This is useful if the image contains transparent pixels. The ImageObserver parameter specifies an object that implements the ImageObserver interface. This object will be notified whenever new information regarding the image becomes available. Tell it to track one or more images. Ask the MediaTracker the status of images.
Frames can be incrementally different images or graphics operations.
A good rule of thumb is that animation should run on a separate thread in order not to adversely affect event handling. Incorporating threading with animation permits the suspension and resumption of animation with button or mouse events. This involves performing multiple graphics operations on an undisplayed graphics buffer and then displaying the completed image on the screen. Besides preventing incomplete images from being drawn to the screen, double buffering improves drawing performance. This is because drawing to an offscreen image is more efficient than drawing to the screen.