Animation of Computer-Generated Display Components of User Interfaces and Content Items

Animation of computer-generated display components of user interfaces and content items is provided. An animation application or engine creates images of individual display components (e.g., bitmap images) and places those images on animation layers. Animation behaviors may be specified for the layers to indicate how the layers and associated display component images animate or behave when their properties change (e.g., a movement of an object contained on a layer), as well as, to change properties on layers in order to trigger animations (e.g., an animation that causes an object to rotate). In order to achieve high animation frame rates, the animation application may utilize three processing threads, including a user interface thread, a compositor thread and a rendering thread. Display behavior may be optimized and controlled by utilizing a declarative markup language, such as the Extensible Markup Language, for defining display behavior functionality and properties.