Method for asynchronously maintaining an image on a display device

摘要

A method for asynchronously maintaining an image on a display device comprises the following steps. First, a drawing request is received from the application program. Then a drawing area of the image is determined in response to the received drawing request and an entry representing the drawing area is inserted into a list of entries representing respective drawing areas. A screen update request is then received from the application program. In response to this received screen update request, an entry representing a drawing area is retrieved from the list, and graphic objects are redrawn if any portion of the graphic object lies within the drawing area represented by the retrieved entry.