1/*
2******************************************************************************
3*
4*   Copyright (C) 2000-2004, International Business Machines
5*   Corporation and others.  All Rights Reserved.
6*
7******************************************************************************
8*   file name:  ushape.h
9*   encoding:   US-ASCII
10*   tab size:   8 (not used)
11*   indentation:4
12*
13*   created on: 2000jun29
14*   created by: Markus W. Scherer
15*/
16
17#ifndef __USHAPE_H__
18#define __USHAPE_H__
19
20#include "unicode/utypes.h"
21
22/**
23 * \file
24 * \brief C API:  Arabic shaping
25 *
26 */
27
28/**
29 * Shape Arabic text on a character basis.
30 *
31 * <p>This function performs basic operations for "shaping" Arabic text. It is most
32 * useful for use with legacy data formats and legacy display technology
33 * (simple terminals). All operations are performed on Unicode characters.</p>
34 *
35 * <p>Text-based shaping means that some character code points in the text are
36 * replaced by others depending on the context. It transforms one kind of text
37 * into another. In comparison, modern displays for Arabic text select
38 * appropriate, context-dependent font glyphs for each text element, which means
39 * that they transform text into a glyph vector.</p>
40 *
41 * <p>Text transformations are necessary when modern display technology is not
42 * available or when text needs to be transformed to or from legacy formats that
43 * use "shaped" characters. Since the Arabic script is cursive, connecting
44 * adjacent letters to each other, computers select images for each letter based
45 * on the surrounding letters. This usually results in four images per Arabic
46 * letter: initial, middle, final, and isolated forms. In Unicode, on the other
47 * hand, letters are normally stored abstract, and a display system is expected
48 * to select the necessary glyphs. (This makes searching and other text
49 * processing easier because the same letter has only one code.) It is possible
50 * to mimic this with text transformations because there are characters in
51 * Unicode that are rendered as letters with a specific shape
52 * (or cursive connectivity). They were included for interoperability with
53 * legacy systems and codepages, and for unsophisticated display systems.</p>
54 *
55 * <p>A second kind of text transformations is supported for Arabic digits:
56 * For compatibility with legacy codepages that only include European digits,
57 * it is possible to replace one set of digits by another, changing the
58 * character code points. These operations can be performed for either
59 * Arabic-Indic Digits (U+0660...U+0669) or Eastern (Extended) Arabic-Indic
60 * digits (U+06f0...U+06f9).</p>
61 *
62 * <p>Some replacements may result in more or fewer characters (code points).
63 * By default, this means that the destination buffer may receive text with a
64 * length different from the source length. Some legacy systems rely on the
65 * length of the text to be constant. They expect extra spaces to be added
66 * or consumed either next to the affected character or at the end of the
67 * text.</p>
68 *
69 * <p>For details about the available operations, see the description of the
70 * <code>U_SHAPE_...</code> options.</p>
71 *
72 * @param source The input text.
73 *
74 * @param sourceLength The number of UChars in <code>source</code>.
75 *
76 * @param dest The destination buffer that will receive the results of the
77 *             requested operations. It may be <code>NULL</code> only if
78 *             <code>destSize</code> is 0. The source and destination must not
79 *             overlap.
80 *
81 * @param destSize The size (capacity) of the destination buffer in UChars.
82 *                 If <code>destSize</code> is 0, then no output is produced,
83 *                 but the necessary buffer size is returned ("preflighting").
84 *
85 * @param options This is a 32-bit set of flags that specify the operations
86 *                that are performed on the input text. If no error occurs,
87 *                then the result will always be written to the destination
88 *                buffer.
89 *
90 * @param pErrorCode must be a valid pointer to an error code value,
91 *        which must not indicate a failure before the function call.
92 *
93 * @return The number of UChars written to the destination buffer.
94 *         If an error occured, then no output was written, or it may be
95 *         incomplete. If <code>U_BUFFER_OVERFLOW_ERROR</code> is set, then
96 *         the return value indicates the necessary destination buffer size.
97 * @stable ICU 2.0
98 */
99U_STABLE int32_t U_EXPORT2
100u_shapeArabic(const UChar *source, int32_t sourceLength,
101              UChar *dest, int32_t destSize,
102              uint32_t options,
103              UErrorCode *pErrorCode);
104
105/**
106 * Memory option: allow the result to have a different length than the source.
107 * @stable ICU 2.0
108 */
109#define U_SHAPE_LENGTH_GROW_SHRINK              0
110
111/**
112 * Memory option: the result must have the same length as the source.
113 * If more room is necessary, then try to consume spaces next to modified characters.
114 * @stable ICU 2.0
115 */
116#define U_SHAPE_LENGTH_FIXED_SPACES_NEAR        1
117
118/**
119 * Memory option: the result must have the same length as the source.
120 * If more room is necessary, then try to consume spaces at the end of the text.
121 * @stable ICU 2.0
122 */
123#define U_SHAPE_LENGTH_FIXED_SPACES_AT_END      2
124
125/**
126 * Memory option: the result must have the same length as the source.
127 * If more room is necessary, then try to consume spaces at the beginning of the text.
