xref: /aoo41x/main/vcl/source/gdi/pngread.cxx (revision 87bc88d3)

/**************************************************************
 *
 * 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_vcl.hxx"

#include <vcl/pngread.hxx>

#include <cmath>
#include <rtl/crc.h>
#include <rtl/memory.h>
#include <rtl/alloc.h>
#include <tools/zcodec.hxx>
#include <tools/stream.hxx>
#include <vcl/bmpacc.hxx>
#include <vcl/svapp.hxx>
#include <vcl/alpha.hxx>
#include <osl/endian.h>

// -----------
// - Defines -
// -----------

#define PNGCHUNK_IHDR 		0x49484452
#define PNGCHUNK_PLTE 		0x504c5445
#define PNGCHUNK_IDAT 		0x49444154
#define PNGCHUNK_IEND 		0x49454e44
#define PNGCHUNK_bKGD 		0x624b4744
#define PNGCHUNK_cHRM		0x6348524d
#define PNGCHUNK_gAMA 		0x67414d41
#define PNGCHUNK_hIST 		0x68495354
#define PNGCHUNK_pHYs 		0x70485973
#define PNGCHUNK_sBIT 		0x73425420
#define PNGCHUNK_tIME		0x74494d45
#define PNGCHUNK_tEXt		0x74455874
#define PNGCHUNK_tRNS 		0x74524e53
#define PNGCHUNK_zTXt 		0x7a545874
#define PMGCHUNG_msOG		0x6d734f47		// Microsoft Office Animated GIF

#define VIEWING_GAMMA		2.35
#define DISPLAY_GAMMA		1.0

namespace vcl
{
// -----------
// - statics -
// -----------

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

static const sal_uInt8 mpDefaultColorTable[ 256 ] =
{	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
	0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
};

// -------------
// - PNGReaderImpl -
// -------------

class PNGReaderImpl
{
private:
    SvStream&           mrPNGStream;
    sal_uInt16          mnOrigStreamMode;

    std::vector< vcl::PNGReader::ChunkData >    maChunkSeq;
    std::vector< vcl::PNGReader::ChunkData >::iterator maChunkIter;
    std::vector< sal_uInt8 >::iterator          maDataIter;

	Bitmap*				mpBmp;
	BitmapWriteAccess*	mpAcc;
	Bitmap*				mpMaskBmp;
	AlphaMask*			mpAlphaMask;
	BitmapWriteAccess*	mpMaskAcc;
	ZCodec* 			mpZCodec;
	sal_uInt8*				mpInflateInBuf; // as big as the size of a scanline + alphachannel + 1
	sal_uInt8*				mpScanPrior;    // pointer to the latest scanline
	sal_uInt8*				mpTransTab;		// for transparency in images with palette colortype
	sal_uInt8*				mpScanCurrent;  // pointer into the current scanline
	sal_uInt8*				mpColorTable;	//
    sal_Size            mnStreamSize;   // estimate of PNG file size
    sal_uInt32          mnChunkType;    // Type of current PNG chunk
    sal_Int32           mnChunkLen;     // Length of current PNG chunk
    Size                maOrigSize;     // pixel size of the full image
    Size                maTargetSize;   // pixel size of the result image
    Size                maPhysSize;     // prefered size in MAP_100TH_MM units
    sal_uInt32          mnBPP;          // number of bytes per pixel
    sal_uInt32          mnScansize;     // max size of scanline
    sal_uInt32          mnYpos;         // latest y position in full image
    int                 mnPass;         // if interlaced the latest pass ( 1..7 ) else 7
    sal_uInt32          mnXStart;       // the starting X for the current pass
    sal_uInt32          mnXAdd;         // the increment for input images X coords for the current pass
    sal_uInt32          mnYAdd;         // the increment for input images Y coords for the current pass
    int                 mnPreviewShift; // shift to convert orig image coords into preview image coords
    int                 mnPreviewMask;  // == ((1 << mnPreviewShift) - 1)
	sal_uInt16				mnIStmOldMode;
	sal_uInt16				mnTargetDepth;		// pixel depth of target bitmap
	sal_uInt8				mnTransRed;
	sal_uInt8				mnTransGreen;
	sal_uInt8				mnTransBlue;
	sal_uInt8				mnPngDepth;		// pixel depth of PNG data
	sal_uInt8				mnColorType;
	sal_uInt8				mnCompressionType;
	sal_uInt8				mnFilterType;
	sal_uInt8				mnInterlaceType;
	BitmapColor			mcTranspColor;  // transparency mask's transparency "color"
	BitmapColor			mcOpaqueColor;  // transparency mask's opaque "color"
	sal_Bool				mbTransparent;	// graphic includes an tRNS Chunk or an alpha Channel
	sal_Bool				mbAlphaChannel;	// is true for ColorType 4 and 6
	sal_Bool				mbRGBTriple;
	sal_Bool				mbPalette;		// sal_False if we need a Palette
	sal_Bool				mbGrayScale;
	sal_Bool				mbzCodecInUse;
	sal_Bool				mbStatus;
	sal_Bool				mbIDAT;			// sal_True if finished with enough IDAT chunks
	sal_Bool				mbGamma;		// sal_True if Gamma Correction available
	sal_Bool				mbpHYs;			// sal_True if pysical size of pixel available
	sal_Bool			mbIgnoreGammaChunk;

    bool                ReadNextChunk();
    void                ReadRemainingChunks();
    void                SkipRemainingChunks();

    void                ImplSetPixel( sal_uInt32 y, sal_uInt32 x, const BitmapColor & );
    void                ImplSetPixel( sal_uInt32 y, sal_uInt32 x, sal_uInt8 nPalIndex );
    void                ImplSetTranspPixel( sal_uInt32 y, sal_uInt32 x, const BitmapColor &, sal_Bool bTrans );
    void                ImplSetAlphaPixel( sal_uInt32 y, sal_uInt32 x, sal_uInt8 nPalIndex, sal_uInt8 nAlpha );
	void				ImplSetAlphaPixel( sal_uInt32 y, sal_uInt32 x, const BitmapColor&, sal_uInt8 nAlpha );
	void				ImplReadIDAT();
    bool                ImplPreparePass();
    void                ImplApplyFilter();
    void                ImplDrawScanline( sal_uInt32 nXStart, sal_uInt32 nXAdd );
	sal_Bool				ImplReadTransparent();
	void				ImplGetGamma();
	void				ImplGetBackground();
	sal_uInt8				ImplScaleColor();
	sal_Bool				ImplReadHeader( const Size& rPreviewSizeHint );
	sal_Bool				ImplReadPalette();
	void				ImplGetGrayPalette( sal_uInt16 );
	sal_uInt32			ImplReadsal_uInt32();

public:

