/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/*

 * This file is part of the LibreOffice project.

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/.

 *

 * This file incorporates work covered by the following license notice:

 *

 *   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 .

 */

#include <salbmp.hxx>

#include <o3tl/enumarray.hxx>

#include <vcl/BitmapColor.hxx>

#include <rtl/crc.h>

#include <algorithm>

static BitmapChecksum scanlineChecksum(BitmapChecksum nCrc, const sal_uInt8* bits, int lineBitsCount, sal_uInt8 extraBitsMask)

{

    if( lineBitsCount / 8 > 0 )

        nCrc = rtl_crc32( nCrc, bits, lineBitsCount / 8 );

    if( extraBitsMask != 0 )

    {

        sal_uInt8 extraByte = bits[ lineBitsCount / 8 ] & extraBitsMask;

        nCrc = rtl_crc32( nCrc, &extraByte, 1 );

    }

    return nCrc;

}

void SalBitmap::updateChecksum() const

{

    if (mbChecksumValid)

        return;

    BitmapChecksum nCrc = 0;

    SalBitmap* pThis = const_cast<SalBitmap*>(this);

    BitmapBuffer* pBuf = pThis->AcquireBuffer(BitmapAccessMode::Read);

    if (pBuf)

    {

        nCrc = pBuf->maPalette.GetChecksum();

        const int lineBitsCount = pBuf->mnWidth * pBuf->mnBitCount;

        // With 1bpp/4bpp format we need to check only used bits in the last byte.

        if (pBuf->meDirection == ScanlineDirection::TopDown)

        {

            if( pBuf->mnScanlineSize == lineBitsCount / 8 )

                nCrc = rtl_crc32(nCrc, pBuf->mpBits, pBuf->mnScanlineSize * pBuf->mnHeight);

            else // Do not include padding with undefined content in the checksum.

                for( tools::Long y = 0; y < pBuf->mnHeight; ++y )

                    nCrc = scanlineChecksum(nCrc, pBuf->mpBits + y * pBuf->mnScanlineSize, lineBitsCount, 0);

        }

        else // Compute checksum in the order of scanlines, to make it consistent between different bitmap implementations.

        {

            for( tools::Long y = pBuf->mnHeight - 1; y >= 0; --y )

                nCrc = scanlineChecksum(nCrc, pBuf->mpBits + y * pBuf->mnScanlineSize, lineBitsCount, 0);

        }

        pThis->ReleaseBuffer(pBuf, BitmapAccessMode::Read);

        pThis->mnChecksum = nCrc;

        pThis->mbChecksumValid = true;

    }

    else

    {

        pThis->mbChecksumValid = false;

    }

}

sal_uInt16 SalBitmap::GetBitCount() const

{

    switch (GetScanlineFormat())

    {

        case ScanlineFormat::NONE: return 0;

        case ScanlineFormat::N8BitPal: return 8;

        case ScanlineFormat::N24BitTcBgr: return 24;

        case ScanlineFormat::N24BitTcRgb: return 24;

        case ScanlineFormat::N32BitTcAbgr:

        case ScanlineFormat::N32BitTcXbgr:

        case ScanlineFormat::N32BitTcArgb:

        case ScanlineFormat::N32BitTcXrgb:

        case ScanlineFormat::N32BitTcBgra:

        case ScanlineFormat::N32BitTcBgrx:

        case ScanlineFormat::N32BitTcRgba:

        case ScanlineFormat::N32BitTcRgbx:

            return 32;

        default: abort();

    }

}

namespace

{

class ImplPixelFormat

{

protected:

    const sal_uInt8* mpData;

public:

    static ImplPixelFormat* GetFormat( sal_uInt16 nBits, const BitmapPalette& rPalette );

    virtual void StartLine( const sal_uInt8* pLine ) { mpData = pLine; }

    virtual const BitmapColor& ReadPixel() = 0;

    virtual ~ImplPixelFormat() { }

};

class ImplPixelFormat8 : public ImplPixelFormat

{

private:

    const BitmapPalette& mrPalette;

public:

    explicit ImplPixelFormat8( const BitmapPalette& rPalette )

    : mrPalette( rPalette )

    {

    }

    virtual const BitmapColor& ReadPixel() override

    {

        assert( mrPalette.GetEntryCount() > *mpData );

        return mrPalette[ *mpData++ ];

    }

};

class ImplPixelFormat4 : public ImplPixelFormat

{

private:

    const BitmapPalette& mrPalette;

    sal_uInt32 mnX;

    sal_uInt32 mnShift;

public:

    explicit ImplPixelFormat4( const BitmapPalette& rPalette )

        : mrPalette( rPalette )

        , mnX(0)

        , mnShift(4)

    {

    }

    virtual void StartLine( const sal_uInt8* pLine ) override

    {

        mpData = pLine;

        mnX = 0;

        mnShift = 4;

    }

    virtual const BitmapColor& ReadPixel() override

    {

        sal_uInt32 nIdx = ( mpData[mnX >> 1] >> mnShift) & 0x0f;

        assert( mrPalette.GetEntryCount() > nIdx );

        const BitmapColor& rColor = mrPalette[nIdx];

        mnX++;

        mnShift ^= 4;

        return rColor;

    }

};

class ImplPixelFormat1 : public ImplPixelFormat

{

private:

    const BitmapPalette& mrPalette;

    sal_uInt32 mnX;

public:

    explicit ImplPixelFormat1( const BitmapPalette& rPalette )

        : mrPalette(rPalette)

        , mnX(0)

    {

    }

    virtual void StartLine( const sal_uInt8* pLine ) override

    {

        mpData = pLine;

        mnX = 0;

    }

    virtual const BitmapColor& ReadPixel() override

    {

        const BitmapColor& rColor = mrPalette[ (mpData[mnX >> 3 ] >> ( 7 - ( mnX & 7 ) )) & 1];

        mnX++;

        return rColor;

    }

};

ImplPixelFormat* ImplPixelFormat::GetFormat( sal_uInt16 nBits, const BitmapPalette& rPalette )

{

    switch( nBits )

    {

    case 1: return new ImplPixelFormat1( rPalette );

    case 4: return new ImplPixelFormat4( rPalette );

    case 8: return new ImplPixelFormat8( rPalette );

    }

    return nullptr;

}

} // namespace

std::unique_ptr< sal_uInt8[] > SalBitmap::convertDataBitCount( const sal_uInt8* src,

    int width, int height, int bitCount, int bytesPerRow, const BitmapPalette& palette, BitConvert type )

{

    assert( bitCount == 4 || bitCount == 8 );

    static const o3tl::enumarray<BitConvert, int> bpp = { 1, 4, 4 };

    std::unique_ptr< sal_uInt8[] > data( new sal_uInt8[width * height * bpp[ type ]] );

    if(type == BitConvert::A8 && bitCount == 8 && palette.IsGreyPalette8Bit())

    { // no actual data conversion

        for( int y = 0; y < height; ++y )

            std::copy_n(src + y * bytesPerRow, width, data.get() + y * width);

        return data;

    }

    std::unique_ptr<ImplPixelFormat> pSrcFormat(ImplPixelFormat::GetFormat(bitCount, palette));

    const sal_uInt8* pSrcData = src;

    sal_uInt8* pDstData = data.get();

    sal_uInt32 nY = height;

    while( nY-- )

    {

        pSrcFormat->StartLine( pSrcData );

        sal_uInt32 nX = width;

        switch( type )

        {

            case BitConvert::A8 :

                while( nX-- )

                {

                    const BitmapColor& c = pSrcFormat->ReadPixel();

                    *pDstData++ = c.GetBlue();

                }

                break;

            case BitConvert::BGRA :

                while( nX-- )

                {

                    const BitmapColor& c = pSrcFormat->ReadPixel();

                    *pDstData++ = c.GetBlue();

                    *pDstData++ = c.GetGreen();

                    *pDstData++ = c.GetRed();

                    *pDstData++ = 0xff;

                }

                break;

            case BitConvert::RGBA :

                while( nX-- )

                {

                    const BitmapColor& c = pSrcFormat->ReadPixel();

                    *pDstData++ = c.GetRed();

                    *pDstData++ = c.GetGreen();

                    *pDstData++ = c.GetBlue();

                    *pDstData++ = 0xff;

                }

                break;

        }

        pSrcData += bytesPerRow;

    }

    return data;

}

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