Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!codonics!bret
From: bret@codonics.COM (Bret Orsburn)
Newsgroups: comp.windows.x
Subject: Re:  how to make a line of text blink?
Message-ID: <2614@codonics.COM>
Date: 25 Jan 91 04:22:13 GMT
Organization: Codonics, Inc., Middleburg Heights, OH
Lines: 43

> Does anybody know of a easy way to draw a line of text and make it
> blink, using XLIB?

> I have been looking through my XLIB manual and couldn't find a good
> way to do this seems-so-easy thing.  The only way I can think of is
> to just draw it repeatedly from my application, any better solution?

It's only easy on conventional terminals with character generating hardware.
On such hardware, blinking is a relatively trivial boolean function, with
the terms being (1) an attribute bit [one per character] (2) a square wave
[at the blinking frequency]. When both of these terms is true, the video
output from the character generator is inverted (or modified in some other
way).

If you ponder this, you'll see that there is no analogous technique available
on a bitmapped display.

I once helped to design a bitmapped terminal which required a very complete
VT220 emulation. We ended up using an entire bit plane to control blinking
for arbitrarily sized bitmapped characters. We were able to enable or disable
blinking for each individual pixel! Effective, but costly.

Donald Knuth wrote a very interesting article on text processing a few years
back. In it he observed that when technologies change, we often spend a
considerable amount of time in the beginning trying to make the new
technology look and feel like the old technology. Eventually, we accept the
new technology as "correct", so that the cycle is repeated anew with the next
innovation.

Knuth was talking about printing technologies, but the observation easily
extends to other technologies. Blinking text is a good example of this.
The full screen crosshair cursor is another.

My advice is to skip the transition phase; come to terms with the new
technology. Don't dwell on a few lost landmarks, focus on the new
possibilities. Forge ahead!

(Finding someone who will *pay* you to Forge Ahead is a separate problem :-)
-- 
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bret@codonics.com
uunet!codonics!bret
Bret Orsburn