BitmapMonochromeFilter.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 <vcl/bitmap.hxx>
#include <vcl/bitmapex.hxx>
#include <vcl/BitmapMonochromeFilter.hxx>
 
#include <bitmap/BitmapWriteAccess.hxx>
 
BitmapEx BitmapMonochromeFilter::execute(BitmapEx const& aBitmapEx) const
{
    Bitmap aBitmap = aBitmapEx.GetBitmap();
    Bitmap::ScopedReadAccess pReadAcc(aBitmap);
    if (!pReadAcc)
        return BitmapEx();
 
    Bitmap aNewBmp(aBitmap.GetSizePixel(), vcl::PixelFormat::N8_BPP, &Bitmap::GetGreyPalette(256));
    BitmapScopedWriteAccess pWriteAcc(aNewBmp);
    if (!pWriteAcc)
        return BitmapEx();
 
    const BitmapColor aBlack(pWriteAcc->GetBestMatchingColor(COL_BLACK));
    const BitmapColor aWhite(pWriteAcc->GetBestMatchingColor(COL_WHITE));
    const sal_Int32 nWidth = pWriteAcc->Width();
    const sal_Int32 nHeight = pWriteAcc->Height();
 
    if (pReadAcc->HasPalette())
    {
        for (sal_Int32 nY = 0; nY < nHeight; nY++)
        {
            Scanline pScanline = pWriteAcc->GetScanline(nY);
            Scanline pScanlineRead = pReadAcc->GetScanline(nY);
            for (sal_Int32 nX = 0; nX < nWidth; nX++)
            {
                const sal_uInt8 cIndex = pReadAcc->GetIndexFromData(pScanlineRead, nX);
                if (pReadAcc->GetPaletteColor(cIndex).GetLuminance() >= mcThreshold)
                {
                    pWriteAcc->SetPixelOnData(pScanline, nX, aWhite);
                }
                else
                {
                    pWriteAcc->SetPixelOnData(pScanline, nX, aBlack);
                }
            }
        }
    }
    else
    {
        for (sal_Int32 nY = 0; nY < nHeight; nY++)
        {
            Scanline pScanline = pWriteAcc->GetScanline(nY);
            Scanline pScanlineRead = pReadAcc->GetScanline(nY);
            for (sal_Int32 nX = 0; nX < nWidth; nX++)
            {
                if (pReadAcc->GetPixelFromData(pScanlineRead, nX).GetLuminance() >= mcThreshold)
                {
                    pWriteAcc->SetPixelOnData(pScanline, nX, aWhite);
                }
                else
                {
                    pWriteAcc->SetPixelOnData(pScanline, nX, aBlack);
                }
            }
        }
    }
 
    pWriteAcc.reset();
    pReadAcc.reset();
 
    const MapMode aMap(aBitmap.GetPrefMapMode());
    const Size aSize(aBitmap.GetPrefSize());
 
    aBitmap = aNewBmp;
 
    aBitmap.SetPrefMapMode(aMap);
    aBitmap.SetPrefSize(aSize);
 
    return BitmapEx(aBitmap);
}
 
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