                        PNGReaderImpl( SvStream& );
                        ~PNGReaderImpl();

    BitmapEx            GetBitmapEx( const Size& rPreviewSizeHint );
    const std::vector< PNGReader::ChunkData >& GetAllChunks();
	void				SetIgnoreGammaChunk( sal_Bool bIgnore ){ mbIgnoreGammaChunk = bIgnore; };
};

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

PNGReaderImpl::PNGReaderImpl( SvStream& rPNGStream )
:   mrPNGStream( rPNGStream ),
	mpBmp			( NULL ),
	mpAcc			( NULL ),
	mpMaskBmp		( NULL ),
	mpAlphaMask		( NULL ),
	mpMaskAcc		( NULL ),
	mpZCodec		( new ZCodec( DEFAULT_IN_BUFSIZE, DEFAULT_OUT_BUFSIZE, MAX_MEM_USAGE ) ),
	mpInflateInBuf	( NULL ),
	mpScanPrior 	( NULL ),
	mpTransTab		( NULL ),
	mpColorTable	( (sal_uInt8*) mpDefaultColorTable ),
	mnColorType( 0xFF ),
	mbPalette( false ),
	mbzCodecInUse	( sal_False ),
    mbStatus( sal_True),
    mbIDAT( sal_False ),
	mbGamma				( sal_False ),
	mbpHYs				( sal_False ),
	mbIgnoreGammaChunk	( sal_False )
{
    // prepare the PNG data stream
    mnOrigStreamMode = mrPNGStream.GetNumberFormatInt();
    mrPNGStream.SetNumberFormatInt( NUMBERFORMAT_INT_BIGENDIAN );

    // prepare the chunk reader
    maChunkSeq.reserve( 16 );
    maChunkIter = maChunkSeq.begin();

    // estimate PNG file size (to allow sanity checks)
    const sal_Size nStreamPos = mrPNGStream.Tell();
    mrPNGStream.Seek( STREAM_SEEK_TO_END );
    mnStreamSize = mrPNGStream.Tell();
    mrPNGStream.Seek( nStreamPos );

    // check the PNG header magic
    sal_uInt32 nDummy = 0;
    mrPNGStream >> nDummy;
    mbStatus = (nDummy == 0x89504e47);
    mrPNGStream >> nDummy;
    mbStatus &= (nDummy == 0x0d0a1a0a);

    mnPreviewShift = 0;
    mnPreviewMask = (1 << mnPreviewShift) - 1;
}

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

PNGReaderImpl::~PNGReaderImpl()
{
    mrPNGStream.SetNumberFormatInt( mnOrigStreamMode );

	if ( mbzCodecInUse )
		mpZCodec->EndCompression();

	if( mpColorTable != mpDefaultColorTable )
		delete[] mpColorTable;

    delete mpBmp;
    delete mpAlphaMask;
    delete mpMaskBmp;
    delete[] mpTransTab;
    delete[] mpInflateInBuf;
    delete[] mpScanPrior;
    delete mpZCodec;
}

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

bool PNGReaderImpl::ReadNextChunk()
{
    if( maChunkIter == maChunkSeq.end() )
    {
        // get the next chunk from the stream

        // unless we are at the end of the PNG stream
        if( mrPNGStream.IsEof() || (mrPNGStream.GetError() != ERRCODE_NONE) )
            return false;
        if( !maChunkSeq.empty() && (maChunkSeq.back().nType == PNGCHUNK_IEND) )
            return false;

        PNGReader::ChunkData aDummyChunk;
        maChunkIter = maChunkSeq.insert( maChunkSeq.end(), aDummyChunk );
        PNGReader::ChunkData& rChunkData = *maChunkIter;

        // read the chunk header
        mrPNGStream >> mnChunkLen >> mnChunkType;
        rChunkData.nType = mnChunkType;

        // #128377#/#149343# sanity check for chunk length
        if( mnChunkLen < 0 )
            return false;
        const sal_Size nStreamPos = mrPNGStream.Tell();
        if( nStreamPos + mnChunkLen >= mnStreamSize )
            return false;

        // calculate chunktype CRC (swap it back to original byte order)
        sal_uInt32 nChunkType = mnChunkType;;
        #if defined(__LITTLEENDIAN) || defined(OSL_LITENDIAN)
        nChunkType = SWAPLONG( nChunkType );
        #endif
        sal_uInt32 nCRC32 = rtl_crc32( 0, &nChunkType, 4 );

        // read the chunk data and check the CRC
        if( mnChunkLen && !mrPNGStream.IsEof() )
        {
            rChunkData.aData.resize( mnChunkLen );

            sal_Int32 nBytesRead = 0;
            do {
                sal_uInt8* pPtr = &rChunkData.aData[ nBytesRead ];
                nBytesRead += mrPNGStream.Read( pPtr, mnChunkLen - nBytesRead );
            } while ( ( nBytesRead < mnChunkLen ) && ( mrPNGStream.GetError() == ERRCODE_NONE ) );

            nCRC32 = rtl_crc32( nCRC32, &rChunkData.aData[ 0 ], mnChunkLen );
            maDataIter = rChunkData.aData.begin();
        }
        sal_uInt32 nCheck;
        mrPNGStream >> nCheck;
        if( nCRC32 != nCheck )
            return false;
    }
    else
    {
        // the next chunk was already read
        mnChunkType = (*maChunkIter).nType;
        mnChunkLen = (*maChunkIter).aData.size();
        maDataIter = (*maChunkIter).aData.begin();
    }

    ++maChunkIter;
    if( mnChunkType == PNGCHUNK_IEND )
        return false;
    return true;
}

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

// read the remaining chunks from mrPNGStream
void PNGReaderImpl::ReadRemainingChunks()
{
    while( ReadNextChunk() ) ;
}

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

// move position of mrPNGStream to the end of the file
void PNGReaderImpl::SkipRemainingChunks()
{
    // nothing to skip if the last chunk was read
    if( !maChunkSeq.empty() && (maChunkSeq.back().nType == PNGCHUNK_IEND) )
        return;

    // read from the stream until the IEND chunk is found
    const sal_Size nStreamPos = mrPNGStream.Tell();
    while( !mrPNGStream.IsEof() && (mrPNGStream.GetError() == ERRCODE_NONE) )
    {
        mrPNGStream >> mnChunkLen >> mnChunkType;
        if( mnChunkLen < 0 )
            break;
        if( nStreamPos + mnChunkLen >= mnStreamSize )
            break;
        mrPNGStream.SeekRel( mnChunkLen + 4 );  // skip data + CRC
        if( mnChunkType == PNGCHUNK_IEND )
            break;
    }
}

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

const std::vector< vcl::PNGReader::ChunkData >& PNGReaderImpl::GetAllChunks()
{
    ReadRemainingChunks();
    return maChunkSeq;
}

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

BitmapEx PNGReaderImpl::GetBitmapEx( const Size& rPreviewSizeHint )
{
    // reset to the first chunk
    maChunkIter = maChunkSeq.begin();

    // read the first chunk which must be the IHDR chunk
    ReadNextChunk();
    mbStatus = (mnChunkType == PNGCHUNK_IHDR) && ImplReadHeader( rPreviewSizeHint );

    // parse the chunks
    while( mbStatus && !mbIDAT && ReadNextChunk() )
    {
        switch( mnChunkType )
		{
			case PNGCHUNK_IHDR :
			{
				mbStatus = false; // only one IHDR possible
			}
			break;

			case PNGCHUNK_gAMA :								// the gamma chunk must precede
			{													// the 'IDAT' and also the 'PLTE'(if available )
				if ( !mbIgnoreGammaChunk && ( mbIDAT == sal_False ) )
					ImplGetGamma();
			}
			break;

			case PNGCHUNK_PLTE :
			{
				if ( !mbPalette )
					mbStatus = ImplReadPalette();
			}
			break;

			case PNGCHUNK_tRNS :
			{
				if ( !mbIDAT )									// the tRNS chunk must precede the IDAT
					mbStatus = ImplReadTransparent();
			}
			break;

			case PNGCHUNK_bKGD :								// the background chunk must appear
			{
				if ( ( mbIDAT == sal_False ) && mbPalette ) 		// before the 'IDAT' and after the
					ImplGetBackground();						// PLTE(if available ) chunk.
			}
			break;

			case PNGCHUNK_IDAT :
			{
				if ( !mpInflateInBuf )	// taking care that the header has properly been read
					mbStatus = sal_False;
				else if ( !mbIDAT )		// the gfx is finished, but there may be left a zlibCRC of about 4Bytes
					ImplReadIDAT();
			}
			break;

			case PNGCHUNK_pHYs :
			{
				if ( !mbIDAT && mnChunkLen == 9 )
				{
                    sal_uInt32 nXPixelPerMeter = ImplReadsal_uInt32();
                    sal_uInt32 nYPixelPerMeter = ImplReadsal_uInt32();

                    sal_uInt8 nUnitSpecifier = *maDataIter++;
                    if( (nUnitSpecifier == 1) && nXPixelPerMeter && nXPixelPerMeter )
                    {
                        mbpHYs = sal_True;

                        // convert into MAP_100TH_MM
                        maPhysSize.Width()  = (sal_Int32)( (100000.0 * maOrigSize.Width()) / nXPixelPerMeter );
                        maPhysSize.Height() = (sal_Int32)( (100000.0 * maOrigSize.Height()) / nYPixelPerMeter );
                    }
				}
			}
			break;

            case PNGCHUNK_IEND:
                mbStatus = mbIDAT;  // there is a problem if the image is not complete yet
            break;
		}
	}

    // release write access of the bitmaps
	if ( mpAcc )
		mpBmp->ReleaseAccess( mpAcc ), mpAcc = NULL;

	if ( mpMaskAcc )
	{
		if ( mpAlphaMask )
			mpAlphaMask->ReleaseAccess( mpMaskAcc );
		else if ( mpMaskBmp )
			mpMaskBmp->ReleaseAccess( mpMaskAcc );

		mpMaskAcc = NULL;
	}

    // return the resulting BitmapEx
    BitmapEx aRet;

    if( !mbStatus || !mbIDAT )
        aRet.Clear();
    else
	{
		if ( mpAlphaMask )
			aRet = BitmapEx( *mpBmp, *mpAlphaMask );
		else if ( mpMaskBmp )
			aRet = BitmapEx( *mpBmp, *mpMaskBmp );
		else
			aRet = *mpBmp;

		if ( mbpHYs && maPhysSize.Width() && maPhysSize.Height() )
		{
			aRet.SetPrefMapMode( MAP_100TH_MM );
			aRet.SetPrefSize( maPhysSize );
		}

#if 0
        // TODO: make sure nobody depends on the stream being after the IEND chunks
        // => let them do ReadChunks before
        ReadRemainingChunks();
#endif
	}

	return aRet;
}

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

sal_Bool PNGReaderImpl::ImplReadHeader( const Size& rPreviewSizeHint )
{
    if( mnChunkLen < 13 )
        return sal_False;

    maOrigSize.Width()  = ImplReadsal_uInt32();
    maOrigSize.Height() = ImplReadsal_uInt32();

    if ( !maOrigSize.Width() || !maOrigSize.Height() )
        return sal_False;

    mnPngDepth = *(maDataIter++);
    mnColorType = *(maDataIter++);

    mnCompressionType = *(maDataIter++);
    if( mnCompressionType != 0 )    // unknown compression type
        return sal_False;

    mnFilterType = *(maDataIter++);
    if( mnFilterType != 0 )         // unknown filter type
        return sal_False;

    mnInterlaceType = *(maDataIter++);
    switch ( mnInterlaceType ) // filter type valid ?
	{
		case 0 :  // progressive image
			mnPass = 7;
			break;
		case 1 :  // Adam7-interlaced image
			mnPass = 0;
			break;
		default:
			return sal_False;
	}

	mbPalette = sal_True;
	mbIDAT = mbAlphaChannel = mbTransparent = sal_False;
	mbGrayScale = mbRGBTriple = sal_False;
	mnTargetDepth = mnPngDepth;
	sal_uInt64 nScansize64 = ( ( static_cast< sal_uInt64 >( maOrigSize.Width() ) * mnPngDepth ) + 7 ) >> 3;

	// valid color types are 0,2,3,4 & 6
	switch ( mnColorType )
	{
		case 0 :	// each pixel is a grayscale
		{
			switch ( mnPngDepth )
			{
				case 2 : // 2bit target not available -> use four bits
					mnTargetDepth = 4;	// we have to expand the bitmap
					mbGrayScale = sal_True;
					break;
				case 16 :
					mnTargetDepth = 8;	// we have to reduce the bitmap
					// fall through
				case 1 :
				case 4 :
				case 8 :
					mbGrayScale = sal_True;
					break;
				default :
					return sal_False;
			}
		}
		break;

		case 2 :	// each pixel is an RGB triple
		{
			mbRGBTriple = sal_True;
			nScansize64 *= 3;
			switch ( mnPngDepth )
			{
				case 16 :			// we have to reduce the bitmap
				case 8 :
					mnTargetDepth = 24;
					break;
				default :
					return sal_False;
			}
		}
		break;

		case 3 :	// each pixel is a palette index
		{
			switch ( mnPngDepth )
			{
				case 2 :
					mnTargetDepth = 4;	// we have to expand the bitmap
					// fall through
				case 1 :
				case 4 :
				case 8 :
					mbPalette = sal_False;
					break;
				default :
					return sal_False;
			}
		}
		break;

		case 4 :	// each pixel is a grayscale sample followed by an alpha sample
		{
			nScansize64 *= 2;
			mbAlphaChannel = sal_True;
			switch ( mnPngDepth )
			{
				case 16 :
					mnTargetDepth = 8;	// we have to reduce the bitmap
				case 8 :
					mbGrayScale = sal_True;
					break;
				default :
					return sal_False;
			}
		}
		break;

		case 6 :	// each pixel is an RGB triple followed by an alpha sample
		{
			mbRGBTriple = sal_True;
			nScansize64 *= 4;
			mbAlphaChannel = sal_True;
			switch (mnPngDepth )
			{
				case 16 :			// we have to reduce the bitmap
				case 8 :
					mnTargetDepth = 24;
					break;
				default :
					return sal_False;
			}
		}
		break;

		default :
			return sal_False;
	}

    mnBPP = static_cast< sal_uInt32 >( nScansize64 / maOrigSize.Width() );
    if ( !mnBPP )
        mnBPP = 1;

    nScansize64++;       // each scanline includes one filterbyte

	if ( nScansize64 > SAL_MAX_UINT32 )
		return sal_False;

	mnScansize = static_cast< sal_uInt32 >( nScansize64 );

    // TODO: switch between both scanlines instead of copying
	mpInflateInBuf = new (std::nothrow) sal_uInt8[ mnScansize ];
    mpScanCurrent = mpInflateInBuf;
	mpScanPrior = new (std::nothrow) sal_uInt8[ mnScansize ];

	if ( !mpInflateInBuf || !mpScanPrior )
		return sal_False;

    // calculate target size from original size and the preview hint
    if( rPreviewSizeHint.Width() || rPreviewSizeHint.Height() )
    {
		Size aPreviewSize( rPreviewSizeHint.Width(), rPreviewSizeHint.Height() );
        maTargetSize = maOrigSize;

		if( aPreviewSize.Width() == 0 ) {
			aPreviewSize.setWidth( ( maOrigSize.Width()*aPreviewSize.Height() )/maOrigSize.Height() );
			if( aPreviewSize.Width() <= 0 )
				aPreviewSize.setWidth( 1 );
		} else if( aPreviewSize.Height() == 0 ) {
			aPreviewSize.setHeight( ( maOrigSize.Height()*aPreviewSize.Width() )/maOrigSize.Width() );
			if( aPreviewSize.Height() <= 0 )
				aPreviewSize.setHeight( 1 );
		}

		if( aPreviewSize.Width() < maOrigSize.Width() && aPreviewSize.Height() < maOrigSize.Height() ) {
			OSL_TRACE("preview size %dx%d", aPreviewSize.Width(), aPreviewSize.Height() );

			for( int i = 1; i < 5; ++i )
				{
					if( (maTargetSize.Width() >> i) < aPreviewSize.Width() )
						break;
					if( (maTargetSize.Height() >> i) < aPreviewSize.Height() )
						break;
					mnPreviewShift = i;
				}
			mnPreviewMask = (1 << mnPreviewShift) - 1;
		}
    }

    maTargetSize.Width()  = (maOrigSize.Width() + mnPreviewMask) >> mnPreviewShift;
    maTargetSize.Height() = (maOrigSize.Height() + mnPreviewMask) >> mnPreviewShift;

    mpBmp = new Bitmap( maTargetSize, mnTargetDepth );
    mpAcc = mpBmp->AcquireWriteAccess();
    if( !mpAcc )
        return sal_False;

    mpBmp->SetSourceSizePixel( maOrigSize );

    if ( mbAlphaChannel )
    {
        mpAlphaMask = new AlphaMask( maTargetSize );
        mpAlphaMask->Erase( 128 );
        mpMaskAcc = mpAlphaMask->AcquireWriteAccess();
        if( !mpMaskAcc )
            return sal_False;
    }

	if ( mbGrayScale )
		ImplGetGrayPalette( mnPngDepth );

    ImplPreparePass();

	return sal_True;
}

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

void PNGReaderImpl::ImplGetGrayPalette( sal_uInt16 nBitDepth )
{
    if( nBitDepth > 8 )
        nBitDepth = 8;

    sal_uInt16  nPaletteEntryCount = 1 << nBitDepth;
	sal_uInt32  nAdd = nBitDepth ? 256 / (nPaletteEntryCount - 1) : 0;

    // no bitdepth==2 available
    // but bitdepth==4 with two unused bits is close enough
    if( nBitDepth == 2 )
        nPaletteEntryCount = 16;

	mpAcc->SetPaletteEntryCount( nPaletteEntryCount );
	for ( sal_uInt32 i = 0, nStart = 0; nStart < 256; i++, nStart += nAdd )
		mpAcc->SetPaletteColor( (sal_uInt16)i, BitmapColor( mpColorTable[ nStart ],
			mpColorTable[ nStart ], mpColorTable[ nStart ] ) );
}

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

sal_Bool PNGReaderImpl::ImplReadPalette()
{
	sal_uInt16 nCount = static_cast<sal_uInt16>( mnChunkLen / 3 );

	if ( ( ( mnChunkLen % 3 ) == 0 ) && ( ( 0 < nCount ) && ( nCount <= 256 ) ) && mpAcc )
	{
		mbPalette = sal_True;
		mpAcc->SetPaletteEntryCount( (sal_uInt16) nCount );

		for ( sal_uInt16 i = 0; i < nCount; i++ )
		{
			sal_uInt8 nRed =   mpColorTable[ *maDataIter++ ];
			sal_uInt8 nGreen = mpColorTable[ *maDataIter++ ];
			sal_uInt8 nBlue =  mpColorTable[ *maDataIter++ ];
			mpAcc->SetPaletteColor( i, Color( nRed, nGreen, nBlue ) );
		}
	}
	else
		mbStatus = sal_False;

	return mbStatus;
}

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

sal_Bool PNGReaderImpl::ImplReadTransparent()
{
    bool bNeedAlpha = false;

	if ( mpTransTab == NULL )
	{
		switch ( mnColorType )
		{
			case 0 :
			{
				if ( mnChunkLen == 2 )
				{
					mpTransTab = new sal_uInt8[ 256 ];
					rtl_fillMemory( mpTransTab, 256, 0xff );
                    // color type 0 and 4 is always greyscale,
                    // so the return value can be used as index
					sal_uInt8 nIndex = ImplScaleColor();
					mpTransTab[ nIndex ] = 0;
					mbTransparent = true;
				}
			}
			break;

