bidi.java

java源代码 请看看啊 提点宝贵的意见

/*
 * @(#)Bidi.java	1.13 03/03/19
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

/*
 * (C) Copyright IBM Corp. 1999-2000 - All Rights Reserved
 *
 * The original version of this source code and documentation is
 * copyrighted and owned by IBM. These materials are provided
 * under terms of a License Agreement between IBM and Sun.
 * This technology is protected by multiple US and International
 * patents. This notice and attribution to IBM may not be removed.
 */

package java.text;

import java.awt.Toolkit;
import java.awt.font.TextAttribute;
import java.awt.font.NumericShaper;

/**
 * This class implements the Unicode Version 3.0 Bidirectional Algorithm.
 * <p>
 * A Bidi object provides information on the bidirectional reordering of the text
 * used to create it.  This is required, for example, to properly display Arabic 
 * or Hebrew text.  These languages are inherently mixed directional, as they order
 * numbers from left-to-right while ordering most other text from right-to-left.
 * <p>
 * Once created, a Bidi object can be queried to see if the text it represents is
 * all left-to-right or all right-to-left.  Such objects are very lightweight and
 * this text is relatively easy to process.
 * <p>
 * If there are multiple runs of text, information about the runs can be accessed
 * by indexing to get the start, limit, and level of a run.  The level represents
 * both the direction and the 'nesting level' of a directional run.  Odd levels
 * are right-to-left, while even levels are left-to-right.  So for example level
 * 0 represents left-to-right text, while level 1 represents right-to-left text, and
 * level 2 represents left-to-right text embedded in a right-to-left run.
 *
 * @since 1.4
 */
public final class Bidi {
    byte dir;
    byte baselevel;
    int length;
    int[] runs;
    int[] cws;

    static {
	java.security.AccessController.doPrivileged(
	    new sun.security.action.LoadLibraryAction("awt"));
	java.security.AccessController.doPrivileged(
	    new sun.security.action.LoadLibraryAction("fontmanager"));
    }

    /** Constant indicating base direction is left-to-right. */
    public static final int DIRECTION_LEFT_TO_RIGHT = 0;

    /** Constant indicating base direction is right-to-left. */
    public static final int DIRECTION_RIGHT_TO_LEFT = 1;

    /** 
     * Constant indicating that the base direction depends on the first strong
     * directional character in the text according to the Unicode
     * Bidirectional Algorithm.  If no strong directional character is present,
     * the base direction is left-to-right.
     */
    public static final int DIRECTION_DEFAULT_LEFT_TO_RIGHT = -2;

    /** 
     * Constant indicating that the base direction depends on the first strong
     * directional character in the text according to the Unicode
     * Bidirectional Algorithm.  If no strong directional character is present,
     * the base direction is right-to-left.
     */
    public static final int DIRECTION_DEFAULT_RIGHT_TO_LEFT = -1;

    private static final int DIR_MIXED = 2;

    /**
     * Create Bidi from the given paragraph of text and base direction.
     * @param paragraph a paragraph of text
     * @param flags a collection of flags that control the algorithm.  The
     * algorithm understands the flags DIRECTION_LEFT_TO_RIGHT, DIRECTION_RIGHT_TO_LEFT,
     * DIRECTION_DEFAULT_LEFT_TO_RIGHT, and DIRECTION_DEFAULT_RIGHT_TO_LEFT.
     * Other values are reserved.
     */
    public Bidi(String paragraph, int flags) {
        if (paragraph == null) {
            throw new IllegalArgumentException("paragraph is null");
        }

        nativeBidiChars(this, paragraph.toCharArray(), 0, null, 0, paragraph.length(), flags);
    }

