TheComposite interface, along withCompositeContext, defines the methods to compose a draw primitive with the underlying graphics area. After theComposite is set in theGraphics2D context, it combines a shape, text, or an image being rendered with the colors that have already been rendered according to pre-defined rules. The classes implementing this interface provide the rules and a method to create the context for a particular operation.CompositeContext is an environment used by the compositing operation, which is created by theGraphics2D prior to the start of the operation.CompositeContext contains private information and resources needed for a compositing operation. When theCompositeContext is no longer needed, theGraphics2D object disposes of it in order to reclaim resources allocated for the operation.

Instances of classes implementingComposite must be immutable because theGraphics2D does not clone these objects when they are set as an attribute with thesetComposite method or when theGraphics2D object is cloned. This is to avoid undefined rendering behavior ofGraphics2D, resulting from the modification of theComposite object after it has been set in theGraphics2D context.