Is it possible to pan around a virtual screen using a smaller touchscreen display

[Daniel Harris]

Thanks Peter

I appreciate your time and help and I will look into it

Dan



On Tue, Apr 21, 2015 at 10:38 PM, Peter Hutterer <peter.hutterer at who-t.net>
wrote:

> On Tue, Apr 21, 2015 at 02:50:47PM +0100, Daniel Harris wrote:
> > Hello Peter
> >
> > I appreciate your reply.  I am not sure we are talking about the same
> thing
> > so I have uploaded a video to youtube showing the problem i am
> experiencing
> >
> > If anyone is interested you can find it here http://youtu.be/n8N0NnB9u7g
>
> yeah, definitely the same thing. look at the distances of the pointer and
> the stylus relative to their origins - when the stylus is half-way down the
> device, the pointer is half-way down the whole screen. That's the basic
> problem - an absolute device is always mapped to the whole screen/desktop
> area.
>
> > are you saying the pointer position can be corrected with a client app or
> > can it only be fixed in X.
>
> yes, google for xinput coordinate transformation matrix and you'll find a
> few tutorials, hints on how to do it. xinput map-to-output does the same,
> though in your case it's a bit trickier because you need to get the
> viewport and calculate the respective matrix. Still just moving numbers
> around, not technically hard.
>
> the difficult bit is getting the current viewport, where the xf86VidMode
> extension looks like the most likely candidate. possibly RandR, but I don't
> know the details on how to do it on either, sorry.
>
> Cheers,
>    Peter
>
>
> > On Tue, Apr 21, 2015 at 2:41 AM, Peter Hutterer <
> peter.hutterer at who-t.net>
> > wrote:
> >
> > > On Mon, Apr 20, 2015 at 05:21:44PM +0100, Daniel Harris wrote:
> > > > I am assuming that it is a limitation that a stylus cannot map it
> > > position
> > > > to a physical screen and a larger virtual screen at the same time.  I
> > > > currently have panning in the virtual screen but calibration is way
> off
> > > on
> > > > the physical screen.  I am assuming no mathematical wizardry with the
> > > > current setting can rectify this.
> > >
> > > should be able to, it just requires more effort once you start panning
> > > around. the mapping of the stylus to screen is done by a matrix that
> takes
> > > the whole desktop size into account. outputs as such don't matter here,
> > > e.g.
> > > mapping to the right of two monitors is done by mapping to the 50% of
> the
> > > width with a 50% offset.
> > >
> > > that means you can map to any part of the desktop, problem is it won't
> > > follow you around as you pan. you'd need some client to track that and
> > > update the coordinate transformation matrix as you go.
> > >
> > > Cheers,
> > >    Peter
> > >
> > >
> > > > On Sat, Apr 18, 2015 at 4:19 PM, Daniel Harris <
> > > mail.dharris at googlemail.com>
> > > > wrote:
> > > >
> > > > > Hello
> > > > >
> > > > > I have a surface pro 2 and would like to create a virtual screen of
> > > > > 3840x2160 and pan around using the 1920x1080 stylus enabled
> > > touchscreen on
> > > > > the surface pro 2.  I have Ubuntu installed and the screen setup
> but I
> > > > > cannot get the stylus to function correctly with that setup.  I
> have
> > > tried
> > > > > experimenting with the translation matrix but with no success.
> > > > >
> > > > > Is the above setup possible?
> > > > >
> > > > > I would welcome any advice as to how to achieve this setup
> > > > >
> > > > > Thanks in advance
> > > > >
> > > > > Dan
> > > > >
> > >
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>
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