save code

solutions/lesson_gui_2.cpp

@@ -0,0 +1,30 @@
+// =====================================================================
+// 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, "请点击按钮抽卡～");
+    result_box->labelsize(20);
+
+    window->end();
+    window->show();
+    return Fl::run();
+}