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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 <vcl/bitmap.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: */
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