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From: davis@3d.enet.dec.com (Peter Davis)
Newsgroups: comp.windows.x
Subject: Re: How to simulate mouse events from a data tablet
Message-ID: <1991May29.150652.20665@engage.pko.dec.com>
Date: 29 May 91 14:57:02 GMT
Sender: newsdaemon@engage.pko.dec.com (USENET News Daemon)
Distribution: usa
Organization: Digital Equipment Corporation
Lines: 49


In article <64370@bbn.BBN.COM>, schroder@bbn.com (Ken Schroder) writes...
>I'm trying to integrate a data tablet with the mouse using X11R4.
>I'd like the cursor to move whenever I move either the mouse of the
>cursor/pen on the tablet.  I'd like X clients to receive a button
>event whenever a button on either the mouse or tablet is pressed
>or released.  Has anyone already done this?
> 
>I've found that using XWarpPointer works fine to drive the pointer
>from the tablet.  The problem is getting a suitable value for the
>window pointer passed in the event structure to XSendEvent.  Does
>anyone know the correct value so the server will map screen (x,y)
>to window and window relative (x,y)?
>
Gee, I'm trying to do almost this exact thing.  I'm looking at a whole
bunch of input devices, and I want to be able to simulate mouse movements
by sending events, and then send any additional data that the devices can
input via the ClientMessage mechanism.

To do motion, I found I had to:

   1	XQueryPointer to get the current position,
   2    find the lowest offspring of the pointer window which still contains
	the pointer position,
   3	XTranslateCoordinates to get the coordinates relative to that
	offspring,
   4	XSendEvent to send a motion event to that window,
   5	XGrabPointer
   6	XWarpPointer
   7	XUngrabPointer
   8	XQueryPointer to see if the pointer window has changed.  If it has,
	repeat steps 2, 3, and 4 for the new window.

To do button transitions, I had to:

   1	XQueryPointer to get the current position, window, etc.
   2	find the lowest offspring of the pointer window which still contains
	the pointer position,
   3	XTranslateCoordinates to get the x, y in the coordinates of that
	offspring window,
   4	Figure out what the button/key mask should be, and
   5	XSendEvent to send the button event to that window.

I still don't have this completely working, so I won't vouch for the
completeness of the above procedures.  If anyone has any improvements or
suggestions, I'd be glad to hear 'em.

Thanks.
-pd