RadioButton (单选按钮)

Gtk::CheckButton 一样,Gtk::RadioButton 也继承自 Gtk::ToggleButton,只是它们是按组工作的,并且一个组内一次只能选中一个 RadioButton。

5.4.1. 

有两种方式创建一个单选按钮的组。第一种方式是先创建按钮,然后再设置它们的组。这种方式只用到了前两个构造函数。在下面的示例中,我们创建了一个新的窗口类 RadioButtons,然后在其中放置3个单选按钮:

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")
{
    Gtk::RadioButton::Group group = m_rb1.get_group();
    m_rb2.set_group(group);
    m_rb3.set_group(group);
}

我们告诉 gtkmm 把三个 RadioButton 都放到一个组内,通过 get_group() 来得到这个组,然后使用 set_group() 告诉其它的 RadioButton 来共享这个组。

注意,你不能只是

m_rb2.set_group(m_rb1.get_group()); //无法工作
因为该组会由 set_group() 修改,所以它不能是一个常量。

第二种创建单选按钮的方式是,先创建一个组,然后再向该组加入按钮。请看下面的示例:

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"));
}

我们通过声明一个类型为 Gtk::RadioButton::Group 的名为 group 的变量。然后我们创建三个单选按钮,用构造函数把它们放置到组 group 中。

5.4.2. 方法

RadioButtons 创建后默认是未选中的,也就是说当你第一次创建一组单选按钮的时候,它们都会是未选中的。所以别忘了使用 set_active() 来选中一个:

参考

5.4.3. 示例

接下来的例子中演示了 RadioButton 的用法:

图 5-3RadioButton (单选按钮)

源代码

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);
}