XInput func param questions

Chuck Robey chuckr at
Tue Sep 2 18:31:08 PDT 2008

My driver, which I think I've been working on now just about forever, is making
my cursor disappear at the moment I actually first move the stylus (when I first
dispatch events).  I've done all of the printf debugging I can do, and
everything SEEMS to be fine, but I'm probably misunderstanding one of more of
the function protos (since I'm doing a sight of guessing here).  I'm going to
ask some of the questions that seem most likely to be wrong, to me, and see if I
can catch some low-hanging fruit.

My driver, first, is a USB graphic tablet, one not covered by any present driver.

First, for the valuators, my 3rd one is the z axis.  It's in fact my stylus tip
pressure, but I haven't seen any way to explicitly tell the server that it IS
tip pressure.  Is there any way to do that, or do I just trust that things
understand that the 3rd and last valuator (for z axis) must be the Tip Pressure?

2nd, function InitValuatorAxisStruct, the 5th, 6th and 7th (last 3) parameters
are "resolution", "min_res", and "max_res".  The two previous parameters (3rd
and 4th) are the min_x and max x.  My X and Y are 15 bit unsigned, my Z is 10
bit unsigned, so I set all of the min/max_x's to (0-32767),(0-32767), and
(0-1023) for X, Y, and Z...  BUT I can't figure out what the heck are those 6th
and 7th params (the min_res and max_res).  The min/max_x seem to do the range
setting, so I can't guess what those min/max_res things could be good for.  I
looked at other drivers, but can't get a clear enough example to do me any good.
 Anyone got any idea what this might be?

I found a "focus" initialization function in another driver
(InitFocusClassDeviceStruct) so I put one  in this driver, but I don't really
know why, and I've set up no focus-type events.  Do I need to send any focus
events for a tablet, and why would I do this (what would happen to the tablet,
that would trigger me to send the event?)  Or can I ignore this?

These are all the items that occur to me immediately.  Thanks for any hints I get.

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