Botón de radio

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.

6.4.1. Grupos

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 segunda manera de establecer botones de radio es hacer primero un grupo y luego añadirle los botones a él. Aquí hay un ejemplo:

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");

Se creó un grupo nuevo simplemente declarando una variable, group, del tipo Gtk::RadioButton::Group. Luego, se hicieron tres botones de radio, usando un constructor para hacer que cada uno sea parte de group.

6.4.2. Métodos

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

6.4.3. Ejemplo

El siguiente ejemplo muestra el uso de RadioButton:

Figura 6-3Botón de radio

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
  set_default_widget(m_Button_Close);

  // 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);
}