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| 1 | /* | ||
| 2 | * Copyright (c) 2000, 2009, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | /* | ||
| 27 | * (C) Copyright IBM Corp. 1999-2003 - All Rights Reserved | ||
| 28 | * | ||
| 29 | * The original version of this source code and documentation is | ||
| 30 | * copyrighted and owned by IBM. These materials are provided | ||
| 31 | * under terms of a License Agreement between IBM and Sun. | ||
| 32 | * This technology is protected by multiple US and International | ||
| 33 | * patents. This notice and attribution to IBM may not be removed. | ||
| 34 | */ | ||
| 35 | |||
| 36 | package java.text; | ||
| 37 | |||
| 38 | import sun.text.bidi.BidiBase; | ||
| 39 | |||
| 40 | /** | ||
| 41 | * This class implements the Unicode Bidirectional Algorithm. | ||
| 42 | * <p> | ||
| 43 | * A Bidi object provides information on the bidirectional reordering of the text | ||
| 44 | * used to create it. This is required, for example, to properly display Arabic | ||
| 45 | * or Hebrew text. These languages are inherently mixed directional, as they order | ||
| 46 | * numbers from left-to-right while ordering most other text from right-to-left. | ||
| 47 | * <p> | ||
| 48 | * Once created, a Bidi object can be queried to see if the text it represents is | ||
| 49 | * all left-to-right or all right-to-left. Such objects are very lightweight and | ||
| 50 | * this text is relatively easy to process. | ||
| 51 | * <p> | ||
| 52 | * If there are multiple runs of text, information about the runs can be accessed | ||
| 53 | * by indexing to get the start, limit, and level of a run. The level represents | ||
| 54 | * both the direction and the 'nesting level' of a directional run. Odd levels | ||
| 55 | * are right-to-left, while even levels are left-to-right. So for example level | ||
| 56 | * 0 represents left-to-right text, while level 1 represents right-to-left text, and | ||
| 57 | * level 2 represents left-to-right text embedded in a right-to-left run. | ||
| 58 | * | ||
| 59 | * @since 1.4 | ||
| 60 | */ | ||
| 61 | public final class Bidi { | ||
| 62 | |||
| 63 | /** Constant indicating base direction is left-to-right. */ | ||
| 64 | public static final int DIRECTION_LEFT_TO_RIGHT = 0; | ||
| 65 | |||
| 66 | /** Constant indicating base direction is right-to-left. */ | ||
| 67 | public static final int DIRECTION_RIGHT_TO_LEFT = 1; | ||
| 68 | |||
| 69 | /** | ||
| 70 | * Constant indicating that the base direction depends on the first strong | ||
| 71 | * directional character in the text according to the Unicode | ||
| 72 | * Bidirectional Algorithm. If no strong directional character is present, | ||
| 73 | * the base direction is left-to-right. | ||
| 74 | */ | ||
| 75 | public static final int DIRECTION_DEFAULT_LEFT_TO_RIGHT = -2; | ||
| 76 | |||
| 77 | /** | ||
| 78 | * Constant indicating that the base direction depends on the first strong | ||
| 79 | * directional character in the text according to the Unicode | ||
| 80 | * Bidirectional Algorithm. If no strong directional character is present, | ||
| 81 | * the base direction is right-to-left. | ||
| 82 | */ | ||
| 83 | public static final int DIRECTION_DEFAULT_RIGHT_TO_LEFT = -1; | ||
| 84 | |||
| 85 | private BidiBase bidiBase; | ||
| 86 | |||
| 87 | /** | ||
| 88 | * Create Bidi from the given paragraph of text and base direction. | ||
| 89 | * @param paragraph a paragraph of text | ||
| 90 | * @param flags a collection of flags that control the algorithm. The | ||
| 91 | * algorithm understands the flags DIRECTION_LEFT_TO_RIGHT, DIRECTION_RIGHT_TO_LEFT, | ||
| 92 | * DIRECTION_DEFAULT_LEFT_TO_RIGHT, and DIRECTION_DEFAULT_RIGHT_TO_LEFT. | ||
| 93 | * Other values are reserved. | ||
| 94 | */ | ||
| 95 | public Bidi(String paragraph, int flags) { | ||
| 96 | if (paragraph == null) { | ||
| 97 | throw new IllegalArgumentException("paragraph is null"); | ||
| 98 | } | ||
