you are right, the subjunctive is required in case of desire/volition. but in this particular case, i would have used l'indicatif, because to me it seems more like a statement than a desire. he says "i am happy you liked the photos" and this implies the fact that the other person has already admitted to liking them. so he is sure the other person liked the photos. it is because of this certainty that i would have used l'indicatif... at least, that's what they taught us in school
et les nombreux exemples.Le subjonctif s’emploie dans la subordonnée si le verbe de la principale exprime le doute, l’improbabilité, la volonté, le désir, la défense, la nécessité, la possibilité, l’impossibilité ou un sentiment.