autosaver.cpp Example File | Qt WebKit Examples 5.4

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- autosaver.cpp Example File
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# autosaver.cpp Example File

webkitwidgets/browser/autosaver.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
    ** Contact: http://www.qt-project.org/legal
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
    ** Commercial License Usage
    ** Licensees holding valid commercial Qt licenses may use this file in
    ** accordance with the commercial license agreement provided with the
    ** Software or, alternatively, in accordance with the terms contained in
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    ** use the contact form at http://qt.digia.com/contact-us.
    **
    ** 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 or version 3 as published by the Free
    ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
    ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
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    ** rights. These rights are described in the Digia Qt LGPL Exception
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    ****************************************************************************/

    #include "autosaver.h"

    #include <QtCore/QDir>
    #include <QtCore/QCoreApplication>
    #include <QtCore/QMetaObject>
    #include <QtDebug>

    #define AUTOSAVE_IN  1000 * 3  // seconds
    #define MAXWAIT      1000 * 15 // seconds

    AutoSaver::AutoSaver(QObject *parent) : QObject(parent)
    {
        Q_ASSERT(parent);
    }

    AutoSaver::~AutoSaver()
    {
        if (m_timer.isActive())
            qWarning() << "AutoSaver: still active when destroyed, changes not saved.";
    }

    void AutoSaver::changeOccurred()
    {
        if (m_firstChange.isNull())
            m_firstChange.start();

        if (m_firstChange.elapsed() > MAXWAIT) {
            saveIfNeccessary();
        } else {
            m_timer.start(AUTOSAVE_IN, this);
        }
    }

    void AutoSaver::timerEvent(QTimerEvent *event)
    {
        if (event->timerId() == m_timer.timerId()) {
            saveIfNeccessary();
        } else {
            QObject::timerEvent(event);
        }
    }

    void AutoSaver::saveIfNeccessary()
    {
        if (!m_timer.isActive())
            return;
        m_timer.stop();
        m_firstChange = QTime();
        if (!QMetaObject::invokeMethod(parent(), "save", Qt::DirectConnection)) {
            qWarning() << "AutoSaver: error invoking slot save() on parent";
        }
    }