Tablet to screen coordinate conversion (again)

Magnus Vigerlöf Magnus.Vigerlof at
Sat Oct 27 09:09:22 PDT 2007

On lördag 27 oktober 2007, Giuseppe Bilotta wrote:
> Hello,
> having just fixed a bug that prevented the acecad driver I'm
> maintaining from working at all with xorg 1.4, I hit the problem
> discussed in this February thread:
> i.e. the fact that the conversion_proc and reverse_conversion_proc
> functions are never called.
> As the driver maintainer and tablet user, I'm left with two rather
> unappealing choices: if I let the tablet driver post motion and
> button events without manually scaling the x and y coordinates, I
> can only use the upper right corner of the tablet; however, if I
> do manually scale the x and y coordinates before posting the
> events (call the conversion_proc manually), thus fixing
> non-XInput-aware clients, I break all XInput-aware clients (gimp,
> inkscape, xournal, ...) since they assume that the posted
> coordinates are in device, not screen coordinates.
> I've noticed a couple of more recent posts about this issues, but
> nothing definitive. So I would like to know what the current
> status is wrt to this issue, and in particular if it will get
> fixed with the next point release.
> Also, is there something I can do to work around this issue, at
> the driver level, other than claiming that the device limits are
> the same as the screen limits? Or would it be better to just wait
> for this to be fixed at the server level?

We (linuxwacom) are scaling the coordinates to the screen size for xserver 
1.4. We also scale the max on X&Y for the tablet to the screen size when 
initializing the tablet. Not the way we would like it to be, but it works at 
least. A better solution where we can report the real coordinates is planned 
for xserver 1.4.1 according to Daniel S [1].

 Magnus V


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