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* Copyright (c) 2003-2006, www.pdfbox.org
* All rights reserved.
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* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
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* contributors may be used to endorse or promote products derived from this
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package org.pdfbox.cos;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;
import org.pdfbox.filter.Filter;
import org.pdfbox.filter.FilterManager;
import org.pdfbox.pdfparser.PDFStreamParser;
import org.pdfbox.exceptions.COSVisitorException;
import org.pdfbox.io.RandomAccess;
import org.pdfbox.io.RandomAccessFileInputStream;
import org.pdfbox.io.RandomAccessFileOutputStream;
/**
* This class represents a stream object in a PDF document.
*
* @author <a href="mailto:ben@benlitchfield.com">Ben Litchfield</a>
* @version $Revision: 1.39 $
*/
public class COSStream extends COSDictionary
{
private static final int BUFFER_SIZE=16384;
private RandomAccess file;
/**
* The stream with all of the filters applied.
*/
private RandomAccessFileOutputStream filteredStream;
/**
* The stream with no filters, this contains the useful data.
*/
private RandomAccessFileOutputStream unFilteredStream;
/**
* Constructor. Creates a new stream with an empty dictionary.
*
* @param storage The intermediate storage for the stream.
*/
public COSStream( RandomAccess storage )
{
super();
file = storage;
}
/**
* Constructor.
*
* @param dictionary The dictionary that is associated with this stream.
* @param storage The intermediate storage for the stream.
*/
public COSStream( COSDictionary dictionary, RandomAccess storage )
{
super( dictionary );
file = storage;
}
/**
* This will replace this object with the data from the new object. This
* is used to easily maintain referential integrity when changing references
* to new objects.
*
* @param stream The stream that have the new values in it.
*/
public void replaceWithStream( COSStream stream )
{
this.clear();
this.addAll( stream );
file = stream.file;
filteredStream = stream.filteredStream;
unFilteredStream = stream.unFilteredStream;
}
/**
* This will get the scratch file associated with this stream.
*
* @return The scratch file where this stream is being stored.
*/
public RandomAccess getScratchFile()
{
return file;
}
/**
* This will get all the tokens in the stream.
*
* @return All of the tokens in the stream.
*
* @throws IOException If there is an error parsing the stream.
*/
public List getStreamTokens() throws IOException
{
PDFStreamParser parser = new PDFStreamParser( this );
parser.parse();
return parser.getTokens();
}
/**
* This will get the stream with all of the filters applied.
*
* @return the bytes of the physical (endoced) stream
*
* @throws IOException when encoding/decoding causes an exception
*/
public InputStream getFilteredStream() throws IOException
{
if( filteredStream == null )
{
doEncode();
}
long position = filteredStream.getPosition();
long length = filteredStream.getLength();
RandomAccessFileInputStream input =
new RandomAccessFileInputStream( file, position, length );
return new BufferedInputStream( input, BUFFER_SIZE );
}
/**
* This will get the logical content stream with none of the filters.
*
* @return the bytes of the logical (decoded) stream
*
* @throws IOException when encoding/decoding causes an exception
*/
public InputStream getUnfilteredStream() throws IOException
{
InputStream retval = null;
if( unFilteredStream == null )
{
doDecode();
}
//if unFilteredStream is still null then this stream has not been
//created yet, so we should return null.
if( unFilteredStream != null )
{
long position = unFilteredStream.getPosition();
long length = unFilteredStream.getLength();
RandomAccessFileInputStream input =
new RandomAccessFileInputStream( file, position, length );
retval = new BufferedInputStream( input, BUFFER_SIZE );
}
else
{
// We should check if the COSStream contains data, maybe it
// has been created with a RandomAccessFile - which is not
// necessary empty.
// In this case, the creation was been done as an input, this should
// be the unfiltered file, since no filter has been applied yet.
// if ( (file != null) &&
// (file.length() > 0) )
// {
// retval = new RandomAccessFileInputStream( file,
// 0,
// file.length() );
// }
// else
// {
//if there is no stream data then simply return an empty stream.
retval = new ByteArrayInputStream( new byte[0] );
// }
}
return retval;
}
/**
* visitor pattern double dispatch method.
*
* @param visitor The object to notify when visiting this object.
* @return any object, depending on the visitor implementation, or null
* @throws COSVisitorException If an error occurs while visiting this object.
*/
public Object accept(ICOSVisitor visitor) throws COSVisitorException
{
return visitor.visitFromStream(this);
}
/**
* This will decode the physical byte stream applying all of the filters to the stream.
*
* @throws IOException If there is an error applying a filter to the stream.
*/
private void doDecode() throws IOException
{
// FIXME: We shouldn't keep the same reference?
unFilteredStream = filteredStream;
COSBase filters = getFilters();
if( filters == null )
{
//then do nothing
}
else if( filters instanceof COSName )
{
doDecode( (COSName)filters );
}
else if( filters instanceof COSArray )
{
COSArray filterArray = (COSArray)filters;
for( int i=0; i<filterArray.size(); i++ )
{
COSName filterName = (COSName)filterArray.get( i );
doDecode( filterName );
}
}
else
{
throw new IOException( "Error: Unknown filter type:" + filters );
}
}
/**
* This will decode applying a single filter on the stream.
