Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cbmvax!jesup
From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: quasi WB2.0 BUGS
Message-ID: <20150@cbmvax.commodore.com>
Date: 27 Mar 91 03:33:05 GMT
References: <3877@bruce.cs.monash.OZ.AU>
Reply-To: jesup@cbmvax.commodore.com (Randell Jesup)
Distribution: comp.sys.amiga.programmer
Organization: Commodore, West Chester, PA
Lines: 44

In article <3877@bruce.cs.monash.OZ.AU> roddi@bruce.cs.monash.OZ.AU (Roddi Walker) writes:
>	I was at a developer friend's house a few days ago, playing with
>WB 2.0.  While it is a huge advance over 1.3, I notices a few nasty things
>happen when fooling around with 10-20 windows, all roughly stacked over each
>other.

	Note that the release is likely to considerably different than a
developer-only beta.

>	First, the updates are SSLLLOOOOOOWWWWWWW - if I close/move/whatever
>a window, I have to wait 10+ seconds for the mouse to unfreeze and the
>update/redraw to finish.  It was this slow in 1.3, but I had hoped things
>would have sped up under 2.0 (this is on a 68000 A2000 with lots of ram,
>btw).  True, people normally fool around with 1-7 (say) windows, but this
>is a nasty limitation.  Just out of interest, I tried the same thing on
>a nasty 8MHz 68000 Mac Plus, and its performance (for window redrawing)
>was MUCH BETTER - Not appreciably slower than when it was redrawing
>just a couple of windows.  I would guess that the Mac uses a much smarter
>algorithm - not only is it unquestionably MUCH faster, but I also don't
>see poorly refreshed windows on the Mac as I do under WB 1.3 (sometimes).

	What's really going on here is that the mac doesn't allow anything
to draw into an unexposed window (notice how windows pop to the front when
you activate them?)  So it doesn't have to save off-screen bitmaps, and doesn't
have to worry much about clipping rectangles - only visible portions count.
Also, work has been done on layers to improve performance (and it has been
improved considerably from earlier 2.0 versions), but the basic algorithms
required to handle multitasking, (partially) obscured windows have an 
exponential component in the recalculation of the clipping rectangles.

>	Also, when 2.0 was redrawing the windoes, it would often leave
>vertical/horizontal 1 pixel wide/thick gaps when redrawing the window
>borders (the box with the scroll bars) and the little rectangle around the
>icons within the window.

	I haven't seen anything like this (if I read it right, it's confusingly
worded) in any recent version.

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.commodore.com  BIX: rjesup  
Thus spake the Master Ninjei: "To program a million-line operating system
is easy, to change a man's temperament is more difficult."
(From "The Zen of Programming")  ;-)