The Basics

Most GObject APIs are mapped straightforwardly into C++. GObject classes are mapped to C++ classes, and their methods are mapped to C++ methods.

The following is an example of invoking the Gtk::Button::set_label and Gtk::Widget::set_valign methods on a button:

#include <peel/Gtk/Gtk.h>

using namespace peel;

Gtk::Button *button = /* ... */;
button->set_label ("My Button");
button->set_valign (Gtk::Align::CENTER);

GObject constructors are mapped to C++ static factory methods, with the “new” part of a constructor name replaced with “create” (because a bare new is a C++ keyword):

#include <peel/Gtk/Gtk.h>

using namespace peel;

auto window = Gtk::Window::create ();
window->set_title ("My Window");

auto button = Gtk::Button::create_with_label ("My Button");

To connect to a GObject signal, use the corresponding .connect_signal_name () method, which you can pass a C++ lambda to:

#include <peel/Gtk/Gtk.h>

using namespace peel;

auto button = Gtk::Button::create_with_label ("Click me");
int times_clicked = 0;
/* Connect a handler to the "clicked" signal of the button */
button->connect_clicked ([&times_clicked] (Gtk::Button *button)
  {
    g_print ("You clicked the button %d times!\n", ++times_clicked);
  });

The following is a complete working example of a tiny application:

#include <peel/Gtk/Gtk.h>
#include <peel/GLib/GLib.h>

using namespace peel;

int
main ()
{
  Gtk::init ();

  auto window = Gtk::Window::create ();
  window->set_title ("Example");

  auto button = Gtk::Button::create_with_label ("Click me");
  int times_clicked = 0;
  button->connect_clicked ([&times_clicked] (Gtk::Button *button)
    {
      g_print ("You clicked the button %d times!\n", ++times_clicked);
    });

  window->set_child (std::move (button));
  window->present ();

  auto main_loop = GLib::MainLoop::create (nullptr, false);
  main_loop->run ();

  return 0;
}