Re: Question on touchscreen devices

[Tristan Van Berkom <tvb gnome org>]

On Wed, Aug 31, 2011 at 4:10 PM, John M Ridge <jmr netseats com> wrote:
> > Hello all,
> >
> > I'm tinkering with the idea of writing a GTK+ app targeted at an
> > industrial touchscreen all-in-one device (like this one:
> > http://www.faytech.com/product_show.php?id=52). But I first would like
> > to write the app to see if works on a "conventional" PC (with mouse)
> > and then port it to the touchscreen device. My questions:
> >
> > 1) Is there (from the application's point of view) any difference
> > between a (left) mouse click and a tap on the screen? That's actually
> > the only action I need -- no dragging, no right or middle mouse
> > buttons.
>
> No.
> > 2) I will do the developing on a Linux box, but the app may end up on
> > a Windows device (this depends on what my employer will ultimately
> > buy). Is the touchscreen handling on Windows different than that on
> > X-Windows?
>
> The application will function the same on both platforms.  The difference
> will be in the device drivers.  Linux will require modification of your
> xorg.conf file and a compatible driver for your device.  Most touchscreens
> come with Windows drivers and associated utilities that make them easier
> to install and configure.
>
> I have had no problems using Elo or Microtouch touchscreens with Linux.

Seconded, I've used the Elo driver extensively and had no problems except:

   a.) I had to hack my own calibration routine that can work without restarting
        the X server, I dont know how far xorg has come since the days I was
        using the XFree86 server (my hack in this case was backwards and
        not worth contributing)

   b.) I had to hack the driver to skip driver recognition phase for one of
        the Elo smartset (2500 ?) controllers as that slimmed down controller
        did not respond to the commands to report it's identity.

As far as actually using the GTK+ toolkit on a touchscreen, you might want to
do some custom things... I was particularly not satisfied with the
GtkScale's behavior
on a touchscreen so I needed to write my own, as well as writing a
generic onscreen
keyboard etc. (I think you should expect to have to write a couple of
custom widgets for
your app to behave the way you want on a touchscreen).

Cheers,
     -Tristan

> > Thanks,
> > robert
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