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Diffstat (limited to 'src/concurrent/qtconcurrentmedian.h')
-rw-r--r-- | src/concurrent/qtconcurrentmedian.h | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/src/concurrent/qtconcurrentmedian.h b/src/concurrent/qtconcurrentmedian.h new file mode 100644 index 0000000000..78fc3d97c8 --- /dev/null +++ b/src/concurrent/qtconcurrentmedian.h @@ -0,0 +1,129 @@ +/**************************************************************************** +** +** 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 <QtCore/qglobal.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 |