<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/tutorial.doc:303 --> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>TQt Tutorial - Chapter 3: Family Values</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 3: Family Values</h1> <p> <center><img src="t3.png" alt="Screenshot of tutorial three"></center> <p> This example shows how to create parent and child widgets. <p> We'll keep it simple and use just a single parent and a lone child. <p> <pre>/**************************************************************** ** ** TQt tutorial 3 ** ****************************************************************/ #include <<a href="qapplication-h.html">ntqapplication.h</a>> #include <<a href="qpushbutton-h.html">ntqpushbutton.h</a>> #include <<a href="qfont-h.html">ntqfont.h</a>> #include <<a href="qvbox-h.html">ntqvbox.h</a>> int main( int argc, char **argv ) { <a href="ntqapplication.html">TQApplication</a> a( argc, argv ); <a href="ntqvbox.html">TQVBox</a> box; box.<a href="tqwidget.html#resize">resize</a>( 200, 120 ); <a href="ntqpushbutton.html">TQPushButton</a> quit( "Quit", &box ); 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="ntqbutton.html#clicked">clicked</a>()), &a, TQ_SLOT(<a href="ntqapplication.html#quit">quit</a>()) ); a.<a href="ntqapplication.html#setMainWidget">setMainWidget</a>( &box ); box.<a href="tqwidget.html#show">show</a>(); return a.<a href="ntqapplication.html#exec">exec</a>(); } </pre> <p> <h2> Line-by-line Walkthrough </h2> <a name="1"></a><p> <pre> #include <<a href="qvbox-h.html">ntqvbox.h</a>> </pre> <p> We add an include of ntqvbox.h to get the layout class we'll use. <p> <pre> <a href="ntqvbox.html">TQVBox</a> box; </pre> <p> Here we simply create a vertical box container. The <a href="ntqvbox.html">TQVBox</a> arranges its child widgets in a vertical row, one above the other, handing out space according to each child's <a href="tqwidget.html#sizePolicy">TQWidget::sizePolicy</a>(). <p> <pre> <a name="x2300"></a> box.<a href="tqwidget.html#resize">resize</a>( 200, 120 ); </pre> <p> We set its width to 200 pixels and the height to 120 pixels. <p> <pre> <a href="ntqpushbutton.html">TQPushButton</a> quit( "Quit", &box ); </pre> <p> A child is born. <p> This <a href="ntqpushbutton.html">TQPushButton</a> is created with both a text ("Quit") and a parent (box). A child widget is always on top of its parent. When displayed, it is clipped by its parent's bounds. <p> The parent widget, the TQVBox, automatically adds the child centered in its box. Because nothing else is added, the button gets all the space the parent has. <p> <pre> <a name="x2302"></a> box.<a href="tqwidget.html#show">show</a>(); </pre> <p> When a parent widget is shown, it will call show for all its children (except those on which you have done an explicit <a href="tqwidget.html#hide">TQWidget::hide</a>()). <p> <h2> Behavior </h2> <a name="2"></a><p> The button no longer fills the entire widget. Instead, it gets a "natural" size. This is because there is now a new top-level widget, which uses the button's size hint and size change policy to set the button's size and position. (See <a href="tqwidget.html#sizeHint">TQWidget::sizeHint</a>() and <a href="tqwidget.html#setSizePolicy">TQWidget::setSizePolicy</a>() for more information about these functions.) <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 resizing the window. How does the button change? What is the button's size-change policy? What happens to the button's height if you run the program with a bigger font? What happens if you try to make the window <em>really</em> small? <p> You're now ready for <a href="tutorial1-04.html">Chapter 4.</a> <p> [<a href="tutorial1-02.html">Previous tutorial</a>] [<a href="tutorial1-04.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>