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/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, 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.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qelapsedtimer.h"
#include "qdatetime.h"
QT_BEGIN_NAMESPACE
/*!
Returns the clock type that this QElapsedTimer implementation uses.
\sa isMonotonic()
*/
QElapsedTimer::ClockType QElapsedTimer::clockType()
{
return SystemTime;
}
/*!
Returns true if this is a monotonic clock, false otherwise. See the
information on the different clock types to understand which ones are
monotonic.
\sa clockType(), QElapsedTimer::ClockType
*/
bool QElapsedTimer::isMonotonic()
{
return false;
}
/*!
Starts this timer. Once started, a timer value can be checked with elapsed() or msecsSinceReference().
Normally, a timer is started just before a lengthy operation, such as:
\snippet doc/src/snippets/qelapsedtimer/main.cpp 0
Also, starting a timer makes it valid again.
\sa restart(), invalidate(), elapsed()
*/
void QElapsedTimer::start()
{
restart();
}
/*!
Restarts the timer and returns the time elapsed since the previous start.
This function is equivalent to obtaining the elapsed time with elapsed()
and then starting the timer again with restart(), but it does so in one
single operation, avoiding the need to obtain the clock value twice.
The following example illustrates how to use this function to calibrate a
parameter to a slow operation (for example, an iteration count) so that
this operation takes at least 250 milliseconds:
\snippet doc/src/snippets/qelapsedtimer/main.cpp 3
\sa start(), invalidate(), elapsed()
*/
qint64 QElapsedTimer::restart()
{
qint64 old = t1;
t1 = QDateTime::currentMSecsSinceEpoch();
t2 = 0;
return t1 - old;
}
/*!
Returns the number of milliseconds since this QElapsedTimer was last
started. Calling this function in a QElapsedTimer that was invalidated
will result in undefined results.
\sa start(), restart(), hasExpired(), invalidate()
*/
qint64 QElapsedTimer::elapsed() const
{
return QDateTime::currentMSecsSinceEpoch() - t1;
}
/*!
Returns the number of milliseconds between last time this QElapsedTimer
object was started and its reference clock's start.
This number is usually arbitrary for all clocks except the
QElapsedTimer::SystemTime clock. For that clock type, this number is the
number of milliseconds since January 1st, 1970 at 0:00 UTC (that is, it
is the Unix time expressed in milliseconds).
\sa clockType(), elapsed()
*/
qint64 QElapsedTimer::msecsSinceReference() const
{
return t1;
}
/*!
Returns the number of milliseconds between this QElapsedTimer and \a
other. If \a other was started before this object, the returned value
will be positive. If it was started later, the returned value will be
negative.
The return value is undefined if this object or \a other were invalidated.
\sa secsTo(), elapsed()
*/
qint64 QElapsedTimer::msecsTo(const QElapsedTimer &other) const
{
qint64 diff = other.t1 - t1;
return diff;
}
/*!
Returns the number of seconds between this QElapsedTimer and \a other. If
\a other was started before this object, the returned value will be
positive. If it was started later, the returned value will be negative.
The return value is undefined if this object or \a other were invalidated.
\sa msecsTo(), elapsed()
*/
qint64 QElapsedTimer::secsTo(const QElapsedTimer &other) const
{
return msecsTo(other) / 1000;
}
/*!
\relates QElapsedTimer
Returns true if \a v1 was started before \a v2, false otherwise.
The returned value is undefined if one of the two parameters is invalid
and the other isn't. However, two invalid timers are equal and thus this
function will return false.
*/
bool operator<(const QElapsedTimer &v1, const QElapsedTimer &v2)
{
return v1.t1 < v2.t1;
}
QT_END_NAMESPACE
|
