For a caller to implement/provide kinetic scrolling ("inertial scrolling",
"fling scrolling"), it needs to know how the scrolling motion was implemented,
and what to expect in the future. Add this information to the pointer axis
event.
The three scroll sources we have are:
* wheels: scrolling is in discreet steps, you don't know when it ends, the
wheel will just stop sending events
* fingers: scrolling is continuous coordinate space, we know when it stops and
we can tell the caller
* continuous: scrolling is in continuous coordinate space but we may or may not
know when it stops. if scroll lock is used, the device may never technically
get out of scroll mode even if it doesn't send events at any given moment
Use case: trackpoint/trackball scroll emulation on button press
The stop event is now codified in the API documentation, so callers can use
that for kinetic scrolling. libinput does not implement kinetic scrolling
itself.
Not covered by this patch:
* The wheel event is currently defined as "typical mouse wheel step", this is
different to Qt where the step value is 1/8 of a degree. Some better
definition here may help.
* It is unclear how an absolute device would map into relative motion if the
device itself is not controlling absolute motion.
* For diagonal scrolling, the vertical/horizontal terminator events would come
in separately. The caller would have to deal with that somehow.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Original patch, before the rebase onto today's master:
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Turn test_trackpoint_scroll into a generic helper function for testing
"button scrolling".
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Fix copy and paste error, causing the function to test trackpoint scrolling
to be named test_2fg_scroll.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
