BitmapMaskToAlphaFilter.cxx

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/* -*- 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/.
 *
 */
 
#include <basegfx/color/bcolortools.hxx>
 
#include <bitmap/BitmapWriteAccess.hxx>
#include <bitmap/BitmapMaskToAlphaFilter.hxx>
 
BitmapEx BitmapMaskToAlphaFilter::execute(BitmapEx const& rBitmapEx) const
{
    const Size aSize(rBitmapEx.GetSizePixel());
 
    Bitmap aBitmap(rBitmapEx.GetBitmap());
    Bitmap aOutBitmap(aSize, vcl::PixelFormat::N8_BPP, &Bitmap::GetGreyPalette(256));
 
    Bitmap::ScopedReadAccess pRead(aBitmap);
    BitmapScopedWriteAccess pWrite(aOutBitmap);
 
    if (pRead && pWrite)
    {
        assert(pRead->HasPalette() && "only supposed to be called with 1-bit mask");
        assert(pRead->GetPaletteEntryCount() == 2);
        for (sal_Int32 nY = 0; nY < sal_Int32(aSize.Height()); ++nY)
        {
            Scanline pScanline = pWrite->GetScanline(nY);
            Scanline pScanlineRead = pRead->GetScanline(nY);
            for (sal_Int32 nX = 0; nX < sal_Int32(aSize.Width()); ++nX)
            {
                BitmapColor aBmpColor = pRead->GetPixelFromData(pScanlineRead, nX);
                if (aBmpColor == COL_BLACK)
                    aBmpColor = COL_ALPHA_OPAQUE;
                else if (aBmpColor == COL_WHITE)
                    aBmpColor = COL_ALPHA_TRANSPARENT;
                else if (aBmpColor == Color(0, 0, 1))
                    aBmpColor = COL_ALPHA_TRANSPARENT;
                else
                    assert(false);
                pWrite->SetPixelOnData(pScanline, nX, aBmpColor);
            }
        }
    }
    pWrite.reset();
    pRead.reset();
 
    return BitmapEx(aOutBitmap);
}
 
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