| 99 | |||
| 100 | bidiBase = new BidiBase(paragraph.toCharArray(), 0, null, 0, paragraph.length(), flags); | ||
| 101 | } | ||
| 102 | |||
| 103 | /** | ||
| 104 | * Create Bidi from the given paragraph of text. | ||
| 105 | * <p> | ||
| 106 | * The RUN_DIRECTION attribute in the text, if present, determines the base | ||
| 107 | * direction (left-to-right or right-to-left). If not present, the base | ||
| 108 | * direction is computes using the Unicode Bidirectional Algorithm, defaulting to left-to-right | ||
| 109 | * if there are no strong directional characters in the text. This attribute, if | ||
| 110 | * present, must be applied to all the text in the paragraph. | ||
| 111 | * <p> | ||
| 112 | * The BIDI_EMBEDDING attribute in the text, if present, represents embedding level | ||
| 113 | * information. Negative values from -1 to -62 indicate overrides at the absolute value | ||
| 114 | * of the level. Positive values from 1 to 62 indicate embeddings. Where values are | ||
| 115 | * zero or not defined, the base embedding level as determined by the base direction | ||
| 116 | * is assumed. | ||
| 117 | * <p> | ||
| 118 | * The NUMERIC_SHAPING attribute in the text, if present, converts European digits to | ||
| 119 | * other decimal digits before running the bidi algorithm. This attribute, if present, | ||
| 120 | * must be applied to all the text in the paragraph. | ||
| 121 | * | ||
| 122 | * @param paragraph a paragraph of text with optional character and paragraph attribute information | ||
| 123 | * | ||
| 124 | * @see java.awt.font.TextAttribute#BIDI_EMBEDDING | ||
| 125 | * @see java.awt.font.TextAttribute#NUMERIC_SHAPING | ||
| 126 | * @see java.awt.font.TextAttribute#RUN_DIRECTION | ||
| 127 | */ | ||
| 128 | public Bidi(AttributedCharacterIterator paragraph) { | ||
| 129 | if (paragraph == null) { | ||
| 130 | throw new IllegalArgumentException("paragraph is null"); | ||
| 131 | } | ||
| 132 | |||
| 133 | bidiBase = new BidiBase(0, 0); | ||
| 134 | bidiBase.setPara(paragraph); | ||
| 135 | } | ||
| 136 | |||
| 137 | /** | ||
| 138 | * Create Bidi from the given text, embedding, and direction information. | ||
| 139 | * The embeddings array may be null. If present, the values represent embedding level | ||
| 140 | * information. Negative values from -1 to -61 indicate overrides at the absolute value | ||
| 141 | * of the level. Positive values from 1 to 61 indicate embeddings. Where values are | ||
| 142 | * zero, the base embedding level as determined by the base direction is assumed. | ||
| 143 | * @param text an array containing the paragraph of text to process. | ||
| 144 | * @param textStart the index into the text array of the start of the paragraph. | ||
| 145 | * @param embeddings an array containing embedding values for each character in the paragraph. | ||
| 146 | * This can be null, in which case it is assumed that there is no external embedding information. | ||
| 147 | * @param embStart the index into the embedding array of the start of the paragraph. | ||
| 148 | * @param paragraphLength the length of the paragraph in the text and embeddings arrays. | ||
| 149 | * @param flags a collection of flags that control the algorithm. The | ||
| 150 | * algorithm understands the flags DIRECTION_LEFT_TO_RIGHT, DIRECTION_RIGHT_TO_LEFT, | ||
| 151 | * DIRECTION_DEFAULT_LEFT_TO_RIGHT, and DIRECTION_DEFAULT_RIGHT_TO_LEFT. | ||
| 152 | * Other values are reserved. | ||
| 153 | */ | ||
| 154 | public Bidi(char[] text, int textStart, byte[] embeddings, int embStart, int paragraphLength, int flags) { | ||
| 155 | if (text == null) { | ||
| 156 | throw new IllegalArgumentException("text is null"); | ||
| 157 | } | ||
| 158 | if (paragraphLength < 0) { | ||
| 159 | throw new IllegalArgumentException("bad length: " + paragraphLength); | ||
| 160 | } | ||
| 161 | if (textStart < 0 || paragraphLength > text.length - textStart) { | ||
| 162 | throw new IllegalArgumentException("bad range: " + textStart + | ||
