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/*
* Copyright (C) 2008-2009 Torch Mobile, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#if ENABLE(IMAGE_DECODER_DOWN_SAMPLING)
#include "config.h"
#include "ImageDecoder.h"
#include <algorithm>
namespace WebCore {
namespace {
enum MatchType {
Exact,
UpperBound,
LowerBound
};
}
template <MatchType type> static int getScaledValue(const Vector<int>& scaledValues, int valueToMatch, int searchStart)
{
const int* dataStart = scaledValues.data();
const int* dataEnd = dataStart + scaledValues.size();
const int* matched = std::lower_bound(dataStart + searchStart, dataEnd, valueToMatch);
switch (type) {
case Exact:
return matched != dataEnd && *matched == valueToMatch ? matched - dataStart : -1;
case LowerBound:
return matched != dataEnd && *matched == valueToMatch ? matched - dataStart : matched - dataStart - 1;
case UpperBound:
default:
return matched != dataEnd ? matched - dataStart : -1;
}
}
int ImageDecoder::upperBoundScaledX(int origX, int searchStart)
{
return getScaledValue<UpperBound>(m_scaledColumns, origX, searchStart);
}
int ImageDecoder::lowerBoundScaledX(int origX, int searchStart)
{
return getScaledValue<LowerBound>(m_scaledColumns, origX, searchStart);
}
int ImageDecoder::scaledY(int origY, int searchStart)
{
return getScaledValue<Exact>(m_scaledRows, origY, searchStart);
}
static inline void fillScaledValues(Vector<int>& scaledValues, double scaleRate, int length)
{
double inflateRate = 1. / scaleRate;
scaledValues.reserveCapacity(static_cast<int>(length * scaleRate + 0.5));
for (int scaledIndex = 0;;) {
int index = static_cast<int>(scaledIndex * inflateRate + 0.5);
if (index < length) {
scaledValues.append(index);
++scaledIndex;
} else
break;
}
}
void ImageDecoder::prepareScaleDataIfNecessary()
{
int width = m_size.width();
int height = m_size.height();
int numPixels = height * width;
if (m_maxNumPixels <= 0 || numPixels <= m_maxNumPixels) {
m_scaled = false;
return;
}
m_scaled = true;
double scale = sqrt(m_maxNumPixels / (double)numPixels);
fillScaledValues(m_scaledColumns, scale, width);
fillScaledValues(m_scaledRows, scale, height);
}
}
#endif // ENABLE(IMAGE_DECODER_DOWN_SAMPLING)
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