The frog Princess

This book is about a princess and a frog who claims to be a prince.
He keeps asking for a kiss and princess Emeralda gives him a kiss. She turned into a frog and has to feed on flies, dragonflies, and rotten fruit.
Emma is a bad swimmer but as a frog she can swim way faster and better. Both frogs have many predators and troubles. With one last kiss they they can see themselves as humans.