visual index map (array) for the characters in the UBiDi (paragraph or line) object.

Some values in the map may be `UBIDI_MAP_NOWHERE` if the corresponding text characters are Bidi controls removed from the visual output by the option `UBIDI_OPTION_REMOVE_CONTROLS`.

When the visual output is altered by using options of `ubidi_writeReordered()` such as `UBIDI_INSERT_LRM_FOR_NUMERIC`, `UBIDI_KEEP_BASE_COMBINING`, `UBIDI_OUTPUT_REVERSE`, `UBIDI_REMOVE_BIDI_CONTROLS`, the visual positions returned may not be correct. It is advised to use, when possible, reordering options such as `UBIDI_OPTION_INSERT_MARKS` and `UBIDI_OPTION_REMOVE_CONTROLS`.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | indexMap | is a pointer to an array of `ubidi_getProcessedLength()` indexes which will reflect the reordering of the characters. If option `UBIDI_OPTION_INSERT_MARKS` is set, the number of elements allocated in `indexMap` must be no less than `ubidi_getResultLength()`. The array does not need to be initialized. The index map will result in `indexMap[logicalIndex]==visualIndex`.
  | pErrorCode | must be a valid pointer to an error code value.

See also:
  ubidi_getVisualMap

  ubidi_getVisualIndex

  ubidi_getProcessedLength

  ubidi_getResultLength

Stable:
  ICU 2.0

void ubidi_getLogicalRun | ( | const UBiDi * | pBiDi,
|  | int32_t | logicalPosition,
|  | int32_t * | pLogicalLimit,
|  | UBiDiLevel * | pLevel |
| ) |  |  |

Get a logical run.

This function returns information about a run and is used to retrieve runs in logical order.

This is especially useful for line-breaking on a paragraph.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | logicalPosition | is a logical position within the source text.
  | pLogicalLimit | will receive the limit of the corresponding run. The l-value that you point to here may be the same expression (variable) as the one for `logicalPosition`. This pointer can be `NULL` if this value is not necessary.
  | pLevel | will receive the level of the corresponding run. This pointer can be `NULL` if this value is not necessary.

See also:
  ubidi_getProcessedLength

Stable:
  ICU 2.0

int32_t ubidi_getParagraph | ( | const UBiDi * | pBiDi,
|  | int32_t | charIndex,
|  | int32_t * | pParaStart,
|  | int32_t * | pParaLimit,
|  | UBiDiLevel * | pParaLevel,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Get a paragraph, given a position within the text.

This function returns information about a paragraph.
Note: if the paragraph index is known, it is more efficient to retrieve the paragraph information using ubidi_getParagraphByIndex().

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | charIndex | is the index of a character within the text, in the range `[0..ubidi_getProcessedLength(pBiDi)-1]`.
  | pParaStart | will receive the index of the first character of the paragraph in the text. This pointer can be `NULL` if this value is not necessary.
  | pParaLimit | will receive the limit of the paragraph. The l-value that you point to here may be the same expression (variable) as the one for `charIndex`. This pointer can be `NULL` if this value is not necessary.
  | pParaLevel | will receive the level of the paragraph. This pointer can be `NULL` if this value is not necessary.
  | pErrorCode | must be a valid pointer to an error code value.

Returns:
  The index of the paragraph containing the specified position.

See also:
  ubidi_getProcessedLength

Stable:
  ICU 3.4

void ubidi_getParagraphByIndex | ( | const UBiDi * | pBiDi,
|  | int32_t | paraIndex,
|  | int32_t * | pParaStart,
|  | int32_t * | pParaLimit,
|  | UBiDiLevel * | pParaLevel,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Get a paragraph, given the index of this paragraph.

This function returns information about a paragraph.

Parameters:

  | pBiDi | is the paragraph `UBiDi` object.
  | paraIndex | is the number of the paragraph, in the range `[0..ubidi_countParagraphs(pBiDi)-1]`.
  | pParaStart | will receive the index of the first character of the paragraph in the text. This pointer can be `NULL` if this value is not necessary.
  | pParaLimit | will receive the limit of the paragraph. This pointer can be `NULL` if this value is not necessary.
  | pParaLevel | will receive the level of the paragraph. This pointer can be `NULL` if this value is not necessary.
  | pErrorCode | must be a valid pointer to an error code value.

Stable:
  ICU 3.4

UBiDiLevel ubidi_getParaLevel | ( | const UBiDi * | pBiDi | ) |

Get the paragraph level of the text.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.

Returns:
  The paragraph level. If there are multiple paragraphs, their level may vary if the required paraLevel is UBIDI_DEFAULT_LTR or UBIDI_DEFAULT_RTL. In that case, the level of the first paragraph is returned.

See also:
  UBiDiLevel

  ubidi_getParagraph

  ubidi_getParagraphByIndex

Stable:
  ICU 2.0

Referenced by ParagraphLayout::getParagraphLevel().

int32_t ubidi_getProcessedLength | ( | const UBiDi * | pBiDi | ) |

Get the length of the source text processed by the last call to `ubidi_setPara()`.

