NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/comp/windows/x/14314

Internet Message Format | 1992-07-23 | 3.3 KB

Path: sparky!uunet!mcsun!Germany.EU.net!Informatik.Uni-Dortmund.DE!tommy!klute
From: [e-mail] (Rainer Klute)
Newsgroups: comp.windows.x
Subject: Re: Touchscreens and Multple Pointer Devices
Date: 24 Jul 1992 05:06:52 GMT
Organization: University of Dortmund, Germany
Lines: 64
Sender: klute@tommy (Rainer Klute)
Distribution: world
Message-ID: <[e-mail]>
References: <[e-mail]> <[e-mail]>
NNTP-Posting-Host: tommy
Keywords: touch pointer

In article <[e-mail]>, [e-mail]
(Michael Doel) writes:
|> In article <[e-mail]>, [e-mail] (Bob
|> Herlien) writes:
|> > I want to add a touchscreen to some X terminals for a control/display
|> app
|> > I'm developing, and I have some general questions about how they're
|> integrated
|> > into an X environment.
|>
|> [...]
|>
|> Not having spoke to your vendor, I can only assume that you were a bit
|> misled.  As I understand it, X11Rn (for all n) will only allow one
|> pointing
|> device.  To allow more than one would require a relatively large change
|> to the X protocol (hence X12R1 ?).  In particular, the event structure
|> would
|> need to include a field to indicate which pointing device generated the
|> event.  You can't just add this to X11R5 and still have X11R4 apps
|> working
|> correctly.

You might wish to take a look into the X Input Extension coming with the
X11R5 source distribution. Here some quotes from the documentation, which
you will find in mit/doc/extensions/xinput:

    The design approach of the extension is to define  functions
    and  events analogous to the core functions and events. This
    allows extension input devices and events to be individually
    distinguishable from each other and from the core input dev-
    ices and events .  These functions and events make use of  a
    device identifier and support the reporting of n-dimensional
    motion data as well as other  data  that  is  not  currently
    reportable via the core input events.

    ...

    The input extension controls access to input  devices  other
    than  the  X  keyboard and X pointer.  It allows client pro-
    grams to select input from these devices independently  from
    each  other  and independently from the core devices.  Input
    events from these devices  are  of  extension  types  (Devi-
    ceKeyPress,  DeviceKeyRelease, DeviceButtonPress, DeviceBut-
    tonRelease, DeviceMotionNotify, etc.) and contain  a  device
    identifier  so that events of the same type coming from dif-
    ferent input devices can be distinguished.

    ...

    This extension is designed to accommodate new types of input
    devices  that  may  be  added  in  the future.  The protocol
    requests that refer to  specific  characteristics  of  input
    devices  organize  that information by input device classes.
    Server implementors may add new  classes  of  input  devices
    without changing the protocol requests.

I hope this helps.

--
  Dipl.-Inform. Rainer Klute      [e-mail]
  Univ. Dortmund, IRB
  Postfach 500500         |)|/    Tel.: [phone]
D-W4600 Dortmund 50       |\|\    Fax : [phone]