Simple_window.h

#include "GUI.h"    // for Simple_window only (doesn't really belong in Window.h)

using namespace Graph_lib;

// Simple_window is basic scaffolding for ultra-simple interaction with graphics
// it provides one window with one "next" button for ultra-simple animation

struct Simple_window : Window {
    Simple_window(Point xy, int w, int h, const string& title)
        : Window(xy, w, h, title),
        button_pushed(false),
        next_button(Point(x_max() - 70, 0), 70, 20, "Next", cb_next) {
        attach(next_button);
    }

    void wait_for_button()
        // modified event loop
        // handle all events (as per default), but quit when button_pushed becomes true
        // this allows graphics without control inversion
    {
        while (!button_pushed) Fl::wait();
        button_pushed = false;
        Fl::redraw();
    }

    Button next_button;
private:
    bool button_pushed;

    static void cb_next(Address, Address addr) // callback for next_button
                                               //   { reference_to<Simple_window>(addr).next(); }
    {
        static_cast<Simple_window*>(addr)->next();
    }

    void next() { button_pushed = true; }

};