autosaver.cpp Example File

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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";
      }
  }