mirror of
https://gitlab.freedesktop.org/libinput/libinput.git
synced 2025-12-20 11:30:06 +01:00
108a191a3e
Instead of an explicit tablet mode that device must be changed into, let the caller decide which coordinates are preferred. The tablet mode may be application-specific and usually depends on the tool as well. This patch adds an interface to get a motion delta for the x/y axes in pixel-like coordinates. libinput provides some magic to convert the tablet data into something that resembles pixels from a mouse motion. For unaccelerated relative motion, the caller should use the mm values from the tablet and calculate deltas manually. Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net> Acked-by: Jason Gerecke <jason.gerecke@wacom.com>
84 lines
3.3 KiB
Text
84 lines
3.3 KiB
Text
/**
|
|
@page motion_normalization Normalization of relative motion
|
|
|
|
Most relative input devices generate input in so-called "mickeys". A
|
|
mickey is in device-specific units that depend on the resolution
|
|
of the sensor. Most optical mice use sensors with 1000dpi resolution, but
|
|
some devices range from 100dpi to well above 8000dpi.
|
|
|
|
Without a physical reference point, a relative coordinate cannot be
|
|
interpreted correctly. A delta of 10 mickeys may be a millimeter of
|
|
physical movement or 10 millimeters, depending on the sensor. This
|
|
affects pointer acceleration in libinput and interpretation of relative
|
|
coordinates in callers.
|
|
|
|
libinput does partial normalization of relative input. For devices with a
|
|
resolution of 1000dpi and higher, motion events are normalized to a default
|
|
of 1000dpi before pointer acceleration is applied. As a result, devices with
|
|
1000dpi and above feel the same.
|
|
|
|
Devices below 1000dpi are not normalized (normalization of a 1-device unit
|
|
movement on a 400dpi mouse would cause a 2.5 pixel movement). Instead,
|
|
libinput applies a dpi-dependent acceleration function. At low speeds, a
|
|
1-device unit movement usually translates into a 1-pixel movements. As the
|
|
movement speed increases, acceleration is applied - at high speeds a low-dpi
|
|
device will roughly feel the same as a higher-dpi mouse.
|
|
|
|
This normalization only applies to accelerated coordinates, unaccelerated
|
|
coordinates are left in device-units. It is up to the caller to interpret
|
|
those coordinates correctly.
|
|
|
|
@section motion_normalization_touchpad Normalization of touchpad coordinates
|
|
|
|
Touchpads may have a different resolution for the horizontal and vertical
|
|
axis. Interpreting coordinates from the touchpad without taking resolution
|
|
into account results in uneven motion.
|
|
|
|
libinput scales unaccelerated touchpad motion to the resolution of the
|
|
touchpad's x axis, i.e. the unaccelerated value for the y axis is:
|
|
y = (x / resolution_x) * resolution_y
|
|
|
|
@section motion_normalization_tablet Normalization of tablet coordinates
|
|
|
|
See @ref tablet-relative-motion
|
|
|
|
@section motion_normalization_customization Setting custom DPI settings
|
|
|
|
Devices usually do not advertise their resolution and libinput relies on
|
|
the udev property <b>MOUSE_DPI</b> for this information. This property is usually
|
|
set via the <a
|
|
href="http://cgit.freedesktop.org/systemd/systemd/tree/hwdb/70-mouse.hwdb">udev hwdb</a>.
|
|
The "mouse-dpi-tool" utility provided by <a
|
|
href="http://freedesktop.org/wiki/Software/libevdev/">libevdev</a> should be
|
|
used to measure a device's resolution.
|
|
|
|
The format of the property for single-resolution mice is:
|
|
@code
|
|
MOUSE_DPI=resolution@frequency
|
|
@endcode
|
|
|
|
The resolution is in dots per inch, the frequency in Hz.
|
|
The format of the property for multi-resolution mice may list multiple
|
|
resolutions and frequencies:
|
|
@code
|
|
MOUSE_DPI=r1@f1 *r2@f2 r3@f3
|
|
@endcode
|
|
|
|
The default frequency must be pre-fixed with an asterisk.
|
|
|
|
For example, these two properties are valid:
|
|
@code
|
|
MOUSE_DPI=800@125
|
|
MOUSE_DPI=400@125 800@125 *1000@500 5500@500
|
|
@endcode
|
|
|
|
The behavior for a malformed property is undefined.
|
|
|
|
If the property is unset, libinput assumes the resolution is 1000dpi.
|
|
|
|
Note that HW does not usually provide information about run-time
|
|
resolution changes, libinput will thus not detect when a resolution
|
|
changes to the non-default value.
|
|
|
|
*/
|
|
|