    /**
     * Create Bidi from the given paragraph of text.
     * <p>
     * The RUN_DIRECTION attribute in the text, if present, determines the base
     * direction (left-to-right or right-to-left).  If not present, the base
     * direction is computes using the Unicode Bidirectional Algorithm, defaulting to left-to-right
     * if there are no strong directional characters in the text.  This attribute, if
     * present, must be applied to all the text in the paragraph.
     * <p>
     * The BIDI_EMBEDDING attribute in the text, if present, represents embedding level
     * information.  Negative values from -1 to -62 indicate overrides at the absolute value
     * of the level.  Positive values from 1 to 62 indicate embeddings.  Where values are
     * zero or not defined, the base embedding level as determined by the base direction
     * is assumed.
     * <p>
     * The NUMERIC_SHAPING attribute in the text, if present, converts European digits to
     * other decimal digits before running the bidi algorithm.  This attribute, if present,
     * must be applied to all the text in the paragraph.
     *
     * @param paragraph a paragraph of text with optional character and paragraph attribute information
     *
     * @see TextAttribute#BIDI_EMBEDDING
     * @see TextAttribute#NUMERIC_SHAPING
     * @see TextAttribute#RUN_DIRECTION
     */
    public Bidi(AttributedCharacterIterator paragraph) {
        if (paragraph == null) {
            throw new IllegalArgumentException("paragraph is null");
        }

        int flags = DIRECTION_DEFAULT_LEFT_TO_RIGHT;
        byte[] embeddings = null;

        int start = paragraph.getBeginIndex();
        int limit = paragraph.getEndIndex();
        int length = limit - start;
        int n = 0;
        char[] text = new char[length];
        for (char c = paragraph.first(); c != paragraph.DONE; c = paragraph.next()) {
            text[n++] = c;
        }

        paragraph.first();
        try {
            Boolean runDirection = (Boolean)paragraph.getAttribute(TextAttribute.RUN_DIRECTION);
            if (runDirection != null) {
                if (TextAttribute.RUN_DIRECTION_LTR.equals(runDirection)) {
                    flags = DIRECTION_LEFT_TO_RIGHT; // clears default setting
                } else {
                    flags = DIRECTION_RIGHT_TO_LEFT;
                }
            }
        }
        catch (ClassCastException e) {
        }

	try {
	    NumericShaper shaper = (NumericShaper)paragraph.getAttribute(TextAttribute.NUMERIC_SHAPING);
	    if (shaper != null) {
		shaper.shape(text, 0, text.length);
	    }
	}
	catch (ClassCastException e) {
	}

        int pos = start;
        do {
            paragraph.setIndex(pos);
            Object embeddingLevel = paragraph.getAttribute(TextAttribute.BIDI_EMBEDDING);
            int newpos = paragraph.getRunLimit(TextAttribute.BIDI_EMBEDDING);

            if (embeddingLevel != null) {
                try {
                    int intLevel = ((Integer)embeddingLevel).intValue();
                    if (intLevel >= -61 && intLevel < 61) {
                        byte level = (byte)(intLevel < 0 ? (-intLevel | 0x80) : intLevel);
                        if (embeddings == null) {
                            embeddings = new byte[length];
                        }
                        for (int i = pos - start; i < newpos - start; ++i) {
                            embeddings[i] = level;
                        }
                    }
                }
		catch (ClassCastException e) {
		}
            }
            pos = newpos;
        } while (pos < limit);

        nativeBidiChars(this, text, 0, embeddings, 0, text.length, flags);
    }
        
    /**
     * Create Bidi from the given text, embedding, and direction information.
     * The embeddings array may be null.  If present, the values represent embedding level
     * information.  Negative values from -1 to -61 indicate overrides at the absolute value
     * of the level.  Positive values from 1 to 61 indicate embeddings.  Where values are
     * zero, the base embedding level as determined by the base direction is assumed.
     * @param text an array containing the paragraph of text to process.
     * @param textStart the index into the text array of the start of the paragraph.
     * @param embeddings an array containing embedding values for each character in the paragraph.
     * This can be null, in which case it is assumed that there is no external embedding information.
     * @param embStart the index into the embedding array of the start of the paragraph.
     * @param paragraphLength the length of the paragraph in the text and embeddings arrays.
     * @param flags a collection of flags that control the algorithm.  The
     * algorithm understands the flags DIRECTION_LEFT_TO_RIGHT, DIRECTION_RIGHT_TO_LEFT,
     * DIRECTION_DEFAULT_LEFT_TO_RIGHT, and DIRECTION_DEFAULT_RIGHT_TO_LEFT.
     * Other values are reserved.
     */
    public Bidi(char[] text, int textStart, byte[] embeddings, int embStart, int paragraphLength, int flags) {
        if (text == null) {
            throw new IllegalArgumentException("text is null");
        }
        if (paragraphLength < 0) {
            throw new IllegalArgumentException("bad length: " + paragraphLength);
        }
        if (textStart < 0 || paragraphLength > text.length - textStart) {
            throw new IllegalArgumentException("bad range: " + textStart + 
                                               " length: " + paragraphLength + 
                                               " for text of length: " + text.length);
        }
        if (embeddings != null && (embStart < 0 || paragraphLength > embeddings.length - embStart)) {
            throw new IllegalArgumentException("bad range: " + embStart + 
                                               " length: " + paragraphLength + 
                                               " for embeddings of length: " + text.length);
        }

