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1 /****************************************************************************
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2 **
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3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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4 ** Contact: Qt Software Information (qt-info@nokia.com)
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5 **
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6 ** This file is part of the demonstration applications of the Qt Toolkit.
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7 **
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8 ** $QT_BEGIN_LICENSE:LGPL$
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9 ** Commercial Usage
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10 ** Licensees holding valid Qt Commercial licenses may use this file in
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11 ** accordance with the Qt Commercial License Agreement provided with the
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12 ** Software or, alternatively, in accordance with the terms contained in
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13 ** a written agreement between you and Nokia.
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14 **
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15 ** GNU Lesser General Public License Usage
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16 ** Alternatively, this file may be used under the terms of the GNU Lesser
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17 ** General Public License version 2.1 as published by the Free Software
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18 ** Foundation and appearing in the file LICENSE.LGPL included in the
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19 ** packaging of this file. Please review the following information to
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20 ** ensure the GNU Lesser General Public License version 2.1 requirements
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21 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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22 **
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23 ** In addition, as a special exception, Nokia gives you certain
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24 ** additional rights. These rights are described in the Nokia Qt LGPL
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25 ** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
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26 ** package.
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27 **
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28 ** GNU General Public License Usage
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29 ** Alternatively, this file may be used under the terms of the GNU
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30 ** General Public License version 3.0 as published by the Free Software
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31 ** Foundation and appearing in the file LICENSE.GPL included in the
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32 ** packaging of this file. Please review the following information to
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33 ** ensure the GNU General Public License version 3.0 requirements will be
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34 ** met: http://www.gnu.org/copyleft/gpl.html.
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35 **
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36 ** If you are unsure which license is appropriate for your use, please
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37 ** contact the sales department at qt-sales@nokia.com.
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38 ** $QT_END_LICENSE$
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39 **
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40 ****************************************************************************/
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41 module autosaver;
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42
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43 import QtCore.QObject;
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44 import QtCore.QBasicTimer;
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45 import QtCore.QTime;
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46
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47 import QtCore.QDir;
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48 import QtCore.QCoreApplication;
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49 import QtCore.QMetaObject;
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50 import QtDebug;
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51
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52 const uint AUTOSAVE_IN = 1000 * 3 // seconds
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53 const uint MAXWAIT = 1000 * 15 // seconds
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54
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55 /*
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56 This class will call the save() slot on the parent object when the parent changes.
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57 It will wait several seconds after changed() to combining multiple changes and
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58 prevent continuous writing to disk.
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59 */
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60 class AutoSaver : public QObject {
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61
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62 Q_OBJECT
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63
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64 public:
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65 this(QObject *parent)
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66 {
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67 super(parent);
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68 Q_ASSERT(parent);
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69 }
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70 ~this();
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71 {
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72 if (m_timer.isActive())
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73 qWarning() << "AutoSaver: still active when destroyed, changes not saved.";
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74 }
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75 void saveIfNeccessary()
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76 {
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77 if (!m_timer.isActive())
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78 return;
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79 m_timer.stop();
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80 m_firstChange = QTime();
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81 if (!QMetaObject::invokeMethod(parent(), "save", Qt::DirectConnection)) {
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82 qWarning() << "AutoSaver: error invoking slot save() on parent";
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83 }
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84 }
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85
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86 public slots:
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87 void changeOccurred();
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88 {
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89 if (m_firstChange.isNull())
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90 m_firstChange.start();
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91
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92 if (m_firstChange.elapsed() > MAXWAIT) {
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93 saveIfNeccessary();
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94 } else {
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95 m_timer.start(AUTOSAVE_IN, this);
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96 }
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97 }
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98
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99 protected:
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100 void timerEvent(QTimerEvent *event)
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101 {
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102 if (event.timerId() == m_timer.timerId()) {
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103 saveIfNeccessary();
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104 } else {
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105 QObject::timerEvent(event);
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106 }
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107 }
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108
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109
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110 private:
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111 QBasicTimer m_timer;
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112 QTime m_firstChange;
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113 }
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114
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