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/*
*******************************************************************************
*
* Copyright (C) 1999, 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
/**
* @name BIDI algorithm for ICU
*
* <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 Technical Report 9</a>,
* version 5, also described in The Unicode Standard, Version 3.0 .<p>
*
* <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 <quote>limit</quote> 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 <quote>runs</quote>.
* Such a <quote>run</quote> 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
*/
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
* pesudo-level values <code>UBIDI_DEFAULT_LTR</code>
* and <code>UBIDI_DEFAULT_RTL</code>.</li>
*
* @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
*/
typedef uint8_t UBiDiLevel;
/** Paragraph level setting.
* If there is no strong character, then set the paragraph level to 0 (left-to-right).
*/
#define UBIDI_DEFAULT_LTR 0xfe
/** Paragraph level setting.
* If there is no strong character, then set the paragraph level to 1 (right-to-left).
*/
#define UBIDI_DEFAULT_RTL 0xff
/**
* Maximum explicit embedding level.
* (The maximum resolved level can be up to <code>UBIDI_MAX_EXPLICIT_LEVEL+1</code>).
*
*/
#define UBIDI_MAX_EXPLICIT_LEVEL 61
/** Bit flag for level input.
* Overrides directional properties.
*/
#define UBIDI_LEVEL_OVERRIDE 0x80
/**
* @memo <code>UBiDiDirection</code> values indicate the text direction.
*/
enum UBiDiDirection {
/** @memo All left-to-right text. This is a 0 value. */
UBIDI_LTR,
/** @memo All right-to-left text. This is a 1 value. */
UBIDI_RTL,
/** @memo Mixed-directional text. */
UBIDI_MIXED
};
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 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 a paragraph which is
* then interpreted as one single line.
*/
struct UBiDi;
typedef struct UBiDi UBiDi;
/**
* Allocate a <code>UBiDi</code> structure.
* Such an object is initially empty. It is assigned
* the BiDi properties of a paragraph by <code>ubidi_setPara()</code>
* or the BiDi properties of a line of a paragraph by
* <code>ubidi_getLine()</code>.<p>
* This object can be reused for as long as it is not deallocated
* by calling <code>ubidi_close()</code>.<p>
* <code>ubidi_set()</code> will allocate additional memory for
* internal structures as necessary.
*
* @return An empty <code>UBiDi</code> object.
*/
U_CAPI 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 paragraph 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,
* which must not indicate a failure before the function call.
*
* @return An empty <code>UBiDi</code> object with preallocated memory.
*/
U_CAPI UBiDi * U_EXPORT2
ubidi_openSized(UTextOffset maxLength, UTextOffset maxRunCount, UErrorCode *pErrorCode);
/**
* <code>ubidi_close()</code> must be called to free the memory
* associated with a UBiDi object.<p>
*
* <strong>Important: </strong>
* If a <code>UBiDi</code> object is the <quote>child</quote>
* of another one (its <quote>parent</quote>), 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
*/
U_CAPI void U_EXPORT2
ubidi_close(UBiDi *pBiDi);
/**
* Perform the Unicode BiDi algorithm. It is defined in the
* <a href="http://www.unicode.org/unicode/reports/tr9/">Unicode Technical Report 9</a>,
* version 5,
* also described in The Unicode Standard, Version 3.0 .<p>
*
* This function takes a single plain text paragraph with or without
* externally specified embedding levels from <quote>styled</quote> text
* and computes the left-right-directionality of each character.<p>
*
* If the entire paragraph consists of text of only one direction, 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 must be externally split into separate paragraphs (rule P1).
* Paragraph separators (B) should appear at most at the very end.
*
* @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 single-paragraph text that the
* BiDi algorithm will be performed on
* (step (P1) of the algorithm is performed externally).
* <strong>The text must be (at least) <code>length</code> long.</strong>
*
* @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 paragraph;
* 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 there is no 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&lt;=embeddingLevels[]&lt;=UBIDI_MAX_EXPLICIT_LEVEL</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,
* which must not indicate a failure before the function call.
*/
U_CAPI void U_EXPORT2
ubidi_setPara(UBiDi *pBiDi, const UChar *text, UTextOffset length,
UBiDiLevel paraLevel, UBiDiLevel *embeddingLevels,
UErrorCode *pErrorCode);
/**
* <code>ubidi_getLine()</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 paragraph of text, and by specifying
* a range of indexes in this paragraph.<p>
* In the new line object, the indexes will range from 0 to <code>limit-start</code>.<p>
*
* This is used after calling <code>ubidi_setPara()</code>
* for a paragraph, and after line-breaking on that paragraph.
* It is not necessary if the 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.
*
* @param pParaBiDi is the parent paragraph object.
*
* @param start is the line's first index into the paragraph text.
*
* @param limit is just behind the line's last index into the paragraph text
* (its last index +1).<br>
* It must be <code>0&lt;=start&lt;=limit&lt;=</code>paragraph length.
*
* @param pLineBiDi is the object that will now represent a line of the paragraph.
*
* @param pErrorCode must be a valid pointer to an error code value,
* which must not indicate a failure before the function call.
*
* @see ubidi_setPara
*/
U_CAPI void U_EXPORT2
ubidi_setLine(const UBiDi *pParaBiDi,
UTextOffset start, UTextOffset 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
*/
U_CAPI UBiDiDirection U_EXPORT2
ubidi_getDirection(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.
*/
U_CAPI UTextOffset 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.
*
* @see UBiDiLevel
*/
U_CAPI UBiDiLevel U_EXPORT2
ubidi_getParaLevel(const UBiDi *pBiDi);
/**
* 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
*/
U_CAPI UBiDiLevel U_EXPORT2
ubidi_getLevelAt(const UBiDi *pBiDi, UTextOffset 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.
*
* @param pErrorCode must be a valid pointer to an error code value,
* which must not indicate a failure before the function call.
*
* @return The levels array for the text,
* or <code>NULL</code> if an error occurs.
*
* @see UBiDiLevel
*/
U_CAPI 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.
*/
U_CAPI void U_EXPORT2
ubidi_getLogicalRun(const UBiDi *pBiDi, UTextOffset logicalStart,
UTextOffset *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,
* which must not indicate a failure before the function call.
*
* @return The number of runs.
*/
U_CAPI UTextOffset 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>
*&nbsp; UTextOffset i, count=ubidi_countRuns(pBiDi),
*&nbsp; logicalStart, visualIndex=0, length;
*&nbsp; for(i=0; i&lt;count; ++i) {
*&nbsp; if(UBIDI_LTR==ubidi_getVisualRun(pBiDi, i, &logicalStart, &length)) {
*&nbsp; do { // LTR
*&nbsp; show_char(text[logicalStart++], visualIndex++);
*&nbsp; } while(--length>0);
*&nbsp; } else {
*&nbsp; logicalStart+=length; // logicalLimit
*&nbsp; do { // RTL
*&nbsp; show_char(text[--logicalStart], visualIndex++);
*&nbsp; } while(--length>0);
*&nbsp; }
*&nbsp; }
* </pre>
*
* Note that in right-to-left runs, code like this places
* modifier letters before base characters and second surrogates
* before first ones.
*/
U_CAPI UBiDiDirection U_EXPORT2
ubidi_getVisualRun(UBiDi *pBiDi, UTextOffset runIndex,
UTextOffset *pLogicalStart, UTextOffset *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,
* which must not indicate a failure before the function call.
*
* @return The visual position of this character.
*
* @see ubidi_getLogicalMap
* @see ubidi_getLogicalIndex
*/
U_CAPI UTextOffset U_EXPORT2
ubidi_getVisualIndex(UBiDi *pBiDi, UTextOffset 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,
* which must not indicate a failure before the function call.
*
* @return The index of this character in the text.
*
* @see ubidi_getVisualMap
* @see ubidi_getVisualIndex
*/
U_CAPI UTextOffset U_EXPORT2
ubidi_getLogicalIndex(UBiDi *pBiDi, UTextOffset 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,
* which must not indicate a failure before the function call.
*
* @see ubidi_getVisualMap
* @see ubidi_getVisualIndex
*/
U_CAPI void U_EXPORT2
ubidi_getLogicalMap(UBiDi *pBiDi, UTextOffset *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,
* which must not indicate a failure before the function call.
*
* @see ubidi_getLogicalMap
* @see ubidi_getLogicalIndex
*/
U_CAPI void U_EXPORT2
ubidi_getVisualMap(UBiDi *pBiDi, UTextOffset *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&gt;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>.
*/
U_CAPI void U_EXPORT2
ubidi_reorderLogical(const UBiDiLevel *levels, UTextOffset length, UTextOffset *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&gt;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>.
*/
U_CAPI void U_EXPORT2
ubidi_reorderVisual(const UBiDiLevel *levels, UTextOffset length, UTextOffset *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.
