This is part of a more general work dedicated to gtkmm accessible here. This example shows how to create a drawing area with Cairo.

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Source code

main.cpp

#include 
#include 


int main(int argc, char* argv[])
{
    // Initialize gtkmm and create the main window
    Glib::RefPtr app = Gtk::Application::create(argc, argv, "www.lucidarme.me");
    Gtk::Window window;
    
    // Create the drawing
    Drawing Dwg;

    // Insert the drawing in the window
    window.add(Dwg);

    // Show the drawing
    Dwg.show();

    // Start main loop
    return app->run(window);
}

drawing.h

#ifndef DRAWING_H
#define DRAWING_H

#include 
#include 

class Drawing : public Gtk::DrawingArea
{
public:
	Drawing();
	
protected:
	//Override default signal handler:
	virtual bool on_draw(const Cairo::RefPtr& cr);
	
};

#endif // DRAWING_H

drawing.cpp

#include "drawing.h"

Drawing::Drawing()
{
}


bool Drawing::on_draw(const Cairo::RefPtr& cr)
{
    // Set color
    cr->set_source_rgb(0, 0.0, 1.0);
    // Set line width
    cr->set_line_width(15.0);
    // Set line cap
    cr->set_line_cap(Cairo::LINE_CAP_ROUND);

    // Draw the lines
    cr->move_to(50, 50);
    cr->line_to(150, 150);
    cr->move_to(150,50);
    cr->line_to(50, 150);

    // Apply drawing
    cr->stroke();

    return true;
}