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From: darren@cbmvax.commodore.com (Darren Greenwald)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Scrollable text windows
Message-ID: <17234@cbmvax.commodore.com>
Date: 8 Jan 91 18:18:19 GMT
References: <677@roo.UUCP> <06qW023804Ym01@JUTS.ccc.amdahl.com> <13421@milton.u.washington.edu>
Reply-To: darren@cbmvax.commodore.com (Darren Greenwald)
Distribution: comp.sys.amiga.tech
Organization: Commodore, West Chester, PA
Lines: 20

In article <13421@milton.u.washington.edu> bryant@milton.u.washington.edu (Jonathan Woolsey) writes:
>Why is it that no one implements smooth scrolling of text on the Amiga?
>I can see that it might be slow, but is easy on the eyes
>
>Jonathan
>bryant@milton.u.washington.edu.

 I have seen it done; it works, though as you noted its slower - For
an 8 pixel high font, you'd be looking at eight times the number of
layer/scroll operations to scroll a pixel at a time.  For some
color combinations it doesn't look so hot (e.g., any color combinations
which require 2+ bit-planes to draw the characters in ... in the case
of pen 1, on pen 0 though its not too bad since the second plane
is all 0's).  If you've seen the color artifacting which is visible
with some color combinations when scrolling (latency as all the bit-planes
are shuffled), smooth scrolling can look terrible.

Another variation on this idea is to smooth scroll when moving slowly
through the text, but use faster scrolling as the user moves the scroll
bar faster.