*/
U_CAPI void U_EXPORT2
ubidi_invertMap(const UTextOffset *srcMap, UTextOffset *destMap, UTextOffset length);
/**
* @name Sample code for the ICU BIDI API
*
* <h2>Rendering a paragraph with the ICU BiDi API</h2>
*
* 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>
*&nbsp; #include "unicode/ubidi.h"
*&nbsp;
*&nbsp; typedef enum {
*&nbsp; styleNormal=0, styleSelected=1,
*&nbsp; styleBold=2, styleItalics=4,
*&nbsp; styleSuper=8, styleSub=16
*&nbsp; } Style;
*&nbsp;
*&nbsp; typedef struct { UTextOffset limit; Style style; } StyleRun;
*&nbsp;
*&nbsp; int getTextWidth(const UChar *text, UTextOffset start, UTextOffset limit,
*&nbsp; const StyleRun *styleRuns, int styleRunCount);
*&nbsp;
*&nbsp; // set *pLimit and *pStyleRunLimit for a line
*&nbsp; // from text[start] and from styleRuns[styleRunStart]
*&nbsp; // using ubidi_getLogicalRun(para, ...)
*&nbsp; void getLineBreak(const UChar *text, UTextOffset start, UTextOffset *pLimit,
*&nbsp; UBiDi *para,
*&nbsp; const StyleRun *styleRuns, int styleRunStart, int *pStyleRunLimit,
*&nbsp; int *pLineWidth);
*&nbsp;
*&nbsp; // render runs on a line sequentially, always from left to right
*&nbsp;
*&nbsp; // prepare rendering a new line
*&nbsp; void startLine(UBiDiDirection textDirection, int lineWidth);
*&nbsp;
*&nbsp; // render a run of text and advance to the right by the run width
*&nbsp; // the text[start..limit-1] is always in logical order
*&nbsp; void renderRun(const UChar *text, UTextOffset start, UTextOffset limit,
*&nbsp; UBiDiDirection textDirection, Style style);
*&nbsp;
*&nbsp; // We could compute a cross-product
*&nbsp; // from the style runs with the directional runs
*&nbsp; // and then reorder it.
*&nbsp; // Instead, here we iterate over each run type
*&nbsp; // and render the intersections -
*&nbsp; // with shortcuts in simple (and common) cases.
*&nbsp; // renderParagraph() is the main function.
*&nbsp;
*&nbsp; // render a directional run with
*&nbsp; // (possibly) multiple style runs intersecting with it
*&nbsp; void renderDirectionalRun(const UChar *text,
*&nbsp; UTextOffset start, UTextOffset limit,
*&nbsp; UBiDiDirection direction,
*&nbsp; const StyleRun *styleRuns, int styleRunCount) {
*&nbsp; int i;
*&nbsp;
*&nbsp; // iterate over style runs
*&nbsp; if(direction==UBIDI_LTR) {
*&nbsp; int styleLimit;
*&nbsp;
*&nbsp; for(i=0; i&lt;styleRunCount; ++i) {
*&nbsp; styleLimit=styleRun[i].limit;
*&nbsp; if(start&lt;styleLimit) {
*&nbsp; if(styleLimit>limit) { styleLimit=limit; }
*&nbsp; renderRun(text, start, styleLimit,
*&nbsp; direction, styleRun[i].style);
*&nbsp; if(styleLimit==limit) { break; }
*&nbsp; start=styleLimit;
*&nbsp; }
*&nbsp; }
*&nbsp; } else {
*&nbsp; int styleStart;
*&nbsp;
*&nbsp; for(i=styleRunCount-1; i>=0; --i) {
*&nbsp; if(i>0) {
*&nbsp; styleStart=styleRun[i-1].limit;
*&nbsp; } else {
*&nbsp; styleStart=0;
*&nbsp; }
*&nbsp; if(limit>=styleStart) {
*&nbsp; if(styleStart&lt;start) { styleStart=start; }
*&nbsp; renderRun(text, styleStart, limit,
*&nbsp; direction, styleRun[i].style);
*&nbsp; if(styleStart==start) { break; }
*&nbsp; limit=styleStart;
*&nbsp; }
*&nbsp; }
*&nbsp; }
*&nbsp; }
*&nbsp;
*&nbsp; // the line object represents text[start..limit-1]
*&nbsp; void renderLine(UBiDi *line, const UChar *text,
*&nbsp; UTextOffset start, UTextOffset limit,
*&nbsp; const StyleRun *styleRuns, int styleRunCount) {
*&nbsp; UBiDiDirection direction=ubidi_getDirection(line);
*&nbsp; if(direction!=UBIDI_MIXED) {
*&nbsp; // unidirectional
*&nbsp; if(styleRunCount&lt;=1) {
