bidiorder.java

iText是一个能够快速产生PDF文件的java类库。iText的java类对于那些要产生包含文本

package com.lowagie.text.pdf;

/*
 * Copyright 2003 Paulo Soares
 *
 * The contents of this file are subject to the Mozilla Public License Version 1.1
 * (the "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the License.
 *
 * The Original Code is 'iText, a free JAVA-PDF library'.
 *
 * The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
 * the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
 * All Rights Reserved.
 * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
 * are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
 *
 * Contributor(s): all the names of the contributors are added in the source code
 * where applicable.
 *
 * Alternatively, the contents of this file may be used under the terms of the
 * LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
 * provisions of LGPL are applicable instead of those above.  If you wish to
 * allow use of your version of this file only under the terms of the LGPL
 * License and not to allow others to use your version of this file under
 * the MPL, indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by the LGPL.
 * If you do not delete the provisions above, a recipient may use your version
 * of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the MPL as stated above or under the terms of the GNU
 * Library General Public License as published by the Free Software Foundation;
 * either version 2 of the License, or any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more
 * details.
 *
 * If you didn't download this code from the following link, you should check if
 * you aren't using an obsolete version:
 * http://www.lowagie.com/iText/
 */

/*
 * (C) Copyright IBM Corp. 1999, All Rights Reserved
 *
 * version 1.1
 */

/*
 * As stated in the Javadoc comments below, materials from Unicode.org
 * are used in this class. The following license applies to these materials:
 * http://www.unicode.org/copyright.html#Exhibit1
 * 
 * EXHIBIT 1
 * UNICODE, INC. LICENSE AGREEMENT - DATA FILES AND SOFTWARE
 * 
 * Unicode Data Files include all data files under the directories
 * http://www.unicode.org/Public/, http://www.unicode.org/reports/,
 * and http://www.unicode.org/cldr/data/ .
 * Unicode Software includes any source code published in the Unicode Standard
 * or under the directories http://www.unicode.org/Public/, http://www.unicode.org/reports/,
 * and http://www.unicode.org/cldr/data/.
 * 
 * NOTICE TO USER: Carefully read the following legal agreement. BY DOWNLOADING,
 * INSTALLING, COPYING OR OTHERWISE USING UNICODE INC.'S DATA FILES ("DATA FILES"),
 * AND/OR SOFTWARE ("SOFTWARE"), YOU UNEQUIVOCALLY ACCEPT, AND AGREE TO BE BOUND BY,
 * ALL OF THE TERMS AND CONDITIONS OF THIS AGREEMENT. IF YOU DO NOT AGREE, DO NOT
 * DOWNLOAD, INSTALL, COPY, DISTRIBUTE OR USE THE DATA FILES OR SOFTWARE.
 * 
 * COPYRIGHT AND PERMISSION NOTICE
 * Copyright (C) 1991-2007 Unicode, Inc. All rights reserved. Distributed under
 * the Terms of Use in http://www.unicode.org/copyright.html.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of the Unicode data files and any associated documentation (the "Data Files")
 * or Unicode software and any associated documentation (the "Software") to deal
 * in the Data Files or Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, and/or sell copies
 * of the Data Files or Software, and to permit persons to whom the Data Files
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 * or Software, (b) both the above copyright notice(s) and this permission notice
 * appear in associated documentation, and (c) there is clear notice in each
 * modified Data File or in the Software as well as in the documentation associated
 * with the Data File(s) or Software that the data or software has been modified.
 * 
 * THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE
 * LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY
 * DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THE DATA FILES OR SOFTWARE.
 * 
 * Except as contained in this notice, the name of a copyright holder shall not
 * be used in advertising or otherwise to promote the sale, use or other dealings
 * in these Data Files or Software without prior written authorization of the
 * copyright holder.
 */

/**
 * Reference implementation of the Unicode 3.0 Bidi algorithm.
 *
 * <p>
 * This implementation is not optimized for performance.  It is intended
 * as a reference implementation that closely follows the specification
 * of the Bidirectional Algorithm in The Unicode Standard version 3.0.
 * <p>
 * <b>Input:</b><br>
 * There are two levels of input to the algorithm, since clients may prefer
 * to supply some information from out-of-band sources rather than relying on
 * the default behavior.
 * <ol>
 * <li>unicode type array
 * <li>unicode type array, with externally supplied base line direction
 * </ol>
 * <p><b>Output:</b><br>
 * Output is separated into several stages as well, to better enable clients
 * to evaluate various aspects of implementation conformance.
 * <ol>
 * <li>levels array over entire paragraph
 * <li>reordering array over entire paragraph
 * <li>levels array over line
 * <li>reordering array over line
 * </ol>
 * Note that for conformance, algorithms are only required to generate correct
 * reordering and character directionality (odd or even levels) over a line.
 * Generating identical level arrays over a line is not required.  Bidi
 * explicit format codes (LRE, RLE, LRO, RLO, PDF) and BN can be assigned
 * arbitrary levels and positions as long as the other text matches.
 * <p>
 * As the algorithm is defined to operate on a single paragraph at a time,
 * this implementation is written to handle single paragraphs.  Thus
 * rule P1 is presumed by this implementation-- the data provided to the
 * implementation is assumed to be a single paragraph, and either contains no
 * 'B' codes, or a single 'B' code at the end of the input.  'B' is allowed
 * as input to illustrate how the algorithm assigns it a level.
 * <p>
 * Also note that rules L3 and L4 depend on the rendering engine that uses
 * the result of the bidi algorithm.  This implementation assumes that the
 * rendering engine expects combining marks in visual order (e.g. to the
 * left of their base character in RTL runs) and that it adjust the glyphs
 * used to render mirrored characters that are in RTL runs so that they
 * render appropriately.
 *
 * @author Doug Felt
 */

public final class BidiOrder {
    private byte[] initialTypes;
    private byte[] embeddings; // generated from processing format codes
    private byte paragraphEmbeddingLevel = -1; // undefined
    
    private int textLength; // for convenience
    private byte[] resultTypes; // for paragraph, not lines
    private byte[] resultLevels; // for paragraph, not lines
    
