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102 lines
5.3 KiB
HTML
102 lines
5.3 KiB
HTML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<!-- trivial.qdoc -->
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<head>
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<title>A Trivial Example</title>
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<link href="classic.css" rel="stylesheet" type="text/css" />
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</head>
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<body>
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<table border="0" cellpadding="0" cellspacing="0" width="100%">
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<tr>
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<td align="left" valign="top" width="32"><img src="images/qt-logo.png" align="left" width="57" height="67" border="0" /></td>
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<td width="1"> </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a></td>
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</tr></table><h1 class="title">A Trivial Example<br /><span class="subtitle"></span>
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</h1>
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<p>The application in this example has a log-view that displays messages sent by further instances of the same application.</p>
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<p>The example demonstrates the use of the <a href="qtsingleapplication.html">QtSingleApplication</a> class to detect and communicate with a running instance of the application using the sendMessage() API. The messageReceived() signal is used to display received messages in a <a href="http://qt.nokia.com/doc/4.6/qtextedit.html">QTextEdit</a> log.</p>
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<pre><span class="comment"> /****************************************************************************
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**
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** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
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** Contact: http://www.qt-project.org/legal
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**
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** This file is part of the Qt Solutions component.
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**
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** You may use this file under the terms of the BSD license as follows:
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**
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** "Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are
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** met:
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in
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** the documentation and/or other materials provided with the
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** distribution.
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** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
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** the names of its contributors may be used to endorse or promote
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** products derived from this software without specific prior written
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** permission.
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**
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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**
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****************************************************************************/</span>
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#include <qtsingleapplication.h>
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#include <QtGui/QTextEdit>
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class TextEdit : public QTextEdit
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{
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Q_OBJECT
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public:
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TextEdit(QWidget *parent = 0)
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: QTextEdit(parent)
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{}
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public slots:
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void append(const QString &str)
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{
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QTextEdit::append(str);
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}
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};
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#include "main.moc"
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int main(int argc, char **argv)
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{
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QtSingleApplication instance(argc, argv);</pre>
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<p>The example has only the <tt>main</tt> entry point function. A <a href="qtsingleapplication.html">QtSingleApplication</a> object is created immediately.</p>
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<pre> if (instance.sendMessage("Wake up!"))
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return 0;</pre>
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<p>If another instance of this application is already running, sendMessage() will succeed, and this instance just exits immediately.</p>
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<pre> TextEdit logview;
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logview.setReadOnly(true);
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logview.show();</pre>
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<p>Otherwise the instance continues as normal and creates the user interface.</p>
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<pre> instance.setActivationWindow(&logview);
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QObject::connect(&instance, SIGNAL(messageReceived(const QString&)),
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&logview, SLOT(append(const QString&)));
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return instance.exec();</pre>
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<p>The <tt>logview</tt> object is also set as the application's activation window. Every time a message is received, the window will be raised and activated automatically.</p>
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<p>The messageReceived() signal is also connected to the <a href="http://qt.nokia.com/doc/4.6/qtextedit.html">QTextEdit</a>'s append() slot. Every message received from further instances of this application will be displayed in the log.</p>
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<p>Finally the event loop is entered.</p>
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<p /><address><hr /><div align="center">
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<table width="100%" cellspacing="0" border="0"><tr class="address">
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<td width="30%" align="left">Copyright © 2010 Nokia Corporation and/or its subsidiary(-ies)</td>
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<td width="40%" align="center"><a href="http://qt.nokia.com/doc/trademarks.html">Trademarks</a></td>
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<td width="30%" align="right"><div align="right">Qt Solutions</div></td>
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</tr></table></div></address></body>
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</html>
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