Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!sgi!daisy!rob
From: rob@daisy.UUCP (Rob Posadas)
Newsgroups: comp.windows.x
Subject: Re: what is backing store?
Message-ID: <1346@daisy.UUCP>
Date: 7 Jul 88 21:01:34 GMT
References: <149@henry.ece.utexas.edu> <19880706125708.8.RWS@KILLINGTON.LCS.MIT.EDU>
Reply-To: rob@daisy.UUCP (Rob Posadas)
Organization: Daisy Systems Corp., Mountain View, Ca.
Lines: 18

In article <19880706125708.8.RWS@KILLINGTON.LCS.MIT.EDU> RWS@ZERMATT.LCS.MIT.EDU (Robert Scheifler) writes:
>server copies the saved contents back onto the screen.  The advantage of
>backing store is that the client doesn't have to repaint regions of the
>window when they become unobscured.  This is a win if the contents of
>the window are relatively complex and expensive to recompute/redraw.  As


The two disadvantages of backing store that I know of are 
    1. Memory must be allocated by the server to save the 
       contents and 
    2. The performance may degrade if the server is performing 
       each output primitive twice, once to the window and once 
       to the backing store pixmap.

-- 
            Rob Posadas -- Daisy Systems Corp
            700 E. Middlefield Rd.
            Mt. View, CA 94039-7006
            ucbvax!imagen!atari!daisy!rob