*&nbsp; renderRun(text, start, limit, direction, styleRuns[0].style);
*&nbsp; } else {
*&nbsp; renderDirectionalRun(text, start, limit,
*&nbsp; direction, styleRuns, styleRunCount);
*&nbsp; }
*&nbsp; } else {
*&nbsp; // mixed-directional
*&nbsp; UTextOffset count, i, length;
*&nbsp; UBiDiLevel level;
*&nbsp;
*&nbsp; count=ubidi_countRuns(para, pErrorCode);
*&nbsp; if(U_SUCCESS(*pErrorCode)) {
*&nbsp; if(styleRunCount&lt;=1) {
*&nbsp; Style style=styleRuns[0].style;
*&nbsp;
*&nbsp; // iterate over directional runs
*&nbsp; for(i=0; i&lt;count; ++i) {
*&nbsp; direction=ubidi_getVisualRun(para, i, &start, &length);
*&nbsp; renderRun(text, start, start+length, direction, style);
*&nbsp; }
*&nbsp; } else {
*&nbsp; UTextOffset j;
*&nbsp;
*&nbsp; // iterate over both directional and style runs
*&nbsp; for(i=0; i&lt;count; ++i) {
*&nbsp; direction=ubidi_getVisualRun(line, i, &start, &length);
*&nbsp; renderDirectionalRun(text, start, start+length,
*&nbsp; direction, styleRuns, styleRunCount);
*&nbsp; }
*&nbsp; }
*&nbsp; }
*&nbsp; }
*&nbsp; }
*&nbsp;
*&nbsp; void renderParagraph(const UChar *text, UTextOffset length,
*&nbsp; UBiDiDirection textDirection,
*&nbsp; const StyleRun *styleRuns, int styleRunCount,
*&nbsp; int lineWidth,
*&nbsp; UErrorCode *pErrorCode) {
*&nbsp; UBiDi *para;
*&nbsp;
*&nbsp; if(pErrorCode==NULL || U_FAILURE(*pErrorCode) || length&lt;=0) {
*&nbsp; return;
*&nbsp; }
*&nbsp;
*&nbsp; para=ubidi_openSized(length, 0, pErrorCode);
*&nbsp; if(para==NULL) { return; }
*&nbsp;
*&nbsp; ubidi_setPara(para, text, length,
*&nbsp; textDirection ? UBIDI_DEFAULT_RTL : UBIDI_DEFAULT_LTR,
*&nbsp; NULL, pErrorCode);
*&nbsp; if(U_SUCCESS(*pErrorCode)) {
*&nbsp; UBiDiLevel paraLevel=1&ubidi_getParaLevel(para);
*&nbsp; StyleRun styleRun={ length, styleNormal };
*&nbsp; int width;
*&nbsp;
*&nbsp; if(styleRuns==NULL || styleRunCount&lt;=0) {
*&nbsp; styleRunCount=1;
*&nbsp; styleRuns=&styleRun;
*&nbsp; }
*&nbsp;
*&nbsp; // assume styleRuns[styleRunCount-1].limit>=length
*&nbsp;
*&nbsp; width=getTextWidth(text, 0, length, styleRuns, styleRunCount);
*&nbsp; if(width&lt;=lineWidth) {
*&nbsp; // everything fits onto one line
*&nbsp;
*&nbsp; // prepare rendering a new line from either left or right
*&nbsp; startLine(paraLevel, width);
*&nbsp;
*&nbsp; renderLine(para, text, 0, length,
*&nbsp; styleRuns, styleRunCount);
*&nbsp; } else {
*&nbsp; UBiDi *line;
*&nbsp;
*&nbsp; // we need to render several lines
*&nbsp; line=ubidi_openSized(length, 0, pErrorCode);
*&nbsp; if(line!=NULL) {
*&nbsp; UTextOffset start=0, limit;
*&nbsp; int styleRunStart=0, styleRunLimit;
*&nbsp;
*&nbsp; for(;;) {
*&nbsp; limit=length;
*&nbsp; styleRunLimit=styleRunCount;
*&nbsp; getLineBreak(text, start, &limit, para,
*&nbsp; styleRuns, styleRunStart, &styleRunLimit,
*&nbsp; &width);
*&nbsp; ubidi_setLine(para, start, limit, line, pErrorCode);
*&nbsp; if(U_SUCCESS(*pErrorCode)) {
*&nbsp; // prepare rendering a new line
*&nbsp; // from either left or right
*&nbsp; startLine(paraLevel, width);
*&nbsp;
*&nbsp; renderLine(line, text, start, limit,
*&nbsp; styleRuns+styleRunStart,
*&nbsp; styleRunLimit-styleRunStart);
*&nbsp; }
*&nbsp; if(limit==length) { break; }
*&nbsp; start=limit;
*&nbsp; styleRunStart=styleRunLimit-1;
*&nbsp; if(start>=styleRuns[styleRunStart].limit) {
*&nbsp; ++styleRunStart;
*&nbsp; }
*&nbsp; }
*&nbsp;
*&nbsp; ubidi_close(line);
*&nbsp; }
*&nbsp; }
*&nbsp; }
*&nbsp;
*&nbsp; ubidi_close(para);
*&nbsp; }
* </pre>
*/
BIDI_SAMPLE_CODE
/*@{*/
/*@}*/
/*@}*/
#endif