<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Signals</title> <link rel="stylesheet" href="style.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.1"> <link rel="home" href="index.html" title="Programming with gtkmm"> <link rel="up" href="chapter-basics.html" title="Chapter 3. Basics"> <link rel="prev" href="sec-widgets-overview.html" title="Widgets"> <link rel="next" href="sec-basics-ustring.html" title="Glib::ustring"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr><th colspan="3" align="center">Signals</th></tr> <tr> <td width="20%" align="left"> <a accesskey="p" href="sec-widgets-overview.html"><img src="icons/prev.png" alt="Prev"></a> </td> <th width="60%" align="center">Chapter 3. Basics</th> <td width="20%" align="right"> <a accesskey="n" href="sec-basics-ustring.html"><img src="icons/next.png" alt="Next"></a> </td> </tr> </table> <hr> </div> <div class="sect1" title="Signals"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="sec-signals-overview"></a>Signals</h2></div></div></div> <p> <span class="application">gtkmm</span>, like most GUI toolkits, is <span class="emphasis"><em>event-driven</em></span>. When an event occurs, such as the press of a mouse button, the appropriate signal will be <span class="emphasis"><em>emitted</em></span> by the Widget that was pressed. Each Widget has a different set of signals that it can emit. To make a button click result in an action, we set up a <span class="emphasis"><em>signal handler</em></span> to catch the button's "clicked" signal. </p> <p><span class="application">gtkmm</span> uses the libsigc++ library to implement signals. Here is an example line of code that connects a Gtk::Button's "clicked" signal with a signal handler called "on_button_clicked": </p> <pre class="programlisting">m_button1.signal_clicked().connect( sigc::mem_fun(*this, &HelloWorld::on_button_clicked) );</pre> <p> </p> <p>For more detailed information about signals, see the <a class="link" href="chapter-signals.html" title="Appendix B. Signals">appendix</a>.</p> <p>For information about implementing your own signals rather than just connecting to the existing <span class="application">gtkmm</span> signals, see the <a class="link" href="chapter-custom-signals.html" title="Appendix C. Creating your own signals">appendix</a>.</p> </div> <div class="navfooter"> <hr> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"> <a accesskey="p" href="sec-widgets-overview.html"><img src="icons/prev.png" alt="Prev"></a> </td> <td width="20%" align="center"><a accesskey="u" href="chapter-basics.html"><img src="icons/up.png" alt="Up"></a></td> <td width="40%" align="right"> <a accesskey="n" href="sec-basics-ustring.html"><img src="icons/next.png" alt="Next"></a> </td> </tr> <tr> <td width="40%" align="left" valign="top">Widgets </td> <td width="20%" align="center"><a accesskey="h" href="index.html"><img src="icons/home.png" alt="Home"></a></td> <td width="40%" align="right" valign="top"> Glib::ustring</td> </tr> </table> </div> </body> </html>