source: trunk/doc/html/process-example.html

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6<title>Starting processes with IO redirection</title>
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32<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Starting processes with IO redirection</h1>
33
34
35<p>
36<p> This example shows you how to start other processes with Qt and how
37IO redirection is done. The example tries to start the uic (a tool
38that comes with the Qt Designer) on a certain ui file and displays the
39output of the command.
40<p> <hr>
41<p> Implementation (process.cpp):
42<p> <pre>/****************************************************************************
43** $Id: process-example.html 2051 2007-02-21 10:04:20Z chehrlic $
44**
45** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
46**
47** This file is part of an example program for Qt. This example
48** program may be used, distributed and modified without limitation.
49**
50*****************************************************************************/
51
52#include &lt;<a href="qobject-h.html">qobject.h</a>&gt;
53#include &lt;<a href="qprocess-h.html">qprocess.h</a>&gt;
54#include &lt;<a href="qvbox-h.html">qvbox.h</a>&gt;
55#include &lt;<a href="qtextview-h.html">qtextview.h</a>&gt;
56#include &lt;<a href="qpushbutton-h.html">qpushbutton.h</a>&gt;
57#include &lt;<a href="qapplication-h.html">qapplication.h</a>&gt;
58#include &lt;<a href="qmessagebox-h.html">qmessagebox.h</a>&gt;
59
60#include &lt;stdlib.h&gt;
61
62class UicManager : public <a href="qvbox.html">QVBox</a>
63{
64 <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
65
66public:
67 UicManager();
68 ~UicManager() {}
69
70public slots:
71 void readFromStdout();
72 void scrollToTop();
73
74private:
75 <a href="qprocess.html">QProcess</a> *proc;
76 <a href="qtextview.html">QTextView</a> *output;
77 <a href="qpushbutton.html">QPushButton</a> *quitButton;
78};
79
80<a name="f204"></a>UicManager::UicManager()
81{
82 // Layout
83 output = new <a href="qtextview.html">QTextView</a>( this );
84 quitButton = new <a href="qpushbutton.html">QPushButton</a>( <a href="qobject.html#tr">tr</a>("Quit"), this );
85 <a href="qobject.html#connect">connect</a>( quitButton, SIGNAL(<a href="qbutton.html#clicked">clicked</a>()),
86 qApp, SLOT(<a href="qapplication.html#quit">quit</a>()) );
87 <a href="qwidget.html#resize">resize</a>( 500, 500 );
88
89 // QProcess related code
90 proc = new <a href="qprocess.html">QProcess</a>( this );
91
92 // Set up the command and arguments.
93 // On the command line you would do:
94 // uic -tr <a href="i18n.html#i18n">i18n</a> "small_dialog.ui"
95<a name="x97"></a> proc-&gt;<a href="qprocess.html#addArgument">addArgument</a>( "uic" );
96 proc-&gt;<a href="qprocess.html#addArgument">addArgument</a>( "-tr" );
97 proc-&gt;<a href="qprocess.html#addArgument">addArgument</a>( "i18n" );
98 proc-&gt;<a href="qprocess.html#addArgument">addArgument</a>( "small_dialog.ui" );
99
100<a name="x100"></a> <a href="qobject.html#connect">connect</a>( proc, SIGNAL(<a href="qprocess.html#readyReadStdout">readyReadStdout</a>()),
101 this, SLOT(readFromStdout()) );
102<a name="x98"></a> <a href="qobject.html#connect">connect</a>( proc, SIGNAL(<a href="qprocess.html#processExited">processExited</a>()),
103 this, SLOT(scrollToTop()) );
104
105<a name="x101"></a> if ( !proc-&gt;<a href="qprocess.html#start">start</a>() ) {
106 // error handling
107<a name="x96"></a> QMessageBox::<a href="qmessagebox.html#critical">critical</a>( 0,
108 <a href="qobject.html#tr">tr</a>("Fatal error"),
109 <a href="qobject.html#tr">tr</a>("Could not start the uic command."),
110 <a href="qobject.html#tr">tr</a>("Quit") );
111 exit( -1 );
112 }
113}
114
115void <a name="f205"></a>UicManager::readFromStdout()
116{
117 // Read and process the data.
118 // Bear in mind that the data might be output in chunks.
119<a name="x99"></a><a name="x103"></a> output-&gt;<a href="qtextedit.html#append">append</a>( proc-&gt;<a href="qprocess.html#readStdout">readStdout</a>() );
120}
121
122void <a name="f206"></a>UicManager::scrollToTop()
123{
124<a name="x102"></a> output-&gt;<a href="qscrollview.html#setContentsPos">setContentsPos</a>( 0, 0 );
125}
126
127int main( int argc, char **argv )
128{
129 <a href="qapplication.html">QApplication</a> a( argc, argv );
130 UicManager manager;
131 a.<a href="qapplication.html#setMainWidget">setMainWidget</a>( &amp;manager );
132 manager.<a href="qwidget.html#show">show</a>();
133 return a.<a href="qapplication.html#exec">exec</a>();
134}
135
136#include "process.moc"
137</pre>
138
139<p>See also <a href="qprocess-examples.html">QProcess Examples</a>.
140
141<!-- eof -->
142<p><address><hr><div align=center>
143<table width=100% cellspacing=0 border=0><tr>
144<td>Copyright &copy; 2007
145<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
146<td align=right><div align=right>Qt 3.3.8</div>
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