*
* @param filterName The name of the filter.
*
* @throws IOException If there is an error parsing the stream.
*/
private void doDecode( COSName filterName ) throws IOException
{
FilterManager manager = getFilterManager();
Filter filter = manager.getFilter( filterName );
InputStream input;
boolean done = false;
IOException exception = null;
long position = unFilteredStream.getPosition();
long length = unFilteredStream.getLength();
if( length == 0 )
{
//if the length is zero then don't bother trying to decode
//some filters don't work when attempting to decode
//with a zero length stream. See zlib_error_01.pdf
unFilteredStream = new RandomAccessFileOutputStream( file );
done = true;
}
else
{
//ok this is a simple hack, sometimes we read a couple extra
//bytes that shouldn't be there, so we encounter an error we will just
//try again with one less byte.
for( int tryCount=0; !done && tryCount<5; tryCount++ )
{
try
{
input = new BufferedInputStream(
new RandomAccessFileInputStream( file, position, length ), BUFFER_SIZE );
unFilteredStream = new RandomAccessFileOutputStream( file );
filter.decode( input, unFilteredStream, this );
done = true;
}
catch( IOException io )
{
length--;
exception = io;
}
}
}
if( !done )
{
throw exception;
}
}
/**
* This will encode the logical byte stream applying all of the filters to the stream.
*
* @throws IOException If there is an error applying a filter to the stream.
*/
private void doEncode() throws IOException
{
filteredStream = unFilteredStream;
COSBase filters = getFilters();
if( filters == null )
{
//there is no filter to apply
}
else if( filters instanceof COSName )
{
doEncode( (COSName)filters );
}
else if( filters instanceof COSArray )
{
// apply filters in reverse order
COSArray filterArray = (COSArray)filters;
for( int i=filterArray.size()-1; i>=0; i-- )
{
COSName filterName = (COSName)filterArray.get( i );
doEncode( filterName );
}
}
}
/**
* This will encode applying a single filter on the stream.
*
* @param filterName The name of the filter.
*
* @throws IOException If there is an error parsing the stream.
*/
private void doEncode( COSName filterName ) throws IOException
{
FilterManager manager = getFilterManager();
Filter filter = manager.getFilter( filterName );
InputStream input;
input = new BufferedInputStream(
new RandomAccessFileInputStream( file, filteredStream.getPosition(),
filteredStream.getLength() ), BUFFER_SIZE );
filteredStream = new RandomAccessFileOutputStream( file );
filter.encode( input, filteredStream, this );
}
/**
* This will return the filters to apply to the byte stream.
* The method will return
* - null if no filters are to be applied
* - a COSName if one filter is to be applied
* - a COSArray containing COSNames if multiple filters are to be applied
*
* @return the COSBase object representing the filters
*/
public COSBase getFilters()
{
return getDictionaryObject(COSName.FILTER);
}
/**
* This will create a new stream for which filtered byte should be
* written to. You probably don't want this but want to use the
* createUnfilteredStream, which is used to write raw bytes to.
*
* @return A stream that can be written to.
*
* @throws IOException If there is an error creating the stream.
*/
public OutputStream createFilteredStream() throws IOException
{
filteredStream = new RandomAccessFileOutputStream( file );
unFilteredStream = null;
return new BufferedOutputStream( filteredStream, BUFFER_SIZE );
}
/**
* This will create a new stream for which filtered byte should be
* written to. You probably don't want this but want to use the
* createUnfilteredStream, which is used to write raw bytes to.
*
* @param expectedLength An entry where a length is expected.
*
* @return A stream that can be written to.
*
* @throws IOException If there is an error creating the stream.
*/
public OutputStream createFilteredStream( COSBase expectedLength ) throws IOException
{
filteredStream = new RandomAccessFileOutputStream( file );
filteredStream.setExpectedLength( expectedLength );
unFilteredStream = null;
return new BufferedOutputStream( filteredStream, BUFFER_SIZE );
}
/**
* set the filters to be applied to the stream.
*
* @param filters The filters to set on this stream.
*
* @throws IOException If there is an error clearing the old filters.
*/
public void setFilters(COSBase filters) throws IOException
{
setItem(COSName.FILTER, filters);
// kill cached filtered streams
filteredStream = null;
}
/**
* This will create an output stream that can be written to.
*
* @return An output stream which raw data bytes should be written to.
*
* @throws IOException If there is an error creating the stream.
*/
public OutputStream createUnfilteredStream() throws IOException
{
unFilteredStream = new RandomAccessFileOutputStream( file );
filteredStream = null;
return new BufferedOutputStream( unFilteredStream, BUFFER_SIZE );
}
}