Interactive white boards and Fedora Xorg setup

[Rodd Clarkson]

On Wed, 2010-07-07 at 11:01 +1000, Peter Hutterer wrote:
> [faked-up reply, I'm not on the list, ajax pointed it out to me on the
> archives. please make sure you CC me for any replies]
> 
> > Unlike a mouse, these pointer devices move the mouse pointer to where
> > you touch the screen.  For example, if the IWB is to the right of my
> > laptop screen and I touch the right edge of the screen then the mouse
> > pointer appears on the right side of my laptop screen, and not where
> > I've touched the screen.
> > 
> > The pointer device included with the IWB needs to be able to be
> > configured to do two things:
> 
> > 1.  Only work as a device for the IWB screen.  The mouse shouldn't be
> > able to be moved off the screen, only around it.
> > 2.  Calibrate the pointer so that you can declare the
> > top/bottom/left/right of the screen (as where the image falls on the
> > pointer device isn't usually at the extremes of the device.)
> >
> > Is this possible?
> 
> The 1.9 X server that's already in rawhide has an coordinate transformation
> matrix to restrict absolute devices to essentially any rectangle on the
> screen. The matrix is a property on each device and can be modified with the
> xinput commandline tool (no GUI tools yet).
> 
> For example, I've got a 1440x900 and a 1920x1200 display. To restrict my
> tablet to the right (larger) screen:
> $> xinput --set-prop "Wacom Intuos4 6x9" "Coordinate Transformation Matrix"
> 0.58 0 0.42 0 1 0 0 0 1  
> 
> The matrix thus looks like this:
> | 0.58 0 0.42 |
> | 0    1 0    |
> | 0    0 1    |
> 
> giving us a scale into 58% of the screen range with an offset of 42%. Your
> numbers will likely vary but that should fix the issue for you.

Peter,

I've finally found a chance to take a look at this (now that I've got
f14 running on my laptop) and I need a little help understanding the
matrix.

In your case you have two screens with the same aspect ratio (16:10), so
I can see you your right hand screen is 0.58 of the total width and 0.42
across from the left hand side of the span.

However, I've got a situation where one of my screens (on my laptop) is
16:9 (1920x1080) and the other is 5:4 (1280x1024) and I'm not sure how
to set up the matrix for this.  Are you able to supply some extra
'clues'?  Can we assume the laptop screen will be on the left hand side
(as this is how it defaults in Fedora, and I should be able to figure
out how to adjust it if it's not)?

Also, where do I get the name for the pointer device?

I'm sorry to ask, but I've done some searching on google and couldn't
come up with the answers.

regards


Rodd