RadioButton (单选按钮)
和 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. 组
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());
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.
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:
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");
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。
5.4.3. 示例
接下来的例子中演示了 RadioButton 的用法:
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. }