Re: Can I limit the scope of an input device to specific processes ?

["Dr. Zimmermann" <R.Zimmermann@UKE.Uni-Hamburg.de>]

Am 28.01.2014 12:15, schrieb David Herrmann:
> Hi
>
> On Tue, Jan 28, 2014 at 11:20 AM, Dr. Zimmermann
> <R.Zimmermann@uke.uni-hamburg.de> wrote:
>> Hi,
>>
>> we've got a special type of keyboard which should only be available in one
>> specific process and not publicly, as usually keyboards are.
>>
>> Is it possible to limit the scope of a specific keyboard?
>>
>> Or is there a more suited forum where to ask?

Hi David,
>
> There is no such interface in the kernel. However, with careful
> access-management, you can get what you want by just allowing your
> single process access to the device. But I guess you are working with
> an X11 system, so a description of what you actually want to achieve
> would help a lot.

Thnx for Your quick reply.

(Yes, we are using X. No, the problem is not specific to X: It'll also 
occur when You switch between system consoles.)

For research purposes we are measuring human brain activity under the 
influence of external stimuli (visual/auditory/somatosensory). The 
subject has to reply to tasks using 'button boxes' which are implemented 
as keyboards. Usually, type and time of the buttonpress are of 
importance (and will probably change further procedere). Keyboard 
responses usually go to that window (or system console) which has the 
current focus or is active and *this* is something, we do not want.

Sometimes we show visual stimuli on one screen(#1) and operate the 
system from another screen(#2). Sometimes we even have no visual stimuli 
at all, but like to read subject responses and control the stimuli from 
within a control window. In all cases it would be helpful if the 
response-boxes would not automatically send their output to the active 
window resp. application.

Helpful would be, if the output of the response-box-keyboards
* could be restricted to a specific process
* is not sent automatically, but only to a program which 'opened' the device
* is not sent automatically, but has to be read from a device.
(Could this be done preserving the exact timepoint of each buttonpress?)

Hope that was not too lengthy...
>
> Thanks
> David
>

Thanks, Roger

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