    // The bidi types
    
    /** Left-to-right*/
    public static final byte L = 0;
    
    /** Left-to-Right Embedding */
    public static final byte LRE = 1;
    
    /** Left-to-Right Override */
    public static final byte LRO = 2;
    
    /** Right-to-Left */
    public static final byte R = 3;
    
    /** Right-to-Left Arabic */
    public static final byte AL = 4;
    
    /** Right-to-Left Embedding */
    public static final byte RLE = 5;
    
    /** Right-to-Left Override */
    public static final byte RLO = 6;
    
    /** Pop Directional Format */
    public static final byte PDF = 7;
    
    /** European Number */
    public static final byte EN = 8;
    
    /** European Number Separator */
    public static final byte ES = 9;
    
    /** European Number Terminator */
    public static final byte ET = 10;
    
    /** Arabic Number */
    public static final byte AN = 11;
    
    /** Common Number Separator */
    public static final byte CS = 12;
    
    /** Non-Spacing Mark */
    public static final byte NSM = 13;
    
    /** Boundary Neutral */
    public static final byte BN = 14;
    
    /** Paragraph Separator */
    public static final byte B = 15;
    
    /** Segment Separator */
    public static final byte S = 16;
    
    /** Whitespace */
    public static final byte WS = 17;
    
    /** Other Neutrals */
    public static final byte ON = 18;
    
    /** Minimum bidi type value. */
    public static final byte TYPE_MIN = 0;
    
    /** Maximum bidi type value. */
    public static final byte TYPE_MAX = 18;
    
    //
    // Input
    //
    
    /**
     * Initialize using an array of direction types.  Types range from TYPE_MIN to TYPE_MAX inclusive
     * and represent the direction codes of the characters in the text.
     *
     * @param types the types array
     */
    public BidiOrder(byte[] types) {
        validateTypes(types);
        
        this.initialTypes = (byte[])types.clone(); // client type array remains unchanged
        
        runAlgorithm();
    }
    
    /**
     * Initialize using an array of direction types and an externally supplied paragraph embedding level.
     * The embedding level may be -1, 0, or 1.  -1 means to apply the default algorithm (rules P2 and P3),
     * 0 is for LTR paragraphs, and 1 is for RTL paragraphs.
     *
     * @param types the types array
     * @param paragraphEmbeddingLevel the externally supplied paragraph embedding level.
     */
    public BidiOrder(byte[] types, byte paragraphEmbeddingLevel) {
        validateTypes(types);
        validateParagraphEmbeddingLevel(paragraphEmbeddingLevel);
        
        this.initialTypes = (byte[])types.clone(); // client type array remains unchanged
        this.paragraphEmbeddingLevel = paragraphEmbeddingLevel;
        
        runAlgorithm();
    }
    
    public BidiOrder(char text[], int offset, int length, byte paragraphEmbeddingLevel) {
        initialTypes = new byte[length];
        for (int k = 0; k < length; ++k) {
            initialTypes[k] = rtypes[text[offset + k]];
        }
        validateParagraphEmbeddingLevel(paragraphEmbeddingLevel);
        
        this.paragraphEmbeddingLevel = paragraphEmbeddingLevel;
        
        runAlgorithm();
    }
    
    public final static byte getDirection(char c) {
        return rtypes[c];
    }
    
    /**
     * The algorithm.
     * Does not include line-based processing (Rules L1, L2).
     * These are applied later in the line-based phase of the algorithm.
     */
    private void runAlgorithm() {
        textLength = initialTypes.length;
        
        // Initialize output types.
        // Result types initialized to input types.
        resultTypes = (byte[])initialTypes.clone();
        
        
        // 1) determining the paragraph level
        // Rule P1 is the requirement for entering this algorithm.
        // Rules P2, P3.
        // If no externally supplied paragraph embedding level, use default.
        if (paragraphEmbeddingLevel == -1) {
            determineParagraphEmbeddingLevel();
        }
        
        // Initialize result levels to paragraph embedding level.
        resultLevels = new byte[textLength];
        setLevels(0, textLength, paragraphEmbeddingLevel);
        
        // 2) Explicit levels and directions
        // Rules X1-X8.
        determineExplicitEmbeddingLevels();
        
        // Rule X9.
        textLength = removeExplicitCodes();
        
        // Rule X10.
        // Run remainder of algorithm one level run at a time
        byte prevLevel = paragraphEmbeddingLevel;
        int start = 0;
        while (start < textLength) {
            byte level = resultLevels[start];
            byte prevType = typeForLevel(Math.max(prevLevel, level));
            
            int limit = start + 1;
            while (limit < textLength && resultLevels[limit] == level) {