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| 4 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
| 5 | <!-- loader.qdoc --> |
| 6 | <head> |
| 7 | <title>Loading Documents</title> |
| 8 | <link href="classic.css" rel="stylesheet" type="text/css" /> |
| 9 | </head> |
| 10 | <body> |
| 11 | <table border="0" cellpadding="0" cellspacing="0" width="100%"> |
| 12 | <tr> |
| 13 | <td align="left" valign="top" width="32"><img src="images/qt-logo.png" align="left" width="57" height="67" border="0" /></td> |
| 14 | <td width="1"> </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a></td> |
| 15 | </tr></table><h1 class="title">Loading Documents<br /><span class="subtitle"></span> |
| 16 | </h1> |
| 17 | <p>The application in this example loads or prints the documents passed as commandline parameters to further instances of this application.</p> |
| 18 | <pre><span class="comment"> /**************************************************************************** |
| 19 | ** |
| 20 | ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). |
| 21 | ** All rights reserved. |
| 22 | ** |
| 23 | ** Contact: Nokia Corporation (qt-info@nokia.com) |
| 24 | ** |
| 25 | ** This file is part of a Qt Solutions component. |
| 26 | ** |
| 27 | ** You may use this file under the terms of the BSD license as follows: |
| 28 | ** |
| 29 | ** "Redistribution and use in source and binary forms, with or without |
| 30 | ** modification, are permitted provided that the following conditions are |
| 31 | ** met: |
| 32 | ** * Redistributions of source code must retain the above copyright |
| 33 | ** notice, this list of conditions and the following disclaimer. |
| 34 | ** * Redistributions in binary form must reproduce the above copyright |
| 35 | ** notice, this list of conditions and the following disclaimer in |
| 36 | ** the documentation and/or other materials provided with the |
| 37 | ** distribution. |
| 38 | ** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor |
| 39 | ** the names of its contributors may be used to endorse or promote |
| 40 | ** products derived from this software without specific prior written |
| 41 | ** permission. |
| 42 | ** |
| 43 | ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 44 | ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 45 | ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 46 | ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 47 | ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 48 | ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 49 | ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 50 | ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 51 | ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 52 | ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 53 | ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." |
| 54 | ** |
| 55 | ****************************************************************************/</span> |
| 56 | |
| 57 | #include <qtsingleapplication.h> |
| 58 | #include <QtCore/QFile> |
| 59 | #include <QtGui/QMainWindow> |
| 60 | #include <QtGui/QPrinter> |
| 61 | #include <QtGui/QPainter> |
| 62 | #include <QtGui/QTextEdit> |
| 63 | #include <QtGui/QMdiArea> |
| 64 | #include <QtCore/QTextStream> |
| 65 | |
| 66 | class MainWindow : public QMainWindow |
| 67 | { |
| 68 | Q_OBJECT |
| 69 | public: |
| 70 | MainWindow(); |
| 71 | |
| 72 | public slots: |
| 73 | void handleMessage(const QString& message); |
| 74 | |
| 75 | signals: |
| 76 | void needToShow(); |
| 77 | |
| 78 | private: |
| 79 | QMdiArea *workspace; |
| 80 | };</pre> |
| 81 | <p>The user interface in this application is a <a href="http://qt.nokia.com/doc/4.6/qmainwindow.html">QMainWindow</a> subclass with a <a href="http://qt.nokia.com/doc/4.6/qmdiarea.html">QMdiArea</a> as the central widget. It implements a slot <tt>handleMessage()</tt> that will be connected to the messageReceived() signal of the <a href="qtsingleapplication.html">QtSingleApplication</a> class.</p> |
| 82 | <pre> MainWindow::MainWindow() |
