Graphics cursor handler

Abstract

A method for handling a cursor during a graphics drawing routine that eliminates the need to insert cursor handling code into graphics function definitions. The method coordinates the placement of the cursor in screen memory with the reading out of the scan lines containing the cursor. During this time, the cursor background is saved in offscreen memory. The cursor is protected by a cursor violation region, and drawing may continue while the cursor is in screen memory so long as the cursor violation region is not infringed, in which case drawing ceases until the cursor is read out of memory. The method prevents the cursor from flickering and maximizes the availability of screen memory to the drawing routine.