176 lines
7.4 KiB
HTML
176 lines
7.4 KiB
HTML
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<?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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<!-- loader.qdoc -->
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<head>
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<title>Loading Documents</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">Loading Documents<br /><span class="subtitle"></span>
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</h1>
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<p>The application in this example loads or prints the documents passed as commandline parameters to further instances of this application.</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 <QtCore/QFile>
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#include <QtGui/QMainWindow>
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#include <QtGui/QPrinter>
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#include <QtGui/QPainter>
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#include <QtGui/QTextEdit>
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#include <QtGui/QMdiArea>
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#include <QtCore/QTextStream>
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class MainWindow : public QMainWindow
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{
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Q_OBJECT
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public:
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MainWindow();
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public slots:
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void handleMessage(const QString& message);
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signals:
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void needToShow();
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private:
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QMdiArea *workspace;
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};</pre>
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<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>
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<pre> MainWindow::MainWindow()
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{
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workspace = new QMdiArea(this);
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setCentralWidget(workspace);
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}</pre>
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<p>The <a href="http://qt.nokia.com/doc/4.6/designer-to-know.html">MainWindow</a> constructor creates a minimal user interface.</p>
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<pre> void MainWindow::handleMessage(const QString& message)
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{
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enum Action {
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Nothing,
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Open,
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Print
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} action;
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action = Nothing;
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QString filename = message;
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if (message.toLower().startsWith("/print ")) {
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filename = filename.mid(7);
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action = Print;
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} else if (!message.isEmpty()) {
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action = Open;
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}
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if (action == Nothing) {
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emit needToShow();
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return;
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}
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QFile file(filename);
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QString contents;
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if (file.open(QIODevice::ReadOnly))
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contents = file.readAll();
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else
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contents = "[[Error: Could not load file " + filename + "]]";
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QTextEdit *view = new QTextEdit;
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view->setPlainText(contents);
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switch(action) {</pre>
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<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>
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<pre> case Print:
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{
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QPrinter printer;
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view->print(&printer);
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delete view;
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}
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break;
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case Open:
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{
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workspace->addSubWindow(view);
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view->setWindowTitle(message);
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view->show();
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emit needToShow();
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}
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break;
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default:
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break;
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};
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}</pre>
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<p>Loading the file will also activate the window.</p>
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<pre> #include "main.moc"
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int main(int argc, char **argv)
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{
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QtSingleApplication instance("File loader QtSingleApplication example", argc, argv);
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QString message;
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for (int a = 1; a < argc; ++a) {
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message += argv[a];
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if (a < argc-1)
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message += " ";
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}
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if (instance.sendMessage(message))
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return 0;</pre>
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<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>
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<pre> MainWindow mw;
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mw.handleMessage(message);
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mw.show();
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QObject::connect(&instance, SIGNAL(messageReceived(const QString&)),
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&mw, SLOT(handleMessage(const QString&)));
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instance.setActivationWindow(&mw, false);
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QObject::connect(&mw, SIGNAL(needToShow()), &instance, SLOT(activateWindow()));
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return instance.exec();
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}</pre>
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<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>
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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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|
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</html>
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