This length may be different from the length of the source text if option `UBIDI_OPTION_STREAMING` has been set.
Note that whenever the length of the text affects the execution or the result of a function, it is the processed length which must be considered, except for `ubidi_setPara` (which receives unprocessed source text) and `ubidi_getLength` (which returns the original length of the source text).
In particular, the processed length is the one to consider in the following cases:

- maximum value of the `limit` argument of `ubidi_setLine`
- maximum value of the `charIndex` argument of `ubidi_getParagraph`
- maximum value of the `charIndex` argument of `ubidi_getLevelAt`
- number of elements in the array returned by `ubidi_getLevels`
- maximum value of the `logicalStart` argument of `ubidi_getLogicalRun`
- maximum value of the `logicalIndex` argument of `ubidi_getVisualIndex`
- number of elements filled in the `*indexMap` argument of `ubidi_getLogicalMap`
- length of text processed by `ubidi_writeReordered`

Parameters:

  | pBiDi | is the paragraph `UBiDi` object.

Returns:
  The length of the part of the source text processed by the last call to `ubidi_setPara`.

See also:
  ubidi_setPara

  UBIDI_OPTION_STREAMING

Stable:
  ICU 3.6

UBiDiReorderingMode ubidi_getReorderingMode | ( | UBiDi * | pBiDi | ) |

What is the requested reordering mode for a given Bidi object?

Parameters:

  | pBiDi | is a `UBiDi` object.

Returns:
  the current reordering mode of the Bidi object

See also:
  ubidi_setReorderingMode

Stable:
  ICU 3.6

uint32_t ubidi_getReorderingOptions | ( | UBiDi * | pBiDi | ) |

What are the reordering options applied to a given Bidi object?

Parameters:

  | pBiDi | is a `UBiDi` object.

Returns:
  the current reordering options of the Bidi object

See also:
  ubidi_setReorderingOptions

Stable:
  ICU 3.6

int32_t ubidi_getResultLength | ( | const UBiDi * | pBiDi | ) |

Get the length of the reordered text resulting from the last call to `ubidi_setPara()`.

This length may be different from the length of the source text if option `UBIDI_OPTION_INSERT_MARKS` or option `UBIDI_OPTION_REMOVE_CONTROLS` has been set.
This resulting length is the one to consider in the following cases:

- maximum value of the `visualIndex` argument of `ubidi_getLogicalIndex`
- number of elements of the `*indexMap` argument of `ubidi_getVisualMap`

Note that this length stays identical to the source text length if Bidi marks are inserted or removed using option bits of `ubidi_writeReordered`, or if option `UBIDI_REORDER_INVERSE_NUMBERS_AS_L` has been set.

Parameters:

  | pBiDi | is the paragraph `UBiDi` object.

Returns:
  The length of the reordered text resulting from the last call to `ubidi_setPara`.

See also:
  ubidi_setPara

  UBIDI_OPTION_INSERT_MARKS

  UBIDI_OPTION_REMOVE_CONTROLS

Stable:
  ICU 3.6

const UChar* ubidi_getText | ( | const UBiDi * | pBiDi | ) |

Get the pointer to the text.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.

Returns:
  The pointer to the text that the UBiDi object was created for.

See also:
  ubidi_setPara

  ubidi_setLine

Stable:
  ICU 2.0

int32_t ubidi_getVisualIndex | ( | UBiDi * | pBiDi,
|  | int32_t | logicalIndex,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Get the visual position from a logical text position.

If such a mapping is used many times on the same `UBiDi` object, then calling `ubidi_getLogicalMap()` is more efficient.

The value returned may be `UBIDI_MAP_NOWHERE` if there is no visual position because the corresponding text character is a Bidi control removed from output by the option `UBIDI_OPTION_REMOVE_CONTROLS`.

When the visual output is altered by using options of `ubidi_writeReordered()` such as `UBIDI_INSERT_LRM_FOR_NUMERIC`, `UBIDI_KEEP_BASE_COMBINING`, `UBIDI_OUTPUT_REVERSE`, `UBIDI_REMOVE_BIDI_CONTROLS`, the visual position returned may not be correct. It is advised to use, when possible, reordering options such as `UBIDI_OPTION_INSERT_MARKS` and `UBIDI_OPTION_REMOVE_CONTROLS`.

Note that in right-to-left runs, this mapping places modifier letters before base characters and second surrogates before first ones.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | logicalIndex | is the index of a character in the text.
  | pErrorCode | must be a valid pointer to an error code value.

Returns:
  The visual position of this character.

See also:
  ubidi_getLogicalMap

  ubidi_getLogicalIndex

  ubidi_getProcessedLength

Stable:
  ICU 2.0

void ubidi_getVisualMap | ( | UBiDi * | pBiDi,
|  | int32_t * | indexMap,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Get a visual-to-logical index map (array) for the characters in the UBiDi (paragraph or line) object.

