- Qt 5.5
- Qt WebEngine Widgets
- WebEngine Tab Browser Example
- autosaver.cpp Example File
- Qt 5.5.1 Reference Documentation

# autosaver.cpp Example File

browser/autosaver.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL$
    ** Commercial License Usage
    ** Licensees holding valid commercial Qt licenses may use this file in
    ** accordance with the commercial license agreement provided with the
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    ** 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
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    ** rights. These rights are described in The Qt Company 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
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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";
        }
    }