设计流程图的系统，有完整的操作界面，较好的交互性，画面比较简单，整个代码的结构比较清晰，对于设计自己的流程图代码有比较好的借鉴作用。-Design flow chart of the system, a complete operator interface, better interactivity, the screen is relatively simple, the whole structure of the code is relatively clear, a good refe