icuSources/common/unicode/ushape.h

   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  */
  99 U_STABLE int32_t U_EXPORT2
 100 u_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