Some values in the map may be `UBIDI_MAP_NOWHERE` if the corresponding text characters are Bidi marks inserted in the visual output by the option `UBIDI_OPTION_INSERT_MARKS`.

When the visual output is altered by using options of `ubidi_writeReordered()` such as `UBIDI_INSERT_LRM_FOR_NUMERIC`, `UBIDI_KEEP_BASE_COMBINING`, `UBIDI_OUTPUT_REVERSE`, `UBIDI_REMOVE_BIDI_CONTROLS`, the logical positions returned may not be correct. It is advised to use, when possible, reordering options such as `UBIDI_OPTION_INSERT_MARKS` and `UBIDI_OPTION_REMOVE_CONTROLS`.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | indexMap | is a pointer to an array of `ubidi_getResultLength()` indexes which will reflect the reordering of the characters. If option `UBIDI_OPTION_REMOVE_CONTROLS` is set, the number of elements allocated in `indexMap` must be no less than `ubidi_getProcessedLength()`. The array does not need to be initialized. The index map will result in `indexMap[visualIndex]==logicalIndex`.
  | pErrorCode | must be a valid pointer to an error code value.

See also:
  ubidi_getLogicalMap

  ubidi_getLogicalIndex

  ubidi_getProcessedLength

  ubidi_getResultLength

Stable:
  ICU 2.0

UBiDiDirection ubidi_getVisualRun | ( | UBiDi * | pBiDi,
|  | int32_t | runIndex,
|  | int32_t * | pLogicalStart,
|  | int32_t * | pLength |
| ) |  |  |

Get one run's logical start, length, and directionality, which can be 0 for LTR or 1 for RTL.

In an RTL run, the character at the logical start is visually on the right of the displayed run. The length is the number of characters in the run.

`ubidi_countRuns()` should be called before the runs are retrieved.

Parameters:

  | pBiDi | is the paragraph or line `UBiDi` object.
  | runIndex | is the number of the run in visual order, in the range `[0..ubidi_countRuns(pBiDi)-1]`.
  | pLogicalStart | is the first logical character index in the text. The pointer may be `NULL` if this index is not needed.
  | pLength | is the number of characters (at least one) in the run. The pointer may be `NULL` if this is not needed.

Returns:
  the directionality of the run, `UBIDI_LTR==0` or `UBIDI_RTL==1`, never `UBIDI_MIXED`.

See also:
  ubidi_countRuns

Example:

     int32_t i, count=ubidi_countRuns(pBiDi),
             logicalStart, visualIndex=0, length;
     for(i=0; i<count; ++i) {
        if(UBIDI_LTR==ubidi_getVisualRun(pBiDi, i, &logicalStart, &length)) {
             do { // LTR
                 show_char(text[logicalStart++], visualIndex++);
             } while(--length>0);
         } else {
             logicalStart+=length;  // logicalLimit
             do { // RTL
                 show_char(text[--logicalStart], visualIndex++);
             } while(--length>0);
         }
     }
     *

Note that in right-to-left runs, code like this places modifier letters before base characters and second surrogates before first ones.

Stable:
  ICU 2.0

void ubidi_invertMap | ( | const int32_t * | srcMap,
|  | int32_t * | destMap,
|  | int32_t | length |
| ) |  |  |

Invert an index map.

The index mapping of the first map is inverted and written to the second one.

Parameters:

  | srcMap | is an array with `length` elements which defines the original mapping from a source array containing `length` elements to a destination array. Some elements of the source array may have no mapping in the destination array. In that case, their value will be the special value `UBIDI_MAP_NOWHERE`. All elements must be >=0 or equal to `UBIDI_MAP_NOWHERE`. Some elements may have a value >= `length`, if the destination array has more elements than the source array. There must be no duplicate indexes (two or more elements with the same value except `UBIDI_MAP_NOWHERE`).
  | destMap | is an array with a number of elements equal to 1 + the highest value in `srcMap`. `destMap` will be filled with the inverse mapping. If element with index i in `srcMap` has a value k different from `UBIDI_MAP_NOWHERE`, this means that element i of the source array maps to element k in the destination array. The inverse map will have value i in its k-th element. For all elements of the destination array which do not map to an element in the source array, the corresponding element in the inverse map will have a value equal to `UBIDI_MAP_NOWHERE`.
  | length | is the length of each array.

See also:
  UBIDI_MAP_NOWHERE

Stable:
  ICU 2.0

UBool ubidi_isInverse | ( | UBiDi * | pBiDi | ) |

Is this Bidi object set to perform the inverse Bidi algorithm?

Note: calling this function after setting the reordering mode with `ubidi_setReorderingMode` will return `TRUE` if the reordering mode was set to `UBIDI_REORDER_INVERSE_NUMBERS_AS_L`, `FALSE` for all other values.

Parameters:

  | pBiDi | is a `UBiDi` object.

Returns:
  TRUE if the Bidi object is set to perform the inverse Bidi algorithm by handling numbers as L.

