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/****************************************************************************
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**
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** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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** All rights reserved.
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** Contact: Nokia Corporation (qt-info@nokia.com)
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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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** No Commercial Usage
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** This file contains pre-release code and may not be distributed.
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** You may use this file in accordance with the terms and conditions
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** contained in the Technology Preview License Agreement accompanying
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** this package.
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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 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL 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 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights. These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** If you have questions regarding the use of this file, please contact
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** Nokia at qt-info@nokia.com.
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**
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**
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**
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**
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**
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**
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "qeventloop.h"
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#include "qabstracteventdispatcher.h"
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#include "qcoreapplication.h"
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#include "qdatetime.h"
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#include "qobject_p.h"
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#include <private/qthread_p.h>
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QT_BEGIN_NAMESPACE
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class QEventLoopPrivate : public QObjectPrivate
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{
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Q_DECLARE_PUBLIC(QEventLoop)
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public:
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inline QEventLoopPrivate()
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: exit(true), inExec(false), returnCode(-1)
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{ }
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bool exit, inExec;
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int returnCode;
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};
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/*!
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\class QEventLoop
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\brief The QEventLoop class provides a means of entering and leaving an event loop.
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At any time, you can create a QEventLoop object and call exec()
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on it to start a local event loop. From within the event loop,
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calling exit() will force exec() to return.
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\sa QAbstractEventDispatcher
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*/
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/*!
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\enum QEventLoop::ProcessEventsFlag
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This enum controls the types of events processed by the
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processEvents() functions.
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\value AllEvents All events. Note that
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\l{QEvent::DeferredDelete}{DeferredDelete} events are processed
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specially. See QObject::deleteLater() for more details.
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\value ExcludeUserInputEvents Do not process user input events,
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such as ButtonPress and KeyPress. Note that the events are not
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discarded; they will be delivered the next time processEvents() is
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called without the ExcludeUserInputEvents flag.
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\value ExcludeSocketNotifiers Do not process socket notifier
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events. Note that the events are not discarded; they will be
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delivered the next time processEvents() is called without the
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ExcludeSocketNotifiers flag.
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\value WaitForMoreEvents Wait for events if no pending events are
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available.
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\omitvalue X11ExcludeTimers
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\omitvalue ExcludeUserInput
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\omitvalue WaitForMore
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\omitvalue EventLoopExec
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\omitvalue DialogExec
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\value DeferredDeletion deprecated - do not use.
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\sa processEvents()
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*/
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/*!
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Constructs an event loop object with the given \a parent.
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*/
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QEventLoop::QEventLoop(QObject *parent)
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: QObject(*new QEventLoopPrivate, parent)
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{
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Q_D(QEventLoop);
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if (!QCoreApplication::instance()) {
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qWarning("QEventLoop: Cannot be used without QApplication");
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} else if (!d->threadData->eventDispatcher) {
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QThreadPrivate::createEventDispatcher(d->threadData);
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}
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}
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/*!
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Destroys the event loop object.
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*/
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QEventLoop::~QEventLoop()
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{ }
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/*!
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Processes pending events that match \a flags until there are no
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more events to process. Returns true if pending events were handled;
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otherwise returns false.
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This function is especially useful if you have a long running
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operation and want to show its progress without allowing user
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input; i.e. by using the \l ExcludeUserInputEvents flag.
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This function is simply a wrapper for
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QAbstractEventDispatcher::processEvents(). See the documentation
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for that function for details.
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*/
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bool QEventLoop::processEvents(ProcessEventsFlags flags)
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{
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Q_D(QEventLoop);
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if (!d->threadData->eventDispatcher)
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return false;
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if (flags & DeferredDeletion)
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QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
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return d->threadData->eventDispatcher->processEvents(flags);
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}
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/*!
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Enters the main event loop and waits until exit() is called.
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Returns the value that was passed to exit().
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If \a flags are specified, only events of the types allowed by
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the \a flags will be processed.
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It is necessary to call this function to start event handling. The
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main event loop receives events from the window system and
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dispatches these to the application widgets.
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Generally speaking, no user interaction can take place before
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calling exec(). As a special case, modal widgets like QMessageBox
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can be used before calling exec(), because modal widgets
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use their own local event loop.
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To make your application perform idle processing (i.e. executing a
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special function whenever there are no pending events), use a
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QTimer with 0 timeout. More sophisticated idle processing schemes
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can be achieved using processEvents().
