The Samyutta Nikaya connects the four brahmaviharas as well as anapanasati with the seven factors of awakening. Altogether, the seven factors almost seem like a way of summing up Samadhi:
Keen investigation of the dhamma (dhammavicaya)
Rapture or happiness (piti)
Right Effort, Right Mindfulness, and Right Concentration all seem to be included; the only trick is that we have discourses showcasing how anapanasati fulfills satipatthana, but I'm not aware of there being an explicit connection like that between the brahmaviharas and satipatthana, although karuna is closely allied with efforts to suppress the hindrance of ill-will.