mirror of https://github.com/qt/qtbase.git
745 lines
24 KiB
C++
745 lines
24 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2016 The Qt Company Ltd.
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** Copyright (C) 2016 Intel Corporation.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "qtimer.h"
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#include "qabstracteventdispatcher.h"
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#include "qcoreapplication.h"
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#include "qobject_p.h"
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#include "qthread.h"
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#include "qcoreapplication_p.h"
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QT_BEGIN_NAMESPACE
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/*!
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\class QTimer
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\inmodule QtCore
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\brief The QTimer class provides repetitive and single-shot timers.
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\ingroup events
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The QTimer class provides a high-level programming interface for
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timers. To use it, create a QTimer, connect its timeout() signal
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to the appropriate slots, and call start(). From then on, it will
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emit the timeout() signal at constant intervals.
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Example for a one second (1000 millisecond) timer (from the
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\l{widgets/analogclock}{Analog Clock} example):
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\snippet ../widgets/widgets/analogclock/analogclock.cpp 4
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\snippet ../widgets/widgets/analogclock/analogclock.cpp 5
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\snippet ../widgets/widgets/analogclock/analogclock.cpp 6
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From then on, the \c update() slot is called every second.
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You can set a timer to time out only once by calling
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setSingleShot(true). You can also use the static
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QTimer::singleShot() function to call a slot after a specified
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interval:
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\snippet timers/timers.cpp 3
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In multithreaded applications, you can use QTimer in any thread
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that has an event loop. To start an event loop from a non-GUI
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thread, use QThread::exec(). Qt uses the timer's
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\l{QObject::thread()}{thread affinity} to determine which thread
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will emit the \l{QTimer::}{timeout()} signal. Because of this, you
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must start and stop the timer in its thread; it is not possible to
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start a timer from another thread.
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As a special case, a QTimer with a timeout of 0 will time out as soon as
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possible, though the ordering between zero timers and other sources of
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events is unspecified. Zero timers can be used to do some work while still
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providing a snappy user interface:
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\snippet timers/timers.cpp 4
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\snippet timers/timers.cpp 5
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\snippet timers/timers.cpp 6
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From then on, \c processOneThing() will be called repeatedly. It
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should be written in such a way that it always returns quickly
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(typically after processing one data item) so that Qt can deliver
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events to the user interface and stop the timer as soon as it has done all
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its work. This is the traditional way of implementing heavy work
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in GUI applications, but as multithreading is nowadays becoming available on
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more and more platforms, we expect that zero-millisecond
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QTimer objects will gradually be replaced by \l{QThread}s.
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\section1 Accuracy and Timer Resolution
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The accuracy of timers depends on the underlying operating system
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and hardware. Most platforms support a resolution of 1 millisecond,
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though the accuracy of the timer will not equal this resolution
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in many real-world situations.
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The accuracy also depends on the \l{Qt::TimerType}{timer type}. For
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Qt::PreciseTimer, QTimer will try to keep the accuracy at 1 millisecond.
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Precise timers will also never time out earlier than expected.
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For Qt::CoarseTimer and Qt::VeryCoarseTimer types, QTimer may wake up
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earlier than expected, within the margins for those types: 5% of the
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interval for Qt::CoarseTimer and 500 ms for Qt::VeryCoarseTimer.
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All timer types may time out later than expected if the system is busy or
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unable to provide the requested accuracy. In such a case of timeout
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overrun, Qt will emit timeout() only once, even if multiple timeouts have
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expired, and then will resume the original interval.
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\section1 Alternatives to QTimer
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An alternative to using QTimer is to call QObject::startTimer()
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for your object and reimplement the QObject::timerEvent() event
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handler in your class (which must inherit QObject). The
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disadvantage is that timerEvent() does not support such
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high-level features as single-shot timers or signals.
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Another alternative is QBasicTimer. It is typically less
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cumbersome than using QObject::startTimer()
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directly. See \l{Timers} for an overview of all three approaches.