128 * @stable ICU 2.0
129 */
130#define U_SHAPE_LENGTH_FIXED_SPACES_AT_BEGINNING 3
131
132/** Bit mask for memory options. @stable ICU 2.0 */
133#define U_SHAPE_LENGTH_MASK                     3
134
135
136/** Direction indicator: the source is in logical (keyboard) order. @stable ICU 2.0 */
137#define U_SHAPE_TEXT_DIRECTION_LOGICAL          0
138
139/**
140 * Direction indicator:
141 * the source is in visual LTR order,
142 * the leftmost displayed character stored first.
143 * @stable ICU 2.0
144 */
145#define U_SHAPE_TEXT_DIRECTION_VISUAL_LTR       4
146
147/** Bit mask for direction indicators. @stable ICU 2.0 */
148#define U_SHAPE_TEXT_DIRECTION_MASK             4
149
150
151/** Letter shaping option: do not perform letter shaping. @stable ICU 2.0 */
152#define U_SHAPE_LETTERS_NOOP                    0
153
154/** Letter shaping option: replace abstract letter characters by "shaped" ones. @stable ICU 2.0 */
155#define U_SHAPE_LETTERS_SHAPE                   8
156
157/** Letter shaping option: replace "shaped" letter characters by abstract ones. @stable ICU 2.0 */
158#define U_SHAPE_LETTERS_UNSHAPE                 0x10
159
160/**
161 * Letter shaping option: replace abstract letter characters by "shaped" ones.
162 * The only difference with U_SHAPE_LETTERS_SHAPE is that Tashkeel letters
163 * are always "shaped" into the isolated form instead of the medial form
164 * (selecting code points from the Arabic Presentation Forms-B block).
165 * @stable ICU 2.0
166 */
167#define U_SHAPE_LETTERS_SHAPE_TASHKEEL_ISOLATED 0x18
168
169/** Bit mask for letter shaping options. @stable ICU 2.0 */
170#define U_SHAPE_LETTERS_MASK                    0x18
171
172
173/** Digit shaping option: do not perform digit shaping. @stable ICU 2.0 */
174#define U_SHAPE_DIGITS_NOOP                     0
175
176/**
177 * Digit shaping option:
178 * Replace European digits (U+0030...) by Arabic-Indic digits.
179 * @stable ICU 2.0
180 */
181#define U_SHAPE_DIGITS_EN2AN                    0x20
182
183/**
184 * Digit shaping option:
185 * Replace Arabic-Indic digits by European digits (U+0030...).
186 * @stable ICU 2.0
187 */
188#define U_SHAPE_DIGITS_AN2EN                    0x40
189
190/**
191 * Digit shaping option:
192 * Replace European digits (U+0030...) by Arabic-Indic digits if the most recent
193 * strongly directional character is an Arabic letter
194 * (<code>u_charDirection()</code> result <code>U_RIGHT_TO_LEFT_ARABIC</code> [AL]).<br>
195 * The direction of "preceding" depends on the direction indicator option.
196 * For the first characters, the preceding strongly directional character
197 * (initial state) is assumed to be not an Arabic letter
198 * (it is <code>U_LEFT_TO_RIGHT</code> [L] or <code>U_RIGHT_TO_LEFT</code> [R]).
199 * @stable ICU 2.0
200 */
201#define U_SHAPE_DIGITS_ALEN2AN_INIT_LR          0x60
202
203/**
204 * Digit shaping option:
205 * Replace European digits (U+0030...) by Arabic-Indic digits if the most recent
206 * strongly directional character is an Arabic letter
207 * (<code>u_charDirection()</code> result <code>U_RIGHT_TO_LEFT_ARABIC</code> [AL]).<br>
208 * The direction of "preceding" depends on the direction indicator option.
209 * For the first characters, the preceding strongly directional character
210 * (initial state) is assumed to be an Arabic letter.
211 * @stable ICU 2.0
212 */
213#define U_SHAPE_DIGITS_ALEN2AN_INIT_AL          0x80
214
215/** Not a valid option value. May be replaced by a new option. @stable ICU 2.0 */
216#define U_SHAPE_DIGITS_RESERVED                 0xa0
217
218/** Bit mask for digit shaping options. @stable ICU 2.0 */
219#define U_SHAPE_DIGITS_MASK                     0xe0
220
221
222/** Digit type option: Use Arabic-Indic digits (U+0660...U+0669). @stable ICU 2.0 */
223#define U_SHAPE_DIGIT_TYPE_AN                   0
224
225/** Digit type option: Use Eastern (Extended) Arabic-Indic digits (U+06f0...U+06f9). @stable ICU 2.0 */
226#define U_SHAPE_DIGIT_TYPE_AN_EXTENDED          0x100
227
228/** Not a valid option value. May be replaced by a new option. @stable ICU 2.0 */
229#define U_SHAPE_DIGIT_TYPE_RESERVED             0x200
230
231/** Bit mask for digit type options. @stable ICU 2.0 */
232#define U_SHAPE_DIGIT_TYPE_MASK                 0x3f00
233
234#endif
235