Introduction - If you have any usage issues, please Google them yourself
The so-called callback virtual COM-based ActiveX control interface, and client communication, generally is the case, that is, within the project in the ActiveX idl file to define a virtual interface, the client program to define a virtual interface to implement a derived class callback function, the client program passes a pointer to a derived class object ActiveX controls within the control interface called the virtual function to stimulate the client program of the derived class corresponding callbacks.