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//
// libavg - Media Playback Engine.
// Copyright (C) 2003-2014 Ulrich von Zadow
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
// Current versions can be found at www.libavg.de
//
#include "FilterUnmultiplyAlpha.h"
#include "Pixeldefs.h"
#include "../base/Exception.h"
#include "../base/ScopeTimer.h"
namespace avg {
FilterUnmultiplyAlpha::FilterUnmultiplyAlpha()
: Filter()
{
}
FilterUnmultiplyAlpha::~FilterUnmultiplyAlpha()
{
}
static ProfilingZoneID ProfilingZone("FilterUnmultiplyAlpha");
void FilterUnmultiplyAlpha::applyInPlace(BitmapPtr pBmp)
{
ScopeTimer Timer(ProfilingZone);
AVG_ASSERT(pBmp->getBytesPerPixel() == 4);
IntPoint size = pBmp->getSize();
for (int y = 0; y < size.y; y++) {
unsigned char * pPixel = pBmp->getPixels() + y*pBmp->getStride();
for (int x = 0; x < size.x; x++) {
int alpha = *(pPixel+ALPHAPOS);
if (alpha != 0) {
*(pPixel+REDPOS) = (int(*(pPixel+REDPOS))*255)/alpha;
*(pPixel+GREENPOS) = (int(*(pPixel+GREENPOS))*255)/alpha;
*(pPixel+BLUEPOS) = (int(*(pPixel+BLUEPOS))*255)/alpha;
}
pPixel += 4;
}
}
// The color values of transparent pixels are used in bilinear texture
// filtering in certain conditions. To avoid artifacts, we transfer the
// color from a neighboring non-transparent pixel.
for (int y = 1; y < size.y-1; y++) {
int stride = pBmp->getStride();
unsigned char * pPixel = pBmp->getPixels() + y*stride;
for (int x = 1; x < size.x-1; x++) {
int alpha = *(pPixel+ALPHAPOS);
if (alpha == 0) {
unsigned char * pSrcPixel = pPixel;
if (*(pPixel+4+ALPHAPOS) != 0) {
pSrcPixel = pPixel+4;
} else if (*(pPixel+stride+4+ALPHAPOS) != 0) {
pSrcPixel = pPixel+stride+4;
} else if (*(pPixel+stride+ALPHAPOS) != 0) {
pSrcPixel = pPixel+stride;
} else if (*(pPixel+stride-4+ALPHAPOS) != 0) {
pSrcPixel = pPixel+stride-4;
} else if (*(pPixel-4+ALPHAPOS) != 0) {
pSrcPixel = pPixel-4;
} else if (*(pPixel-stride-4+ALPHAPOS) != 0) {
pSrcPixel = pPixel-stride-4;
} else if (*(pPixel-stride+ALPHAPOS) != 0) {
pSrcPixel = pPixel-stride;
} else if (*(pPixel-stride+4+ALPHAPOS) != 0) {
pSrcPixel = pPixel-stride+4;
}
*(pPixel+REDPOS) = *(pSrcPixel+REDPOS);
*(pPixel+GREENPOS) = *(pSrcPixel+GREENPOS);
*(pPixel+BLUEPOS) = *(pSrcPixel+BLUEPOS);
}
pPixel += 4;
}
}
}
}
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