See also:
  ubidi_setInverse

  ubidi_setReorderingMode

Stable:
  ICU 2.0

UBool ubidi_isOrderParagraphsLTR | ( | UBiDi * | pBiDi | ) |

Is this Bidi object set to allocate level 0 to block separators so that successive paragraphs progress from left to right?

Parameters:

  | pBiDi | is a `UBiDi` object.

Returns:
  TRUE if the Bidi object is set to allocate level 0 to block separators.

See also:
  ubidi_orderParagraphsLTR

Stable:
  ICU 3.4

UBiDi* ubidi_open | ( | void |  | ) |

Allocate a `UBiDi` structure.

Such an object is initially empty. It is assigned the Bidi properties of a piece of text containing one or more paragraphs by `ubidi_setPara()` or the Bidi properties of a line within a paragraph by `ubidi_setLine()`.

This object can be reused for as long as it is not deallocated by calling `ubidi_close()`.

`ubidi_setPara()` and `ubidi_setLine()` will allocate additional memory for internal structures as necessary.

Returns:
  An empty `UBiDi` object.

Stable:
  ICU 2.0

UBiDi* ubidi_openSized | ( | int32_t | maxLength,
|  | int32_t | maxRunCount,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Allocate a `UBiDi` structure with preallocated memory for internal structures.

This function provides a `UBiDi` object like `ubidi_open()` with no arguments, but it also preallocates memory for internal structures according to the sizings supplied by the caller.

Subsequent functions will not allocate any more memory, and are thus guaranteed not to fail because of lack of memory.

The preallocation can be limited to some of the internal memory by setting some values to 0 here. That means that if, e.g., `maxRunCount` cannot be reasonably predetermined and should not be set to `maxLength` (the only failproof value) to avoid wasting memory, then `maxRunCount` could be set to 0 here and the internal structures that are associated with it will be allocated on demand, just like with `ubidi_open()`.

Parameters:

  | maxLength | is the maximum text or line length that internal memory will be preallocated for. An attempt to associate this object with a longer text will fail, unless this value is 0, which leaves the allocation up to the implementation.
  | maxRunCount | is the maximum anticipated number of same-level runs that internal memory will be preallocated for. An attempt to access visual runs on an object that was not preallocated for as many runs as the text was actually resolved to will fail, unless this value is 0, which leaves the allocation up to the implementation. The number of runs depends on the actual text and maybe anywhere between 1 and `maxLength`. It is typically small.
  | pErrorCode | must be a valid pointer to an error code value.

Returns:
  An empty `UBiDi` object with preallocated memory.

Stable:
  ICU 2.0

void ubidi_orderParagraphsLTR | ( | UBiDi * | pBiDi,
|  | UBool | orderParagraphsLTR |
| ) |  |  |

Specify whether block separators must be allocated level zero, so that successive paragraphs will progress from left to right.

This function must be called before `ubidi_setPara()`. Paragraph separators (B) may appear in the text. Setting them to level zero means that all paragraph separators (including one possibly appearing in the last text position) are kept in the reordered text after the text that they follow in the source text. When this feature is not enabled, a paragraph separator at the last position of the text before reordering will go to the first position of the reordered text when the paragraph level is odd.

Parameters:

  | pBiDi | is a `UBiDi` object.
  | orderParagraphsLTR | specifies whether paragraph separators (B) must receive level 0, so that successive paragraphs progress from left to right.

See also:
  ubidi_setPara

Stable:
  ICU 3.4

void ubidi_reorderLogical | ( | const UBiDiLevel * | levels,
|  | int32_t | length,
|  | int32_t * | indexMap |
| ) |  |  |

This is a convenience function that does not use a UBiDi object.

It is intended to be used for when an application has determined the levels of objects (character sequences) and just needs to have them reordered (L2). This is equivalent to using `ubidi_getLogicalMap()` on a `UBiDi` object.

Parameters:

  | levels | is an array with `length` levels that have been determined by the application.
  | length | is the number of levels in the array, or, semantically, the number of objects to be reordered. It must be `length>0`.
  | indexMap | is a pointer to an array of `length` indexes which will reflect the reordering of the characters. The array does not need to be initialized.

The index map will result in `indexMap[logicalIndex]==visualIndex`.

Stable:
  ICU 2.0

void ubidi_reorderVisual | ( | const UBiDiLevel * | levels,
|  | int32_t | length,
|  | int32_t * | indexMap |
| ) |  |  |

This is a convenience function that does not use a UBiDi object.

It is intended to be used for when an application has determined the levels of objects (character sequences) and just needs to have them reordered (L2). This is equivalent to using `ubidi_getVisualMap()` on a `UBiDi` object.

Parameters:

  | levels | is an array with `length` levels that have been determined by the application.
  | length | is the number of levels in the array, or, semantically, the number of objects to be reordered. It must be `length>0`.
  | indexMap | is a pointer to an array of `length` indexes which will reflect the reordering of the characters. The array does not need to be initialized.

The index map will result in `indexMap[visualIndex]==logicalIndex`.

Stable:
  ICU 2.0

void ubidi_setClassCallback | ( | UBiDi * | pBiDi,
|  | UBiDiClassCallback * | newFn,
|  | const void * | newContext,
|  | UBiDiClassCallback ** | oldFn,
|  | const void ** | oldContext,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Set the callback function and callback data used by the UBA implementation for Bidi class determination.

This may be useful for assigning Bidi classes to PUA characters, or for special application needs. For instance, an application may want to handle all spaces like L or R characters (according to the base direction) when creating the visual ordering of logical lines which are part of a report organized in columns: there should not be interaction between adjacent cells.

Parameters:

  | pBiDi | is the paragraph `UBiDi` object.
  | newFn | is the new callback function pointer.
  | newContext | is the new callback context pointer. This can be NULL.
  | oldFn | fillin: Returns the old callback function pointer. This can be NULL.
  | oldContext | fillin: Returns the old callback's context. This can be NULL.
  | pErrorCode | must be a valid pointer to an error code value.

See also:
  ubidi_getClassCallback

Stable:
  ICU 3.6

void ubidi_setInverse | ( | UBiDi * | pBiDi,
|  | UBool | isInverse |
| ) |  |  |

Modify the operation of the Bidi algorithm such that it approximates an "inverse Bidi" algorithm.

This function must be called before `ubidi_setPara()`.

The normal operation of the Bidi algorithm as described in the Unicode Technical Report is to take text stored in logical (keyboard, typing) order and to determine the reordering of it for visual rendering. Some legacy systems store text in visual order, and for operations with standard, Unicode-based algorithms, the text needs to be transformed to logical order. This is effectively the inverse algorithm of the described Bidi algorithm. Note that there is no standard algorithm for this "inverse Bidi" and that the current implementation provides only an approximation of "inverse Bidi".

With `isInverse` set to `TRUE`, this function changes the behavior of some of the subsequent functions in a way that they can be used for the inverse Bidi algorithm. Specifically, runs of text with numeric characters will be treated in a special way and may need to be surrounded with LRM characters when they are written in reordered sequence.

Output runs should be retrieved using `ubidi_getVisualRun()`. Since the actual input for "inverse Bidi" is visually ordered text and `ubidi_getVisualRun()` gets the reordered runs, these are actually the runs of the logically ordered output.

Calling this function with argument `isInverse` set to `TRUE` is equivalent to calling `ubidi_setReorderingMode` with argument `reorderingMode` set to `UBIDI_REORDER_INVERSE_NUMBERS_AS_L`.
Calling this function with argument `isInverse` set to `FALSE` is equivalent to calling `ubidi_setReorderingMode` with argument `reorderingMode` set to `UBIDI_REORDER_DEFAULT`.

Parameters:

  | pBiDi | is a `UBiDi` object.
  | isInverse | specifies "forward" or "inverse" Bidi operation.

See also:
  ubidi_setPara

  ubidi_writeReordered

  ubidi_setReorderingMode

Stable:
  ICU 2.0

void ubidi_setLine | ( | const UBiDi * | pParaBiDi,
|  | int32_t | start,
|  | int32_t | limit,
|  | UBiDi * | pLineBiDi,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

`ubidi_setLine()` sets a `UBiDi` to contain the reordering information, especially the resolved levels, for all the characters in a line of text.

This line of text is specified by referring to a `UBiDi` object representing this information for a piece of text containing one or more paragraphs, and by specifying a range of indexes in this text.

In the new line object, the indexes will range from 0 to `limit-start-1`.

This is used after calling `ubidi_setPara()` for a piece of text, and after line-breaking on that text. It is not necessary if each paragraph is treated as a single line.

After line-breaking, rules (L1) and (L2) for the treatment of trailing WS and for reordering are performed on a `UBiDi` object that represents a line.

Important: `pLineBiDi` shares data with `pParaBiDi`. You must destroy or reuse `pLineBiDi` before `pParaBiDi`. In other words, you must destroy or reuse the `UBiDi` object for a line before the object for its parent paragraph.

The text pointer that was stored in `pParaBiDi` is also copied, and `start` is added to it so that it points to the beginning of the line for this object.

Parameters:

  | pParaBiDi | is the parent paragraph object. It must have been set by a successful call to ubidi_setPara.
  | start | is the line's first index into the text.
  | limit | is just behind the line's last index into the text (its last index +1). It must be `0<=start<limit<=`containing paragraph limit. If the specified line crosses a paragraph boundary, the function will terminate with error code U_ILLEGAL_ARGUMENT_ERROR.
  | pLineBiDi | is the object that will now represent a line of the text.
  | pErrorCode | must be a valid pointer to an error code value.

See also:
  ubidi_setPara

  ubidi_getProcessedLength

Stable:
  ICU 2.0

void ubidi_setPara | ( | UBiDi * | pBiDi,
|  | const UChar * | text,
|  | int32_t | length,
|  | UBiDiLevel | paraLevel,
|  | UBiDiLevel * | embeddingLevels,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Perform the Unicode Bidi algorithm.

It is defined in the Unicode Standard Anned #9, version 13, also described in The Unicode Standard, Version 4.0 .

This function takes a piece of plain text containing one or more paragraphs, with or without externally specified embedding levels from styled text and computes the left-right-directionality of each character.

If the entire text is all of the same directionality, then the function may not perform all the steps described by the algorithm, i.e., some levels may not be the same as if all steps were performed. This is not relevant for unidirectional text.
For example, in pure LTR text with numbers the numbers would get a resolved level of 2 higher than the surrounding text according to the algorithm. This implementation may set all resolved levels to the same value in such a case.

The text can be composed of multiple paragraphs. Occurrence of a block separator in the text terminates a paragraph, and whatever comes next starts a new paragraph. The exception to this rule is when a Carriage Return (CR) is followed by a Line Feed (LF). Both CR and LF are block separators, but in that case, the pair of characters is considered as terminating the preceding paragraph, and a new paragraph will be started by a character coming after the LF.

Parameters:

  | pBiDi | A `UBiDi` object allocated with `ubidi_open()` which will be set to contain the reordering information, especially the resolved levels for all the characters in `text`.
  | text | is a pointer to the text that the Bidi algorithm will be performed on. This pointer is stored in the UBiDi object and can be retrieved with `ubidi_getText()`. Note: the text must be (at least) `length` long.
  | length | is the length of the text; if `length==-1` then the text must be zero-terminated.
  | paraLevel | specifies the default level for the text; it is typically 0 (LTR) or 1 (RTL). If the function shall determine the paragraph level from the text, then `paraLevel` can be set to either `UBIDI_DEFAULT_LTR` or `UBIDI_DEFAULT_RTL`; if the text contains multiple paragraphs, the paragraph level shall be determined separately for each paragraph; if a paragraph does not include any strongly typed character, then the desired default is used (0 for LTR or 1 for RTL). Any other value between 0 and `UBIDI_MAX_EXPLICIT_LEVEL` is also valid, with odd levels indicating RTL.
  | embeddingLevels | (in) may be used to preset the embedding and override levels, ignoring characters like LRE and PDF in the text. A level overrides the directional property of its corresponding (same index) character if the level has the `UBIDI_LEVEL_OVERRIDE` bit set. Except for that bit, it must be `paraLevel<=embeddingLevels[]<=UBIDI_MAX_EXPLICIT_LEVEL`, with one exception: a level of zero may be specified for a paragraph separator even if `paraLevel>0` when multiple paragraphs are submitted in the same call to `ubidi_setPara()`. Caution: A copy of this pointer, not of the levels, will be stored in the `UBiDi` object; the `embeddingLevels` array must not be deallocated before the `UBiDi` structure is destroyed or reused, and the `embeddingLevels` should not be modified to avoid unexpected results on subsequent Bidi operations. However, the `ubidi_setPara()` and `ubidi_setLine()` functions may modify some or all of the levels. After the `UBiDi` object is reused or destroyed, the caller must take care of the deallocation of the `embeddingLevels` array. Note: the `embeddingLevels` array must be at least `length` long.
  | pErrorCode | must be a valid pointer to an error code value.

Stable:
  ICU 2.0

void ubidi_setReorderingMode | ( | UBiDi * | pBiDi,
|  | UBiDiReorderingMode | reorderingMode |
| ) |  |  |

Modify the operation of the Bidi algorithm such that it implements some variant to the basic Bidi algorithm or approximates an "inverse Bidi" algorithm, depending on different values of the "reordering mode".

This function must be called before `ubidi_setPara()`, and stays in effect until called again with a different argument.

The normal operation of the Bidi algorithm as described in the Unicode Standard Annex #9 is to take text stored in logical (keyboard, typing) order and to determine how to reorder it for visual rendering.

With the reordering mode set to a value other than `UBIDI_REORDER_DEFAULT`, this function changes the behavior of some of the subsequent functions in a way such that they implement an inverse Bidi algorithm or some other algorithm variants.

Some legacy systems store text in visual order, and for operations with standard, Unicode-based algorithms, the text needs to be transformed into logical order. This is effectively the inverse algorithm of the described Bidi algorithm. Note that there is no standard algorithm for this "inverse Bidi", so a number of variants are implemented here.

In other cases, it may be desirable to emulate some variant of the Logical to Visual algorithm (e.g. one used in MS Windows), or perform a Logical to Logical transformation.

- When the reordering mode is set to `UBIDI_REORDER_DEFAULT`, the standard Bidi Logical to Visual algorithm is applied.

- When the reordering mode is set to `UBIDI_REORDER_NUMBERS_SPECIAL`, the algorithm used to perform Bidi transformations when calling `ubidi_setPara` should approximate the algorithm used in Microsoft Windows XP rather than strictly conform to the Unicode Bidi algorithm.
  The differences between the basic algorithm and the algorithm addressed by this option are as follows:
  - Within text at an even embedding level, the sequence "123AB" (where AB represent R or AL letters) is transformed to "123BA" by the Unicode algorithm and to "BA123" by the Windows algorithm.
  - Arabic-Indic numbers (AN) are handled by the Windows algorithm just like regular numbers (EN).

- When the reordering mode is set to `UBIDI_REORDER_GROUP_NUMBERS_WITH_R`, numbers located between LTR text and RTL text are associated with the RTL text. For instance, an LTR paragraph with content "abc 123 DEF" (where upper case letters represent RTL characters) will be transformed to "abc FED 123" (and not "abc 123 FED"), "DEF 123 abc" will be transformed to "123 FED abc" and "123 FED abc" will be transformed to "DEF 123 abc". This makes the algorithm reversible and makes it useful when round trip (from visual to logical and back to visual) must be achieved without adding LRM characters. However, this is a variation from the standard Unicode Bidi algorithm.
  The source text should not contain Bidi control characters other than LRM or RLM.

- When the reordering mode is set to `UBIDI_REORDER_RUNS_ONLY`, a "Logical to Logical" transformation must be performed:
  - If the default text level of the source text (argument `paraLevel` in `ubidi_setPara`) is even, the source text will be handled as LTR logical text and will be transformed to the RTL logical text which has the same LTR visual display.
  - If the default level of the source text is odd, the source text will be handled as RTL logical text and will be transformed to the LTR logical text which has the same LTR visual display.
  This mode may be needed when logical text which is basically Arabic or Hebrew, with possible included numbers or phrases in English, has to be displayed as if it had an even embedding level (this can happen if the displaying application treats all text as if it was basically LTR).
  This mode may also be needed in the reverse case, when logical text which is basically English, with possible included phrases in Arabic or Hebrew, has to be displayed as if it had an odd embedding level.
  Both cases could be handled by adding LRE or RLE at the head of the text, if the display subsystem supports these formatting controls. If it does not, the problem may be handled by transforming the source text in this mode before displaying it, so that it will be displayed properly.
  The source text should not contain Bidi control characters other than LRM or RLM.

- When the reordering mode is set to `UBIDI_REORDER_INVERSE_NUMBERS_AS_L`, an "inverse Bidi" algorithm is applied. Runs of text with numeric characters will be treated like LTR letters and may need to be surrounded with LRM characters when they are written in reordered sequence (the option `UBIDI_INSERT_LRM_FOR_NUMERIC` can be used with function `ubidi_writeReordered` to this end. This mode is equivalent to calling `ubidi_setInverse()` with argument `isInverse` set to `TRUE`.

- When the reordering mode is set to `UBIDI_REORDER_INVERSE_LIKE_DIRECT`, the "direct" Logical to Visual Bidi algorithm is used as an approximation of an "inverse Bidi" algorithm. This mode is similar to mode `UBIDI_REORDER_INVERSE_NUMBERS_AS_L` but is closer to the regular Bidi algorithm.
  For example, an LTR paragraph with the content "FED 123 456 CBA" (where upper case represents RTL characters) will be transformed to "ABC 456 123 DEF", as opposed to "DEF 123 456 ABC" with mode `UBIDI_REORDER_INVERSE_NUMBERS_AS_L`.
  When used in conjunction with option `UBIDI_OPTION_INSERT_MARKS`, this mode generally adds Bidi marks to the output significantly more sparingly than mode `UBIDI_REORDER_INVERSE_NUMBERS_AS_L` with option `UBIDI_INSERT_LRM_FOR_NUMERIC` in calls to `ubidi_writeReordered`.

- When the reordering mode is set to `UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL`, the Logical to Visual Bidi algorithm used in Windows XP is used as an approximation of an "inverse Bidi" algorithm.
  For example, an LTR paragraph with the content "abc FED123" (where upper case represents RTL characters) will be transformed to "abc 123DEF.

In all the reordering modes specifying an "inverse Bidi" algorithm (i.e. those with a name starting with `UBIDI_REORDER_INVERSE`), output runs should be retrieved using `ubidi_getVisualRun()`, and the output text with `ubidi_writeReordered()`. The caller should keep in mind that in "inverse Bidi" modes the input is actually visually ordered text and reordered output returned by `ubidi_getVisualRun()` or `ubidi_writeReordered()` are actually runs or character string of logically ordered output.
For all the "inverse Bidi" modes, the source text should not contain Bidi control characters other than LRM or RLM.

Note that option `UBIDI_OUTPUT_REVERSE` of `ubidi_writeReordered` has no useful meaning and should not be used in conjunction with any value of the reordering mode specifying "inverse Bidi" or with value `UBIDI_REORDER_RUNS_ONLY`.

Parameters:

  | pBiDi | is a `UBiDi` object.
  | reorderingMode | specifies the required variant of the Bidi algorithm.