| 163 | " length: " + paragraphLength + | ||
| 164 | " for text of length: " + text.length); | ||
| 165 | } | ||
| 166 | if (embeddings != null && (embStart < 0 || paragraphLength > embeddings.length - embStart)) { | ||
| 167 | throw new IllegalArgumentException("bad range: " + embStart + | ||
| 168 | " length: " + paragraphLength + | ||
| 169 | " for embeddings of length: " + text.length); | ||
| 170 | } | ||
| 171 | |||
| 172 | bidiBase = new BidiBase(text, textStart, embeddings, embStart, paragraphLength, flags); | ||
| 173 | } | ||
| 174 | |||
| 175 | /** | ||
| 176 | * Create a Bidi object representing the bidi information on a line of text within | ||
| 177 | * the paragraph represented by the current Bidi. This call is not required if the | ||
| 178 | * entire paragraph fits on one line. | ||
| 179 | * @param lineStart the offset from the start of the paragraph to the start of the line. | ||
| 180 | * @param lineLimit the offset from the start of the paragraph to the limit of the line. | ||
| 181 | */ | ||
| 182 | public Bidi createLineBidi(int lineStart, int lineLimit) { | ||
| 183 | AttributedString astr = new AttributedString(""); | ||
| 184 | Bidi newBidi = new Bidi(astr.getIterator()); | ||
| 185 | |||
| 186 | return bidiBase.setLine(this, bidiBase, newBidi, newBidi.bidiBase,lineStart, lineLimit); | ||
| 187 | } | ||
| 188 | |||
| 189 | /** | ||
| 190 | * Return true if the line is not left-to-right or right-to-left. This means it either has mixed runs of left-to-right | ||
| 191 | * and right-to-left text, or the base direction differs from the direction of the only run of text. | ||
| 192 | * @return true if the line is not left-to-right or right-to-left. | ||
| 193 | */ | ||
| 194 | public boolean isMixed() { | ||
| 195 | return bidiBase.isMixed(); | ||
| 196 | } | ||
| 197 | |||
| 198 | /** | ||
| 199 | * Return true if the line is all left-to-right text and the base direction is left-to-right. | ||
| 200 | * @return true if the line is all left-to-right text and the base direction is left-to-right | ||
| 201 | */ | ||
| 202 | public boolean isLeftToRight() { | ||
| 203 | return bidiBase.isLeftToRight(); | ||
| 204 | } | ||
| 205 | |||
| 206 | /** | ||
| 207 | * Return true if the line is all right-to-left text, and the base direction is right-to-left. | ||
| 208 | * @return true if the line is all right-to-left text, and the base direction is right-to-left | ||
| 209 | */ | ||
| 210 | public boolean isRightToLeft() { | ||
| 211 | return bidiBase.isRightToLeft(); | ||
| 212 | } | ||
| 213 | |||
| 214 | /** | ||
| 215 | * Return the length of text in the line. | ||
| 216 | * @return the length of text in the line | ||
| 217 | */ | ||
| 218 | public int getLength() { | ||
| 219 | return bidiBase.getLength(); | ||
| 220 | } | ||
| 221 | |||
| 222 | /** | ||
| 223 | * Return true if the base direction is left-to-right. | ||
| 224 | * @return true if the base direction is left-to-right | ||
| 225 | */ | ||
| 226 | public boolean baseIsLeftToRight() { | ||
| 227 | return bidiBase.baseIsLeftToRight(); | ||
| 228 | } | ||
| 229 | |||
| 230 | /** | ||
| 231 | * Return the base level (0 if left-to-right, 1 if right-to-left). | ||
| 232 | * @return the base level | ||
| 233 | */ | ||
| 234 | public int getBaseLevel() { | ||
| 235 | return bidiBase.getParaLevel(); | ||
| 236 | } | ||
| 237 | |||
| 238 | /** | ||
| 239 | * Return the resolved level of the character at offset. If offset is <0 or >= | ||
| 240 | * the length of the line, return the base direction level. | ||
| 241 | * @param offset the index of the character for which to return the level | ||
| 242 | * @return the resolved level of the character at offset | ||
| 243 | */ | ||
| 244 | public int getLevelAt(int offset) { | ||
| 245 | return bidiBase.getLevelAt(offset); | ||
| 246 | } | ||
| 247 | |||
| 248 | /** | ||
| 249 | * Return the number of level runs. | ||
