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cbd4f35442
This is a large commit because it's difficult to split this up and we don't care about bisecting here anyway. doxygen is going to produce the API documentation only sphinx is going to produce the prose user (and a bit of developer) documentation. The source split is doc/api and doc/user. Steps performed: - run the doxygen-to-sphinx.sh script to convert all .dox sources to .rst - manually fixed the .rst to render correctly - add a few extra .rst documents to generate the right hierarchy - hook up sphinx-build in meson - add a new @mainpage for doxygen more aimed at developers For the build directory: - sphinx produces /Documentation - doxygen now produces /api/ These need to be manually combined in the wayland-web repo, meson doesn't support subdirectories as output paths within the build dir and the documentation doesn't need to be installed anywhere. Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
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2.6 KiB
ReStructuredText
51 lines
2.6 KiB
ReStructuredText
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.. _button_debouncing:
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==============================================================================
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Button debouncing
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==============================================================================
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Physical buttons experience wear-and-tear with usage. On some devices this
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can result in an effect called "contact bouncing" or "chatter". This effect
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can cause the button to send multiple events within a short time frame, even
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though the user only pressed or clicked the button once. This effect can be
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counteracted by "debouncing" the buttons, usually by ignoring erroneous
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events.
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libinput provides two methods of debouncing buttons, referred to as the
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"bounce" and "spurious" methods:
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- In the "bounce" method, libinput monitors hardware bouncing on button
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state changes, i.e. when a user clicks or releases a button. For example,
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if a user presses a button but the hardware generates a
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press-release-press sequence in quick succession, libinput ignores the
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release and second press event. This method is always enabled.
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- in the "spurious" method, libinput detects spurious releases of a button
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while the button is physically held down by the user. These releases are
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immediately followed by a press event. libinput monitors for these events
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and ignores the release and press event. This method is disabled by
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default and enables once libinput detects the first faulty event sequence.
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The "bounce" method guarantees that all press events are delivered
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immediately and most release events are delivered immediately. The
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"spurious" method requires that release events are delayed, libinput thus
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does not enable this method unless a faulty event sequence is detected. A
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message is printed to the log when spurious deboucing was detected.
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Note that libinput's debouncing intended to correct hardware damage or
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substandard hardware. Debouncing is also used as an accessibility feature
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but the requirements are different. In the accessibility feature, multiple
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physical key presses, usually caused by involuntary muscle movement, must be
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filtered to only one key press. This feature must be implemented higher in
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the stack, libinput is limited to hardware debouncing.
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Below is an illustration of the button debouncing modes to show the relation
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of the physical button state and the application state. Where applicable, an
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extra line is added to show the timeouts used by libinput that
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affect the button state handling. The waveform's high and low states
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correspond to the buttons 'pressed' and 'released' states, respectively.
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.. figure:: button-debouncing-wave-diagram.svg
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:align: center
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Diagram illustrating button debouncing"
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