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Some operating systems limit the number of timers that may be
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used; Qt tries to work around these limitations.
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\sa QBasicTimer, QTimerEvent, QObject::timerEvent(), Timers,
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{Analog Clock Example}, {Wiggly Example}
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*/
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static const int INV_TIMER = -1; // invalid timer id
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/*!
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Constructs a timer with the given \a parent.
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*/
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QTimer::QTimer(QObject *parent)
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: QObject(parent), id(INV_TIMER), inter(0), del(0), single(0), nulltimer(0), type(Qt::CoarseTimer)
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{
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Q_UNUSED(del); // ### Qt 6: remove field
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}
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/*!
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Destroys the timer.
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*/
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QTimer::~QTimer()
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{
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if (id != INV_TIMER) // stop running timer
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stop();
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}
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/*!
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\fn void QTimer::timeout()
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This signal is emitted when the timer times out.
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\sa interval, start(), stop()
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*/
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/*!
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\property QTimer::active
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\since 4.3
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This boolean property is \c true if the timer is running; otherwise
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false.
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*/
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/*!
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\fn bool QTimer::isActive() const
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Returns \c true if the timer is running (pending); otherwise returns
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false.
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*/
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/*!
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\fn int QTimer::timerId() const
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Returns the ID of the timer if the timer is running; otherwise returns
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-1.
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*/
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/*! \overload start()
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Starts or restarts the timer with the timeout specified in \l interval.
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If the timer is already running, it will be
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\l{QTimer::stop()}{stopped} and restarted.
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If \l singleShot is true, the timer will be activated only once.
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*/
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void QTimer::start()
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{
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if (id != INV_TIMER) // stop running timer
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stop();
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nulltimer = (!inter && single);
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id = QObject::startTimer(inter, Qt::TimerType(type));
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}
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/*!
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Starts or restarts the timer with a timeout interval of \a msec
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milliseconds.
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If the timer is already running, it will be
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\l{QTimer::stop()}{stopped} and restarted.
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If \l singleShot is true, the timer will be activated only once.
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*/
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void QTimer::start(int msec)
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{
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inter = msec;
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start();
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}
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/*!
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Stops the timer.
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\sa start()
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*/
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void QTimer::stop()
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{
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if (id != INV_TIMER) {
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QObject::killTimer(id);
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id = INV_TIMER;
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}
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}
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/*!
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\reimp
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*/
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void QTimer::timerEvent(QTimerEvent *e)
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{
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if (e->timerId() == id) {
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if (single)
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stop();
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emit timeout(QPrivateSignal());
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}
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}
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class QSingleShotTimer : public QObject
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{
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Q_OBJECT
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int timerId;
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bool hasValidReceiver;
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QPointer<const QObject> receiver;
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QtPrivate::QSlotObjectBase *slotObj;
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public:
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~QSingleShotTimer();
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QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, const char * m);
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QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, QtPrivate::QSlotObjectBase *slotObj);
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Q_SIGNALS:
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void timeout();
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protected:
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void timerEvent(QTimerEvent *) override;
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};
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QSingleShotTimer::QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, const char *member)
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: QObject(QAbstractEventDispatcher::instance()), hasValidReceiver(true), slotObj(nullptr)
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{
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timerId = startTimer(msec, timerType);
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connect(this, SIGNAL(timeout()), r, member);
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}
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QSingleShotTimer::QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, QtPrivate::QSlotObjectBase *slotObj)
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: QObject(QAbstractEventDispatcher::instance()), hasValidReceiver(r), receiver(r), slotObj(slotObj)
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{
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timerId = startTimer(msec, timerType);
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if (r && thread() != r->thread()) {
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// Avoid leaking the QSingleShotTimer instance in case the application exits before the timer fires
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connect(QCoreApplication::instance(), &QCoreApplication::aboutToQuit, this, &QObject::deleteLater);
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setParent(nullptr);
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moveToThread(r->thread());
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}
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}
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QSingleShotTimer::~QSingleShotTimer()
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{
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if (timerId > 0)
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killTimer(timerId);
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if (slotObj)
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slotObj->destroyIfLastRef();
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}
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void QSingleShotTimer::timerEvent(QTimerEvent *)
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{
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// need to kill the timer _before_ we emit timeout() in case the
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// slot connected to timeout calls processEvents()
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if (timerId > 0)
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killTimer(timerId);
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timerId = -1;
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if (slotObj) {
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// If the receiver was destroyed, skip this part
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if (Q_LIKELY(!receiver.isNull() || !hasValidReceiver)) {
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// We allocate only the return type - we previously checked the function had
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// no arguments.
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void *args[1] = { nullptr };
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slotObj->call(const_cast<QObject*>(receiver.data()), args);
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}
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} else {
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emit timeout();
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}
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// we would like to use delete later here, but it feels like a
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// waste to post a new event to handle this event, so we just unset the flag
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// and explicitly delete...
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qDeleteInEventHandler(this);
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}
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/*!
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\internal
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Implementation of the template version of singleShot
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\a msec is the timer interval
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\a timerType is the timer type
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\a receiver is the receiver object, can be null. In such a case, it will be the same
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as the final sender class.
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\a slot a pointer only used when using Qt::UniqueConnection
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\a slotObj the slot object
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*/
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void QTimer::singleShotImpl(int msec, Qt::TimerType timerType,
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const QObject *receiver,
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QtPrivate::QSlotObjectBase *slotObj)
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{
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if (msec == 0) {
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bool deleteReceiver = false;
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// Optimize: set a receiver context when none is given, such that we can use
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// QMetaObject::invokeMethod which is more efficient than going through a timer.
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// We need a QObject living in the current thread. But the QThread itself lives
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// in a different thread - with the exception of the main QThread which lives in
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// itself. And QThread::currentThread() is among the few QObjects we know that will
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// most certainly be there. Note that one can actually call singleShot before the
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// QApplication is created!
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if (!receiver && QThread::currentThread() == QCoreApplicationPrivate::mainThread()) {
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// reuse main thread as context object
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receiver = QThread::currentThread();
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} else if (!receiver) {
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// Create a receiver context object on-demand. According to the benchmarks,
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// this is still more efficient than going through a timer.
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receiver = new QObject;
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deleteReceiver = true;
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}
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QMetaObject::invokeMethodImpl(const_cast<QObject *>(receiver), slotObj,
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Qt::QueuedConnection, nullptr);
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if (deleteReceiver)
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const_cast<QObject *>(receiver)->deleteLater();
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return;
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}
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new QSingleShotTimer(msec, timerType, receiver, slotObj);
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}
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/*!
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\reentrant
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This static function calls a slot after a given time interval.
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It is very convenient to use this function because you do not need
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to bother with a \l{QObject::timerEvent()}{timerEvent} or
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create a local QTimer object.
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Example:
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\snippet code/src_corelib_kernel_qtimer.cpp 0
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This sample program automatically terminates after 10 minutes
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(600,000 milliseconds).
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The \a receiver is the receiving object and the \a member is the
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slot. The time interval is \a msec milliseconds.
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\sa start()
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*/
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void QTimer::singleShot(int msec, const QObject *receiver, const char *member)
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{
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// coarse timers are worst in their first firing
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// so we prefer a high precision timer for something that happens only once
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// unless the timeout is too big, in which case we go for coarse anyway
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singleShot(msec, msec >= 2000 ? Qt::CoarseTimer : Qt::PreciseTimer, receiver, member);
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}
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/*! \overload
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\reentrant
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This static function calls a slot after a given time interval.
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It is very convenient to use this function because you do not need
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to bother with a \l{QObject::timerEvent()}{timerEvent} or
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create a local QTimer object.
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The \a receiver is the receiving object and the \a member is the slot. The
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time interval is \a msec milliseconds. The \a timerType affects the
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accuracy of the timer.
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\sa start()
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*/
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void QTimer::singleShot(int msec, Qt::TimerType timerType, const QObject *receiver, const char *member)
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{
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if (Q_UNLIKELY(msec < 0)) {
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qWarning("QTimer::singleShot: Timers cannot have negative timeouts");
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return;
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}
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if (receiver && member) {
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if (msec == 0) {
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// special code shortpath for 0-timers
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const char* bracketPosition = strchr(member, '(');
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if (!bracketPosition || !(member[0] >= '0' && member[0] <= '2')) {
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qWarning("QTimer::singleShot: Invalid slot specification");
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return;
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}
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QByteArray methodName(member+1, bracketPosition - 1 - member); // extract method name
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QMetaObject::invokeMethod(const_cast<QObject *>(receiver), methodName.constData(), Qt::QueuedConnection);
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return;
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}
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(void) new QSingleShotTimer(msec, timerType, receiver, member);
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}
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}
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/*! \fn template<typename PointerToMemberFunction> void QTimer::singleShot(int msec, const QObject *receiver, PointerToMemberFunction method)
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\since 5.4
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\overload
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\reentrant
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This static function calls a member function of a QObject after a given time interval.
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It is very convenient to use this function because you do not need
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to bother with a \l{QObject::timerEvent()}{timerEvent} or
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create a local QTimer object.
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The \a receiver is the receiving object and the \a method is the member function. The
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time interval is \a msec milliseconds.
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If \a receiver is destroyed before the interval occurs, the method will not be called.
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The function will be run in the thread of \a receiver. The receiver's thread must have
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a running Qt event loop.
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\sa start()
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*/
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/*! \fn template<typename PointerToMemberFunction> void QTimer::singleShot(int msec, Qt::TimerType timerType, const QObject *receiver, PointerToMemberFunction method)
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\since 5.4
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\overload
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\reentrant
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This static function calls a member function of a QObject after a given time interval.
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It is very convenient to use this function because you do not need
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to bother with a \l{QObject::timerEvent()}{timerEvent} or
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create a local QTimer object.
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The \a receiver is the receiving object and the \a method is the member function. The
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time interval is \a msec milliseconds. The \a timerType affects the
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accuracy of the timer.
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If \a receiver is destroyed before the interval occurs, the method will not be called.
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The function will be run in the thread of \a receiver. The receiver's thread must have
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a running Qt event loop.
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\sa start()
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*/
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/*! \fn template<typename Functor> void QTimer::singleShot(int msec, Functor functor)
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\since 5.4
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\overload
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\reentrant
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This static function calls \a functor after a given time interval.
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It is very convenient to use this function because you do not need
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to bother with a \l{QObject::timerEvent()}{timerEvent} or
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create a local QTimer object.
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The time interval is \a msec milliseconds.
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\sa start()
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*/
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/*! \fn template<typename Functor> void QTimer::singleShot(int msec, Qt::TimerType timerType, Functor functor)
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\since 5.4
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\overload
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\reentrant
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This static function calls \a functor after a given time interval.
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It is very convenient to use this function because you do not need
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to bother with a \l{QObject::timerEvent()}{timerEvent} or
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create a local QTimer object.
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The time interval is \a msec milliseconds. The \a timerType affects the
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accuracy of the timer.
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\sa start()
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*/
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/*! \fn template<typename Functor> void QTimer::singleShot(int msec, const QObject *context, Functor functor)
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\since 5.4
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\overload
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\reentrant
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This static function calls \a functor after a given time interval.
