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doc: update the pointer acceleration page for the 1.9 trackpoint accel

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Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
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Peter Hutterer 2017-11-29 12:47:25 +10:00
parent c727ee7f23
commit ac9c3f53b9
1 changed files with 11 additions and 8 deletions
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19
doc/pointer-acceleration.dox
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@ -117,20 +117,23 @@ properties. Measuring pressure objectively across a variety of hardware is
nontrivial. nontrivial.
libinput's pointer acceleration is a function of the total available libinput's pointer acceleration is a function of the total available
pressure range on a device. pressure range on a device. See @ref trackpoint_range for details.
libinput relies on some sytem-wide configured properties, specifically the libinput relies on some system-wide configured properties, specifically the
@ref udev_config. The two properties that influence trackpoint acceleration @ref udev_config. The property that influences trackpoint acceleration is
````POINTINGSTICK_CONST_ACCEL```` which is a constant factor applied to the `LIBINPUT_ATTR_TRACKPOINT_RANGE` which specifies the total delta range for
trackpoint's motion data. For example, a factor of 3 will see all input data the trackpoint. See @ref trackpoint_range for details.
multipled by 3. This multiplication is done by libinput.
Additionally, some trackpoints provide the ability to adjust the sensitivity in Additionally, some trackpoints provide the ability to adjust the sensitivity in
hardware by modifying a sysfs file on the serio node. The udev property hardware by modifying a sysfs file on the serio node. The udev property
````POINTINGSTICK_SENSITIVITY```` indicates the desired value, a udev `POINTINGSTICK_SENSITIVITY` indicates the desired value, a udev
builtin is expected to apply this to the device, i.e. libinput does not builtin is expected to apply this to the device, i.e. libinput does not
handle this property. Once applied, the sensitivity adjusts the deltas handle this property. Once applied, the sensitivity adjusts the deltas
coming out of the hardware. coming out of the hardware. When the sensitivity changes, the trackpoint
range changes and thus the `LIBINPUT_ATTR_TRACKPOINT_RANGE` property
becomes invalid.
As of version 1.9, libinput does not parse the `POINTINGSTICK_CONST_ACCEL` property anymore.
@image html ptraccel-trackpoint.svg "Pointer acceleration curves for trackpoints" @image html ptraccel-trackpoint.svg "Pointer acceleration curves for trackpoints"