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The Apache PDFBox library is an open source Java tool for working with PDF documents.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.pdfbox.filter;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* This class represents an ASCII85 output stream.
*
* @author Ben Litchfield
*
*/
final class ASCII85OutputStream extends FilterOutputStream
{
private int lineBreak;
private int count;
private byte[] indata;
private byte[] outdata;
/**
* Function produces five ASCII printing characters from
* four bytes of binary data.
*/
private int maxline;
private boolean flushed;
private char terminator;
private static final char OFFSET = '!';
private static final char NEWLINE = '\n';
private static final char Z = 'z';
/**
* Constructor.
*
* @param out The output stream to write to.
*/
ASCII85OutputStream(OutputStream out)
{
super(out);
lineBreak = 36 * 2;
maxline = 36 * 2;
count = 0;
indata = new byte[4];
outdata = new byte[5];
flushed = true;
terminator = '~';
}
/**
* This will set the terminating character.
*
* @param term The terminating character.
*/
public void setTerminator(char term)
{
if (term < 118 || term > 126 || term == Z)
{
throw new IllegalArgumentException("Terminator must be 118-126 excluding z");
}
terminator = term;
}
/**
* This will get the terminating character.
*
* @return The terminating character.
*/
public char getTerminator()
{
return terminator;
}
/**
* This will set the line length that will be used.
*
* @param l The length of the line to use.
*/
public void setLineLength(int l)
{
if (lineBreak > l)
{
lineBreak = l;
}
maxline = l;
}
/**
* This will get the length of the line.
*
* @return The line length attribute.
*/
public int getLineLength()
{
return maxline;
}
/**
* This will transform the next four ascii bytes.
*/
private void transformASCII85()
{
long word = ((((indata[0] << 8) | (indata[1] & 0xFF)) << 16) | ((indata[2] & 0xFF) << 8) | (indata[3] & 0xFF)) & 0xFFFFFFFFL;
if (word == 0)
{
outdata[0] = (byte) Z;
outdata[1] = 0;
return;
}
long x;
x = word / (85L * 85L * 85L * 85L);
outdata[0] = (byte) (x + OFFSET);
word -= x * 85L * 85L * 85L * 85L;
x = word / (85L * 85L * 85L);
outdata[1] = (byte) (x + OFFSET);
word -= x * 85L * 85L * 85L;
x = word / (85L * 85L);
outdata[2] = (byte) (x + OFFSET);
word -= x * 85L * 85L;
x = word / 85L;
outdata[3] = (byte) (x + OFFSET);
outdata[4] = (byte) ((word % 85L) + OFFSET);
}
/**
* This will write a single byte.
*
* @param b The byte to write.
*
* @throws IOException If there is an error writing to the stream.
*/
@Override
public void write(int b) throws IOException
{
flushed = false;
indata[count++] = (byte) b;
if (count < 4)
{
return;
}
transformASCII85();
for (int i = 0; i < 5; i++)
{
if (outdata[i] == 0)
{
break;
}
out.write(outdata[i]);
if (--lineBreak == 0)
{
out.write(NEWLINE);
lineBreak = maxline;
}
}
count = 0;
}
/**
* This will flush the data to the stream.
*
* @throws IOException If there is an error writing the data to the stream.
*/
@Override
public void flush() throws IOException
{
if (flushed)
{
return;
}
if (count > 0)
{
for (int i = count; i < 4; i++)
{
indata[i] = 0;
}
transformASCII85();
if (outdata[0] == Z)
{
for (int i = 0; i < 5; i++) // expand 'z',
{
outdata[i] = (byte) OFFSET;
}
}
for (int i = 0; i < count + 1; i++)
{
out.write(outdata[i]);
if (--lineBreak == 0)
{
out.write(NEWLINE);
lineBreak = maxline;
}
}
}
if (--lineBreak == 0)
{
out.write(NEWLINE);
}
out.write(terminator);
out.write('>');
out.write(NEWLINE);
count = 0;
lineBreak = maxline;
flushed = true;
super.flush();
}
/**
* This will close the stream.
*
* @throws IOException If there is an error closing the wrapped stream.
*/
@Override
public void close() throws IOException
{
try
{
flush();
super.close();
}
finally
{
indata = outdata = null;
}
}
}