Path: utzoo!attcan!uunet!snorkelwacker!apple!well!cbm
From: cbm@well.sf.ca.us (Chris Muir)
Newsgroups: comp.sys.mac
Subject: Re: Help! Anyone know how to force the mouse to a location?
Message-ID: <18417@well.sf.ca.us>
Date: 9 Jun 90 11:34:25 GMT
References: <1990Jun5.091419.14219@portia.Stanford.EDU> <16995@phoenix.Princeton.EDU> <1990Jun6.083741.4740@canon.co.uk> <3668@rodan.acs.syr.edu> <17078@phoenix.Princeton.EDU>
Reply-To: cbm@well.sf.ca.us (Chris Muir)
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 30

In article <17078@phoenix.Princeton.EDU> bskendig@phoenix.Princeton.EDU (Brian
Kendig) writes:

-A program doesn't have to know -- and, actually, shouldn't know --
-what input device the user is using.  Absolute devices such as
-graphics tablets typically have the interface in hardware; they move
-from place to place by simulating a corresponding sudden mouse
-movement.

In fact, if an absolute device was going to position the pointer using
"sudden mouse movement" to the mouse driver it would have to "home" the
pointer (moving to a corner of the screen by outputting the screen width
and screen height of pulses in the proper direction) every time the pen (or
puck) touched down on the tablet. Not the way to do it.

-Your program doesn't have to move the pointer, the interface does.
-Since there are no system calls to move the pointer, you have to do it
-through hardware.

A ridiculous conclusion. Apple has even published a tablet driver in their
sample code series that (shudder) moves the pointer by mucking with low
memory globals.



-- 
__________________________________________________________________________
Chris Muir                              |   "There is no language in our
cbm@well.sf.ca.us                       |    lungs to tell the world just
{hplabs,pacbell,ucbvax,apple}!well!cbm  |    how we feel"  - A. Partridge