autosaver.cpp Example File | Qt WebKit Examples 5.9

Qt 5.9 | Qt WebKit Examples | Tab Browser | autosaver.cpp Example File

Qt 5.9.2 Reference Documentation

# autosaver.cpp Example File

webkitwidgets/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.
      **
      ** $QT_BEGIN_LICENSE:LGPL21$
      ** Commercial License Usage
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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 or version 3 as published by the Free
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      ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
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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";
          }
      }