Botão de opção

Como os de seleção, botões de opção também é uma classe filho de Gtk::ToggleButton, mas eles trabalham em grupos, e só um botão de opção em um grupo pode estar selecionado por vez.

5.4.1 Grupos

Existem duas maneiras de definir um grupo de botões de opção. A primeira é criar os botões e configurar os seus grupos em seguida. Somente os dois primeiros construtores são usados. No exemplo a seguir, fazemos uma nova classe janela chamada RadioButtons, e então colocamos três botões nela:

class RadioButtons : public Gtk::Window
{
public:
    RadioButtons();

protected:
    Gtk::RadioButton m_rb1, m_rb2, m_rb3;
};

RadioButtons::RadioButtons()
  : m_rb1("botão1"),
    m_rb2("botão2"),
    m_rb3("botão3")
{
    Gtk::RadioButton::Group grupo = m_rb1.get_group();
    m_rb2.set_group(grupo);
    m_rb3.set_group(grupo);
}

We told gtkmm to put all three RadioButtons in the same group by obtaining the group with get_group() and using set_group() to tell the other RadioButtons to share that group.

Note that you can't just do 

m_rb2.set_group(m_rb1.get_group()); //doesn't work
because the group is modified by set_group() and therefore 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;
    Gtk::RadioButton *m_rb1 = Gtk::manage(
      new Gtk::RadioButton(group,"button1"));
    Gtk::RadioButton *m_rb2 = manage(
      new Gtk::RadioButton(group,"button2"));
      Gtk::RadioButton *m_rb3 = manage(
        new 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.

5.4.2 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():

Referência

5.4.3 Exemplo

The following example demonstrates the use of RadioButtons:

Figura 5.3 ‒ Botão de opção

Código-fonte

File: radiobuttons.h (For use with gtkmm 3, not gtkmm 2) 

#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 3, not gtkmm 2) 

#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:
  Gtk::RadioButton::Group group = m_RadioButton1.get_group();
  m_RadioButton2.set_group(group);
  m_RadioButton3.set_group(group);

  // 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.
}

File: main.cc (For use with gtkmm 3, not gtkmm 2) 

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

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

  RadioButtons buttons;

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

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