说明：  ugui是一个极为精简的gui框架，适合于嵌入式系统简单界面开发，只有两个文件组成，使用极为方便。
(μGUI is a free and open source graphic library for embedded systems. It is platform-independent and can be easily ported to almost any microcontroller system. As long as the display is capable of showing graphics, μGUI is not restricted to a certain display technology. Therefore, display technologies such as LCD, TFT, E-Paper, LED or OLED are supported. The whole module consists of two files: ugui.c and ugui.h.)