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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
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73
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44 import qt.core.QObject;
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45 import qt.core.QBasicTimer;
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46 import qt.core.QTime;
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47 import qt.core.QDir;
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48 import qt.core.QCoreApplication;
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49 import qt.core.QMetaObject;
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50
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45
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51 import QtDebug;
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52
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73
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53
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45
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54 const uint AUTOSAVE_IN = 1000 * 3 // seconds
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55 const uint MAXWAIT = 1000 * 15 // seconds
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56
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73
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57
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45
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58 /*
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59 This class will call the save() slot on the parent object when the parent changes.
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60 It will wait several seconds after changed() to combining multiple changes and
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61 prevent continuous writing to disk.
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62 */
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63
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45
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64 class AutoSaver : public QObject {
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65
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66 public:
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67
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68 this(QObject parent)
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69 {
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70 super(parent);
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71 assert(parent);
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72 }
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73
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74 ~this();
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75 {
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76 if (m_timer.isActive())
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77 qWarning() << "AutoSaver: still active when destroyed, changes not saved.";
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78 }
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79
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80 void saveIfNeccessary()
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81 {
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82 if (!m_timer.isActive())
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83 return;
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84 m_timer.stop();
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85 m_firstChange = QTime();
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86 if (!QMetaObject.invokeMethod(parent(), "save", Qt.DirectConnection)) {
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87 qWarning() << "AutoSaver: error invoking slot save() on parent";
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88 }
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89 }
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90
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91 public:
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92
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93 void changeOccurred();
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94 {
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95 if (m_firstChange.isNull())
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96 m_firstChange.start();
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97
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98 if (m_firstChange.elapsed() > MAXWAIT) {
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99 saveIfNeccessary();
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100 } else {
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101 m_timer.start(AUTOSAVE_IN, this);
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102 }
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103 }
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104
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105 protected:
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106
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107 void timerEvent(QTimerEvent event)
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108 {
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109 if (event.timerId() == m_timer.timerId()) {
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110 saveIfNeccessary();
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111 } else {
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112 QObject.timerEvent(event);
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113 }
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114 }
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115
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116 private:
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117
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118 QBasicTimer m_timer;
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119 QTime m_firstChange;
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45
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120 }
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121
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