| 250 | * @return the number of level runs | ||
| 251 | */ | ||
| 252 | public int getRunCount() { | ||
| 253 | return bidiBase.countRuns(); | ||
| 254 | } | ||
| 255 | |||
| 256 | /** | ||
| 257 | * Return the level of the nth logical run in this line. | ||
| 258 | * @param run the index of the run, between 0 and <code>getRunCount()</code> | ||
| 259 | * @return the level of the run | ||
| 260 | */ | ||
| 261 | public int getRunLevel(int run) { | ||
| 262 | return bidiBase.getRunLevel(run); | ||
| 263 | } | ||
| 264 | |||
| 265 | /** | ||
| 266 | * Return the index of the character at the start of the nth logical run in this line, as | ||
| 267 | * an offset from the start of the line. | ||
| 268 | * @param run the index of the run, between 0 and <code>getRunCount()</code> | ||
| 269 | * @return the start of the run | ||
| 270 | */ | ||
| 271 | public int getRunStart(int run) { | ||
| 272 | return bidiBase.getRunStart(run); | ||
| 273 | } | ||
| 274 | |||
| 275 | /** | ||
| 276 | * Return the index of the character past the end of the nth logical run in this line, as | ||
| 277 | * an offset from the start of the line. For example, this will return the length | ||
| 278 | * of the line for the last run on the line. | ||
| 279 | * @param run the index of the run, between 0 and <code>getRunCount()</code> | ||
| 280 | * @return limit the limit of the run | ||
| 281 | */ | ||
| 282 | public int getRunLimit(int run) { | ||
| 283 | return bidiBase.getRunLimit(run); | ||
| 284 | } | ||
| 285 | |||
| 286 | /** | ||
| 287 | * Return true if the specified text requires bidi analysis. If this returns false, | ||
| 288 | * the text will display left-to-right. Clients can then avoid constructing a Bidi object. | ||
| 289 | * Text in the Arabic Presentation Forms area of Unicode is presumed to already be shaped | ||
| 290 | * and ordered for display, and so will not cause this function to return true. | ||
| 291 | * | ||
| 292 | * @param text the text containing the characters to test | ||
| 293 | * @param start the start of the range of characters to test | ||
| 294 | * @param limit the limit of the range of characters to test | ||
| 295 | * @return true if the range of characters requires bidi analysis | ||
| 296 | */ | ||
| 297 | public static boolean requiresBidi(char[] text, int start, int limit) { | ||
| 298 | return BidiBase.requiresBidi(text, start, limit); | ||
| 299 | } | ||
| 300 | |||
| 301 | /** | ||
| 302 | * Reorder the objects in the array into visual order based on their levels. | ||
| 303 | * This is a utility function to use when you have a collection of objects | ||
| 304 | * representing runs of text in logical order, each run containing text | ||
| 305 | * at a single level. The elements at <code>index</code> from | ||
| 306 | * <code>objectStart</code> up to <code>objectStart + count</code> | ||
| 307 | * in the objects array will be reordered into visual order assuming | ||
| 308 | * each run of text has the level indicated by the corresponding element | ||
| 309 | * in the levels array (at <code>index - objectStart + levelStart</code>). | ||
| 310 | * | ||
| 311 | * @param levels an array representing the bidi level of each object | ||
| 312 | * @param levelStart the start position in the levels array | ||
| 313 | * @param objects the array of objects to be reordered into visual order | ||
| 314 | * @param objectStart the start position in the objects array | ||
| 315 | * @param count the number of objects to reorder | ||
| 316 | */ | ||
| 317 | public static void reorderVisually(byte[] levels, int levelStart, Object[] objects, int objectStart, int count) { | ||
| 318 | BidiBase.reorderVisually(levels, levelStart, objects, objectStart, count); | ||
| 319 | } | ||
| 320 | |||
| 321 | /** | ||
| 322 | * Display the bidi internal state, used in debugging. | ||
| 323 | */ | ||
| 324 | public String toString() { | ||
| 325 | return bidiBase.toString(); | ||
| 326 | } | ||
| 327 | |||
| 328 | } | ||