为上述建立的控件建立callBack(回调函数) Creates callbacks for these controls that implement the visualizations. The visualizations are implemented by sending an array of strings to the animation manager – the animation manager will then implement the animation, and handle all of the animation controls for you 为这些实现可视化的控件创建回调。 通过向动画管理器发送字符串数组来实现可视化 - 动画管理器将实现动画,并为您处理所有动画控件
Listen for an undo event from the animation manager. When an undo event is detected, roll back the last operation 从动画管理器中听取撤消事件。 当检测到撤消事件时,回退上次的操作(“上一步骤”按钮功能响应?)