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|
|
|
It is very convenient to use this function because you do not need
|
|
to bother with a \l{QObject::timerEvent()}{timerEvent} or
|
|
create a local QTimer object.
|
|
|
|
The time interval is \a msec milliseconds.
|
|
|
|
If \a context is destroyed before the interval occurs, the method will not be called.
|
|
The function will be run in the thread of \a context. The context's thread must have
|
|
a running Qt event loop.
|
|
|
|
\sa start()
|
|
*/
|
|
|
|
/*! \fn template<typename Functor> void QTimer::singleShot(int msec, Qt::TimerType timerType, const QObject *context, Functor functor)
|
|
|
|
\since 5.4
|
|
|
|
\overload
|
|
\reentrant
|
|
This static function calls \a functor after a given time interval.
|
|
|
|
It is very convenient to use this function because you do not need
|
|
to bother with a \l{QObject::timerEvent()}{timerEvent} or
|
|
create a local QTimer object.
|
|
|
|
The time interval is \a msec milliseconds. The \a timerType affects the
|
|
accuracy of the timer.
|
|
|
|
If \a context is destroyed before the interval occurs, the method will not be called.
|
|
The function will be run in the thread of \a context. The context's thread must have
|
|
a running Qt event loop.
|
|
|
|
\sa start()
|
|
*/
|
|
|
|
/*!
|
|
\fn void QTimer::singleShot(std::chrono::milliseconds msec, const QObject *receiver, const char *member)
|
|
\since 5.8
|
|
\overload
|
|
\reentrant
|
|
|
|
This static function calls a slot after a given time interval.
|
|
|
|
It is very convenient to use this function because you do not need
|
|
to bother with a \l{QObject::timerEvent()}{timerEvent} or
|
|
create a local QTimer object.
|
|
|
|
The \a receiver is the receiving object and the \a member is the slot. The
|
|
time interval is given in the duration object \a msec.
|
|
|
|
\sa start()
|
|
*/
|
|
|
|
/*!
|
|
\fn void QTimer::singleShot(std::chrono::milliseconds msec, Qt::TimerType timerType, const QObject *receiver, const char *member)
|
|
\since 5.8
|
|
\overload
|
|
\reentrant
|
|
|
|
This static function calls a slot after a given time interval.
|
|
|
|
It is very convenient to use this function because you do not need
|
|
to bother with a \l{QObject::timerEvent()}{timerEvent} or
|
|
create a local QTimer object.
|
|
|
|
The \a receiver is the receiving object and the \a member is the slot. The
|
|
time interval is given in the duration object \a msec. The \a timerType affects the
|
|
accuracy of the timer.
|
|
|
|
\sa start()
|
|
*/
|
|
|
|
/*!
|
|
\fn template <typename Functor> QMetaObject::Connection QTimer::callOnTimeout(Functor slot, Qt::ConnectionType connectionType = Qt::AutoConnection)
|
|
\since 5.12
|
|
\overload
|
|
|
|
Creates a connection of type \a connectionType from the timeout() signal
|
|
to \a slot, and returns a handle to the connection.
|
|
|
|
This method is provided for convenience.
|
|
It's equivalent to calling \c {QObject::connect(timer, &QTimer::timeout, timer, slot, connectionType)}.
|
|
|
|
\sa QObject::connect(), timeout()
|
|
*/
|
|
|
|
/*!
|
|
\fn template <typename Functor> QMetaObject::Connection QTimer::callOnTimeout(const QObject *context, Functor slot, Qt::ConnectionType connectionType = Qt::AutoConnection)
|
|
\since 5.12
|
|
\overload callOnTimeout()
|
|
|
|
Creates a connection from the timeout() signal to \a slot to be placed in a specific
|
|
event loop of \a context, and returns a handle to the connection.
|
|
|
|
This method is provided for convenience. It's equivalent to calling
|
|
\c {QObject::connect(timer, &QTimer::timeout, context, slot, connectionType)}.
|
|
|
|
\sa QObject::connect(), timeout()
|
|
*/
|
|
|
|
/*!
