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scuffed-code/icu4c/source/common/unicode/ubidi.h
Doug Felt 3120d08ecc ICU-4386 update based on review comments, extend tests 
X-SVN-Rev: 17197
2005-02-14 19:15:44 +00:00

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/*
******************************************************************************
*
* Copyright (C) 1999-2005, International Business Machines
* Corporation and others. All Rights Reserved.
*
******************************************************************************
* file name: ubidi.h
* encoding: US-ASCII
* tab size: 8 (not used)
* indentation:4
*
* created on: 1999jul27
* created by: Markus W. Scherer
*/
#ifndef UBIDI_H
#define UBIDI_H
#include "unicode/utypes.h"
#include "unicode/uchar.h"
/*
* javadoc-style comments are intended to be transformed into HTML
* using DOC++ - see
* http://www.zib.de/Visual/software/doc++/index.html .
*
* The HTML documentation is created with
* doc++ -H ubidi.h
*
* The following #define trick allows us to do it all in one file
* and still be able to compile it.
*/
/*#define DOCXX_TAG*/
/*#define BIDI_SAMPLE_CODE*/
/**
*\file
* \brief C API: BIDI algorithm
*
* <h2>BIDI algorithm for ICU</h2>
*
* This is an implementation of the Unicode Bidirectional algorithm.
* The algorithm is defined in the
* <a href="http://www.unicode.org/unicode/reports/tr9/">Unicode Standard Annex #9</a>,
* version 13, also described in The Unicode Standard, Version 4.0 .<p>
*
* 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".
*
* <h3>General remarks about the API:</h3>
*
* In functions with an error code parameter,
* the <code>pErrorCode</code> 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.<p>
*
* The &quot;limit&quot; of a sequence of characters is the position just after their
* last character, i.e., one more than that position.<p>
*
* Some of the API functions provide access to &quot;runs&quot;.
* Such a &quot;run&quot; is defined as a sequence of characters
* that are at the same embedding level
* after performing the BIDI algorithm.<p>
*
* @author Markus W. Scherer
* @version 1.0
*
*
* <h4> Sample code for the ICU BIDI API </h4>
*
* <h5>Rendering a paragraph with the ICU BiDi API</h5>
*
* 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.
*
* <p>The basic assumptions are:</p>
* <ul>
* <li>Rendering is done from left to right on a horizontal line.</li>
* <li>A run of single-style, unidirectional text can be rendered at once.</li>
* <li>Such a run of text is passed to the graphics system with
* characters (code units) in logical order.</li>
* <li>The line-breaking algorithm is very complicated
* and Locale-dependent -
* and therefore its implementation omitted from this sample code.</li>
* </ul>
*
* <pre>
* \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);
*}
*\endcode
* </pre>
*/
/*DOCXX_TAG*/
/*@{*/
/**
* 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&nbsp;0 (even/odd value).<p>
*
* It can also hold non-level values for the
* <code>paraLevel</code> and <code>embeddingLevels</code>
* arguments of <code>ubidi_setPara()</code>; there:
* <ul>
* <li>bit&nbsp;7 of an <code>embeddingLevels[]</code>
* value indicates whether the using application is
* specifying the level of a character to <i>override</i> whatever the
* BiDi implementation would resolve it to.</li>
* <li><code>paraLevel</code> can be set to the
* pseudo-level values <code>UBIDI_DEFAULT_LTR</code>
* and <code>UBIDI_DEFAULT_RTL</code>.</li>
* </ul>
*
* @see ubidi_setPara
*
* <p>The related constants are not real, valid level values.
* <code>UBIDI_DEFAULT_XXX</code> can be used to specify
* a default for the paragraph level for
* when the <code>ubidi_setPara()</code> function
* shall determine it but there is no
* strongly typed character in the input.<p>
*
* Note that the value for <code>UBIDI_DEFAULT_LTR</code> is even
* and the one for <code>UBIDI_DEFAULT_RTL</code> 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 UBIDI_DEFAULT_LTR
* @see UBIDI_DEFAULT_RTL
* @see UBIDI_LEVEL_OVERRIDE
* @see UBIDI_MAX_EXPLICIT_LEVEL
* @stable ICU 2.0
*/
typedef uint8_t UBiDiLevel;
/** Paragraph level setting.
* If there is no strong character, then set the paragraph level to 0 (left-to-right).
