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<HTML><HEAD><TITLE>Radio Buttons</TITLE><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.49"><LINKREL="HOME"TITLE="GTK+ 1.2 Tutorial"HREF="gtk-tut.html"><LINKREL="UP"TITLE="The Button Widget"HREF="ch-buttonwidget.html"><LINKREL="PREVIOUS"TITLE="Check Buttons"HREF="sec-checkbuttons.html"><LINKREL="NEXT"TITLE="Adjustments"HREF="ch-adjustments.html"></HEAD></head><body bgcolor="#FFFFFF" marginheight=0 marginwidth=0 width="100%"><table cellspacing=6 border=0 cellpadding=0 width="100%">  <tr>    <td bgcolor="#FFFFFF" valign=top nowrap>    <centeR><A HREF="/"><img src="/images/gtk-logo-rgb.gif" width=107 height=140 border=0></A>      <font face="helvetica,lucidia" color="#000000"><BR><BR><b>GTK+<BR>The GIMP Toolkit</b></center><BR><table width=100% cellspacing=0 cellpadding=2 border=0><tr><td bgcolor="#000000"><table width=100% cellspacing=0 cellpadding=4 border=0><tr><td bgcolor="#AAAAEE" nowrap><B>General</B></td></tr><tr><td bgcolor="#FFFFFF" nowrap><A HREF="/">Introduction</A><BR><A HREF="/screenshots/">Screenshots</A><br><A HREF="/download/">Download</A><br><A HREF="/mailinglists.html">Mailing Lists</A><BR><A HREF="/bindings.html">Language Bindings</A><BR><A HREF="http://gtk.themes.org/">Themes</A><BR><A HREF="/bugs.html">Bug Tracker</A><BR></td></tr></table></td></tr></table><BR>  <table width=100% cellspacing=0 cellpadding=2 border=0><tr><td bgcolor="#000000"><table width=100% cellspacing=0 cellpadding=4 border=0><tr><td bgcolor="#AAAAEE" nowrap><B>Documentation</B></td></tr><tr><td bgcolor="#FFFFFF" nowrap><A HREF="/faq/">FAQ</A><br><A HREF="/tutorial/">Tutorial</A><BR><A HREF="/api/">API Reference</A><br><A HREF="/books.html">Published Books</A><BR></td></tr></table></td></tr></table><BR>  <table width=100% cellspacing=0 cellpadding=2 border=0><tr><td bgcolor="#000000"><table width=100% cellspacing=0 cellpadding=4 border=0><tr><td bgcolor="#AAAAEE" nowrap><B>Projects</B></td></tr><tr><td bgcolor="#FFFFFF" nowrap><A HREF="http://www.pango.org/">Pango</A><BR><A HREF="http://sources.redhat.com/inti/">Inti</A><BR><A HREF="http://www.gnome.org/">GNOME</A><BR><A HREF="http://user.sgic.fi/~tml/gimp/win32/">GTK+ for Win32</A><br><A HREF="http://people.redhat.com/sopwith/gtkfb/">GtkFB (Framebuffer)</A><br><A HREF="http://www.directfb.org/gtk.xml">GTK+ on DirectFB</A><BR><A HREF="/beos/">GTK+ for BeOS</A></td></tr></table></td></tr></table><BR>  <table width=100% cellspacing=0 cellpadding=2 border=0><tr><td bgcolor="#000000"><table width=100% cellspacing=0 cellpadding=4 border=0><tr><td bgcolor="#AAAAEE" nowrap><B><B>Applications</B></B></td></tr><tr><td bgcolor="#FFFFFF" nowrap><A HREF="http://www.gimp.org/">GIMP</A><BR><A HREF="http://www.abiword.org/">Abiword</A><BR><A HREF="http://www.lysator.liu.se/~alla/dia/dia.html">Dia</A><BR><A HREF="http://glade.pn.org/">Glade</A><BR><A HREF="http://www.gnucash.org/">GnuCash</A><BR><A HREF="http://www.gnome.org/projects/gnumeric/">Gnumeric</A><BR><BR><A HREF="http://www.gnome.org/applist/">GNOME Software Map</A><br></td></tr></table></td></tr></table><BR>      </td>  <td bgcolor="#ffffff" valign=top width="99%"><font face="lucida,helvetica"><BODYCLASS="SECT1"BGCOLOR="#FFFFFF"TEXT="#000000"LINK="#0000FF"VLINK="#840084"ALINK="#0000FF"><DIVCLASS="NAVHEADER"><TABLEWIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">GTK+ 1.2 Tutorial</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><AHREF="sec-checkbuttons.html">&#60;&#60;&#60; Previous</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom">Chapter 6. The Button Widget</TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="ch-adjustments.html">Next &#62;&#62;&#62;</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="SECT1"><H1CLASS="SECT1"><ANAME="SEC-RADIOBUTTONS">6.4. Radio Buttons</A></H1><P>Radio buttons are similar to check buttons except they are grouped sothat only one may be selected/depressed at a time. This is good forplaces in your application where you need to select from a short listof options.</P><P>Creating a new radio button is done with one of these calls:</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">GtkWidget *gtk_radio_button_new( GSList *group );GtkWidget *gtk_radio_button_new_with_label( GSList *group,                                            gchar  *label );</PRE></TD></TR></TABLE><P>You'll notice the extra argument to these calls. They require a groupto perform their duty properly. The first call togtk_radio_button_new or gtk_radio_button_new_with_labelshould pass NULL as the first argument. Then create a group using:</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">GSList *gtk_radio_button_group( GtkRadioButton *radio_button );</PRE></TD></TR></TABLE><P>The important thing to remember is that gtk_radio_button_group must becalled for each new button added to the group, with the previousbutton passed in as an argument. The result is then passed into thenext call to gtk_radio_button_new orgtk_radio_button_new_with_label. This allows a chain of buttons to beestablished. The example below should make this clear.