Mouse acceleration

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Revision as of 06:10, 28 July 2013 by Ndt (talk | contribs) (Using xset: adds description of threshold)
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There are several ways of setting mouse acceleration:

  1. By editing xorg configuration files
  2. The xorg-server-utils package provides two programs that can be used to change those settings from a shell or a script:
    • xset
    • xinput
  3. Many desktop environments provide a configuration GUI for mouse settings. They should be easy to find and use.

Setting mouse acceleration

In Xorg configuration

See man xorg.conf for details.


Section "InputClass"
	Identifier "My Mouse"
	MatchIsPointer "yes"
# set the following to 1 1 0 respectively to disable acceleration.
	Option "AccelerationNumerator" "2"
	Option "AccelerationDenominator" "1"
	Option "AccelerationThreshold" "4"
Section "InputClass"
	Identifier "My Mouse"
	MatchIsPointer "yes"
# some curved deceleration
#	Option "AdaptiveDeceleration" "2"
# linear deceleration (mouse speed reduction)
	Option "ConstantDeceleration" "2"

You can also assign settings to specific hardware by using "MatchProduct", "MatchVendor" and other matches inside class sections.

Using xset

To get the current values, use:

$ xset q | grep -A 1 Pointer

To set new values, type:

$ xset m acceleration threshold

where acceleration defines how many times faster the cursor will move than the default speed. threshold is the velocity required for acceleration to become effective, usually measured in device units per 10ms. acceleration can be a fraction, so if you want to slow down the mouse you can use 1/2, 1/3, 1/4, ... if you want to make it faster you can use 2/1, 3/1, 4/1, ...

Threshold defines the point at which acceleration should occur in pixels per 10 ms. If threshold is zero, e.g. if you use:

$ xset m 3/2 0

as suggested in the man page, then acceleration is treated as "the exponent of a more natural and continuous formula."

To get the default settings back:

$ xset m default

For more info see man xset.

To make it permanent, edit xorg configuration (see above) or add commands to xprofile. The latter won't affect speed in a display manager.

Using xinput

First, get a list of devices plugged in (ignore any virtual pointers):

$ xinput list

Take note of the ID. You may also use the full name in commands if the ID is prone to changing.

Get a list of available properties and their current values available for modification with

$ xinput list-props 9

where 9 is the ID of the device you wish to use. Or

$ xinput list-props mouse brand

where mouse brand is the name of your mouse given by $ xinput list

Example, changing the property of Constant Deceleration to 2:

$ xinput list-props 9
Device 'mouse brand':
       Device Enabled (121):   1
       Device Accel Profile (240):     0
       Device Accel Constant Deceleration (241):       1.000000
       Device Accel Adaptive Deceleration (243):       1.000000
       Device Accel Velocity Scaling (244):    10.000000
$ xinput --set-prop 'mouse brand' 'Device Accel Constant Deceleration' 2

To make it permanent, edit xorg configuration (see above) or add commands to xprofile. The latter won't affect speed in a Display Manager.

Configuration example

You may need to resort to using more than one method to achieve your desired mouse settings. Here's what I did to configure a generic optical mouse: First, slow down the default movement speed 3 times so that it's more precise.

$ xinput --set-prop 9 'Device Accel Constant Deceleration' 3 &

Then, enable acceleration and make it 3 times faster after moving past 6 units.

$ xset mouse 3 6 &

If you are satisfied of the results, store the preceding commands in ~/.xinitrc.

Disabling mouse acceleration

Mouse acceleration has changed dramatically in recent X server versions; using xset to disable acceleration doesn't work as it used to and is not recommended anymore.

Recent changes on PointerAcceleration can be read here.

To completely disable any sort of acceleration/deceleration, create the following file:

Section "InputClass"
	Identifier "My Mouse"
	MatchIsPointer "yes"
	Option "AccelerationProfile" "-1"
	Option "AccelerationScheme" "none"

and restart X.