| 83 | { |
| 84 | workspace = new QMdiArea(this); |
| 85 | |
| 86 | setCentralWidget(workspace); |
| 87 | }</pre> |
| 88 | <p>The <a href="http://qt.nokia.com/doc/4.6/designer-to-know.html">MainWindow</a> constructor creates a minimal user interface.</p> |
| 89 | <pre> void MainWindow::handleMessage(const QString& message) |
| 90 | { |
| 91 | enum Action { |
| 92 | Nothing, |
| 93 | Open, |
| 94 | Print |
| 95 | } action; |
| 96 | |
| 97 | action = Nothing; |
| 98 | QString filename = message; |
| 99 | if (message.toLower().startsWith("/print ")) { |
| 100 | filename = filename.mid(7); |
| 101 | action = Print; |
| 102 | } else if (!message.isEmpty()) { |
| 103 | action = Open; |
| 104 | } |
| 105 | if (action == Nothing) { |
| 106 | emit needToShow(); |
| 107 | return; |
| 108 | } |
| 109 | |
| 110 | QFile file(filename); |
| 111 | QString contents; |
| 112 | if (file.open(QIODevice::ReadOnly)) |
| 113 | contents = file.readAll(); |
| 114 | else |
| 115 | contents = "[[Error: Could not load file " + filename + "]]"; |
| 116 | |
| 117 | QTextEdit *view = new QTextEdit; |
| 118 | view->setPlainText(contents); |
| 119 | |
| 120 | switch(action) {</pre> |
| 121 | <p>The handleMessage() slot interprets the message passed in as a filename that can be prepended with <i>/print</i> to indicate that the file should just be printed rather than loaded.</p> |
| 122 | <pre> case Print: |
| 123 | { |
| 124 | QPrinter printer; |
| 125 | view->print(&printer); |
| 126 | delete view; |
| 127 | } |
| 128 | break; |
| 129 | |
| 130 | case Open: |
| 131 | { |
| 132 | workspace->addSubWindow(view); |
| 133 | view->setWindowTitle(message); |
| 134 | view->show(); |
| 135 | emit needToShow(); |
| 136 | } |
| 137 | break; |
| 138 | default: |
| 139 | break; |
| 140 | }; |
| 141 | }</pre> |
| 142 | <p>Loading the file will also activate the window.</p> |
| 143 | <pre> #include "main.moc" |
| 144 | |
| 145 | int main(int argc, char **argv) |
| 146 | { |
| 147 | QtSingleApplication instance("File loader QtSingleApplication example", argc, argv); |
| 148 | QString message; |
| 149 | for (int a = 1; a < argc; ++a) { |
| 150 | message += argv[a]; |
| 151 | if (a < argc-1) |
| 152 | message += " "; |
| 153 | } |
| 154 | |
| 155 | if (instance.sendMessage(message)) |
| 156 | return 0;</pre> |
| 157 | <p>The <tt>main</tt> entry point function creates a <a href="qtsingleapplication.html">QtSingleApplication</a> object, and creates a message to send to a running instance of the application. If the message was sent successfully the process exits immediately.</p> |
| 158 | <pre> MainWindow mw; |
| 159 | mw.handleMessage(message); |
| 160 | mw.show(); |
| 161 | |
| 162 | QObject::connect(&instance, SIGNAL(messageReceived(const QString&)), |
| 163 | &mw, SLOT(handleMessage(const QString&))); |
| 164 | |
| 165 | instance.setActivationWindow(&mw, false); |
| 166 | QObject::connect(&mw, SIGNAL(needToShow()), &instance, SLOT(activateWindow())); |
| 167 | |
| 168 | return instance.exec(); |
| 169 | }</pre> |
| 170 | <p>If the message could not be sent the application starts up. Note that <tt>false</tt> is passed to the call to setActivationWindow() to prevent automatic activation for every message received, e.g. when the application should just print a file. Instead, the message handling function determines whether activation is requested, and signals that by emitting the needToShow() signal. This is then simply connected directly to <a href="qtsingleapplication.html">QtSingleApplication</a>'s activateWindow() slot.</p> |
| 171 | <p /><address><hr /><div align="center"> |
| 172 | <table width="100%" cellspacing="0" border="0"><tr class="address"> |
| 173 | <td width="30%" align="left">Copyright © 2010 Nokia Corporation and/or its subsidiary(-ies)</td> |
| 174 | <td width="40%" align="center"><a href="http://qt.nokia.com/doc/trademarks.html">Trademarks</a></td> |
| 175 | <td width="30%" align="right"><div align="right">Qt Solutions</div></td> |
| 176 | </tr></table></div></address></body> |
| 177 | </html> |