	if (embeddings != null) {
	    // native uses high bit to indicate override, not negative value, sigh

	    for (int i = embStart, embLimit = embStart + paragraphLength; i < embLimit; ++i) {
		if (embeddings[i] < 0) {
		    byte[] temp = new byte[paragraphLength];
		    System.arraycopy(embeddings, embStart, temp, 0, paragraphLength);

		    for (i -= embStart; i < paragraphLength; ++i) {
			if (temp[i] < 0) {
			    temp[i] = (byte)(-temp[i] | 0x80);
			}
		    }

		    embeddings = temp;
		    embStart = 0;
		    break;
		}
	    }
	}

        nativeBidiChars(this, text, textStart, embeddings, embStart, paragraphLength, flags);
    }

    /**
     * Private constructor used by line bidi.
     */
    private Bidi(int dir, int baseLevel, int length, int[] data, int[] cws) {
        reset(dir, baseLevel, length, data, cws);
    }

    /**
     * Private mutator used by native code.
     */
    private void reset(int dir, int baselevel, int length, int[] data, int[] cws) {
        this.dir = (byte)dir;
        this.baselevel = (byte)baselevel;
        this.length = length;
        this.runs = data;
        this.cws = cws;
    }

    /**
     * Create a Bidi object representing the bidi information on a line of text within
     * the paragraph represented by the current Bidi.  This call is not required if the
     * entire paragraph fits on one line.
     * @param lineStart the offset from the start of the paragraph to the start of the line.
     * @param lineLimit the offset from the start of the paragraph to the limit of the line.
     */
    public Bidi createLineBidi(int lineStart, int lineLimit) {
	if (lineStart == 0 && lineLimit == length) {
	    return this;
	}

	int lineLength = lineLimit - lineStart;
        if (lineStart < 0 ||
            lineLimit < lineStart ||
            lineLimit > length) {
            throw new IllegalArgumentException("range " + lineStart + 
                                               " to " + lineLimit + 
                                               " is invalid for paragraph of length " + length);
        }

        if (runs == null) {
            return new Bidi(dir, baselevel, lineLength, null, null);
        } else {
            int cwspos = -1;
            int[] ncws = null;
            if (cws != null) {
                int cwss = 0;
                int cwsl = cws.length;
                while (cwss < cwsl) {
                    if (cws[cwss] >= lineStart) {
                        cwsl = cwss;
                        while (cwsl < cws.length && cws[cwsl] < lineLimit) {
                            cwsl++;
                        }
                        int ll = lineLimit-1;
                        while (cwsl > cwss && cws[cwsl-1] == ll) {
                            cwspos = ll; // record start of counter-directional whitespace
                            --cwsl;
                            --ll;
                        }
                        
			if (cwspos == lineStart) { // entire line is cws, so ignore
			    return new Bidi(dir, baselevel, lineLength, null, null);
			}

                        int ncwslen = cwsl - cwss;
                        if (ncwslen > 0) {
                            ncws = new int[ncwslen];
                            for (int i = 0; i < ncwslen; ++i) {
                                ncws[i] = cws[cwss+i] - lineStart;
                            }
                        }