tiffdirectory.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

/*
 * Copyright (c) 2001 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduct the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
 * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
 * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
 * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
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 *
 * You acknowledge that Software is not designed,licensed or intended for use in
 * the design, construction, operation or maintenance of any nuclear facility.
 */
package com.lowagie.text.pdf.codec;
import java.io.EOFException;
import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Hashtable;

import com.lowagie.text.pdf.RandomAccessFileOrArray;

/**
 * A class representing an Image File Directory (IFD) from a TIFF 6.0
 * stream.  The TIFF file format is described in more detail in the
 * comments for the TIFFDescriptor class.
 *
 * <p> A TIFF IFD consists of a set of TIFFField tags.  Methods are
 * provided to query the set of tags and to obtain the raw field
 * array.  In addition, convenience methods are provided for acquiring
 * the values of tags that contain a single value that fits into a
 * byte, int, long, float, or double.
 *
 * <p> Every TIFF file is made up of one or more public IFDs that are
 * joined in a linked list, rooted in the file header.  A file may
 * also contain so-called private IFDs that are referenced from
 * tag data and do not appear in the main list.
 *
 * <p><b> This class is not a committed part of the JAI API.  It may
 * be removed or changed in future releases of JAI.</b>
 *
 * @see TIFFField
 */
public class TIFFDirectory extends Object implements Serializable {
    
    private static final long serialVersionUID = -168636766193675380L;

	/** A boolean storing the endianness of the stream. */
    boolean isBigEndian;
    
    /** The number of entries in the IFD. */
    int numEntries;
    
    /** An array of TIFFFields. */
    TIFFField[] fields;
    
    /** A Hashtable indexing the fields by tag number. */
    Hashtable fieldIndex = new Hashtable();
    
    /** The offset of this IFD. */
    long IFDOffset = 8;
    
    /** The offset of the next IFD. */
    long nextIFDOffset = 0;
    
    /** The default constructor. */
    TIFFDirectory() {}
    
    private static boolean isValidEndianTag(int endian) {
        return ((endian == 0x4949) || (endian == 0x4d4d));
    }
    
    /**
     * Constructs a TIFFDirectory from a SeekableStream.
     * The directory parameter specifies which directory to read from
     * the linked list present in the stream; directory 0 is normally
     * read but it is possible to store multiple images in a single
     * TIFF file by maintaing multiple directories.
     *
     * @param stream a SeekableStream to read from.
     * @param directory the index of the directory to read.
     */
    public TIFFDirectory(RandomAccessFileOrArray stream, int directory)
    throws IOException {
        
        long global_save_offset = stream.getFilePointer();
        long ifd_offset;
        
        // Read the TIFF header
        stream.seek(0L);
        int endian = stream.readUnsignedShort();
        if (!isValidEndianTag(endian)) {
            throw new
            IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
        }
        isBigEndian = (endian == 0x4d4d);
        
        int magic = readUnsignedShort(stream);
        if (magic != 42) {
            throw new
            IllegalArgumentException("Bad magic number, should be 42.");
        }
        
        // Get the initial ifd offset as an unsigned int (using a long)
        ifd_offset = readUnsignedInt(stream);
        
        for (int i = 0; i < directory; i++) {
            if (ifd_offset == 0L) {
                throw new
                IllegalArgumentException("Directory number too large.");
            }
            
            stream.seek(ifd_offset);
            int entries = readUnsignedShort(stream);
            stream.skip(12*entries);
            
            ifd_offset = readUnsignedInt(stream);
        }
        
        stream.seek(ifd_offset);
        initialize(stream);
        stream.seek(global_save_offset);
    }
    
    /**
     * Constructs a TIFFDirectory by reading a SeekableStream.
     * The ifd_offset parameter specifies the stream offset from which
     * to begin reading; this mechanism is sometimes used to store
     * private IFDs within a TIFF file that are not part of the normal
     * sequence of IFDs.
     *
     * @param stream a SeekableStream to read from.
     * @param ifd_offset the long byte offset of the directory.
     * @param directory the index of the directory to read beyond the
     *        one at the current stream offset; zero indicates the IFD
     *        at the current offset.
     */
    public TIFFDirectory(RandomAccessFileOrArray stream, long ifd_offset, int directory)
    throws IOException {
        
        long global_save_offset = stream.getFilePointer();
        stream.seek(0L);
        int endian = stream.readUnsignedShort();
        if (!isValidEndianTag(endian)) {
            throw new
            IllegalArgumentException("Bad endianness tag (not 0x4949 or 0x4d4d).");
        }
        isBigEndian = (endian == 0x4d4d);
        
        // Seek to the first IFD.
        stream.seek(ifd_offset);
        
