As the name suggests, a display object is something that will be displayed on the screen. We can think of display objects as separate graphical entities that contain different kinds of graphical data. While this may sound a bit abstract at first, every image (SPImage), quads (SPQuad), or other geometrical shapes are derived from the SPDisplayObject class, which is the representation of a display object in Sparrow.
A display object container (SPDisplayObjectContainer) inherits from SPDisplayObject, adding the facility to own a set of child display objects. When you add a child display object to a parent display object container, you can think of it as attaching one display object to another. If you move, scale, or rotate the parent display object, all the changes are inherited by any children it might have. This concept is more or less identical to how objects on the screen are managed in the Adobe Flash API. The full set of...