* @stable ICU 2.0
*/
#define UBIDI_DEFAULT_LTR 0xfe
/** Paragraph level setting.
* If there is no strong character, then set the paragraph level to 1 (right-to-left).
* @stable ICU 2.0
*/
#define UBIDI_DEFAULT_RTL 0xff
/**
* Maximum explicit embedding level.
* (The maximum resolved level can be up to <code>UBIDI_MAX_EXPLICIT_LEVEL+1</code>).
* @stable ICU 2.0
*/
#define UBIDI_MAX_EXPLICIT_LEVEL 61
/** Bit flag for level input.
* Overrides directional properties.
* @stable ICU 2.0
*/
#define UBIDI_LEVEL_OVERRIDE 0x80
/**
* <code>UBiDiDirection</code> values indicate the text direction.
* @stable ICU 2.0
*/
enum UBiDiDirection {
/** All left-to-right text. This is a 0 value. @stable ICU 2.0 */
UBIDI_LTR,
/** All right-to-left text. This is a 1 value. @stable ICU 2.0 */
UBIDI_RTL,
/** Mixed-directional text. @stable ICU 2.0 */
UBIDI_MIXED
};
/** @stable ICU 2.0 */
typedef enum UBiDiDirection UBiDiDirection;
/**
* Forward declaration of the <code>UBiDi</code> structure for the declaration of
* the API functions. Its fields are implementation-specific.<p>
* This structure holds information about a paragraph (or multiple paragraphs)
* of text with BiDi-algorithm-related details, or about one line of
* such a paragraph.<p>
* Reordering can be done on a line, or on one or more paragraphs which are
* then interpreted each as one single line.
* @stable ICU 2.0
*/
struct UBiDi;
/** @stable ICU 2.0 */
typedef struct UBiDi UBiDi;
/**
* Allocate a <code>UBiDi</code> structure.
* Such an object is initially empty. It is assigned
* the BiDi properties of a piece of text containing one or more paragraphs
* by <code>ubidi_setPara()</code>
* or the BiDi properties of a line within a paragraph by
* <code>ubidi_setLine()</code>.<p>
* This object can be reused for as long as it is not deallocated
* by calling <code>ubidi_close()</code>.<p>
* <code>ubidi_setPara()</code> and <code>ubidi_setLine()</code> will allocate
* additional memory for internal structures as necessary.
*
* @return An empty <code>UBiDi</code> object.
* @stable ICU 2.0
*/
U_STABLE UBiDi * U_EXPORT2
ubidi_open(void);
/**
* Allocate a <code>UBiDi</code> structure with preallocated memory
* for internal structures.
* This function provides a <code>UBiDi</code> object like <code>ubidi_open()</code>
* with no arguments, but it also preallocates memory for internal structures
* according to the sizings supplied by the caller.<p>
* Subsequent functions will not allocate any more memory, and are thus
* guaranteed not to fail because of lack of memory.<p>
* The preallocation can be limited to some of the internal memory
* by setting some values to 0 here. That means that if, e.g.,
* <code>maxRunCount</code> cannot be reasonably predetermined and should not
* be set to <code>maxLength</code> (the only failproof value) to avoid
* wasting memory, then <code>maxRunCount</code> could be set to 0 here
* and the internal structures that are associated with it will be allocated
* on demand, just like with <code>ubidi_open()</code>.
*
* @param 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.
*
* @param 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.<p>
* The number of runs depends on the actual text and maybe anywhere between
* 1 and <code>maxLength</code>. It is typically small.<p>
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return An empty <code>UBiDi</code> object with preallocated memory.
* @stable ICU 2.0
*/
U_STABLE UBiDi * U_EXPORT2
ubidi_openSized(int32_t maxLength, int32_t maxRunCount, UErrorCode *pErrorCode);
/**
* <code>ubidi_close()</code> must be called to free the memory
* associated with a UBiDi object.<p>
*
* <strong>Important: </strong>
* A parent <code>UBiDi</code> object must not be destroyed or reused if
* it still has children.
* If a <code>UBiDi</code> object is the <i>child</i>
* of another one (its <i>parent</i>), after calling
* <code>ubidi_setLine()</code>, then the child object must
* be destroyed (closed) or reused (by calling
* <code>ubidi_setPara()</code> or <code>ubidi_setLine()</code>)
* before the parent object.
*
* @param pBiDi is a <code>UBiDi</code> object.
*
* @see ubidi_setPara
* @see ubidi_setLine
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_close(UBiDi *pBiDi);
/**
* Modify the operation of the BiDi algorithm such that it
* approximates an "inverse BiDi" algorithm. This function
* must be called before <code>ubidi_setPara()</code>.
*
* <p>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".</p>
*
* <p>With <code>isInverse</code> set to <code>TRUE</code>,
* 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.</p>
*
* <p>Output runs should be retrieved using <code>ubidi_getVisualRun()</code>.
* Since the actual input for "inverse BiDi" is visually ordered text and
* <code>ubidi_getVisualRun()</code> gets the reordered runs, these are actually
* the runs of the logically ordered output.</p>
*
* @param pBiDi is a <code>UBiDi</code> object.
*
* @param isInverse specifies "forward" or "inverse" BiDi operation
*
* @see ubidi_setPara
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_setInverse(UBiDi *pBiDi, UBool isInverse);
/**
* Is this BiDi object set to perform the inverse BiDi algorithm?
*
* @param pBiDi is a <code>UBiDi</code> object.
* @return TRUE if the BiDi object is set to perform the inverse BiDi algorithm
*
* @see ubidi_setInverse
* @stable ICU 2.0
*/
U_STABLE UBool U_EXPORT2
ubidi_isInverse(UBiDi *pBiDi);
/**
* 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 <code>ubidi_setPara()</code>.
* 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.
*
* @param pBiDi is a <code>UBiDi</code> object.
*
* @param orderParagraphsLTR specifies whether paragraph separators (B) must
* receive level 0, so that successive paragraphs progress from left to right.
*
* @see ubidi_setPara
* @stable ICU 3.4
*/
U_STABLE void U_EXPORT2
ubidi_orderParagraphsLTR(UBiDi *pBiDi, UBool orderParagraphsLTR);
/**
* Is this BiDi object set to allocate level 0 to block separators so that
* successive paragraphs progress from left to right?
*
* @param pBiDi is a <code>UBiDi</code> object.
* @return TRUE if the BiDi object is set to allocate level 0 to block
* separators.
*
* @see ubidi_orderParagraphsLTR
* @stable ICU 3.4
*/
U_STABLE UBool U_EXPORT2
ubidi_isOrderParagraphsLTR(UBiDi *pBiDi);
/**
* Perform the Unicode BiDi algorithm. It is defined in the
* <a href="http://www.unicode.org/unicode/reports/tr9/">Unicode Standard Anned #9</a>,
* version 13,
* also described in The Unicode Standard, Version 4.0 .<p>
*
* This function takes a piece of plain text containing one or more paragraphs,
* with or without externally specified embedding levels from <i>styled</i>
* text and computes the left-right-directionality of each character.<p>
*
* 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.<br>
* 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.<p>
*
* 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.
*
* @param pBiDi A <code>UBiDi</code> object allocated with <code>ubidi_open()</code>
* which will be set to contain the reordering information,
* especially the resolved levels for all the characters in <code>text</code>.
*
* @param text is a pointer to the text that the
* BiDi algorithm will be performed on
* <strong>The text must be (at least) <code>length</code> long.</strong>
* This pointer is stored in the UBiDi object and can be retrieved
* with <code>ubidi_getText()</code>.
*
* @param length is the length of the text; if <code>length==-1</code> then
* the text must be zero-terminated.
*
* @param 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 <code>paraLevel</code> can be set to
* either <code>UBIDI_DEFAULT_LTR</code>
* or <code>UBIDI_DEFAULT_RTL</code>; 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 <code>UBIDI_MAX_EXPLICIT_LEVEL</code> is also valid,
* with odd levels indicating RTL.
*
* @param 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
* <code>UBIDI_LEVEL_OVERRIDE</code> bit set.<p>
* Except for that bit, it must be
* <code>paraLevel<=embeddingLevels[]<=UBIDI_MAX_EXPLICIT_LEVEL</code>,
* with one exception: a level of zero may be specified for a paragraph
* separator even if <code>paraLevel>0</code> when multiple paragraphs
* are submitted in the same call to <code>ubidi_setPara()</code>.<p>
* <strong>Caution: </strong>A copy of this pointer, not of the levels,
* will be stored in the <code>UBiDi</code> object;
* the <code>embeddingLevels</code> array must not be
* deallocated before the <code>UBiDi</code> structure is destroyed or reused,
* and the <code>embeddingLevels</code>
* should not be modified to avoid unexpected results on subsequent BiDi operations.
* However, the <code>ubidi_setPara()</code> and
* <code>ubidi_setLine()</code> functions may modify some or all of the levels.<p>
* After the <code>UBiDi</code> object is reused or destroyed, the caller
* must take care of the deallocation of the <code>embeddingLevels</code> array.<p>
* <strong>The <code>embeddingLevels</code> array must be
* at least <code>length</code> long.</strong>
*
* @param pErrorCode must be a valid pointer to an error code value.
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_setPara(UBiDi *pBiDi, const UChar *text, int32_t length,
UBiDiLevel paraLevel, UBiDiLevel *embeddingLevels,
UErrorCode *pErrorCode);
/**
* <code>ubidi_setLine()</code> sets a <code>UBiDi</code> 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 <code>UBiDi</code> object representing
* this information for a piece of text containing one or more paragraphs,
* and by specifying a range of indexes in this text.<p>
* In the new line object, the indexes will range from 0 to <code>limit-start-1</code>.<p>
*
* This is used after calling <code>ubidi_setPara()</code>
* 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.<p>
*
* After line-breaking, rules (L1) and (L2) for the treatment of
* trailing WS and for reordering are performed on
* a <code>UBiDi</code> object that represents a line.<p>
*
* <strong>Important: </strong><code>pLineBiDi</code> shares data with
* <code>pParaBiDi</code>.
* You must destroy or reuse <code>pLineBiDi</code> before <code>pParaBiDi</code>.
* In other words, you must destroy or reuse the <code>UBiDi</code> object for a line
* before the object for its parent paragraph.<p>
*
* The text pointer that was stored in <code>pParaBiDi</code> is also copied,
* and <code>start</code> is added to it so that it points to the beginning of the
* line for this object.
*
* @param pParaBiDi is the parent paragraph object. It must have been set
* by a successful call to ubidi_setPara.
*
* @param start is the line's first index into the text.
*
* @param limit is just behind the line's last index into the text
* (its last index +1).<br>
* It must be <code>0<=start<=limit<=</code>containing paragraph limit.
* If the specified line crosses a paragraph boundary, the function
* will terminate with error code U_ILLEGAL_ARGUMENT_ERROR.
*
* @param pLineBiDi is the object that will now represent a line of the text.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @see ubidi_setPara
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_setLine(const UBiDi *pParaBiDi,
int32_t start, int32_t limit,
UBiDi *pLineBiDi,
UErrorCode *pErrorCode);
/**
* Get the directionality of the text.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return A <code>UBIDI_XXX</code> value that indicates if the entire text
* represented by this object is unidirectional,
* and which direction, or if it is mixed-directional.
*
* @see UBiDiDirection
* @stable ICU 2.0
*/
U_STABLE UBiDiDirection U_EXPORT2
ubidi_getDirection(const UBiDi *pBiDi);
/**
* Get the pointer to the text.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return The pointer to the text that the UBiDi object was created for.
*
* @see ubidi_setPara
* @see ubidi_setLine
* @stable ICU 2.0
*/
U_STABLE const UChar * U_EXPORT2
ubidi_getText(const UBiDi *pBiDi);
/**
* Get the length of the text.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return The length of the text that the UBiDi object was created for.
* @stable ICU 2.0
*/
U_STABLE int32_t U_EXPORT2
ubidi_getLength(const UBiDi *pBiDi);
/**
* Get the paragraph level of the text.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return 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 UBiDiLevel
* @see ubidi_getParagraph
* @see ubidi_getParagraphByIndex
* @stable ICU 2.0
*/
U_STABLE UBiDiLevel U_EXPORT2
ubidi_getParaLevel(const UBiDi *pBiDi);
/**
* Get the number of paragraphs.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return The number of paragraphs.
* @stable ICU 3.4
*/
U_STABLE int32_t U_EXPORT2
ubidi_countParagraphs(UBiDi *pBiDi);
/**
* Get a paragraph, given a position within the text.
* This function returns information about a paragraph.<p>
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param charIndex is the index of a character within the text, in the
* range <code>[0..ubidi_getLength(pBiDi)-1]</code>.
*
* @param pParaStart will receive the index of the first character of the
* paragraph in the text.
* This pointer can be <code>NULL</code> if this
* value is not necessary.
*
* @param 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
* <code>charIndex</code>.
* This pointer can be <code>NULL</code> if this
* value is not necessary.
*
* @param pParaLevel will receive the level of the paragraph.
* This pointer can be <code>NULL</code> if this
* value is not necessary.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The index of the paragraph containing the specified position.
* @stable ICU 3.4
*/
U_STABLE int32_t U_EXPORT2
ubidi_getParagraph(const UBiDi *pBiDi, int32_t charIndex, 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.<p>
*
* @param pBiDi is the paragraph <code>UBiDi</code> object.
*
* @param paraIndex is the number of the paragraph, in the
* range <code>[0..ubidi_countParagraphs(pBiDi)-1]</code>.
*
* @param pParaStart will receive the index of the first character of the
* paragraph in the text.
* This pointer can be <code>NULL</code> if this
* value is not necessary.
*
* @param pParaLimit will receive the limit of the paragraph.
* This pointer can be <code>NULL</code> if this
* value is not necessary.
*
* @param pParaLevel will receive the level of the paragraph.
* This pointer can be <code>NULL</code> if this
* value is not necessary.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @stable ICU 3.4
*/
U_STABLE void U_EXPORT2
ubidi_getParagraphByIndex(const UBiDi *pBiDi, int32_t paraIndex,
int32_t *pParaStart, int32_t *pParaLimit,
UBiDiLevel *pParaLevel, UErrorCode *pErrorCode);
/**
* Get the level for one character.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param charIndex the index of a character.
*
* @return The level for the character at charIndex.
*
* @see UBiDiLevel
* @stable ICU 2.0
*/
U_STABLE UBiDiLevel U_EXPORT2
ubidi_getLevelAt(const UBiDi *pBiDi, int32_t charIndex);
/**
* Get an array of levels for each character.<p>
*
* Note that this function may allocate memory under some
* circumstances, unlike <code>ubidi_getLevelAt()</code>.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object, whose
* text length must be strictly positive.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The levels array for the text,
* or <code>NULL</code> if an error occurs.
*
* @see UBiDiLevel
* @stable ICU 2.0
*/
U_STABLE const UBiDiLevel * U_EXPORT2
ubidi_getLevels(UBiDi *pBiDi, UErrorCode *pErrorCode);
/**
* Get a logical run.
* This function returns information about a run and is used
* to retrieve runs in logical order.<p>
* This is especially useful for line-breaking on a paragraph.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param logicalStart is the first character of the run.
*
* @param pLogicalLimit will receive the limit of the run.
* The l-value that you point to here may be the
* same expression (variable) as the one for
* <code>logicalStart</code>.
* This pointer can be <code>NULL</code> if this
* value is not necessary.
*
* @param pLevel will receive the level of the run.
* This pointer can be <code>NULL</code> if this
* value is not necessary.
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_getLogicalRun(const UBiDi *pBiDi, int32_t logicalStart,
int32_t *pLogicalLimit, UBiDiLevel *pLevel);
/**
* Get the number of runs.
* This function may invoke the actual reordering on the
* <code>UBiDi</code> object, after <code>ubidi_setPara()</code>
* may have resolved only the levels of the text. Therefore,
* <code>ubidi_countRuns()</code> may have to allocate memory,
* and may fail doing so.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The number of runs.
* @stable ICU 2.0
*/
U_STABLE int32_t U_EXPORT2
ubidi_countRuns(UBiDi *pBiDi, UErrorCode *pErrorCode);
/**
* 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.<p>
* <code>ubidi_countRuns()</code> should be called
* before the runs are retrieved.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param runIndex is the number of the run in visual order, in the
* range <code>[0..ubidi_countRuns(pBiDi)-1]</code>.
*
* @param pLogicalStart is the first logical character index in the text.
* The pointer may be <code>NULL</code> if this index is not needed.
*
* @param pLength is the number of characters (at least one) in the run.
* The pointer may be <code>NULL</code> if this is not needed.
*
* @return the directionality of the run,
* <code>UBIDI_LTR==0</code> or <code>UBIDI_RTL==1</code>,
* never <code>UBIDI_MIXED</code>.