			case 2 :
			{
				if ( mnChunkLen == 6 )
				{
					mnTransRed = ImplScaleColor();
					mnTransGreen = ImplScaleColor();
					mnTransBlue = ImplScaleColor();
					mbTransparent = true;
				}
			}
			break;

			case 3 :
			{
				if ( mnChunkLen <= 256 )
				{
					mpTransTab = new sal_uInt8 [ 256 ];
					rtl_fillMemory( mpTransTab, 256, 0xff );
					rtl_copyMemory( mpTransTab, &(*maDataIter), mnChunkLen );
					maDataIter += mnChunkLen;
					mbTransparent = true;
					// need alpha transparency if not on/off masking
					for( int i = 0; i < mnChunkLen; ++i )
					   bNeedAlpha |= (mpTransTab[i]!=0x00) && (mpTransTab[i]!=0xFF);
				}
			}
			break;
		}
	}

    if( mbTransparent && !mbAlphaChannel && !mpMaskBmp )
    {
        if( bNeedAlpha)
        {
            mpAlphaMask = new AlphaMask( maTargetSize );
            mpMaskAcc = mpAlphaMask->AcquireWriteAccess();
        }
        else
        {
            mpMaskBmp = new Bitmap( maTargetSize, 1 );
            mpMaskAcc = mpMaskBmp->AcquireWriteAccess();
        }
        mbTransparent = (mpMaskAcc != NULL);
        if( !mbTransparent )
            return sal_False;
        mcOpaqueColor = BitmapColor( 0x00 );
        mcTranspColor = BitmapColor( 0xFF );
        mpMaskAcc->Erase( 0x00 );
    }

    return sal_True;
}

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

void PNGReaderImpl::ImplGetGamma()
{
	if( mnChunkLen < 4 )
	    return;

	sal_uInt32	nGammaValue = ImplReadsal_uInt32();
	double		fGamma = ( ( VIEWING_GAMMA / DISPLAY_GAMMA ) * ( (double)nGammaValue / 100000 ) );
	double 		fInvGamma = ( fGamma <= 0.0 || fGamma > 10.0 ) ? 1.0 : ( 1.0 / fGamma );

	if ( fInvGamma != 1.0 )
	{
		mbGamma = sal_True;

		if ( mpColorTable == mpDefaultColorTable )
			mpColorTable = new sal_uInt8[ 256 ];

		for ( sal_Int32 i = 0; i < 256; i++ )
			mpColorTable[ i ] = (sal_uInt8)(pow((double)i/255.0, fInvGamma) * 255.0 + 0.5);

		if ( mbGrayScale )
			ImplGetGrayPalette( mnPngDepth );
	}
}

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

void PNGReaderImpl::ImplGetBackground()
{
	switch ( mnColorType )
	{
		case 3 :
		{
			if ( mnChunkLen == 1 )
			{
				sal_uInt16 nCol = *maDataIter++;
				if ( nCol < mpAcc->GetPaletteEntryCount() )
				{
					mpAcc->Erase( mpAcc->GetPaletteColor( (sal_uInt8)nCol ) );
					break;
				}
			}
		}
		break;

		case 0 :
		case 4 :
		{
			if ( mnChunkLen == 2 )
			{
                // the color type 0 and 4 is always greyscale,
                // so the return value can be used as index
				sal_uInt8 nIndex = ImplScaleColor();
				mpAcc->Erase( mpAcc->GetPaletteColor( nIndex ) );
			}
		}
		break;

		case 2 :
		case 6 :
		{
			if ( mnChunkLen == 6 )
			{
				sal_uInt8 nRed = ImplScaleColor();
				sal_uInt8 nGreen = ImplScaleColor();
				sal_uInt8 nBlue = ImplScaleColor();
				mpAcc->Erase( Color( nRed, nGreen, nBlue ) );
			}
		}
		break;
	}
}

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

// for color type 0 and 4 (greyscale) the return value is always index to the color
//                2 and 6 (RGB)       the return value is always the 8 bit color component
sal_uInt8 PNGReaderImpl::ImplScaleColor()
{
    sal_uInt32 nMask = ( ( 1 << mnPngDepth ) - 1 );
	sal_uInt16 nCol = ( *maDataIter++ << 8 );

	nCol += *maDataIter++ & (sal_uInt16)nMask;

	if ( mnPngDepth > 8 )	// convert 16bit graphics to 8
		nCol >>= 8;

	return (sal_uInt8) nCol;
}

// ------------------------------------------------------------------------
// ImplReadIDAT reads as much image data as needed

void PNGReaderImpl::ImplReadIDAT()
{
	if( mnChunkLen > 0 )
	{
		if ( mbzCodecInUse == sal_False )
		{
			mbzCodecInUse = sal_True;
			mpZCodec->BeginCompression( ZCODEC_PNG_DEFAULT );
		}
		mpZCodec->SetBreak( mnChunkLen );
		SvMemoryStream aIStrm( &(*maDataIter), mnChunkLen, STREAM_READ );

		while ( ( mpZCodec->GetBreak() ) )
		{
            // get bytes needed to fill the current scanline
            sal_Int32 nToRead = mnScansize - (mpScanCurrent - mpInflateInBuf);
            sal_Int32 nRead = mpZCodec->ReadAsynchron( aIStrm, mpScanCurrent, nToRead );
            if ( nRead < 0 )
			{
				mbStatus = sal_False;
				break;
			}
			if ( nRead < nToRead )
			{
				mpScanCurrent += nRead; // more ZStream data in the next IDAT chunk
				break;
			}
			else  // this scanline is Finished
			{
				mpScanCurrent = mpInflateInBuf;
                ImplApplyFilter();

                ImplDrawScanline( mnXStart, mnXAdd );
                mnYpos += mnYAdd;
			}

			if ( mnYpos >= (sal_uInt32)maOrigSize.Height() )
			{
                if( (mnPass < 7) && mnInterlaceType )
                    if( ImplPreparePass() )
                        continue;
                mbIDAT = true;
                break;
			}
		}
	}

	if( mbIDAT )
	{
		mpZCodec->EndCompression();
		mbzCodecInUse = sal_False;
	}
}

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

bool PNGReaderImpl::ImplPreparePass()
{
    struct InterlaceParams{ int mnXStart, mnYStart, mnXAdd, mnYAdd; };
    static const InterlaceParams aInterlaceParams[8] =
    {
        // non-interlaced
        { 0, 0, 1, 1 },
        // Adam7-interlaced
        { 0, 0, 8, 8 },    // pass 1
        { 4, 0, 8, 8 },    // pass 2
        { 0, 4, 4, 8 },    // pass 3
        { 2, 0, 4, 4 },    // pass 4
        { 0, 2, 2, 4 },    // pass 5
        { 1, 0, 2, 2 },    // pass 6
        { 0, 1, 1, 2 }     // pass 7
    };

    const InterlaceParams* pParam = &aInterlaceParams[ 0 ];
    if( mnInterlaceType )
    {
        while( ++mnPass <= 7 )
        {
            pParam = &aInterlaceParams[ mnPass ];

            // skip this pass if the original image is too small for it
            if( (pParam->mnXStart < maOrigSize.Width())
            &&  (pParam->mnYStart < maOrigSize.Height()) )
                break;
        }
        if( mnPass > 7 )
            return false;

        // skip the last passes if possible (for scaled down target images)
        if( mnPreviewMask & (pParam->mnXStart | pParam->mnYStart) )
            return false;
    }

    mnYpos      = pParam->mnYStart;
    mnXStart    = pParam->mnXStart;
    mnXAdd      = pParam->mnXAdd;
    mnYAdd      = pParam->mnYAdd;

    // in Interlace mode the size of scanline is not constant
    // so first we calculate the number of entrys
    long nScanWidth = (maOrigSize.Width() - mnXStart + mnXAdd - 1) / mnXAdd;
    mnScansize = nScanWidth;

    if( mbRGBTriple )
        mnScansize = 3 * nScanWidth;

    if( mbAlphaChannel )
        mnScansize += nScanWidth;

    // convert to width in bytes
    mnScansize = ( mnScansize*mnPngDepth + 7 ) >> 3;

    ++mnScansize; // scan size also needs room for the filtertype byte
    rtl_zeroMemory( mpScanPrior, mnScansize );

    return true;
}

// ----------------------------------------------------------------------------
// ImplApplyFilter writes the complete Scanline (nY)
// in interlace mode the parameter nXStart and nXAdd are non-zero

void PNGReaderImpl::ImplApplyFilter()
{
	OSL_ASSERT( mnScansize >= mnBPP + 1 );
    const sal_uInt8* const pScanEnd = mpInflateInBuf + mnScansize;

    sal_uInt8 nFilterType = *mpInflateInBuf; // the filter type may change each scanline
    switch ( nFilterType )
    {
        default: // unknown Scanline Filter Type
        case 0: // Filter Type "None"
            // we let the pixels pass and display the data unfiltered
            break;

        case 1: // Scanline Filter Type "Sub"
        {
            sal_uInt8* p1 = mpInflateInBuf + 1;
            const sal_uInt8* p2 = p1;
            p1 += mnBPP;

            // use left pixels
            do
                *p1 = static_cast<sal_uInt8>( *p1 + *(p2++) );
            while( ++p1 < pScanEnd );
        }
        break;

        case 2: // Scanline Filter Type "Up"
        {
            sal_uInt8* p1 = mpInflateInBuf + 1;
            const sal_uInt8* p2 = mpScanPrior + 1;

            // use pixels from prior line
			while( p1 < pScanEnd )
			{
                *p1 = static_cast<sal_uInt8>( *p1 + *(p2++) );
				++p1;
			}
        }
        break;

        case 3: // Scanline Filter Type "Average"
        {
            sal_uInt8* p1 = mpInflateInBuf + 1;
            const sal_uInt8* p2 = mpScanPrior + 1;
            const sal_uInt8* p3 = p1;

            // use one pixel from prior line
            for( int n = mnBPP; --n >= 0; ++p1, ++p2)
                *p1 = static_cast<sal_uInt8>( *p1 + (*p2 >> 1) );

            // predict by averaging the left and prior line pixels
			while( p1 < pScanEnd )
			{
                *p1 = static_cast<sal_uInt8>( *p1 + ((*(p2++) + *(p3++)) >> 1) );
				++p1;
			}
        }
        break;

        case 4: // Scanline Filter Type "PaethPredictor"
        {
            sal_uInt8* p1 = mpInflateInBuf + 1;
            const sal_uInt8* p2 = mpScanPrior + 1;
            const sal_uInt8* p3 = p1;
            const sal_uInt8* p4 = p2;

            // use one pixel from prior line
            for( int n = mnBPP; --n >= 0; ++p1)
                *p1 = static_cast<sal_uInt8>( *p1 + *(p2++) );

            // predict by using the left and the prior line pixels
            while( p1 < pScanEnd )
            {
                int na = *(p2++);
                int nb = *(p3++);
                int nc = *(p4++);

                int npa = nb - (int)nc;
                int npb = na - (int)nc;
                int npc = npa + npb;

                if( npa < 0 )
                    npa =-npa;
                if( npb < 0 )
                    npb =-npb;
                if( npc < 0 )
                    npc =-npc;

                if( npa > npb )
                    na = nb, npa = npb;
                if( npa > npc )
                    na = nc;

                *p1 = static_cast<sal_uInt8>( *p1 + na );
				++p1;
			}
        }
        break;
    }

    rtl_copyMemory( mpScanPrior, mpInflateInBuf, mnScansize );
}

// ---------------------------------------------------------------------------------------------------
// ImplDrawScanlines draws the complete Scanline (nY) into the target bitmap
// In interlace mode the parameter nXStart and nXAdd append to the currently used pass

void PNGReaderImpl::ImplDrawScanline( sal_uInt32 nXStart, sal_uInt32 nXAdd )
{
    // optimization for downscaling
    if( mnYpos & mnPreviewMask )
        return;
    if( nXStart & mnPreviewMask )
        return;

    // convert nY to pixel units in the target image
    // => TODO; also do this for nX here instead of in the ImplSet*Pixel() methods
    const sal_uInt32 nY = mnYpos >> mnPreviewShift;

    const sal_uInt8* pTmp = mpInflateInBuf + 1;
	if ( mpAcc->HasPalette() ) // alphachannel is not allowed by pictures including palette entries
	{
		switch ( mpAcc->GetBitCount() )
		{
			case 1 :
			{
				if ( mbTransparent )
				{
                    for ( sal_Int32 nX = nXStart, nShift = 0; nX < maOrigSize.Width(); nX += nXAdd )
					{
                        sal_uInt8 nCol;
                        nShift = (nShift - 1) & 7;
						if ( nShift == 0 )
							nCol = *(pTmp++);
						else
							nCol = static_cast<sal_uInt8>( *pTmp >> nShift );
                        nCol &= 1;

						ImplSetAlphaPixel( nY, nX, nCol, mpTransTab[ nCol ] );
					}
				}
				else
				{   // BMP_FORMAT_1BIT_MSB_PAL
					for ( sal_Int32 nX = nXStart, nShift = 0; nX < maOrigSize.Width(); nX += nXAdd )
					{
                        nShift = (nShift - 1) & 7;

                        sal_uInt8 nCol;
						if ( nShift == 0 )
							nCol = *(pTmp++);
						else
							nCol = static_cast<sal_uInt8>( *pTmp >> nShift );
                        nCol &= 1;

                        ImplSetPixel( nY, nX, nCol );
					}
				}
			}
			break;

			case 4 :
			{
				if ( mbTransparent )
				{
					if ( mnPngDepth == 4 )	// check if source has a two bit pixel format
					{
						for ( sal_Int32 nX = nXStart, nXIndex = 0; nX < maOrigSize.Width(); nX += nXAdd, ++nXIndex )
						{
							if( nXIndex & 1 )
							{
								ImplSetAlphaPixel( nY, nX, *pTmp & 0x0f, mpTransTab[ *pTmp & 0x0f ] );
								pTmp++;
							}
							else
							{
								ImplSetAlphaPixel( nY, nX, ( *pTmp >> 4 ) & 0x0f, mpTransTab[ *pTmp >> 4 ] );
							}
						}
					}
					else // if ( mnPngDepth == 2 )
					{
						for ( sal_Int32 nX = nXStart, nXIndex = 0; nX < maOrigSize.Width(); nX += nXAdd, nXIndex++ )
						{
                            sal_uInt8 nCol;
							switch( nXIndex & 3 )
							{
								case 0 :
									nCol = *pTmp >> 6;
								break;

								case 1 :
									nCol = ( *pTmp >> 4 ) & 0x03 ;
								break;

								case 2 :
									nCol = ( *pTmp >> 2 ) & 0x03;
								break;

								case 3 :
									nCol = ( *pTmp++ ) & 0x03;
								break;

                                default:    // get rid of nCol uninitialized warning
                                    nCol = 0;
                                    break;
							}

							ImplSetAlphaPixel( nY, nX, nCol, mpTransTab[ nCol ] );
						}
					}
				}
				else
				{
					if ( mnPngDepth == 4 )	// maybe the source is a two bitmap graphic
					{   // BMP_FORMAT_4BIT_LSN_PAL
						for ( sal_Int32 nX = nXStart, nXIndex = 0; nX < maOrigSize.Width(); nX += nXAdd, nXIndex++ )
						{
							if( nXIndex & 1 )
								ImplSetPixel( nY, nX, *pTmp++ & 0x0f );
							else
								ImplSetPixel( nY, nX, ( *pTmp >> 4 ) & 0x0f );
						}
					}
					else // if ( mnPngDepth == 2 )
					{
						for ( sal_Int32 nX = nXStart, nXIndex = 0; nX < maOrigSize.Width(); nX += nXAdd, nXIndex++ )
						{
							switch( nXIndex & 3 )
							{
								case 0 :
									ImplSetPixel( nY, nX, *pTmp >> 6 );
								break;

								case 1 :
									ImplSetPixel( nY, nX, ( *pTmp >> 4 ) & 0x03 );
								break;

								case 2 :
									ImplSetPixel( nY, nX, ( *pTmp >> 2 ) & 0x03 );
								break;

								case 3 :
									ImplSetPixel( nY, nX, *pTmp++ & 0x03 );
								break;
							}
						}
					}
				}
			}
			break;

			case 8 :
			{
				if ( mbAlphaChannel )
				{
					if ( mnPngDepth == 8 )	// maybe the source is a 16 bit grayscale
					{
						for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 2 )
							ImplSetAlphaPixel( nY, nX, pTmp[ 0 ], pTmp[ 1 ] );
					}
					else
					{
						for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 4 )
							ImplSetAlphaPixel( nY, nX, pTmp[ 0 ], pTmp[ 2 ] );
					}
				}
				else if ( mbTransparent )
				{
					if ( mnPngDepth == 8 )	// maybe the source is a 16 bit grayscale
					{
						for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp++ )
							ImplSetAlphaPixel( nY, nX, *pTmp, mpTransTab[ *pTmp ] );
					}
					else
					{
						for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 2 )
							ImplSetAlphaPixel( nY, nX, *pTmp, mpTransTab[ *pTmp ] );
					}
				}
				else // neither alpha nor transparency
				{
					if ( mnPngDepth == 8 )	// maybe the source is a 16 bit grayscale
					{
                        if( nXAdd == 1 && mnPreviewShift == 0 )  // copy raw line data if possible
                        {
                            int nLineBytes = maOrigSize.Width();
                            mpAcc->CopyScanline( nY, pTmp, BMP_FORMAT_8BIT_PAL, nLineBytes );
                            pTmp += nLineBytes;
                        }
                        else
                        {
                            for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd )
                                ImplSetPixel( nY, nX, *pTmp++ );
                        }
					}
					else
					{
						for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 2 )
							ImplSetPixel( nY, nX, *pTmp );
					}
				}
			}
			break;

			default :
				mbStatus = sal_False;
			break;
		}
	}
	else // no palette => truecolor
	{
		if( mbAlphaChannel ) // has RGB + alpha
		{   // BMP_FORMAT_32BIT_TC_RGBA
			if ( mnPngDepth == 8 )  // maybe the source has 16 bit per sample
			{
                if ( mpColorTable != mpDefaultColorTable )
                {
                    for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 4 )
                       ImplSetAlphaPixel( nY, nX, BitmapColor( mpColorTable[ pTmp[ 0 ] ],
                                                               mpColorTable[ pTmp[ 1 ] ],
                                                               mpColorTable[ pTmp[ 2 ] ] ), pTmp[ 3 ] );
                }
                else
                {
//                  if ( nXAdd == 1 && mnPreviewShift == 0 ) // copy raw line data if possible
//                  {
//                      int nLineBytes = 4 * maOrigSize.Width();
//                      mpAcc->CopyScanline( nY, pTmp, BMP_FORMAT_32BIT_TC_RGBA, nLineBytes );
//                      pTmp += nLineBytes;
//                  }
//                  else
                    {
                        for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 4 )
                            ImplSetAlphaPixel( nY, nX, BitmapColor( pTmp[0], pTmp[1], pTmp[2] ), pTmp[3] );
                    }
                }
			}
			else
			{   // BMP_FORMAT_64BIT_TC_RGBA
				for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 8 )
					ImplSetAlphaPixel( nY, nX, BitmapColor( mpColorTable[ pTmp[ 0 ] ],
														mpColorTable[ pTmp[ 2 ] ],
														mpColorTable[ pTmp[ 4 ] ] ), pTmp[6] );
			}
		}
		else if( mbTransparent ) // has RGB + transparency
		{   // BMP_FORMAT_24BIT_TC_RGB
			if ( mnPngDepth == 8 )  // maybe the source has 16 bit per sample
			{
				for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 3 )
				{
					sal_uInt8 nRed = pTmp[ 0 ];
					sal_uInt8 nGreen = pTmp[ 1 ];
					sal_uInt8 nBlue = pTmp[ 2 ];
					sal_Bool bTransparent = ( ( nRed == mnTransRed )
							 			&& ( nGreen == mnTransGreen )
										&& ( nBlue == mnTransBlue ) );

					ImplSetTranspPixel( nY, nX, BitmapColor( mpColorTable[ nRed ],
														mpColorTable[ nGreen ],
														mpColorTable[ nBlue ] ), bTransparent );
				}
			}
			else
			{   // BMP_FORMAT_48BIT_TC_RGB
				for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 6 )
				{
					sal_uInt8 nRed = pTmp[ 0 ];
					sal_uInt8 nGreen = pTmp[ 2 ];
					sal_uInt8 nBlue = pTmp[ 4 ];
					sal_Bool bTransparent = ( ( nRed == mnTransRed )
										&& ( nGreen == mnTransGreen )
										&& ( nBlue == mnTransBlue ) );

					ImplSetTranspPixel( nY, nX, BitmapColor( mpColorTable[ nRed ],
														mpColorTable[ nGreen ],
														mpColorTable[ nBlue ] ), bTransparent );
				}
			}
		}
		else  // has RGB but neither alpha nor transparency
		{   // BMP_FORMAT_24BIT_TC_RGB
			if ( mnPngDepth == 8 )   // maybe the source has 16 bit per sample
			{
                if ( mpColorTable != mpDefaultColorTable )
                {
                    for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 3 )
                        ImplSetPixel( nY, nX, BitmapColor( mpColorTable[ pTmp[ 0 ] ],
                                                            mpColorTable[ pTmp[ 1 ] ],
                                                            mpColorTable[ pTmp[ 2 ] ] ) );
                }
                else
                {
                    if( nXAdd == 1 && mnPreviewShift == 0 ) // copy raw line data if possible
                    {
                        int nLineBytes = maOrigSize.Width() * 3;
                        mpAcc->CopyScanline( nY, pTmp, BMP_FORMAT_24BIT_TC_RGB, nLineBytes );
                        pTmp += nLineBytes;
                    }
                    else
                    {
                        for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 3 )
                            ImplSetPixel( nY, nX, BitmapColor( pTmp[0], pTmp[1], pTmp[2] ) );
                    }
                }
			}
			else
			{   // BMP_FORMAT_48BIT_TC_RGB
				for ( sal_Int32 nX = nXStart; nX < maOrigSize.Width(); nX += nXAdd, pTmp += 6 )
					ImplSetPixel( nY, nX, BitmapColor( mpColorTable[ pTmp[ 0 ] ],
														mpColorTable[ pTmp[ 2 ] ],
														mpColorTable[ pTmp[ 4 ] ] ) );
			}
		}
	}
}

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

void PNGReaderImpl::ImplSetPixel( sal_uInt32 nY, sal_uInt32 nX, const BitmapColor& rBitmapColor )
{
    // TODO: get preview mode checks out of inner loop
    if( nX & mnPreviewMask )
        return;
    nX >>= mnPreviewShift;

    mpAcc->SetPixel( nY, nX, rBitmapColor );
}

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

void PNGReaderImpl::ImplSetPixel( sal_uInt32 nY, sal_uInt32 nX, sal_uInt8 nPalIndex )
{
    // TODO: get preview mode checks out of inner loop
    if( nX & mnPreviewMask )
        return;
    nX >>= mnPreviewShift;

    mpAcc->SetPixelIndex( nY, nX, nPalIndex );
}

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

void PNGReaderImpl::ImplSetTranspPixel( sal_uInt32 nY, sal_uInt32 nX, const BitmapColor& rBitmapColor, sal_Bool bTrans )
{
    // TODO: get preview mode checks out of inner loop
    if( nX & mnPreviewMask )
        return;
    nX >>= mnPreviewShift;

    mpAcc->SetPixel( nY, nX, rBitmapColor );

    if ( bTrans )
        mpMaskAcc->SetPixel( nY, nX, mcTranspColor );
    else
        mpMaskAcc->SetPixel( nY, nX, mcOpaqueColor );
}

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

void PNGReaderImpl::ImplSetAlphaPixel( sal_uInt32 nY, sal_uInt32 nX,
    sal_uInt8 nPalIndex, sal_uInt8 nAlpha )
{
    // TODO: get preview mode checks out of inner loop
    if( nX & mnPreviewMask )
        return;
    nX >>= mnPreviewShift;

    mpAcc->SetPixelIndex( nY, nX, nPalIndex );
    mpMaskAcc->SetPixelIndex( nY, nX, ~nAlpha );
}

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

void PNGReaderImpl::ImplSetAlphaPixel( sal_uInt32 nY, sal_uInt32 nX,
    const BitmapColor& rBitmapColor, sal_uInt8 nAlpha )
{
    // TODO: get preview mode checks out of inner loop
    if( nX & mnPreviewMask )
        return;
    nX >>= mnPreviewShift;

    mpAcc->SetPixel( nY, nX, rBitmapColor );
    mpMaskAcc->SetPixelIndex( nY, nX, ~nAlpha );
}

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

sal_uInt32 PNGReaderImpl::ImplReadsal_uInt32()
{
	sal_uInt32 nRet;
	nRet = *maDataIter++;
	nRet <<= 8;
	nRet |= *maDataIter++;
	nRet <<= 8;
	nRet |= *maDataIter++;
	nRet <<= 8;
	nRet |= *maDataIter++;
	return nRet;
}

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

// -------------
// - PNGReader -
// -------------

PNGReader::PNGReader( SvStream& rIStm ) :
	mpImpl( new ::vcl::PNGReaderImpl( rIStm ) )
{
}

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

PNGReader::~PNGReader()
{
	delete mpImpl;
}

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

BitmapEx PNGReader::Read( const Size& i_rPreviewSizeHint )
{
    return mpImpl->GetBitmapEx( i_rPreviewSizeHint );
}

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

const std::vector< vcl::PNGReader::ChunkData >& PNGReader::GetChunks() const
{
	return mpImpl->GetAllChunks();
}

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

void PNGReader::SetIgnoreGammaChunk( sal_Bool b )
{
	mpImpl->SetIgnoreGammaChunk( b );
}


} // namespace vcl