BitmapPopArtFilter.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 <tools/solar.h>
#include <vcl/bitmap.hxx>
#include <vcl/bitmapex.hxx>
#include <vcl/BitmapPopArtFilter.hxx>
 
#include <bitmap/BitmapWriteAccess.hxx>
 
BitmapEx BitmapPopArtFilter::execute(BitmapEx const& rBitmapEx) const
{
    Bitmap aBitmap(rBitmapEx.GetBitmap());
 
    bool bRet = isPalettePixelFormat(aBitmap.getPixelFormat())
                || aBitmap.Convert(BmpConversion::N8BitColors);
 
    if (bRet)
    {
        bRet = false;
 
        BitmapScopedWriteAccess pWriteAcc(aBitmap);
 
        if (pWriteAcc)
        {
            const sal_Int32 nWidth = pWriteAcc->Width();
            const sal_Int32 nHeight = pWriteAcc->Height();
            const int nEntryCount = 1 << pWriteAcc->GetBitCount();
            int n = 0;
            std::vector<PopArtEntry> aPopArtTable(nEntryCount);
 
            for (n = 0; n < nEntryCount; n++)
            {
                PopArtEntry& rEntry = aPopArtTable[n];
                rEntry.mnIndex = static_cast<sal_uInt16>(n);
                rEntry.mnCount = 0;
            }
 
            // get pixel count for each palette entry
            for (sal_Int32 nY = 0; nY < nHeight; nY++)
            {
                Scanline pScanline = pWriteAcc->GetScanline(nY);
                for (sal_Int32 nX = 0; nX < nWidth; nX++)
                {
                    aPopArtTable[pWriteAcc->GetIndexFromData(pScanline, nX)].mnCount++;
                }
            }
 
            // sort table
            std::sort(aPopArtTable.begin(), aPopArtTable.end(),
                      [](const PopArtEntry& lhs, const PopArtEntry& rhs) {
                          return lhs.mnCount < rhs.mnCount;
                      });
 
            // get last used entry
            sal_uLong nFirstEntry;
            sal_uLong nLastEntry = 0;
 
            for (n = 0; n < nEntryCount; n++)
            {
                if (aPopArtTable[n].mnCount)
                    nLastEntry = n;
            }
 
            // rotate palette (one entry)
            const BitmapColor aFirstCol(pWriteAcc->GetPaletteColor(
                sal::static_int_cast<sal_uInt16>(aPopArtTable[0].mnIndex)));
 
            for (nFirstEntry = 0; nFirstEntry < nLastEntry; nFirstEntry++)
            {
                pWriteAcc->SetPaletteColor(
                    sal::static_int_cast<sal_uInt16>(aPopArtTable[nFirstEntry].mnIndex),
                    pWriteAcc->GetPaletteColor(
                        sal::static_int_cast<sal_uInt16>(aPopArtTable[nFirstEntry + 1].mnIndex)));
            }
 
            pWriteAcc->SetPaletteColor(
                sal::static_int_cast<sal_uInt16>(aPopArtTable[nLastEntry].mnIndex), aFirstCol);
 
            // cleanup
            pWriteAcc.reset();
            bRet = true;
        }
    }
 
    if (bRet)
        return BitmapEx(aBitmap);
 
    return BitmapEx();
}
 
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */