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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/.
+ *
+ * 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 .
+ */
+
+#ifndef INCLUDED_VCL_INC_SCANLINEWRITER_HXX
+#define INCLUDED_VCL_INC_SCANLINEWRITER_HXX
+
+#include <tools/long.hxx>
+#include <vcl/BitmapPalette.hxx>
+
+namespace vcl
+{
+// Write color information for 1, 4 and 8 bit palette bitmap scanlines.
+class ScanlineWriter
+{
+ BitmapPalette& maPalette;
+ sal_uInt8 const mnColorsPerByte; // number of colors that are stored in one byte
+ sal_uInt8 const mnColorBitSize; // number of bits a color takes
+ sal_uInt8 const mnColorBitMask; // bit mask used to isolate the color
+ sal_uInt8* mpCurrentScanline;
+ tools::Long mnX;
+
+public:
+ ScanlineWriter(BitmapPalette& aPalette, sal_Int8 nColorsPerByte)
+ : maPalette(aPalette)
+ , mnColorsPerByte(nColorsPerByte)
+ , mnColorBitSize(
+ 8
+ / mnColorsPerByte) // bit size is number of bit in a byte divided by number of colors per byte (8 / 2 = 4 for 4-bit)
+ , mnColorBitMask((1 << mnColorBitSize) - 1) // calculate the bit mask from the bit size
+ , mpCurrentScanline(nullptr)
+ , mnX(0)
+ {
+ }
+
+ static std::unique_ptr<ScanlineWriter> Create(sal_uInt16 nBits, BitmapPalette& aPalette)
+ {
+ switch (nBits)
+ {
+ case 1:
+ return std::make_unique<ScanlineWriter>(aPalette, 8);
+ case 4:
+ return std::make_unique<ScanlineWriter>(aPalette, 2);
+ case 8:
+ return std::make_unique<ScanlineWriter>(aPalette, 1);
+ default:
+ abort();
+ }
+ }
+
+ void writeRGB(sal_uInt8 nR, sal_uInt8 nG, sal_uInt8 nB)
+ {
+ // calculate to which index we will write
+ tools::Long nScanlineIndex = mnX / mnColorsPerByte;
+
+ // calculate the number of shifts to get the color information to the right place
+ tools::Long nShift = (8 - mnColorBitSize) - ((mnX % mnColorsPerByte) * mnColorBitSize);
+
+ sal_uInt16 nColorIndex = maPalette.GetBestIndex(BitmapColor(nR, nG, nB));
+ mpCurrentScanline[nScanlineIndex] &= ~(mnColorBitMask << nShift); // clear
+ mpCurrentScanline[nScanlineIndex] |= (nColorIndex & mnColorBitMask) << nShift; // set
+ mnX++;
+ }
+
+ void nextLine(sal_uInt8* pScanline)
+ {
+ mnX = 0;
+ mpCurrentScanline = pScanline;
+ }
+};
+
+} // namespace vcl
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */