/* -*- 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 <config_features.h>

#include <tools/color.hxx>

#include <vcl/alpha.hxx>

#include <vcl/BitmapWriteAccess.hxx>

#include <salinst.hxx>

#include <svdata.hxx>

#include <salbmp.hxx>

#include <sal/log.hxx>

#if HAVE_FEATURE_SKIA

#include <vcl/skia/SkiaHelper.hxx>

#endif

AlphaMask::AlphaMask() = default;

AlphaMask::AlphaMask( const Bitmap& rBitmap ) :

    maBitmap( rBitmap )

{

    if ( !rBitmap.IsEmpty() )

        maBitmap.Convert( BmpConversion::N8BitNoConversion );

#if HAVE_FEATURE_SKIA

    // Related tdf#156866 force snapshot of alpha mask when using Skia

    // In release builds, tdf#156629 and tdf#156630 reappear in many

    // cases because a BitmapInfoAccess is in a debug block. So, instead

    // of relying on other code to a create a BitmapInfoAccess instance,

    // create one here to force the alpha mask to handle any pending

    // scaling and make the alpha mask immutable.

    else if ( SkiaHelper::isVCLSkiaEnabled() )

        BitmapInfoAccess aInfoAccess( maBitmap );

#endif

    assert( (IsEmpty() || maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP) && "alpha bitmap should be 8bpp" );

    assert( (IsEmpty() || maBitmap.HasGreyPalette8Bit()) && "alpha bitmap should have greyscale palette" );

}

AlphaMask::AlphaMask( const AlphaMask& ) = default;

AlphaMask::AlphaMask( AlphaMask&& ) = default;

AlphaMask::AlphaMask( const Size& rSizePixel, const sal_uInt8* pEraseTransparency )

    : maBitmap(rSizePixel, vcl::PixelFormat::N8_BPP, &Bitmap::GetGreyPalette(256))

{

    if( pEraseTransparency )

    {

        sal_uInt8 nAlpha = 255 - *pEraseTransparency;

        maBitmap.Erase( Color( nAlpha, nAlpha, nAlpha ) );

    }

    else

        maBitmap.Erase( COL_ALPHA_OPAQUE );

}

AlphaMask::~AlphaMask() = default;

AlphaMask& AlphaMask::operator=( const Bitmap& rBitmap )

{

    maBitmap = rBitmap;

    if( !rBitmap.IsEmpty() )

        maBitmap.Convert( BmpConversion::N8BitNoConversion );

    assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );

    assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );

    return *this;

}

void AlphaMask::Erase( sal_uInt8 cTransparency )

{

    sal_uInt8 nAlpha = 255 - cTransparency;

    maBitmap.Erase( Color( nAlpha, nAlpha, nAlpha ) );

}

void AlphaMask::BlendWith(const AlphaMask& rOther)

{

    std::shared_ptr<SalBitmap> xImpBmp(GetSalInstance()->CreateSalBitmap());

    if (xImpBmp->Create(*maBitmap.ImplGetSalBitmap()) && xImpBmp->AlphaBlendWith(*rOther.maBitmap.ImplGetSalBitmap()))

    {

        maBitmap.ImplSetSalBitmap(xImpBmp);

        assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );

        assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );

        return;

    }

    BitmapScopedReadAccess pOtherAcc(rOther);

    BitmapScopedWriteAccess pAcc(*this);

    assert (pOtherAcc && pAcc && pOtherAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8 && "cannot BlendWith this combination");

    if (!(pOtherAcc && pAcc && pOtherAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8))

    {

        SAL_WARN("vcl", "cannot BlendWith this combination");

        return;

    }

    const tools::Long nHeight = std::min(pOtherAcc->Height(), pAcc->Height());

    const tools::Long nWidth = std::min(pOtherAcc->Width(), pAcc->Width());

    for (tools::Long y = 0; y < nHeight; ++y)

    {

        Scanline scanline = pAcc->GetScanline( y );

        ConstScanline otherScanline = pOtherAcc->GetScanline( y );

        for (tools::Long x = 0; x < nWidth; ++x)

        {

            // Use sal_uInt16 for following multiplication

            const sal_uInt16 nGrey1 = *scanline;

            const sal_uInt16 nGrey2 = *otherScanline;

            // Awkward calculation because the original used transparency, and to replicate

            // the logic we need to translate into transparency, perform the original logic,

            // then translate back to alpha.

            // The original looked like:

            //   auto tmp = nGrey1 + nGrey2 - (nGrey1 * nGrey2 / 255)

            // which, when converted to using alpha looks like

            //   auto tmp = 255 - ((255 - nGrey1) + (255 - nGrey2) - (255 - nGrey1) * (255 - nGrey2) / 255);

            // which then simplifies to:

            auto tmp = nGrey1 * nGrey2 / 255;

            *scanline = static_cast<sal_uInt8>(tmp);

            ++scanline;

            ++otherScanline;

        }

    }

    pAcc.reset();

    assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );

    assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );

}

bool AlphaMask::hasAlpha() const

{

    // no content, no alpha

    if(IsEmpty())

        return false;

    BitmapScopedReadAccess pAcc(*this);

    const tools::Long nHeight(pAcc->Height());

    const tools::Long nWidth(pAcc->Width());

    // no content, no alpha

    if(0 == nHeight || 0 == nWidth)

        return false;

    for (tools::Long y = 0; y < nHeight; ++y)

    {

        for (tools::Long x = 0; x < nWidth; ++x)

        {

            if (255 != pAcc->GetColor(y, x).GetRed())

            {

                return true;

            }

        }

    }

    return false;

}

bool AlphaMask::AlphaCombineOr(const AlphaMask& rMask)

{

    BitmapScopedReadAccess pMaskAcc(rMask);

    BitmapScopedWriteAccess pAcc(*this);

    if (!pMaskAcc || !pAcc)

        return false;

    assert (pMaskAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8);

    const tools::Long nWidth = std::min(pMaskAcc->Width(), pAcc->Width());

    const tools::Long nHeight = std::min(pMaskAcc->Height(), pAcc->Height());

    for (tools::Long nY = 0; nY < nHeight; nY++)

    {

        Scanline pScanline = pAcc->GetScanline(nY);

        ConstScanline pScanlineMask = pMaskAcc->GetScanline(nY);

        for (tools::Long nX = 0; nX < nWidth; nX++)

        {

            if (*pScanlineMask != 255 || *pScanline != 255)

                *pScanline = 0;

            else

                *pScanline = 255;

            ++pScanline;

            ++pScanlineMask;

        }

    }

    return true;

}

bool AlphaMask::Invert()

{

    if (IsEmpty())

        return false;

    bool b = maBitmap.Invert();

    assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );

    assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );

    return b;

}

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