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Smooth Moving for Rectangular Raster Display Areas

IP.com Disclosure Number: IPCOM000063292D
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18

Publishing Venue

IBM

Related People

Authors:
Webster, JW [+details]

Abstract

This article relates generally to methods for controlling the position of elements on a raster display and more particularly to a method for smoothly moving a rectangular area on a display with a minimum of screen flicker. To achieve smooth movement of a rectangular area with minimum flicker, the total number of bits drawn when the rectangular area is moved must be reduced. It was noted that the least number of bits which can be drawn and still have the desired function performed is equal to the total number of bits (n) in the area being moved. A known algorithm always draws (2n) bits. If the known algorithm is to be improved, somewhere between (n) and (2n) bits must be drawn. This can be accomplished by not drawing the region which results from the overlap between the old and new positions of the rectangular areas. Fig.