Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!ucdavis!iris!rogers
From: rogers@iris.ucdavis.edu (Brewski Rogers)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Fast Scrolling
Summary: uhh...
Keywords: scroll
Message-ID: <6096@ucdavis.ucdavis.edu>
Date: 30 Nov 89 02:35:06 GMT
References: <13939@eerie.acsu.Buffalo.EDU>
Sender: uucp@ucdavis.ucdavis.edu
Reply-To: rogers@iris.ucdavis.edu (Brewski Rogers)
Organization: U.C. Davis - Department of Electrical Engineering and Computer Science
Lines: 25

In article <13939@eerie.acsu.Buffalo.EDU> gbbrooks@sybil.cs.buffalo.edu (G. Brandon Brooks) writes:
>	I use Benchmark Modula-2, and to scroll a view, all I do is:
>
>ViewPort.DxOffset := 10;
>ViewPort.DyOffset := 5;
>ScrollVPort(ViewPort);
>
>	This moves a view IMMEDIATELY 10 pixels to the right, and 5 pixels
>down; effextively making (10,5) the origin of the screen (0,0).

ScrollVPort is actually pretty slow. Also, in the RKM's it is described
as having a slight bug where it may flicker periodically.
Doesn't ScrollVPort do a MergeCopList (or whatever its called)?
Basically, any system command is going to have to do some big data
moving to get the screen's new copperlist to work with the screen-dragging
the O.S. supports.

It depends on how much CPU time you want to spend scrolling your view.


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