See also:
  UBiDiReorderingMode

  ubidi_setInverse

  ubidi_setPara

  ubidi_writeReordered

Stable:
  ICU 3.6

void ubidi_setReorderingOptions | ( | UBiDi * | pBiDi,
|  | uint32_t | reorderingOptions |
| ) |  |  |

Specify which of the reordering options should be applied during Bidi transformations.

Parameters:

  | pBiDi | is a `UBiDi` object.
  | reorderingOptions | is a combination of zero or more of the following options: `UBIDI_OPTION_DEFAULT`, `UBIDI_OPTION_INSERT_MARKS`, `UBIDI_OPTION_REMOVE_CONTROLS`, `UBIDI_OPTION_STREAMING`.

See also:
  ubidi_getReorderingOptions

Stable:
  ICU 3.6

int32_t ubidi_writeReordered | ( | UBiDi * | pBiDi,
|  | UChar * | dest,
|  | int32_t | destSize,
|  | uint16_t | options,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Take a `UBiDi` object containing the reordering information for a piece of text (one or more paragraphs) set by `ubidi_setPara()` or for a line of text set by `ubidi_setLine()` and write a reordered string to the destination buffer.

This function preserves the integrity of characters with multiple code units and (optionally) modifier letters. Characters in RTL runs can be replaced by mirror-image characters in the destination buffer. Note that "real" mirroring has to be done in a rendering engine by glyph selection and that for many "mirrored" characters there are no Unicode characters as mirror-image equivalents. There are also options to insert or remove Bidi control characters; see the description of the `destSize` and `options` parameters and of the option bit flags.

Parameters:

  | pBiDi | A pointer to a `UBiDi` object that is set by `ubidi_setPara()` or `ubidi_setLine()` and contains the reordering information for the text that it was defined for, as well as a pointer to that text. The text was aliased (only the pointer was stored without copying the contents) and must not have been modified since the `ubidi_setPara()` call.
  | dest | A pointer to where the reordered text is to be copied. The source text and `dest[destSize]` must not overlap.
  | destSize | The size of the `dest` buffer, in number of UChars. If the `UBIDI_INSERT_LRM_FOR_NUMERIC` option is set, then the destination length could be as large as `ubidi_getLength(pBiDi)+2*ubidi_countRuns(pBiDi)`. If the `UBIDI_REMOVE_BIDI_CONTROLS` option is set, then the destination length may be less than `ubidi_getLength(pBiDi)`. If none of these options is set, then the destination length will be exactly `ubidi_getProcessedLength(pBiDi)`.
  | options | A bit set of options for the reordering that control how the reordered text is written. The options include mirroring the characters on a code point basis and inserting LRM characters, which is used especially for transforming visually stored text to logically stored text (although this is still an imperfect implementation of an "inverse Bidi" algorithm because it uses the "forward Bidi" algorithm at its core). The available options are: `UBIDI_DO_MIRRORING`, `UBIDI_INSERT_LRM_FOR_NUMERIC`, `UBIDI_KEEP_BASE_COMBINING`, `UBIDI_OUTPUT_REVERSE`, `UBIDI_REMOVE_BIDI_CONTROLS`
  | pErrorCode | must be a valid pointer to an error code value.

Returns:
  The length of the output string.

See also:
  ubidi_getProcessedLength

Stable:
  ICU 2.0

int32_t ubidi_writeReverse | ( | const UChar * | src,
|  | int32_t | srcLength,
|  | UChar * | dest,
|  | int32_t | destSize,
|  | uint16_t | options,
|  | UErrorCode * | pErrorCode |
| ) |  |  |

Reverse a Right-To-Left run of Unicode text.

This function preserves the integrity of characters with multiple code units and (optionally) modifier letters. Characters can be replaced by mirror-image characters in the destination buffer. Note that "real" mirroring has to be done in a rendering engine by glyph selection and that for many "mirrored" characters there are no Unicode characters as mirror-image equivalents. There are also options to insert or remove Bidi control characters.

This function is the implementation for reversing RTL runs as part of `ubidi_writeReordered()`. For detailed descriptions of the parameters, see there. Since no Bidi controls are inserted here, the output string length will never exceed `srcLength`.

See also:
  ubidi_writeReordered

Parameters:

  | src | A pointer to the RTL run text.
  | srcLength | The length of the RTL run.
  | dest | A pointer to where the reordered text is to be copied. `src[srcLength]` and `dest[destSize]` must not overlap.
  | destSize | The size of the `dest` buffer, in number of UChars. If the `UBIDI_REMOVE_BIDI_CONTROLS` option is set, then the destination length may be less than `srcLength`. If this option is not set, then the destination length will be exactly `srcLength`.
  | options | A bit set of options for the reordering that control how the reordered text is written. See the `options` parameter in `ubidi_writeReordered()`.
  | pErrorCode | must be a valid pointer to an error code value.

Returns:
  The length of the output string.

Stable:
  ICU 2.0