It's about a boy who escapes the real world and goes to this fantasy world where he befriends these big furry trolls, the trolls are animated, but the boy is played by an actor.
Where the Wild Things Are (2009)?
A young boy named Max has an active imagination, and he will throw fits if others don't go along with what he wants. Max - following an incident with Claire (his sister) and her friends, and following a tantrum which he throws as a result of his Mother paying more attention to her boyfriend than to him - runs away from home. Wearing his wolf costume at the time, Max not only runs away physically, but runs toward a world in his imagination. This world, an ocean away, is inhabited by large wild beasts, including one named Carol who is much like Max himself in temperament. Instead of eating Max like they normally would with creatures of his type, the wild things befriend Max after he proclaims himself a king who can magically solve all their problems.
Found by memory. Never seen it but I remembered the big furry things as well (and the funny pun in the translated title in my mother tongue, French).
This seems like Where the Wild Things Are:
In the movie, a boy name Max runs away, traversing a pond that becomes an ocean to find an island with Wild Things, which do look like trolls.