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From: trb@stag.UUCP ( Todd Burkey )
Newsgroups: comp.sys.atari.st
Subject: Re: MicroGnuEmacs
Message-ID: <233@stag.UUCP>
Date: Sat, 10-Oct-87 11:28:28 EDT
Article-I.D.: stag.233
Posted: Sat Oct 10 11:28:28 1987
Date-Received: Sat, 17-Oct-87 03:41:09 EDT
References: <8710071414.AA01109@work3.icase> <168@decvax.UUCP>
Reply-To: trb@stag.UUCP ( Todd Burkey )
Organization: Mindtools ST Access Group, Plymouth, MN
Lines: 27

In article <168@decvax.UUCP> minow@decvax.UUCP (Martin Minow) writes:
>calls vro_cpyfm() to scroll the screen directly.   If you can do this,
>you have demonstrated a good understanding both of the internal structure
>of MicroEmacs and of Gem.  Good luck.

Also, if you do this, be sure to set_screen (logical) to an off screen
buffer before doing the blit, then blit to it, write out the new line
(top or bottom, depending on the scroll direction), rewrite the
bottom status line, and finally set_screen (physical) to the offscreen
buffer...sounds messy, but it eliminates the blur effect on color
monitors. Take a look at the multi-lingual editor if you want to
see what updating just the current screen will do to you (a demo
version was floating around the bbs's recently). This method also
makes paging look instantaneous (and a lot easier on the eyes...and
yes, all that work can be done faster than using the vt52 calls (at
least in MWC 2.0). Keep in mind that this operation will run faster
with the blitter, so don't make paging or scrolling too fast :-).

   -Todd Burkey
   trb@stag.UUCP

PS...one other thing I noticed when I was doing the scrolling manager
on my editor...If you are shifting the page sideways by more than 4
characters (I use the shift left/right arrows to shift the page back
and forth by 20 chars at a shot), just redraw the page one character
at a time...it is much faster than blitting sideways (kind of makes
sense because of the way the screen is layed out).