Hi @innerscript and thanks for your query. With regard to blink detection, I am afraid this is not something that is implemented as a ready to use algorithm within the Tobii Core SDK. To detect blinks, you would need to set up your own customised counter based upon the typical human blink duration of approximately 300ms.
For detecting the presence of a user, you have already the ‘userpresence’ state which you can implement according to the documentation as described @ https://tobii.github.io/CoreSDK/articles/states.html
Additionally, you can download our Core SDK sample programs demonstrating the use of this state @ https://github.com/Tobii/CoreSDK and navigate to the ‘Interaction States’ directory.
Accordingly, if you are tracking gaze upon an object, with the userpresence state as a conditional expectation, you can count the duration that no gaze data is found until reaching a pre-determined blink threshold. This should similarly allow you to detect the presence of a user when eyes are closed and of course when the eyes open once.
Apologies that you need to create some of this functionality yourself, but hopefully the above links will prove useful for your needs. In any event, please don’t hesitate to let us know if we can provide any further assistance.