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48 lines
2.4 KiB
Text
48 lines
2.4 KiB
Text
/**
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@page tapping Tap-to-click behaviour
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"Tapping" or "tap-to-click" is the name given to the behavior where a short
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finger touch down/up sequence maps into a button click. This is most
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commonly used on touchpads, but may be available on other devices.
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libinput implements tapping for one, two, and three fingers, where supported
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by the hardware, and maps those taps into a left, right, and middle button
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click, respectively. Not all devices support three fingers, libinput will
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support tapping up to whatever is supported by the hardware. libinput does
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not support four-finger taps or any tapping with more than four fingers,
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even though some hardware can distinguish between that many fingers.
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Tapping is **disabled** by default, see [this
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commit](http://cgit.freedesktop.org/wayland/libinput/commit/?id=2219c12c3aa45b80f235e761e87c17fb9ec70eae)
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because:
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- if you don't know that tapping is a thing (or enabled by default), you get
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spurious button events that make the desktop feel buggy.
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- if you do know what tapping is and you want it, you usually know where to
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enable it, or at least you can search for it.
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Tapping can be enabled on a per-device basis. See
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libinput_device_config_tap_set_enabled() for details.
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@section tapndrag Tap-and-drag
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libinput also supports "tap-and-drag" where a tap immediately followed by a
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finger down and that finger being held down emulates a button press. Moving
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the finger around can thus drag the selected item on the screen. Lifting the
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finger and putting it back down immediately (i.e. within the timeout) will
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continue the dragging process, so that multiple touchpad-widths of distance
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can be covered easily. If two-fingers are supported by the hardware, a
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second finger can be used to drag while the first is held in-place.
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@section tap_constraints Constraints while tapping
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A couple of constraints apply to the contact to be converted into a press, the most common ones are:
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- the touch down and touch up must happen within an implementation-defined timeout
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- if a finger moves more than an implementation-defined distance while in contact, it's not a tap
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- tapping within @ref clickpad_softbuttons "clickpad software buttons" may not trigger an event
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- a tap not meeting required pressure thresholds can be ignored as accidental touch
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- a tap exceeding certain pressure thresholds can be ignored (see @ref
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palm_detection)
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- a tap on the edges of the touchpad can usually be ignored (see @ref
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palm_detection)
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*/
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