When a guy hugs you how can you tell the difference between a jokingly hug and an affectionate one?

i like this guy the other day he pulled me twords him for a hug of course i took then he groped my bicep a little, and then he hugged me and pulled me over to where he was sitting (my arms were pinned down and it was a pretty tight hug but his head was on my shoulder) and made me sit with him, anyway how can you tell when its a "im only hugging you bc i like you as a friend type of hug" to a "im only hugging you bc i want to be this close to your body" type of hug.