Hi @hmlee,
I think the point @grant-rogers is trying to make is that the Tobii Engine SDK license agreement does not allow for storing eye-gaze data on disk or storage media for later analysis. The eye-gaze data is free to be used for gaze interaction purposes in games and applications, using it real-time so to speak.
It seems your questions are mostly related to how to implement things in C. The minimal C samples are not really meant to be a basis to build an application on top of. They are supposed to show the different functions that are available in the API. I would assume most people use C++ to code against the C API and use bits and pieces from the sample code in their own application.
While we are happy to help you with questions about eye tracking data and the API itself, I would have to point you to online C and C++ programming resources to figure out how to program in general or how to use things like ‘_getch()’. Google and Stackoverflow are your friends for this 🙂
Here are some hints how to get data “from the HandleEvent function to the main function”, though:
The callbacks to HandleEvent come on a background thread, so you need to temporarily store the gaze point and eye position values in variables that are accessible from the main loop, and then read the values in the main loop when you get the user input. I guess the fast and easy way to do this is to store the values in global variables.
Happy coding!