qt 调用库文件，能支持检查到USB连接，简单测试代码-qt called library files, to support the inspection to the USB connectivity, a simple test code

设计一个keypad UI 然后通过windows API调用一个ＵＳＢ软件，达到控制投影机的功能，UI做的非常的好，如果想做QT界面可以好好看看。-Design a keypad UI and then through a USB software windows API call, to control the projector function, UI do very well, if you want to do QT interface can have a good look.