|
|
\fn template <typename MemberFunction> QMetaObject::Connection QTimer::callOnTimeout(const QObject *receiver, MemberFunction *slot, Qt::ConnectionType connectionType = Qt::AutoConnection)
|
|
\since 5.12
|
|
\overload callOnTimeout()
|
|
|
|
Creates a connection from the timeout() signal to the \a slot in the \a receiver object. Returns
|
|
a handle to the connection.
|
|
|
|
This method is provided for convenience. It's equivalent to calling
|
|
\c {QObject::connect(timer, &QTimer::timeout, receiver, slot, connectionType)}.
|
|
|
|
\sa QObject::connect(), timeout()
|
|
*/
|
|
|
|
/*!
|
|
\fn void QTimer::start(std::chrono::milliseconds msec)
|
|
\since 5.8
|
|
\overload
|
|
|
|
Starts or restarts the timer with a timeout of duration \a msec milliseconds.
|
|
|
|
If the timer is already running, it will be
|
|
\l{QTimer::stop()}{stopped} and restarted.
|
|
|
|
If \l singleShot is true, the timer will be activated only once.
|
|
*/
|
|
|
|
/*!
|
|
\fn std::chrono::milliseconds QTimer::intervalAsDuration() const
|
|
\since 5.8
|
|
|
|
Returns the interval of this timer as a \c std::chrono::milliseconds object.
|
|
|
|
\sa interval
|
|
*/
|
|
|
|
/*!
|
|
\fn std::chrono::milliseconds QTimer::remainingTimeAsDuration() const
|
|
\since 5.8
|
|
|
|
Returns the time remaining in this timer object as a \c
|
|
std::chrono::milliseconds object. If this timer is due or overdue, the
|
|
returned value is \c std::chrono::milliseconds::zero(). If the remaining
|
|
time could not be found or the timer is not active, this function returns a
|
|
negative duration.
|
|
|
|
\sa remainingTime()
|
|
*/
|
|
|
|
/*!
|
|
\property QTimer::singleShot
|
|
\brief whether the timer is a single-shot timer
|
|
|
|
A single-shot timer fires only once, non-single-shot timers fire
|
|
every \l interval milliseconds.
|
|
|
|
The default value for this property is \c false.
|
|
|
|
\sa interval, singleShot()
|
|
*/
|
|
|
|
/*!
|
|
\property QTimer::interval
|
|
\brief the timeout interval in milliseconds
|
|
|
|
The default value for this property is 0. A QTimer with a timeout
|
|
interval of 0 will time out as soon as all the events in the window
|
|
system's event queue have been processed.
|
|
|
|
Setting the interval of an active timer changes its timerId().
|
|
|
|
\sa singleShot
|
|
*/
|
|
void QTimer::setInterval(int msec)
|
|
{
|
|
inter = msec;
|
|
if (id != INV_TIMER) { // create new timer
|
|
QObject::killTimer(id); // restart timer
|
|
id = QObject::startTimer(msec, Qt::TimerType(type));
|
|
}
|
|
}
|
|
|
|
/*!
|
|
\property QTimer::remainingTime
|
|
\since 5.0
|
|
\brief the remaining time in milliseconds
|
|
|
|
Returns the timer's remaining value in milliseconds left until the timeout.
|
|
If the timer is inactive, the returned value will be -1. If the timer is
|
|
overdue, the returned value will be 0.
|
|
|
|
\sa interval
|
|
*/
|
|
int QTimer::remainingTime() const
|
|
{
|
|
if (id != INV_TIMER) {
|
|
return QAbstractEventDispatcher::instance()->remainingTime(id);
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
/*!
|
|
\property QTimer::timerType
|
|
\brief controls the accuracy of the timer
|
|
|
|
The default value for this property is \c Qt::CoarseTimer.
|
|
|
|
\sa Qt::TimerType
|
|
*/
|
|
|
|
QT_END_NAMESPACE
|
|
|
|
#include "qtimer.moc"
|
|
#include "moc_qtimer.cpp"
|