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diff --git a/vcl/inc/bitmap/ScanlineTools.hxx b/vcl/inc/bitmap/ScanlineTools.hxx
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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/.
+ *
+ */
+
+#ifndef INCLUDED_VCL_INC_BITMAP_SCANLINETOOLS_HXX
+#define INCLUDED_VCL_INC_BITMAP_SCANLINETOOLS_HXX
+
+#include <tools/color.hxx>
+#include <vcl/BitmapPalette.hxx>
+
+namespace vcl::bitmap
+{
+class ScanlineTransformer
+{
+public:
+ virtual void startLine(sal_uInt8* pLine) = 0;
+ virtual void skipPixel(sal_uInt32 nPixel) = 0;
+ virtual Color readPixel() = 0;
+ virtual void writePixel(Color nColor) = 0;
+
+ virtual ~ScanlineTransformer() = default;
+};
+
+class ScanlineTransformer_ARGB final : public ScanlineTransformer
+{
+private:
+ sal_uInt8* pData;
+
+public:
+ virtual void startLine(sal_uInt8* pLine) override { pData = pLine; }
+
+ virtual void skipPixel(sal_uInt32 nPixel) override { pData += nPixel << 2; }
+
+ virtual Color readPixel() override
+ {
+ const Color aColor(ColorAlpha, pData[4], pData[1], pData[2], pData[3]);
+ pData += 4;
+ return aColor;
+ }
+
+ virtual void writePixel(Color nColor) override
+ {
+ *pData++ = nColor.GetAlpha();
+ *pData++ = nColor.GetRed();
+ *pData++ = nColor.GetGreen();
+ *pData++ = nColor.GetBlue();
+ }
+};
+
+class ScanlineTransformer_BGR final : public ScanlineTransformer
+{
+private:
+ sal_uInt8* pData;
+
+public:
+ virtual void startLine(sal_uInt8* pLine) override { pData = pLine; }
+
+ virtual void skipPixel(sal_uInt32 nPixel) override { pData += (nPixel << 1) + nPixel; }
+
+ virtual Color readPixel() override
+ {
+ const Color aColor(pData[2], pData[1], pData[0]);
+ pData += 3;
+ return aColor;
+ }
+
+ virtual void writePixel(Color nColor) override
+ {
+ *pData++ = nColor.GetBlue();
+ *pData++ = nColor.GetGreen();
+ *pData++ = nColor.GetRed();
+ }
+};
+
+class ScanlineTransformer_8BitPalette final : public ScanlineTransformer
+{
+private:
+ sal_uInt8* pData;
+ const BitmapPalette& mrPalette;
+
+public:
+ explicit ScanlineTransformer_8BitPalette(const BitmapPalette& rPalette)
+ : pData(nullptr)
+ , mrPalette(rPalette)
+ {
+ }
+
+ virtual void startLine(sal_uInt8* pLine) override { pData = pLine; }
+
+ virtual void skipPixel(sal_uInt32 nPixel) override { pData += nPixel; }
+
+ virtual Color readPixel() override
+ {
+ const sal_uInt8 nIndex(*pData++);
+ if (nIndex < mrPalette.GetEntryCount())
+ return mrPalette[nIndex];
+ else
+ return COL_BLACK;
+ }
+
+ virtual void writePixel(Color nColor) override
+ {
+ *pData++ = static_cast<sal_uInt8>(mrPalette.GetBestIndex(nColor));
+ }
+};
+
+class ScanlineTransformer_4BitPalette final : public ScanlineTransformer
+{
+private:
+ sal_uInt8* pData;
+ const BitmapPalette& mrPalette;
+ sal_uInt32 mnX;
+ sal_uInt32 mnShift;
+
+public:
+ explicit ScanlineTransformer_4BitPalette(const BitmapPalette& rPalette)
+ : pData(nullptr)
+ , mrPalette(rPalette)
+ , mnX(0)
+ , mnShift(0)
+ {
+ }
+
+ virtual void skipPixel(sal_uInt32 nPixel) override
+ {
+ mnX += nPixel;
+ if (nPixel & 1) // is nPixel an odd number
+ mnShift ^= 4;
+ }
+
+ virtual void startLine(sal_uInt8* pLine) override
+ {
+ pData = pLine;
+ mnX = 0;
+ mnShift = 4;
+ }
+
+ virtual Color readPixel() override
+ {
+ const sal_uInt32 nDataIndex = mnX / 2;
+ const sal_uInt8 nIndex((pData[nDataIndex] >> mnShift) & 0x0f);
+ mnX++;
+ mnShift ^= 4;
+
+ if (nIndex < mrPalette.GetEntryCount())
+ return mrPalette[nIndex];
+ else
+ return COL_BLACK;
+ }
+
+ virtual void writePixel(Color nColor) override
+ {
+ const sal_uInt32 nDataIndex = mnX / 2;
+ const sal_uInt8 nColorIndex = mrPalette.GetBestIndex(nColor);
+ pData[nDataIndex] |= (nColorIndex & 0x0f) << mnShift;
+ mnX++;
+ mnShift ^= 4;
+ }
+};
+
+class ScanlineTransformer_1BitPalette final : public ScanlineTransformer
+{
+private:
+ sal_uInt8* pData;
+ const BitmapPalette& mrPalette;
+ sal_uInt32 mnX;
+
+public:
+ explicit ScanlineTransformer_1BitPalette(const BitmapPalette& rPalette)
+ : pData(nullptr)
+ , mrPalette(rPalette)
+ , mnX(0)
+ {
+ }
+
+ virtual void skipPixel(sal_uInt32 nPixel) override { mnX += nPixel; }
+
+ virtual void startLine(sal_uInt8* pLine) override
+ {
+ pData = pLine;
+ mnX = 0;
+ }
+
+ virtual Color readPixel() override
+ {
+ const sal_uInt8 nIndex((pData[mnX >> 3] >> (7 - (mnX & 7))) & 1);
+ mnX++;
+
+ if (nIndex < mrPalette.GetEntryCount())
+ return mrPalette[nIndex];
+ else
+ return COL_BLACK;
+ }
+
+ virtual void writePixel(Color nColor) override
+ {
+ if (mrPalette.GetBestIndex(nColor) & 1)
+ pData[mnX >> 3] |= 1 << (7 - (mnX & 7));
+ else
+ pData[mnX >> 3] &= ~(1 << (7 - (mnX & 7)));
+ mnX++;
+ }
+};
+
+std::unique_ptr<ScanlineTransformer> getScanlineTransformer(sal_uInt16 nBits,
+ const BitmapPalette& rPalette)
+{
+ switch (nBits)
+ {
+ case 1:
+ return std::make_unique<ScanlineTransformer_1BitPalette>(rPalette);
+ case 4:
+ return std::make_unique<ScanlineTransformer_4BitPalette>(rPalette);
+ case 8:
+ return std::make_unique<ScanlineTransformer_8BitPalette>(rPalette);
+ case 24:
+ return std::make_unique<ScanlineTransformer_BGR>();
+ case 32:
+ return std::make_unique<ScanlineTransformer_ARGB>();
+ default:
+ assert(false);
+ break;
+ }
+ return nullptr;
+}
+}
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */