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39
40#include "qtickclock_p.h"
41
42#include <QtCore/QThread>
43
44#include <Qt3DCore/private/corelogging_p.h>
45
46QT_BEGIN_NAMESPACE
47
48namespace Qt3DCore {
49
50QTickClock::QTickClock()
51 : m_tickInterval(1000000000 / 60) // Nanoseconds
52 , m_time(0)
53{
54}
55
56void QTickClock::setTickFrequency(float frequency)
57{
58 Q_ASSERT(frequency > 0.0f);
59 m_tickInterval = static_cast<qint64>(1000000000 / frequency);
60}
61
62void QTickClock::start()
63{
64 m_timer.start();
65 m_time = m_timer.nsecsElapsed();
66 qCDebug(ChangeArbiter) << "tickInterval =" << m_tickInterval << "ns";
67}
68
69void QTickClock::reset()
70{
71 m_time = 0;
72}
73
74qint64 QTickClock::waitForNextTick()
75{
76 qint64 t = m_timer.nsecsElapsed();
77 qint64 dt = t - m_time;
78 qint64 timeToSleep = m_tickInterval - dt;
79
80 // If we are lagging behind don't delay
81 // TODO: Do we want a mode where if we are lagging we instead wait
82 // for the next tick instead?
83 if (timeToSleep < 0) {
84 qCDebug(ChangeArbiter) << "Lagging behind desired tick interval";
85 m_time = t;
86 return m_time;
87 }
88
89 unsigned long sleepTimeMicroSeconds = static_cast<unsigned long>(timeToSleep / 1000);
90 //qCDebug(ChangeArbiter) << "sleeping for" << sleepTimeMicroSeconds << "us";
91 QThread::usleep(sleepTimeMicroSeconds);
92
93#if defined(QT3DCORE_DEBUG_TICKCLOCK)
94 qint64 expectedWakeTime = t + sleepTimeMicroSeconds * 1000;
95 qint64 wakeTime = m_timer.nsecsElapsed();
96 qCDebug(ChangeArbiter) << "t =" << t / 1000000 << "timeToSleep =" << timeToSleep / 1000000
97 << "due to wake at =" << expectedWakeTime / 1000000
98 << "actually woke at" << wakeTime / 1000000
99 << "delta =" << (expectedWakeTime - wakeTime) / 1000000;
100#endif
101
102 m_time = m_timer.nsecsElapsed();
103 return m_time;
104}
105
106} // namespace Qt3DCore
107
108QT_END_NAMESPACE
109

source code of qt3d/src/core/qtickclock.cpp