/*
Copyright 2006 Stefano Chizzolini. http://clown.stefanochizzolini.it
Contributors:
* Stefano Chizzolini (original code developer, http://www.stefanochizzolini.it)
This file should be part of the source code distribution of "PDF Clown library"
(the Program): see the accompanying README files for more info.
This Program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later version.
This Program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY, either expressed or implied; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the License for more details.
You should have received a copy of the GNU General Public License along with this
Program (see README files); if not, go to the GNU website (http://www.gnu.org/).
Redistribution and use, with or without modification, are permitted provided that such
redistributions retain the above copyright notice, license and disclaimer, along with
this list of conditions.
*/
using System;
using System.IO;
// using System.IO.Compression;
using ZipICSharpCode.SharpZipLib.Zip.Compression;
namespace it.stefanochizzolini.clown.bytes.filters{
/**
<summary>zlib/deflate [RFC:1950,1951] filter [PDF:1.6:3.3.3].</summary>
*/
public class FlateFilter
: Filter
{
#region dynamic
#region constructors
internal FlateFilter(
)
{}
#endregion
#region interface
#region public
public override byte[] Decode(
byte[] data,
int offset,
int length
)
{
/* TODO:IMPL This chunk of code is the canonical implementation using System.IO.Compression; however,
we couldn't make it work due to an issue with the mono implementation (OutOfMemoryException during DeflateStream instantiation -- probably related to an incompatibility with the underlying zlib on my system): if you solved this problem, you could get a try to the code, disabling the SharpZipLib implementation.
MemoryStream outputStream = new MemoryStream();
DeflateStream inputFilter = new DeflateStream(
new MemoryStream(data,offset,length),
CompressionMode.Decompress
);
Transform(inputFilter,outputStream);
return outputStream.ToArray();
*/
/*
NOTE: This is an alternative implementation using ICSharpCode.SharpZipLib instead of
System.IO.Compression. It should be eventually replaced by the canonical implementation above.
*/
MemoryStream outputStream = new MemoryStream();
Zip.Streams.InflaterInputStream inputFilter = new Zip.Streams.InflaterInputStream(
new MemoryStream(data,offset,length)
);
Transform(inputFilter,outputStream);
return outputStream.ToArray();
}
public override byte[] Encode(
byte[] data,
int offset,
int length
)
{
/* TODO:IMPL See Decode() commented block on the same issue.
MemoryStream outputStream = new MemoryStream();
DeflateStream outputFilter = new DeflateStream(
outputStream,
CompressionMode.Compress,
true
);
MemoryStream inputStream = new MemoryStream(data,offset,length);
Transform(inputStream,outputFilter);
return outputStream.ToArray();
*/
/*
NOTE: This is an alternative implementation using ICSharpCode.SharpZipLib instead of
System.IO.Compression. It should be eventually replaced by the canonical implementation above.
*/
MemoryStream outputStream = new MemoryStream();
Zip.Streams.DeflaterOutputStream outputFilter = new Zip.Streams.DeflaterOutputStream(
outputStream,
new Zip.Deflater(Zip.Deflater.BEST_COMPRESSION)
);
MemoryStream inputStream = new MemoryStream(data,offset,length);
Transform(inputStream,outputFilter);
return outputStream.ToArray();
}
#endregion
#region private
private void Transform(
System.IO.Stream input,
System.IO.Stream output
)
{
byte[] buffer = new byte[8192]; int bufferLength;
while((bufferLength = input.Read(buffer, 0, buffer.Length)) != 0)
{output.Write(buffer, 0, bufferLength);}
input.Close(); output.Close();
}
#endregion
#endregion
#endregion
}
}
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