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\sa QApplication::quit(), exit(), processEvents()
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*/
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int QEventLoop::exec(ProcessEventsFlags flags)
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{
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Q_D(QEventLoop);
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if (d->threadData->quitNow)
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return -1;
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if (d->inExec) {
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qWarning("QEventLoop::exec: instance %p has already called exec()", this);
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return -1;
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}
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d->inExec = true;
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d->exit = false;
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++d->threadData->loopLevel;
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d->threadData->eventLoops.push(this);
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// remove posted quit events when entering a new event loop
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QCoreApplication *app = QCoreApplication::instance();
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if (app && app->thread() == thread())
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QCoreApplication::removePostedEvents(app, QEvent::Quit);
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#if defined(QT_NO_EXCEPTIONS)
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while (!d->exit)
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processEvents(flags | WaitForMoreEvents | EventLoopExec);
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#else
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try {
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while (!d->exit)
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processEvents(flags | WaitForMoreEvents | EventLoopExec);
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} catch (...) {
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qWarning("Qt has caught an exception thrown from an event handler. Throwing\n"
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"exceptions from an event handler is not supported in Qt. You must\n"
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"reimplement QApplication::notify() and catch all exceptions there.\n");
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// copied from below
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QEventLoop *eventLoop = d->threadData->eventLoops.pop();
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Q_ASSERT_X(eventLoop == this, "QEventLoop::exec()", "internal error");
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Q_UNUSED(eventLoop); // --release warning
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d->inExec = false;
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--d->threadData->loopLevel;
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throw;
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}
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#endif
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// copied above
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QEventLoop *eventLoop = d->threadData->eventLoops.pop();
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Q_ASSERT_X(eventLoop == this, "QEventLoop::exec()", "internal error");
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Q_UNUSED(eventLoop); // --release warning
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d->inExec = false;
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--d->threadData->loopLevel;
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return d->returnCode;
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}
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/*!
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Process pending events that match \a flags for a maximum of \a
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maxTime milliseconds, or until there are no more events to
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process, whichever is shorter.
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This function is especially useful if you have a long running
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operation and want to show its progress without allowing user
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input, i.e. by using the \l ExcludeUserInputEvents flag.
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\bold{Notes:}
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\list
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\o This function does not process events continuously; it
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returns after all available events are processed.
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\o Specifying the \l WaitForMoreEvents flag makes no sense
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and will be ignored.
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\endlist
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*/
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void QEventLoop::processEvents(ProcessEventsFlags flags, int maxTime)
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{
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Q_D(QEventLoop);
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if (!d->threadData->eventDispatcher)
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return;
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QTime start;
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start.start();
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if (flags & DeferredDeletion)
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QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
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while (processEvents(flags & ~WaitForMoreEvents)) {
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if (start.elapsed() > maxTime)
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break;
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if (flags & DeferredDeletion)
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QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
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}
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}
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/*!
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Tells the event loop to exit with a return code.
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After this function has been called, the event loop returns from
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the call to exec(). The exec() function returns \a returnCode.
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By convention, a \a returnCode of 0 means success, and any non-zero
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value indicates an error.
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Note that unlike the C library function of the same name, this
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function \e does return to the caller -- it is event processing that
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stops.
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\sa QCoreApplication::quit(), quit(), exec()
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*/
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void QEventLoop::exit(int returnCode)
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{
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Q_D(QEventLoop);
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if (!d->threadData->eventDispatcher)
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return;
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d->returnCode = returnCode;
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d->exit = true;
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d->threadData->eventDispatcher->interrupt();
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}
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/*!
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Returns true if the event loop is running; otherwise returns
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false. The event loop is considered running from the time when
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exec() is called until exit() is called.
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\sa exec() exit()
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*/
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bool QEventLoop::isRunning() const
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{
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Q_D(const QEventLoop);
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return !d->exit;
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}
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/*!
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Wakes up the event loop.
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\sa QAbstractEventDispatcher::wakeUp()
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*/
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void QEventLoop::wakeUp()
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{
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Q_D(QEventLoop);
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if (!d->threadData->eventDispatcher)
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return;
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d->threadData->eventDispatcher->wakeUp();
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}
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/*!
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Tells the event loop to exit normally.
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Same as exit(0).
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\sa QCoreApplication::quit(), exit()
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*/
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void QEventLoop::quit()
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{ exit(0); }
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QT_END_NAMESPACE
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