128 lines
6.1 KiB
128 lines
6.1 KiB
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
|
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
|
<title>TQt Tutorial - Chapter 2: Calling it Quits</title>
|
|
<style type="text/css"><!--
|
|
fn { margin-left: 1cm; text-indent: -1cm; }
|
|
a:link { color: #004faf; text-decoration: none }
|
|
a:visited { color: #672967; text-decoration: none }
|
|
body { background: #ffffff; color: black; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
|
|
<table border="0" cellpadding="0" cellspacing="0" width="100%">
|
|
<tr bgcolor="#E5E5E5">
|
|
<td valign=center>
|
|
<a href="index.html">
|
|
<font color="#004faf">Home</font></a>
|
|
| <a href="classes.html">
|
|
<font color="#004faf">All Classes</font></a>
|
|
| <a href="mainclasses.html">
|
|
<font color="#004faf">Main Classes</font></a>
|
|
| <a href="annotated.html">
|
|
<font color="#004faf">Annotated</font></a>
|
|
| <a href="groups.html">
|
|
<font color="#004faf">Grouped Classes</font></a>
|
|
| <a href="functions.html">
|
|
<font color="#004faf">Functions</font></a>
|
|
</td>
|
|
<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>TQt Tutorial - Chapter 2: Calling it Quits</h1>
|
|
|
|
|
|
<p> <center><img src="t2.png" alt="Screenshot of tutorial two"></center>
|
|
<p> Having created a window in <a href="tutorial1-01.html">Chapter 1,</a> we will
|
|
now go on to make the application quit properly when the user tells it to.
|
|
<p> We will also use a font that is more exciting than the default one.
|
|
<p> <pre>/****************************************************************
|
|
**
|
|
** TQt tutorial 2
|
|
**
|
|
****************************************************************/
|
|
|
|
#include <<a href="tqapplication-h.html">tqapplication.h</a>>
|
|
#include <<a href="tqpushbutton-h.html">tqpushbutton.h</a>>
|
|
#include <<a href="tqfont-h.html">tqfont.h</a>>
|
|
|
|
|
|
int main( int argc, char **argv )
|
|
{
|
|
<a href="tqapplication.html">TQApplication</a> a( argc, argv );
|
|
|
|
<a href="tqpushbutton.html">TQPushButton</a> quit( "Quit", 0 );
|
|
quit.<a href="tqwidget.html#resize">resize</a>( 75, 30 );
|
|
quit.<a href="tqwidget.html#setFont">setFont</a>( TQFont( "Times", 18, TQFont::Bold ) );
|
|
|
|
TQObject::<a href="tqobject.html#connect">connect</a>( &quit, TQ_SIGNAL(<a href="tqbutton.html#clicked">clicked</a>()), &a, TQ_SLOT(<a href="tqapplication.html#quit">quit</a>()) );
|
|
|
|
a.<a href="tqapplication.html#setMainWidget">setMainWidget</a>( &quit );
|
|
quit.<a href="tqwidget.html#show">show</a>();
|
|
return a.<a href="tqapplication.html#exec">exec</a>();
|
|
}
|
|
</pre>
|
|
|
|
|
|
|
|
<p> <h2> Line-by-line Walkthrough
|
|
</h2>
|
|
<a name="1"></a><p> <pre> #include <<a href="tqfont-h.html">tqfont.h</a>>
|
|
</pre>
|
|
<p> Since this program uses <a href="tqfont.html">TQFont</a>, it needs to include tqfont.h. TQt's font
|
|
abstraction is rather different from the horror provided by X, and
|
|
loading and using fonts has been highly optimized.
|
|
<p> <pre> <a href="tqpushbutton.html">TQPushButton</a> quit( "Quit", 0 );
|
|
</pre>
|
|
<p> This time, the button says "Quit" and that's exactly what the program
|
|
will do when the user clicks the button. This is not a coincidence.
|
|
We still pass 0 as the parent, since the button is a top-level window.
|
|
<p> <pre> <a name="x2292"></a> quit.<a href="tqwidget.html#resize">resize</a>( 75, 30 );
|
|
</pre>
|
|
<p> We've chosen another size for the button since the text is a bit
|
|
shorter than "Hello world!". We could also have used <a href="tqfontmetrics.html">TQFontMetrics</a>
|
|
to set right size.
|
|
<p> <pre> <a name="x2293"></a> quit.<a href="tqwidget.html#setFont">setFont</a>( TQFont( "Times", 18, TQFont::Bold ) );
|
|
</pre>
|
|
<p> Here we choose a new font for the button, an 18-point bold font from
|
|
the Times family. Note that we create the font on the spot.
|
|
<p> It is also possible to change the default font (using <a href="tqapplication.html#setFont">TQApplication::setFont</a>()) for the whole application.
|
|
<p> <pre> <a name="x2291"></a><a name="x2290"></a><a name="x2288"></a> TQObject::<a href="tqobject.html#connect">connect</a>( &quit, TQ_SIGNAL(<a href="tqbutton.html#clicked">clicked</a>()), &a, TQ_SLOT(<a href="tqapplication.html#quit">quit</a>()) );
|
|
</pre>
|
|
<p> connect() is perhaps <em>the</em> most central feature of TQt.
|
|
Note that connect() is a static function in <a href="tqobject.html">TQObject</a>. Do not confuse it
|
|
with the connect() function in the socket library.
|
|
<p> This line establishes a one-way connection between two TQt objects (objects
|
|
that inherit TQObject, directly or indirectly). Every TQt object can have
|
|
both <tt>signals</tt> (to send messages) and <tt>slots</tt> (to receive messages). All
|
|
widgets are TQt objects. They inherit <a href="tqwidget.html">TQWidget</a> which in turn inherits
|
|
TQObject.
|
|
<p> Here, the <em>clicked()</em> signal of <em>quit</em> is connected to the <em>quit()</em> slot of <em>a</em>, so that when the button is clicked, the
|
|
application quits.
|
|
<p> The <a href="signalsandslots.html">Signals and Slots</a> documentation
|
|
describes this topic in detail.
|
|
<p> <h2> Behavior
|
|
</h2>
|
|
<a name="2"></a><p> When you run this program, you will see an even smaller window than in
|
|
Chapter 1, filled with an even smaller button.
|
|
<p> (See <a href="tutorial1-01.html#compiling">Compiling</a> for how to create a
|
|
makefile and build the application.)
|
|
<p> <h2> Exercises
|
|
</h2>
|
|
<a name="3"></a><p> Try to resize the window. Press the button. Oops! That connect()
|
|
would seem to make some difference.
|
|
<p> Are there any other signals in <a href="tqpushbutton.html">TQPushButton</a> you can connect to quit?
|
|
Hint: The TQPushButton inherits most of its behavior from <a href="tqbutton.html">TQButton</a>.
|
|
<p> You're now ready for <a href="tutorial1-03.html">Chapter 3.</a>
|
|
<p> [<a href="tutorial1-01.html">Previous tutorial</a>]
|
|
[<a href="tutorial1-03.html">Next tutorial</a>]
|
|
[<a href="tutorial.html">Main tutorial page</a>]
|
|
<p>
|
|
<!-- eof -->
|
|
<p><address><hr><div align=center>
|
|
<table width=100% cellspacing=0 border=0><tr>
|
|
<td>Copyright © 2007
|
|
<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
|
|
<td align=right><div align=right>TQt 3.3.8</div>
|
|
</table></div></address></body>
|
|
</html>
|