/*
 * OS:				Ubuntu 18.04
 * Kernel:			Linux 4.15.0-42-generic
 * Compiler:		GCC 7.3.0
 * Libraries:		gtkmm 3.22.2-2
 * Instructions:	Compile with 'g++ -o test main.cpp `pkg-config --libs --cflags gtkmm-3.0`'
 *					and run with './test'.
 * Description:	Creates window called 'TITLE' of size 'WIDTH' x 'HEIGHT'
 *					and fills it with RGB color that is specified using 'Color' struct.
 *					The drawing area onto which is drawn is placed into scrolled window
 *					so that we can use the scrollbars to navigate the drawing area
 *		 			if the window is resized to smaller than initial size.
 *					The problem is that these scrollbars are not shown.
*/

#include <gtkmm.h>
#include <string>

// window attributes
#define TITLE "Test"
#define WIDTH 640
#define HEIGHT 480

// color to display in RGB format
struct Color
{
	double black = 0.0;
	double green = 0.0;
	double red = 0.0;
};

class DrawingArea : public Gtk::DrawingArea
{
	public:
		// copies dimensions of the window so the whole window is filled
		void copy_dimensions(Gdk::Rectangle& dimensions)
		{
			memcpy(&_dimensions, &dimensions, sizeof(Gdk::Rectangle));
			signal_draw().connect(sigc::mem_fun(*this, &DrawingArea::render));
			size_allocate(_dimensions);
		}

	private:
		Gdk::Rectangle _dimensions;

		// renders color onto the surface
		bool render(const Cairo::RefPtr<Cairo::Context>& cr)
		{
			Color color;
			cr->set_source_rgb(color.black, color.green, color.red);
			cr->rectangle(_dimensions.get_x(), _dimensions.get_y(), _dimensions.get_width(), _dimensions.get_height());
			cr->fill();
			return true;
		}
};

class Window : public Gtk::Window
{
	public:
		Window(const int width, const int height)
		{
			// set dimensions
			_dimensions.set_x(0);
			_dimensions.set_y(0);
			_dimensions.set_width(width);
			_dimensions.set_height(height);

			// set properties of window and its elements
			describe_window();

			// set drawing area
			_drawing_area.copy_dimensions(_dimensions);

			// attach all together
			attach_elements();
		}
	private:
		Gdk::Rectangle _dimensions;
		Gtk::ScrolledWindow _scroll_win;;
		DrawingArea _drawing_area;

		// set major window properties
		void describe_window()
		{
			// window itself
			set_title(TITLE);
			set_default_size(_dimensions.get_width(), _dimensions.get_height());

			// scrolling area
			_scroll_win.set_policy(Gtk::PolicyType::POLICY_AUTOMATIC, Gtk::PolicyType::POLICY_AUTOMATIC);
			_scroll_win.set_overlay_scrolling(true);
			_scroll_win.set_hexpand(true);
			_scroll_win.set_vexpand(true);
		}

		// properly glues all elements together
		void attach_elements()
		{
			_scroll_win.add(_drawing_area);
			add(_scroll_win);
		}
};

int main(int argc, char *argv[])
{
	// create app and run it
	Glib::RefPtr<Gtk::Application> test = Gtk::Application::create(argc, argv, "this.is.just.a.test");
	Window win(WIDTH, HEIGHT);
	win.show_all();
	return test->run(win);
}