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41
42#ifndef QTCONCURRENT_MEDIAN_H
43#define QTCONCURRENT_MEDIAN_H
44
45#include <QtCore/qglobal.h>
46
47#ifndef QT_NO_CONCURRENT
48
49#include <QtCore/qvector.h>
50#include <QtCore/qalgorithms.h>
51
52QT_BEGIN_HEADER
53QT_BEGIN_NAMESPACE
54
55QT_MODULE(Core)
56
57#ifndef qdoc
58
59namespace QtConcurrent {
60
61template <typename T>
62class Median
63{
64public:
65 Median(int _bufferSize)
66 : currentMedian(), bufferSize(_bufferSize), currentIndex(0), valid(false), dirty(true)
67 {
68 values.resize(bufferSize);
69 }
70
71 void reset()
72 {
73 values.fill(0);
74 currentIndex = 0;
75 valid = false;
76 dirty = true;
77 }
78
79 void addValue(T value)
80 {
81 currentIndex = ((currentIndex + 1) % bufferSize);
82 if (valid == false && currentIndex % bufferSize == 0)
83 valid = true;
84
85 // Only update the cached median value when we have to, that
86 // is when the new value is on then other side of the median
87 // compared to the current value at the index.
88 const T currentIndexValue = values[currentIndex];
89 if ((currentIndexValue > currentMedian && currentMedian > value)
90 || (currentMedian > currentIndexValue && value > currentMedian)) {
91 dirty = true;
92 }
93
94 values[currentIndex] = value;
95 }
96
97 bool isMedianValid() const
98 {
99 return valid;
100 }
101
102 T median()
103 {
104 if (dirty) {
105 dirty = false;
106 QVector<T> sorted = values;
107 qSort(sorted);
108 currentMedian = sorted.at(bufferSize / 2 + 1);
109 }
110 return currentMedian;
111 }
112private:
113 QVector<T> values;
114 T currentMedian;
115 int bufferSize;
116 int currentIndex;
117 bool valid;
118 bool dirty;
119};
120
121} // namespace QtConcurrent
122
123#endif //qdoc
124
125QT_END_NAMESPACE
126QT_END_HEADER
127
128#endif // QT_NO_CONCURRENT
129
130#endif
131