*
* @see ubidi_countRuns
*
* Example:
* <pre>
* \code
* 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);
* }
* }
*\endcode
* </pre>
*
* 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
*/
U_STABLE UBiDiDirection U_EXPORT2
ubidi_getVisualRun(UBiDi *pBiDi, int32_t runIndex,
int32_t *pLogicalStart, int32_t *pLength);
/**
* Get the visual position from a logical text position.
* If such a mapping is used many times on the same
* <code>UBiDi</code> object, then calling
* <code>ubidi_getLogicalMap()</code> is more efficient.<p>
*
* Note that in right-to-left runs, this mapping places
* modifier letters before base characters and second surrogates
* before first ones.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param logicalIndex is the index of a character in the text.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The visual position of this character.
*
* @see ubidi_getLogicalMap
* @see ubidi_getLogicalIndex
* @stable ICU 2.0
*/
U_STABLE int32_t U_EXPORT2
ubidi_getVisualIndex(UBiDi *pBiDi, int32_t logicalIndex, UErrorCode *pErrorCode);
/**
* Get the logical text position from a visual position.
* If such a mapping is used many times on the same
* <code>UBiDi</code> object, then calling
* <code>ubidi_getVisualMap()</code> is more efficient.<p>
*
* This is the inverse function to <code>ubidi_getVisualIndex()</code>.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param visualIndex is the visual position of a character.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The index of this character in the text.
*
* @see ubidi_getVisualMap
* @see ubidi_getVisualIndex
* @stable ICU 2.0
*/
U_STABLE int32_t U_EXPORT2
ubidi_getLogicalIndex(UBiDi *pBiDi, int32_t visualIndex, UErrorCode *pErrorCode);
/**
* Get a logical-to-visual index map (array) for the characters in the UBiDi
* (paragraph or line) object.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param indexMap is a pointer to an array of <code>ubidi_getLength()</code>
* indexes which will reflect the reordering of the characters.
* The array does not need to be initialized.<p>
* The index map will result in <code>indexMap[logicalIndex]==visualIndex</code>.<p>
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @see ubidi_getVisualMap
* @see ubidi_getVisualIndex
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_getLogicalMap(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.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param indexMap is a pointer to an array of <code>ubidi_getLength()</code>
* indexes which will reflect the reordering of the characters.
* The array does not need to be initialized.<p>
* The index map will result in <code>indexMap[visualIndex]==logicalIndex</code>.<p>
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @see ubidi_getLogicalMap
* @see ubidi_getLogicalIndex
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_getVisualMap(UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode);
/**
* 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 <code>ubidi_getLogicalMap</code> on a
* <code>UBiDi</code> object.
*
* @param levels is an array with <code>length</code> levels that have been determined by
* the application.
*
* @param length is the number of levels in the array, or, semantically,
* the number of objects to be reordered.
* It must be <code>length>0</code>.
*
* @param indexMap is a pointer to an array of <code>length</code>
* indexes which will reflect the reordering of the characters.
* The array does not need to be initialized.<p>
* The index map will result in <code>indexMap[logicalIndex]==visualIndex</code>.
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
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 <code>ubidi_getVisualMap</code> on a
* <code>UBiDi</code> object.
*
* @param levels is an array with <code>length</code> levels that have been determined by
* the application.
*
* @param length is the number of levels in the array, or, semantically,
* the number of objects to be reordered.
* It must be <code>length>0</code>.
*
* @param indexMap is a pointer to an array of <code>length</code>
* indexes which will reflect the reordering of the characters.
* The array does not need to be initialized.<p>
* The index map will result in <code>indexMap[visualIndex]==logicalIndex</code>.
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_reorderVisual(const UBiDiLevel *levels, int32_t length, int32_t *indexMap);
/**
* Invert an index map.
* The one-to-one index mapping of the first map is inverted and written to
* the second one.
*
* @param srcMap is an array with <code>length</code> indexes
* which define the original mapping.
*
* @param destMap is an array with <code>length</code> indexes
* which will be filled with the inverse mapping.
*
* @param length is the length of each array.
