Like check buttons, radio buttons also inherit from
Gtk::ToggleButton, but these work in groups, and only
one RadioButton in a group can be selected at any one time.
There are two ways to set up a group of radio buttons. The first way
is to create the buttons, and set up their groups afterwards. Only
the constructors without a Gtk::RadioButton::Group
parameter are used. In the following example, we
make a new window class called RadioButtons, and then
put three radio buttons in it:
class RadioButtons : public Gtk::Window
{
public:
RadioButtons();
protected:
Gtk::RadioButton m_rb1, m_rb2, m_rb3;
};
RadioButtons::RadioButtons()
: m_rb1("button1"),
m_rb2("button2"),
m_rb3("button3")
{
m_rb2.join_group(m_rb1);
m_rb3.join_group(m_rb1);
}
We told gtkmm to put all three RadioButtons in the
same group by using join_group() to tell the other
RadioButtons to share group with the first
RadioButton.
Note that you can't do
m_rb2.set_group(m_rb1.get_group()); //doesn't work
because get_group() returns a RadioButton::Group
which is modified by set_group() and therefore is non-const.
The second way to set up radio buttons is to make a group first, and then add radio buttons to it. Here's an example:
class RadioButtons : public Gtk::Window
{
public:
RadioButtons();
};
RadioButtons::RadioButtons()
{
Gtk::RadioButton::Group group;
auto m_rb1 = Gtk::make_managed<Gtk::RadioButton>(group, "button1");
auto m_rb2 = Gtk::make_managed<Gtk::RadioButton>(group, "button2");
auto m_rb3 = Gtk::make_managed<Gtk::RadioButton>(group, "button3");
}
We made a new group by simply declaring a variable, group,
of type Gtk::RadioButton::Group. Then we made three radio
buttons, using a constructor to make each of them part of group.
RadioButtons are "off" when created; this means that
when you first make a group of them, they will all be off. Don't forget to turn
one of them on using set_active().
The following example demonstrates the use of
RadioButtons:
File: radiobuttons.h (For use with gtkmm 4)
#ifndef GTKMM_EXAMPLE_RADIOBUTTONS_H
#define GTKMM_EXAMPLE_RADIOBUTTONS_H
#include <gtkmm/box.h>
#include <gtkmm/window.h>
#include <gtkmm/radiobutton.h>
#include <gtkmm/separator.h>
class RadioButtons : public Gtk::Window
{
public:
RadioButtons();
virtual ~RadioButtons();
protected:
//Signal handlers:
void on_button_clicked();
//Child widgets:
Gtk::Box m_Box_Top, m_Box1, m_Box2;
Gtk::RadioButton m_RadioButton1, m_RadioButton2, m_RadioButton3;
Gtk::Separator m_Separator;
Gtk::Button m_Button_Close;
};
#endif //GTKMM_EXAMPLE_RADIOBUTTONS_H
File: radiobuttons.cc (For use with gtkmm 4)
#include "radiobuttons.h"
RadioButtons::RadioButtons() :
m_Box_Top(Gtk::Orientation::VERTICAL),
m_Box1(Gtk::Orientation::VERTICAL, 10),
m_Box2(Gtk::Orientation::VERTICAL, 10),
m_RadioButton1("button1"),
m_RadioButton2("button2"),
m_RadioButton3("button3"),
m_Button_Close("close")
{
// Set title and border of the window
set_title("radio buttons");
// Put radio buttons 2 and 3 in the same group as 1:
m_RadioButton2.join_group(m_RadioButton1);
m_RadioButton3.join_group(m_RadioButton1);
// Add outer box to the window (because the window
// can only contain a single widget)
add(m_Box_Top);
//Put the inner boxes and the separator in the outer box:
m_Box_Top.add(m_Box1);
m_Box_Top.add(m_Separator);
m_Box_Top.add(m_Box2);
m_Separator.set_expand();
// Set the inner boxes' margins
m_Box1.set_margin(10);
m_Box2.set_margin(10);
// Put the radio buttons in Box1:
m_Box1.add(m_RadioButton1);
m_Box1.add(m_RadioButton2);
m_Box1.add(m_RadioButton3);
m_RadioButton1.set_expand();
m_RadioButton2.set_expand();
m_RadioButton3.set_expand();
// Set the second button active
m_RadioButton2.set_active();
// Put Close button in Box2:
m_Box2.add(m_Button_Close);
m_Button_Close.set_expand();
// Make the button the default widget
m_Button_Close.set_can_default();
m_Button_Close.grab_default();
// Connect the clicked signal of the button to
// RadioButtons::on_button_clicked()
m_Button_Close.signal_clicked().connect(sigc::mem_fun(*this,
&RadioButtons::on_button_clicked) );
}
RadioButtons::~RadioButtons()
{
}
void RadioButtons::on_button_clicked()
{
hide(); //to close the application.
}
File: main.cc (For use with gtkmm 4)
#include "radiobuttons.h"
#include <gtkmm/application.h>
int main(int argc, char *argv[])
{
auto app = Gtk::Application::create("org.gtkmm.example");
RadioButtons buttons;
//Shows the window and returns when it is closed.
return app->run(buttons, argc, argv);
}