how to design a tablet driver?

Chuck Robey chuckr at
Wed Mar 5 17:44:31 PST 2008

Hash: SHA1

My current project is making a usb driver for my "Superpen" WP8060 Tablet.
 It's a cheaper version of the better known Wacom Tablet, which i couldn't
afford for my use in Gimp.  I figure, I better ask myu questions here,
because they don't really bear so much on usb as they bear upon the basic
architecture of a mouselike drvice that must be absolute, not relative, in

OK, that means that I have to know the graphic point size (is there a
better term for that?) for the screen I'm wokring with.  I remember about
20 years ago, when I worked for MCI, i spent a bit of time in their
drafting area, and they had a high end graphic tablet.  Teh way that one
worked, various areas were marked off on the graphjic tab, and if you
marked in thjose regions, you were performing some extra feature.  I say
this to show that basically, it's really not possible to consider
implementing this beast by just converting an absolute movement to some
relative set of steps.  You have to know where you are at asll times, with
no relative ambiguity.

Does that make sense, so far?

Well, if it does, then it also means that I need to find the absoluite
point size of whatever screen you're playing with, no matter if I'm talking
about an X11 screen or a screen from a vty.  I mean, vty's use mice now,
isn't it possible for use a tablet on a vtyt also?  OR, extra possibility,
maybe if we're in a non-X11 environment, fall back to a relative use, and
only go to absolute when you go to X11.  If I have too much trouble getting
and keeping an idea of the screen size oout of X11, I could do that.

I'm suggesting this because I'm very, very confused as to how I would
figure out what the screen size is for a vty.  If I gotta do a absolute gig
on a bty, then I gotta find some way to ask the size of the cry, and get me
driver in the list of those to be notified if the size of a vty changes.

Please, if you have any comment, feel free to interrupt all over me, sir!
The sooner I get some of this, the sooner that really cheap (~$60) 8"X6"
tablet is ours, especially for Gimp.
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