* @stable ICU 2.0
*/
U_STABLE void U_EXPORT2
ubidi_invertMap(const int32_t *srcMap, int32_t *destMap, int32_t length);
/** option flags for ubidi_writeReordered() */
/**
* option bit for ubidi_writeReordered():
* keep combining characters after their base characters in RTL runs
*
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_KEEP_BASE_COMBINING 1
/**
* option bit for ubidi_writeReordered():
* replace characters with the "mirrored" property in RTL runs
* by their mirror-image mappings
*
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_DO_MIRRORING 2
/**
* option bit for ubidi_writeReordered():
* surround the run with LRMs if necessary;
* this is part of the approximate "inverse BiDi" algorithm
*
* @see ubidi_setInverse
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_INSERT_LRM_FOR_NUMERIC 4
/**
* option bit for ubidi_writeReordered():
* remove BiDi control characters
* (this does not affect UBIDI_INSERT_LRM_FOR_NUMERIC)
*
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_REMOVE_BIDI_CONTROLS 8
/**
* option bit for ubidi_writeReordered():
* write the output in reverse order
*
* <p>This has the same effect as calling <code>ubidi_writeReordered()</code>
* first without this option, and then calling
* <code>ubidi_writeReverse()</code> 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.</p>
*
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_OUTPUT_REVERSE 16
/**
* Take a <code>UBiDi</code> object containing the reordering
* information for a piece of text (one or more paragraphs) set by
* <code>ubidi_setPara()</code> or for a line of text set by <code>ubidi_setLine()</code>
* 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 <code>destSize</code>
* and <code>options</code> parameters and of the option bit flags.
*
* @see UBIDI_DO_MIRRORING
* @see UBIDI_INSERT_LRM_FOR_NUMERIC
* @see UBIDI_KEEP_BASE_COMBINING
* @see UBIDI_OUTPUT_REVERSE
* @see UBIDI_REMOVE_BIDI_CONTROLS
*
* @param pBiDi A pointer to a <code>UBiDi</code> object that
* is set by <code>ubidi_setPara()</code> or
* <code>ubidi_setLine()</code> and contains the reordering
* information for the text that it was defined for,
* as well as a pointer to that text.
* <p>The text was aliased (only the pointer was stored
* without copying the contents) and must not have been modified
* since the <code>ubidi_setPara()</code> call.</p>
*
* @param dest A pointer to where the reordered text is to be copied.
* The source text and <code>dest[destSize]</code>
* must not overlap.
*
* @param destSize The size of the <code>dest</code> buffer,
* in number of UChars.
* If the <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>
* option is set, then the destination length could be
* as large as
* <code>ubidi_getLength(pBiDi)+2*ubidi_countRuns(pBiDi)</code>.
* If the <code>UBIDI_REMOVE_BIDI_CONTROLS</code> option
* is set, then the destination length may be less than
* <code>ubidi_getLength(pBiDi)</code>.
* If none of these options is set, then the destination length
* will be exactly <code>ubidi_getLength(pBiDi)</code>.
*
* @param 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:
* <code>#UBIDI_DO_MIRRORING</code>,
* <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
* <code>#UBIDI_KEEP_BASE_COMBINING</code>,
* <code>#UBIDI_OUTPUT_REVERSE</code>,
* <code>#UBIDI_REMOVE_BIDI_CONTROLS</code>
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The length of the output string.
* @stable ICU 2.0
*/
U_STABLE int32_t U_EXPORT2
ubidi_writeReordered(UBiDi *pBiDi,
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 <code>ubidi_writeReordered()</code>. For detailed descriptions
* of the parameters, see there.
* Since no BiDi controls are inserted here, the output string length
* will never exceed <code>srcLength</code>.
*
* @see ubidi_writeReordered
*
* @param src A pointer to the RTL run text.
*
* @param srcLength The length of the RTL run.
*
* @param dest A pointer to where the reordered text is to be copied.
* <code>src[srcLength]</code> and <code>dest[destSize]</code>
* must not overlap.
*
* @param destSize The size of the <code>dest</code> buffer,
* in number of UChars.
* If the <code>UBIDI_REMOVE_BIDI_CONTROLS</code> option
* is set, then the destination length may be less than
* <code>srcLength</code>.
* If this option is not set, then the destination length
* will be exactly <code>srcLength</code>.
*
* @param options A bit set of options for the reordering that control
* how the reordered text is written.
* See the <code>options</code> parameter in <code>ubidi_writeReordered()</code>.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The length of the output string.
* @stable ICU 2.0
*/
U_STABLE int32_t U_EXPORT2
ubidi_writeReverse(const UChar *src, int32_t srcLength,
UChar *dest, int32_t destSize,
uint16_t options,
UErrorCode *pErrorCode);
/*#define BIDI_SAMPLE_CODE*/
/*@}*/
#endif
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