        // Seek to desired IFD if necessary.
        int dirNum = 0;
        while(dirNum < directory) {
            // Get the number of fields in the current IFD.
            int numEntries = readUnsignedShort(stream);
            
            // Skip to the next IFD offset value field.
            stream.seek(ifd_offset + 12*numEntries);
            
            // Read the offset to the next IFD beyond this one.
            ifd_offset = readUnsignedInt(stream);
            
            // Seek to the next IFD.
            stream.seek(ifd_offset);
            
            // Increment the directory.
            dirNum++;
        }
        
        initialize(stream);
        stream.seek(global_save_offset);
    }
    
    private static final int[] sizeOfType = {
        0, //  0 = n/a
        1, //  1 = byte
        1, //  2 = ascii
        2, //  3 = short
        4, //  4 = long
        8, //  5 = rational
        1, //  6 = sbyte
        1, //  7 = undefined
        2, //  8 = sshort
        4, //  9 = slong
        8, // 10 = srational
        4, // 11 = float
        8  // 12 = double
    };
    
    private void initialize(RandomAccessFileOrArray stream) throws IOException {
        long nextTagOffset = 0L;
        long maxOffset = stream.length();
        int i, j;
        
        IFDOffset = stream.getFilePointer();
        
        numEntries = readUnsignedShort(stream);
        fields = new TIFFField[numEntries];
        
        for (i = 0; (i < numEntries) && (nextTagOffset < maxOffset); i++) {
            int tag = readUnsignedShort(stream);
            int type = readUnsignedShort(stream);
            int count = (int)(readUnsignedInt(stream));
            boolean processTag = true;
            
            // The place to return to to read the next tag
            nextTagOffset = stream.getFilePointer() + 4;
            
            try {
                // If the tag data can't fit in 4 bytes, the next 4 bytes
                // contain the starting offset of the data
                if (count*sizeOfType[type] > 4) {
                    long valueOffset = readUnsignedInt(stream);
                    
                    // bounds check offset for EOF
                    if (valueOffset < maxOffset) {
                    	stream.seek(valueOffset);
                    }
                    else {
                    	// bad offset pointer .. skip tag
                    	processTag = false;
                    }
                }
            } catch (ArrayIndexOutOfBoundsException ae) {
                // if the data type is unknown we should skip this TIFF Field
                processTag = false;
            }
            
            if (processTag) {
            fieldIndex.put(new Integer(tag), new Integer(i));
            Object obj = null;
            
            switch (type) {
                case TIFFField.TIFF_BYTE:
                case TIFFField.TIFF_SBYTE:
                case TIFFField.TIFF_UNDEFINED:
                case TIFFField.TIFF_ASCII:
                    byte[] bvalues = new byte[count];
                    stream.readFully(bvalues, 0, count);
                    
                    if (type == TIFFField.TIFF_ASCII) {
                        
                        // Can be multiple strings
                        int index = 0, prevIndex = 0;
                        ArrayList v = new ArrayList();
                        
                        while (index < count) {
                            
                            while ((index < count) && (bvalues[index++] != 0));
                            
                            // When we encountered zero, means one string has ended
                            v.add(new String(bvalues, prevIndex,
                            (index - prevIndex)) );
                            prevIndex = index;
                        }
                        
                        count = v.size();
                        String strings[] = new String[count];
                        for (int c = 0 ; c < count; c++) {
                            strings[c] = (String)v.get(c);
                        }
                        
                        obj = strings;
                    } else {
                        obj = bvalues;
                    }
                    
                    break;
                    
                case TIFFField.TIFF_SHORT:
                    char[] cvalues = new char[count];
                    for (j = 0; j < count; j++) {
                        cvalues[j] = (char)(readUnsignedShort(stream));
                    }
                    obj = cvalues;
                    break;
                    
                case TIFFField.TIFF_LONG:
                    long[] lvalues = new long[count];
                    for (j = 0; j < count; j++) {
                        lvalues[j] = readUnsignedInt(stream);
                    }
                    obj = lvalues;
                    break;
                    
                case TIFFField.TIFF_RATIONAL:
                    long[][] llvalues = new long[count][2];
                    for (j = 0; j < count; j++) {
                        llvalues[j][0] = readUnsignedInt(stream);
                        llvalues[j][1] = readUnsignedInt(stream);
                    }
                    obj = llvalues;
                    break;
                    
                case TIFFField.TIFF_SSHORT:
                    short[] svalues = new short[count];
                    for (j = 0; j < count; j++) {
                        svalues[j] = readShort(stream);
                    }
                    obj = svalues;
                    break;
                    
                case TIFFField.TIFF_SLONG:
                    int[] ivalues = new int[count];
                    for (j = 0; j < count; j++) {
                        ivalues[j] = readInt(stream);
                    }
                    obj = ivalues;
                    break;
                    
                case TIFFField.TIFF_SRATIONAL: