Touchegg not for mobile!

Harald Sitter apachelogger at
Tue May 17 13:02:30 UTC 2011

2011/5/17 Rodrigo Belém <rclbelem at>:
> Would't it work on touchscreen devices, which are evdev too?

Sure it would, however I do not think the usage paradigm makes much
sense. At any rate we'd need to be careful with what we do by
On a touchscreen you are suggested to interact with things as they are
presented. So you have a window, if you want to drag the window you
press on the window's occupied space, hold and move. Having a gesture
that goes like "swipe two fingers from left to right to switch track
in amarok" does not necessarily match up to what you would expect it
to do as there is no visual connection between what you do and what
you do it on (i.e. plasma or a currently focused window).

For touchpads this is a no-brainer as the touchpad itself is not
directly linked to the screen space, or what you see there (e.g. by
default you will not have a 1:1 mapping between screen space and
world/touchpad space, meaning you might need to move >1 one times from
top of your touchpad to bottom to get from top most point to bottom
most point of the screen space).

So, what I am saying is not that it does not work, but we should be
verrryyyy careful about what we do by default on a touchscreen setup.
In my opinion gestures only make sense on an application level for
touchscreens. Like in marble you might want to have pinch-to-zoom, if
you had the same gestures defined for touchegg, but doing something
entirely different that would cause problems. Additionally if the
touch interactions are not global but scoped to a widget/element
within an application it maps perfectly with the whole usage paradigm
of touchscreens with having a 1:1 mapping from world space to
(visible) screen space.

I hope this was somewhat understandable, I fear I might have been
thinking faster than I was writing ^^


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