drawing_in_gtkmm

bool DrawingArea::on_draw(const Cairo::RefPtr<Cairo::Context>& cr)
{
cr->set_source_rgb(1.0, 1.0, 1.0);   // white background
cr->paint();

cr->set_line_width(2.0);

if(entity == 1)  // draw point
{
cr->set_source_rgb(0.0, 0.26, 0.26);
cr->save();
cr->arc(205.0, 110.0, 1.0, 0.0, 2 * M_PI); // full circle
cr->restore();
cr->stroke();
}

if(entity == 2)  // draw line
{
cr->set_source_rgb(0.0, 0.26, 0.26);
cr->save();
cr->move_to(0,0);
cr->line_to(100,100);
cr->restore();
cr->stroke();
}
    return true;
}

void DrawingArea :: on_point_cb()
{
entity = 1;
queue_draw();
std::cout<<"Point created"<<std::endl;
}

void DrawingArea :: on_line_cb()
{
entity = 2;
queue_draw();
std::cout<<"Line created"<<std::endl;
}