It sounds like you are asking if there is a way to determine what type of a control either A) the user is currently focused in, or B) is bound to a particular field in your DOM.
The answer is that you can't... at least not directly.
There might be a round-about way to do this which is to load the particular view into your code, and search it for the field in question, and then from there step back up the DOM to determine which control is being used.
This will take some good coding on your part, but I believe it is doable.
Greg Collins [InfoPath MVP]
InfoPath Dev