// =====================================================================
// 第 2 课：按钮与回调 —— 老师完整答案
// =====================================================================

#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Button.H>
#include <FL/Fl_Box.H>

Fl_Box *result_box;

void draw_callback(Fl_Widget *w, void *data) {
    result_box->label("你点击了抽卡按钮！");
    result_box->labelcolor(FL_RED);
}

int main() {
    Fl_Window *window = new Fl_Window(400, 300, "抽卡世界 - 第2课");

    Fl_Button *btn = new Fl_Button(130, 40, 140, 50, "抽一张！");
    btn->labelsize(18);
    btn->callback(draw_callback);

    result_box = new Fl_Box(50, 130, 300, 100, "");
    result_box->labelsize(20);

    window->end();
    window->show();
    return Fl::run();
}