// Example comes from:
// https://translate.google.com/translate?hl=en&sl=ru&u=https://habr.com/post/145160/&prev=search

#include <gtkmm.h> 
#include <cairomm/cairomm.h> 
/** Main window class. */ 
class MainWindow: public Gtk::Window { 
private: 
	/** Subclass for drawing area. */ 
	class CDrawingArea: public Gtk::DrawingArea { 
	public: 
		typedef enum { SHAPE_RECTANGLE, SHAPE_ELLIPSE, SHAPE_TRIANGLE } shape_t; 
	private: 
		shape_t _curShape = SHAPE_RECTANGLE; 

		/** Drawing event handler. */ 
		virtual bool on_draw(const Cairo::RefPtr<Cairo::Context>& cr) { 
			switch (_curShape) { 
				case SHAPE_RECTANGLE: 
					cr->rectangle(20, 20, 200, 100); 
					cr->set_source_rgb(0, 0.8, 0); 
					cr->fill_preserve(); 
					break; 
				case SHAPE_ELLIPSE: 
					cr->arc(150, 100, 90, 0, 2 * 3.14); 
					cr->set_source_rgb(0.8, 0, 0); 
					cr->fill_preserve(); 
					break; 
				case SHAPE_TRIANGLE: 
					cr->move_to(40, 40); 
					cr->line_to(200, 40); 
					cr->line_to(120, 160); 
					cr->line_to(40, 40); 
					cr->set_source_rgb(0.8, 0, 0.8); 
					cr->fill_preserve(); 
					cr->set_line_cap(Cairo::LINE_CAP_ROUND); 
					cr->set_line_join(Cairo::LINE_JOIN_ROUND); 
					break; 
				} 
				cr->set_line_width(3); 
				cr->set_source_rgb(0, 0, 0); 
				cr->stroke(); 
				return true; 
			} 
	public: 
		CDrawingArea(BaseObjectType* cobject, const Glib::RefPtr<Gtk::Builder>& builder)
			: Gtk::DrawingArea(cobject) {} 

		void SetShape(shape_t shape) { 
			if (_curShape != shape) { 
				_curShape = shape; 
				queue_draw(); // Request re-drawing. 
			} 
		} 
	};

	Glib::RefPtr<Gtk::Builder> _builder; 
	Gtk::RadioButton *_rbRect, *_rbEllipse, *_rbTriangle; 
	Gtk::ScrolledWindow *_swin;
	CDrawingArea *_drawingArea; 
public: 
	/** Signal handler which is called when any radio button is clicked. */ 
	void OnRadiobuttonClick() { 
		if (_rbRect->get_active()) { 
			_drawingArea->SetShape(CDrawingArea::SHAPE_RECTANGLE); 
		} else if (_rbEllipse->get_active()) { 
			_drawingArea->SetShape(CDrawingArea::SHAPE_ELLIPSE); 
		} else if (_rbTriangle->get_active()) { 
			_drawingArea->SetShape(CDrawingArea::SHAPE_TRIANGLE); 
		} 
	} 

	/** "quit" action handler. */ 
	void OnQuit() { hide(); } 

	MainWindow(BaseObjectType* cobject, const Glib::RefPtr<Gtk::Builder>& builder): Gtk::Window(cobject), _builder(builder) {
		/* Retrieve all widgets. */ 
		_builder->get_widget("rbutRectangle", _rbRect); 
		_builder->get_widget("rbutEllipse", _rbEllipse); 
		_builder->get_widget("rbutTriangle", _rbTriangle); 
		_builder->get_widget("scrolledwindow1", _swin);
		_builder->get_widget_derived("drawingarea", _drawingArea); 
		_drawingArea->set_size_request( 300, 200 );
		_swin->set_min_content_height( 200 );
		_swin->set_min_content_width( 300 );

		/* Connect signals. */ 
		_rbRect->signal_clicked().connect(sigc::mem_fun(*this, &MainWindow::OnRadiobuttonClick)); 
		_rbEllipse->signal_clicked().connect(sigc::mem_fun(*this, &MainWindow::OnRadiobuttonClick)); 
		_rbTriangle->signal_clicked().connect(sigc::mem_fun(*this, &MainWindow::OnRadiobuttonClick)); 

		/* Actions. */ 
		Glib::RefPtr<Gtk::Action>::cast_dynamic( _builder->get_object("action_quit"))-> 
			signal_activate().connect(sigc::mem_fun(*this, &MainWindow::OnQuit)); 
	}
}; 

int main(int argc, char **argv) { 
	Gtk::Main app(argc, argv); 
	Glib::RefPtr<Gtk::Builder> builder = Gtk::Builder::create_from_file("sample.glade"); 
	MainWindow *mainWindow = nullptr; 
	builder->get_widget_derived("topWindow", mainWindow); 
	app.run(*mainWindow); 
	delete mainWindow; 
	return 0; 
}