Chapter 16. Dialogs

# Chapter 16. Dialogs

Dialogs are used as secondary windows, to provide specific information or to ask questions. `Gtk::Dialog` windows contain a few pre-packed widgets to ensure consistency, and a `run()` method which blocks until the user dismisses the dialog.

There are several derived `Dialog` classes which you might find useful. `Gtk::MessageDialog` is used for most simple notifications. But at other times you might need to derive your own dialog class to provide more complex functionality.

To pack widgets into a custom dialog, you should pack them into the `Gtk::Box`, available via `get_content_area()`. To just add a `Button` to the bottom of the `Dialog`, you could use the `add_button()` method.

The `run()` method returns an `int`. This may be a value from the `Gtk::ResponseType` if the user closed the dialog by clicking a standard button, or it could be the custom response value that you specified when using `add_button()`.

Reference

## MessageDialog

`MessageDialog` is a convenience class, used to create simple, standard message dialogs, with a message, an icon, and buttons for user response. You can specify the type of message and the text in the constructor, as well as specifying standard buttons via the `Gtk::ButtonsType` enum.

Reference

### Example

Figure 16.1. MessageDialog

Source Code

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

    #ifndef GTKMM_EXAMPLEWINDOW_H
    #define GTKMM_EXAMPLEWINDOW_H

    #include <gtkmm.h>

    class ExampleWindow : public Gtk::Window
    {
    public:
      ExampleWindow();
      virtual ~ExampleWindow();

    protected:
      //Signal handlers:
      void on_button_info_clicked();
      void on_button_question_clicked();

      //Child widgets:
      Gtk::ButtonBox m_ButtonBox;
      Gtk::Button m_Button_Info, m_Button_Question;
    };

    #endif //GTKMM_EXAMPLEWINDOW_H

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

    #include "examplewindow.h"
    #include <gtkmm/messagedialog.h>
    #include <iostream>

    ExampleWindow::ExampleWindow()
    : m_ButtonBox(Gtk::ORIENTATION_VERTICAL),
      m_Button_Info("Show Info MessageDialog"),
      m_Button_Question("Show Question MessageDialog")
    {
      set_title("Gtk::MessageDialog example");

      add(m_ButtonBox);

      m_ButtonBox.pack_start(m_Button_Info);
      m_Button_Info.signal_clicked().connect(sigc::mem_fun(*this,
                  &ExampleWindow::on_button_info_clicked) );

      m_ButtonBox.pack_start(m_Button_Question);
      m_Button_Question.signal_clicked().connect(sigc::mem_fun(*this,
                  &ExampleWindow::on_button_question_clicked) );

      show_all_children();
    }

    ExampleWindow::~ExampleWindow()
    {
    }

    void ExampleWindow::on_button_info_clicked()
    {
      Gtk::MessageDialog dialog(*this, "This is an INFO MessageDialog");
      dialog.set_secondary_text(
              "And this is the secondary text that explains things.");

      dialog.run();
    }

    void ExampleWindow::on_button_question_clicked()
    {
      Gtk::MessageDialog dialog(*this, "This is a QUESTION MessageDialog",
              false /* use_markup */, Gtk::MESSAGE_QUESTION,
              Gtk::BUTTONS_OK_CANCEL);
      dialog.set_secondary_text(
              "And this is the secondary text that explains things.");

      int result = dialog.run();

      //Handle the response:
      switch(result)
      {
        case(Gtk::RESPONSE_OK):
        {
          std::cout << "OK clicked." << std::endl;
          break;
        }
        case(Gtk::RESPONSE_CANCEL):
        {
          std::cout << "Cancel clicked." << std::endl;
          break;
        }
        default:
        {
          std::cout << "Unexpected button clicked." << std::endl;
          break;
        }
      }
    }

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

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

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

      ExampleWindow window;

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

Chapter 15. Widgets Without X-Windows |  | FileChooserDialog