</P><P>You can shorten this slightly by using the following syntax, whichremoves the need for a variable to hold the list of buttons. This formis used in the example to create the third button:</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">     button2 = gtk_radio_button_new_with_label(                 gtk_radio_button_group (GTK_RADIO_BUTTON (button1)),                 "button2");</PRE></TD></TR></TABLE><P>It is also a good idea to explicitly set which button should be thedefault depressed button with:</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">void gtk_toggle_button_set_active( GtkToggleButton *toggle_button,                                  gint             state );</PRE></TD></TR></TABLE><P>This is described in the section on toggle buttons, and works inexactly the same way.  Once the radio buttons are grouped together,only one of the group may be active at a time. If the user clicks onone radio button, and then on another, the first radio button willfirst emit a "toggled" signal (to report becoming inactive), and thenthe second will emit its "toggled" signal (to report becoming active).</P><P>The following example creates a radio button group with three buttons.</P><TABLEBORDER="0"BGCOLOR="#E0E0E0"WIDTH="100%"><TR><TD><PRECLASS="PROGRAMLISTING">/* example-start radiobuttons radiobuttons.c */#include &#60;gtk/gtk.h&#62;#include &#60;glib.h&#62;gint close_application( GtkWidget *widget,                        GdkEvent  *event,                        gpointer   data ){  gtk_main_quit();  return(FALSE);}int main( int   argc,          char *argv[] ){    GtkWidget *window = NULL;    GtkWidget *box1;    GtkWidget *box2;    GtkWidget *button;    GtkWidget *separator;    GSList *group;      gtk_init(&#38;argc,&#38;argv);              window = gtk_window_new (GTK_WINDOW_TOPLEVEL);      gtk_signal_connect (GTK_OBJECT (window), "delete_event",		        GTK_SIGNAL_FUNC(close_application),                        NULL);    gtk_window_set_title (GTK_WINDOW (window), "radio buttons");    gtk_container_set_border_width (GTK_CONTAINER (window), 0);    box1 = gtk_vbox_new (FALSE, 0);    gtk_container_add (GTK_CONTAINER (window), box1);    gtk_widget_show (box1);    box2 = gtk_vbox_new (FALSE, 10);    gtk_container_set_border_width (GTK_CONTAINER (box2), 10);    gtk_box_pack_start (GTK_BOX (box1), box2, TRUE, TRUE, 0);    gtk_widget_show (box2);    button = gtk_radio_button_new_with_label (NULL, "button1");    gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);    gtk_widget_show (button);    group = gtk_radio_button_group (GTK_RADIO_BUTTON (button));    button = gtk_radio_button_new_with_label(group, "button2");    gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);    gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);    gtk_widget_show (button);    button = gtk_radio_button_new_with_label(	         gtk_radio_button_group (GTK_RADIO_BUTTON (button)),                 "button3");    gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);    gtk_widget_show (button);    separator = gtk_hseparator_new ();    gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 0);    gtk_widget_show (separator);    box2 = gtk_vbox_new (FALSE, 10);    gtk_container_set_border_width (GTK_CONTAINER (box2), 10);    gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, TRUE, 0);    gtk_widget_show (box2);    button = gtk_button_new_with_label ("close");    gtk_signal_connect_object (GTK_OBJECT (button), "clicked",                               GTK_SIGNAL_FUNC(close_application),                               GTK_OBJECT (window));    gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);    GTK_WIDGET_SET_FLAGS (button, GTK_CAN_DEFAULT);    gtk_widget_grab_default (button);    gtk_widget_show (button);    gtk_widget_show (window);         gtk_main();    return(0);}/* example-end */</PRE></TD></TR></TABLE></DIV><DIVCLASS="NAVFOOTER"><HRALIGN="LEFT"WIDTH="100%"><TABLEWIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top"><AHREF="sec-checkbuttons.html">&#60;&#60;&#60; Previous</A></TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="gtk-tut.html">Home</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top"><AHREF="ch-adjustments.html">Next &#62;&#62;&#62;</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Check Buttons</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="ch-buttonwidget.html">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">Adjustments</TD></TR></TABLE></DIV>        </td>    </tr></table>  </td>  </tr></table></body></BODY></HTML>
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