Bouton radio

De même que les cases à cocher, les boutons radio héritent aussi des propriétés des Gtk::ToggleButton, mais les boutons radio fonctionnent en groupe et, dans un groupe, un seul et unique bouton radio peut être sélectionné à un moment donné.

V.IV.I. Groupes

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 put 3 radio buttons in a group:

auto rb1 = Gtk::make_managed<Gtk::RadioButton>("button1");
auto rb2 = Gtk::make_managed<Gtk::RadioButton>("button2");
auto rb3 = Gtk::make_managed<Gtk::RadioButton>("button3");
rb2->join_group(*rb1);
rb3->join_group(*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.

The purpose of join_group() is to make it easier to express that you want a given button to use a group established by another. There is another way to do this, using get_group() and set_group(). However, this has a pitfall: Note that you can't do

rb2->set_group(rb1->get_group());
because get_group() returns a RadioButton::Group by value, and an unnamed rvalue cannot be passed as the lvalue reference needed by set_group(). Instead, you must assign the result of get_group() to a variable and pass that to set_group() as an lvalue:

auto rb1 = Gtk::make_managed<Gtk::RadioButton>("button1");
auto rb2 = Gtk::make_managed<Gtk::RadioButton>("button2");
auto rb3 = Gtk::make_managed<Gtk::RadioButton>("button3");
auto group = rb1->get_group();
rb2->set_group(group);
rb3->set_group(group);

This works because the group is really a handle and therefore can be discarded once it has been used to tell the radio buttons to group with each other. Still, as join_group() does the same thing in one less line, you might not find much use for this pattern, but it is shown for completeness.

La deuxième façon pour grouper des boutons radio consiste à créer un groupement au préalable, puis y intégrer les boutons. Voici un exemple :

Gtk::RadioButton::Group group;
auto rb1 = Gtk::make_managed<Gtk::RadioButton>(group, "button1");
auto rb2 = Gtk::make_managed<Gtk::RadioButton>(group, "button2");
auto rb3 = Gtk::make_managed<Gtk::RadioButton>(group, "button3");

Nous générons un nouveau groupe par une simple déclaration de variable, group, du type Gtk::RadioButton::Group, puis nous créons trois boutons radio avec le constructeur indiquant qu'ils font partie du groupe group.

V.IV.II. Fonctions membres

À leur création, les objets de la classe RadioButtons sont « inactifs », donc, lors de la création du groupe, tous les boutons sont désactivés. N'oubliez donc pas d'en activer un avec set_active() :

Reference

V.IV.III. Exemple

L'exemple suivant montre l'utilisation de la classe RadioButton :

Figure V.3 Bouton radio

Source Code

File: radiobuttons.h (For use with gtkmm 3)

#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: main.cc (For use with gtkmm 3)

#include "radiobuttons.h"
#include <gtkmm/application.h>

int main(int argc, char *argv[])
{
  auto app = Gtk::Application::create(argc, argv, "org.gtkmm.example");

  RadioButtons buttons;

  //Shows the window and returns when it is closed.
  return app->run(buttons);
}

File: radiobuttons.cc (For use with gtkmm 3)

#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");
  set_border_width(0);

  // 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.pack_start(m_Box1);
  m_Box_Top.pack_start(m_Separator);
  m_Box_Top.pack_start(m_Box2);

  // Set the inner boxes' borders
  m_Box2.set_border_width(10);
  m_Box1.set_border_width(10);

  // Put the radio buttons in Box1:
  m_Box1.pack_start(m_RadioButton1);
  m_Box1.pack_start(m_RadioButton2);
  m_Box1.pack_start(m_RadioButton3);

  // Set the second button active
  m_RadioButton2.set_active();

  // Put Close button in Box2:
  m_Box2.pack_start(m_Button_Close);

  // 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) );

  // Show all children of the window
  show_all_children();
}

RadioButtons::~RadioButtons()
{
}

void RadioButtons::on_button_clicked()
{
  hide(); //to close the application.
}