RadioButton

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.

Groups

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.

Methods

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().

Reference

Example

The following example demonstrates the use of RadioButtons:

Figure 6.3. RadioButton

RadioButton

Source Code

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);
}