xref: /aoo4110/main/filter/source/graphicfilter/egif/giflzwc.cxx (revision b1cdbd2c)

/**************************************************************
 *
 * 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.
 *
 *************************************************************/



// MARKER(update_precomp.py): autogen include statement, do not remove
#include "precompiled_filter.hxx"

#include <tools/stream.hxx>
#include "giflzwc.hxx"

// ----------------------------
// - GIFImageDataOutputStream -
// ----------------------------

class GIFImageDataOutputStream
{
private:

	void		FlushBlockBuf();
	inline void	FlushBitsBufsFullBytes();

	SvStream&	rStream;
	sal_uInt8*		pBlockBuf;
	sal_uInt8		nBlockBufSize;
	sal_uLong		nBitsBuf;
	sal_uInt16		nBitsBufSize;

public:

				GIFImageDataOutputStream( SvStream & rGIF, sal_uInt8 nLZWDataSize );
				~GIFImageDataOutputStream();

	inline void	WriteBits( sal_uInt16 nCode, sal_uInt16 nCodeLen );
};

// ------------------------------------------------------------------------

inline void GIFImageDataOutputStream::FlushBitsBufsFullBytes()
{
	while (nBitsBufSize>=8)
	{
		if( nBlockBufSize==255 )
			FlushBlockBuf();

		pBlockBuf[nBlockBufSize++] = (sal_uInt8) nBitsBuf;
		nBitsBuf >>= 8;
		nBitsBufSize -= 8;
	}
}

// ------------------------------------------------------------------------

inline void GIFImageDataOutputStream::WriteBits( sal_uInt16 nCode, sal_uInt16 nCodeLen )
{
	if( nBitsBufSize+nCodeLen>32 )
		FlushBitsBufsFullBytes();

	nBitsBuf |= (sal_uLong) nCode << nBitsBufSize;
	nBitsBufSize = nBitsBufSize + nCodeLen;
}

// ------------------------------------------------------------------------

GIFImageDataOutputStream::GIFImageDataOutputStream( SvStream & rGIF, sal_uInt8 nLZWDataSize ) :
		rStream(rGIF)
{
	pBlockBuf = new sal_uInt8[ 255 ];
	nBlockBufSize = 0;
	nBitsBufSize = 0;
	nBitsBuf = 0;
	rStream << nLZWDataSize;
}

// ------------------------------------------------------------------------


GIFImageDataOutputStream::~GIFImageDataOutputStream()
{
	WriteBits(0,7);
	FlushBitsBufsFullBytes();
	FlushBlockBuf();
	rStream << (sal_uInt8)0;
	delete[] pBlockBuf;
}

// ------------------------------------------------------------------------

void GIFImageDataOutputStream::FlushBlockBuf()
{
	if( nBlockBufSize )
	{
		rStream << (sal_uInt8) nBlockBufSize;
		rStream.Write( pBlockBuf,nBlockBufSize );
		nBlockBufSize = 0;
	}
}

// -------------------
// - GIFLZWCTreeNode -
// -------------------

struct GIFLZWCTreeNode
{

	GIFLZWCTreeNode*	pBrother;		// naechster Knoten, der den selben Vater hat
	GIFLZWCTreeNode*	pFirstChild;	// erster Sohn
	sal_uInt16				nCode;			// Der Code fuer den String von Pixelwerten, der sich ergibt, wenn
	sal_uInt16				nValue;			// Der Pixelwert
};

// --------------------
// - GIFLZWCompressor -
// --------------------

GIFLZWCompressor::GIFLZWCompressor()
{
	pIDOS=NULL;
}

// ------------------------------------------------------------------------

GIFLZWCompressor::~GIFLZWCompressor()
{
	if (pIDOS!=NULL) EndCompression();
}

// ------------------------------------------------------------------------

void GIFLZWCompressor::StartCompression( SvStream& rGIF, sal_uInt16 nPixelSize )
{
	if( !pIDOS )
	{
		sal_uInt16 i;

		nDataSize = nPixelSize;

		if( nDataSize < 2 )
			nDataSize=2;

		nClearCode=1<<nDataSize;
		nEOICode=nClearCode+1;
		nTableSize=nEOICode+1;
		nCodeSize=nDataSize+1;

		pIDOS=new GIFImageDataOutputStream(rGIF,(sal_uInt8)nDataSize);
		pTable=new GIFLZWCTreeNode[4096];

		for (i=0; i<4096; i++)
		{
			pTable[i].pBrother = pTable[i].pFirstChild = NULL;
			pTable[i].nValue = (sal_uInt8) ( pTable[i].nCode = i );
		}

		pPrefix = NULL;
		pIDOS->WriteBits( nClearCode,nCodeSize );
	}
}

// ------------------------------------------------------------------------

void GIFLZWCompressor::Compress( HPBYTE pSrc, sal_uLong nSize )
{
	if( pIDOS )
	{
		GIFLZWCTreeNode*	p;
		sal_uInt16				i;
		sal_uInt8				nV;

		if( !pPrefix && nSize )
		{
			pPrefix=pTable+(*pSrc++);
			nSize--;
		}

		while( nSize )
		{
			nSize--;
			nV=*pSrc++;
			for( p=pPrefix->pFirstChild; p!=NULL; p=p->pBrother )
			{
				if (p->nValue==nV)
					break;
			}

			if( p)
				pPrefix=p;
			else
			{
				pIDOS->WriteBits(pPrefix->nCode,nCodeSize);

				if (nTableSize==4096)
				{
					pIDOS->WriteBits(nClearCode,nCodeSize);

					for (i=0; i<nClearCode; i++)
						pTable[i].pFirstChild=NULL;

					nCodeSize=nDataSize+1;
					nTableSize=nEOICode+1;
				}
				else
				{
					if(nTableSize==(sal_uInt16)(1<<nCodeSize))
						nCodeSize++;

					p=pTable+(nTableSize++);
					p->pBrother=pPrefix->pFirstChild;
					pPrefix->pFirstChild=p;
					p->nValue=nV;
					p->pFirstChild=NULL;
				}

				pPrefix=pTable+nV;
			}
		}
	}
}

// ------------------------------------------------------------------------

void GIFLZWCompressor::EndCompression()
{
	if( pIDOS )
	{
		if( pPrefix )
			pIDOS->WriteBits(pPrefix->nCode,nCodeSize);

		pIDOS->WriteBits( nEOICode,nCodeSize );
		delete[] pTable;
		delete pIDOS;
		pIDOS=NULL;
	}
}