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/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QTCONCURRENT_MEDIAN_H
#define QTCONCURRENT_MEDIAN_H
#include <QtConcurrent/qtconcurrent_global.h>
#ifndef QT_NO_CONCURRENT
#include <QtCore/qvector.h>
#include <QtCore/qalgorithms.h>
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
#ifndef qdoc
namespace QtConcurrent {
template <typename T>
class Median
{
public:
Median(int _bufferSize)
: currentMedian(), bufferSize(_bufferSize), currentIndex(0), valid(false), dirty(true)
{
values.resize(bufferSize);
}
void reset()
{
values.fill(0);
currentIndex = 0;
valid = false;
dirty = true;
}
void addValue(T value)
{
currentIndex = ((currentIndex + 1) % bufferSize);
if (valid == false && currentIndex % bufferSize == 0)
valid = true;
// Only update the cached median value when we have to, that
// is when the new value is on then other side of the median
// compared to the current value at the index.
const T currentIndexValue = values[currentIndex];
if ((currentIndexValue > currentMedian && currentMedian > value)
|| (currentMedian > currentIndexValue && value > currentMedian)) {
dirty = true;
}
values[currentIndex] = value;
}
bool isMedianValid() const
{
return valid;
}
T median()
{
if (dirty) {
dirty = false;
QVector<T> sorted = values;
qSort(sorted);
currentMedian = sorted.at(bufferSize / 2 + 1);
}
return currentMedian;
}
private:
QVector<T> values;
T currentMedian;
int bufferSize;
int currentIndex;
bool valid;
bool dirty;
};
} // namespace QtConcurrent
#endif //qdoc
QT_END_NAMESPACE
QT_END_HEADER
#endif // QT_NO_CONCURRENT
#endif
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