mirror of
https://gitlab.freedesktop.org/libinput/libinput.git
synced 2025-12-24 19:20:05 +01:00
75581d5829
In some applications, notably Inkscape, where it is common to frequently drag objects a short distance the default to drag-lock always-on is frustrating for users. Make it configurable, with the current default to "on". New API: libinput_device_config_tap_set_drag_lock_enabled libinput_device_config_tap_get_drag_lock_enabled libinput_device_config_tap_get_default_drag_lock_enabled Any device capable of tapping is capable of drag lock, there is no explicit availability check for drag lock. Configuration is independent, drag lock may be enabled when tapping is disabled. In the tests, enable/disable drag-lock explicitly where the tests depend on it. https://bugs.freedesktop.org/show_bug.cgi?id=90928 Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
66 lines
3.3 KiB
Text
66 lines
3.3 KiB
Text
/**
|
|
@page tapping Tap-to-click behaviour
|
|
|
|
"Tapping" or "tap-to-click" is the name given to the behavior where a short
|
|
finger touch down/up sequence maps into a button click. This is most
|
|
commonly used on touchpads, but may be available on other devices.
|
|
|
|
libinput implements tapping for one, two, and three fingers, where supported
|
|
by the hardware, and maps those taps into a left, right, and middle button
|
|
click, respectively. Not all devices support three fingers, libinput will
|
|
support tapping up to whatever is supported by the hardware. libinput does
|
|
not support four-finger taps or any tapping with more than four fingers,
|
|
even though some hardware can distinguish between that many fingers.
|
|
|
|
Tapping is **disabled** by default, see [this
|
|
commit](http://cgit.freedesktop.org/wayland/libinput/commit/?id=2219c12c3aa45b80f235e761e87c17fb9ec70eae)
|
|
because:
|
|
- if you don't know that tapping is a thing (or enabled by default), you get
|
|
spurious button events that make the desktop feel buggy.
|
|
- if you do know what tapping is and you want it, you usually know where to
|
|
enable it, or at least you can search for it.
|
|
|
|
Tapping can be enabled on a per-device basis. See
|
|
libinput_device_config_tap_set_enabled() for details.
|
|
|
|
@section tapndrag Tap-and-drag
|
|
|
|
libinput also supports "tap-and-drag" where a tap immediately followed by a
|
|
finger down and that finger being held down emulates a button press. Moving
|
|
the finger around can thus drag the selected item on the screen.
|
|
|
|
Optional is a feature called "drag lock". With drag lock disabled, lifting
|
|
the finger will stop any drag process. When enabled, libinput will ignore a
|
|
finger up event during a drag process, provided the finger is set down again
|
|
within a implementation-specific timeout. Drag lock can be enabled and
|
|
disabled with libinput_device_config_tap_set_drag_lock_enabled().
|
|
|
|
@image html tap-n-drag.svg "Tap-and-drag process"
|
|
|
|
The above diagram explains the process, a tap (a) followed by a finger held
|
|
down (b) starts the drag process and logically holds the left mouse button
|
|
down. A movement of the finger (c) will drag the selected item until the
|
|
finger is relased (e). If needed and drag lock is enabled, the finger's
|
|
position can be reset by lifting and quickly setting it down again on the
|
|
touchpad (d). This will be interpreted as continuing move and is especially
|
|
useful on small touchpads or with slow pointer acceleration.
|
|
If drag lock is enabled, the release of the mouse buttons after the finger
|
|
release (e) is triggered by a timeout. To release the button immediately,
|
|
simply tap again (f).
|
|
|
|
If two fingers are supported by the hardware, a second finger can be used to
|
|
drag while the first is held in-place.
|
|
|
|
@section tap_constraints Constraints while tapping
|
|
|
|
A couple of constraints apply to the contact to be converted into a press, the most common ones are:
|
|
- the touch down and touch up must happen within an implementation-defined timeout
|
|
- if a finger moves more than an implementation-defined distance while in contact, it's not a tap
|
|
- tapping within @ref clickpad_softbuttons "clickpad software buttons" may not trigger an event
|
|
- a tap not meeting required pressure thresholds can be ignored as accidental touch
|
|
- a tap exceeding certain pressure thresholds can be ignored (see @ref
|
|
palm_detection)
|
|
- a tap on the edges of the touchpad can usually be ignored (see @ref
|
|
palm_detection)
|
|
|
|
*/
|