按钮未显示

Question

我应该画一个带灯泡的窗口，并有一个按钮可以打开（白色）和关闭（黑色）。这是完整的目标：编写一个程序来显示一个窗口，其中一个圆圈代表一个灯泡，一个标有＆＃34; ON / OFF＆＃34;的按钮。灯泡从黑色开始，即关闭。当点击按钮时，灯泡打开，即白色。再次单击该按钮时，指示灯熄灭，依此类推。 但出于某种原因，圆圈没有出现在窗口中这是我的代码：

#include "std_lib_facilities_5.h"
#include "Simple_window.h"
#include "Graph.h"
#include "Window.h"
#include "Point.h"

struct Lines_window : Graph_lib::Window {
    Lines_window(Point xy, int w, int h, const string& title);

    Circle light_bulb{Point{400,400},150};

private:
    Button on;

    bool button_pushed;

    static void cb_on1(Address, Address);       // callback for next_button

    void on1();  // action to be done when next_button is pressed
};

Lines_window::Lines_window(Point xy, int w, int h, const string& title)
:Window{xy,w,h,title},
on{Point{x_max()-100,0}, 70, 20, "ON/OFF",cb_on1},
button_pushed{false}
{
    attach(on);
}


void Lines_window::cb_on1(Address, Address pw)
// call Simple_window::next() for the window located at pw
{
    reference_to<Lines_window>(pw).on1();
}

void Lines_window::on1(){

    if (button_pushed)
    {
        light_bulb.set_fill_color(Color::white);
        button_pushed = false;
        redraw();
    }
    else
    {
        light_bulb.set_fill_color(Color::black);
        button_pushed = true;
        redraw();
    }
    redraw();
}

int main ()
{
    try{
        Lines_window win {Point{100,100},800,800,"Light Bulb"};
        return gui_main();

    }
    catch (exception& e){ //catches range errors and run_time_errors
        cerr << "error: "<< e.what() <<'\n';
        return 1;
    }
    catch (...){ //catch any exception
        cerr <<"Exception: something went wrong \n";
        return 2;
    }
}