XChangeDeviceControl/XGetDeviceControl ?

Andrew Zabolotny anpaza at mail.ru
Sun Apr 16 17:01:39 PDT 2006

On Sun, 16 Apr 2006 21:06:08 +0300
Daniel Stone <daniel at freedesktop.org> wrote:

> Uhm, XChangeDeviceControl has n+1 parameters.  One is the control
> the other n is the arbitrary data structure associated with the
> control.  You can do what you like with it.
Hmm, what's DEVICE_TOUCHSCREEN and DEVICE_CORE? By looking
into extensions/XI.h I can see only DEVICE_RESOLUTION there. And using
anything but DEVICE_RESOLUTION will end in getting BadValue, as you can
clearly see from xc/programs/Xserver/Xi/getdctl.c function
ProcXGetDeviceControl(). Besides, the protocol is tied to the specific
'control' values, because the structure is being serialized into the
wires, and it contains pointers.

Too bad there's no way to use that in a generic way; that would make
prototyping and developing stuff a lot easier.

> If the Wacom guys need to use their own controls, they should get in
> touch with us, and we can get their specific needs integrated into a
> later version of Xorg.  Having an abundance of modules like SISCTRL[0]
> is not useful in the long term.  Having widely configurable input, is.
I don't like the idea to have specialized structures for every input
device in the world; the structures will be different even amongst
different tablet drivers, not speaking of more exotic devices. What I
have now is about 50 parameters which are quite different e.g. I
wouldn't like to have them all changed in one call.

And one question still left unanswered: how do I get something back
from the driver? Notably what I want is to have a tool that could save
driver state to a file in order to load it later at will; the current
implementation is that the driver itself saves and loads its state to
/etc/wacom.dat which looks crappy.


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