The current debouncing code monitors events and switches on when events are too close together. From then on, any event can be delayed. Vicente Bergas provided an algorithm that avoids most of these delays: on a button state change we now forward the change without delay but start a timer. If the button changes state during that timer, the changes are ignored. On timer expiry, events are sent to match the hardware state with the client's view of the device. This is only done if needed. Thus, a press-release sequence of: PRP sends a single press event, a sequence of PRPR sends press and then the release at the end of the timeout. The timeout is short enough that the delay should not be noticeable. This new mode is called the 'bounce' mode. The old mode is now referred to as 'spurious' mode and only covers the case of a button held down that loses contact. It works as before, monitoring a button for these spurious contact losses and switching on. When on, button release events are delayed as before. The whole button debouncing moves to a state machine which makes debugging a lot easier. See the accompanying SVG for the diagram. Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net> |
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libinput
libinput is a library that handles input devices for display servers and other applications that need to directly deal with input devices.
It provides device detection, device handling, input device event processing and abstraction so minimize the amount of custom input code the user of libinput need to provide the common set of functionality that users expect. Input event processing includes scaling touch coordinates, generating pointer events from touchpads, pointer acceleration, etc.
libinput originates from weston, the Wayland reference compositor.
Architecture
libinput is not used directly by applications, rather it is used by the xf86-input-libinput X.Org driver or wayland compositors. The typical software stack for a system running Wayland is:
@dotfile libinput-stack-wayland.gv
Where the Wayland compositor may be Weston, mutter, KWin, etc. Note that Wayland encourages the use of toolkits, so the Wayland client (your application) does not usually talk directly to the compositor but rather employs a toolkit (e.g. GTK) to do so.
The simplified software stack for a system running X.Org is:
@dotfile libinput-stack-xorg.gv
Again, on a modern system the application does not usually talk directly to the X server using Xlib but rather employs a toolkit to do so.
Source code
The source code of libinput can be found at: http://cgit.freedesktop.org/wayland/libinput
For a list of current and past releases visit: http://www.freedesktop.org/wiki/Software/libinput/
Build instructions: http://wayland.freedesktop.org/libinput/doc/latest/building_libinput.html
Reporting Bugs
Bugs can be filed in the libinput component of Wayland: https://bugs.freedesktop.org/enter_bug.cgi?product=Wayland&component=libinput
Where possible, please provide an evemu recording of the input device and/or the event sequence in question.
See @ref reporting_bugs for more info.
Documentation
- Developer API documentation: http://wayland.freedesktop.org/libinput/doc/latest/modules.html
- High-level documentation about libinput's features: http://wayland.freedesktop.org/libinput/doc/latest/pages.html
- Build instructions: http://wayland.freedesktop.org/libinput/doc/latest/building_libinput.html
- Documentation for previous versions of libinput: https://wayland.freedesktop.org/libinput/doc/
Examples of how to use libinput are the debugging tools in the libinput repository. Developers are encouraged to look at those tools for a real-world (yet simple) example on how to use libinput.
- A commandline debugging tool: https://cgit.freedesktop.org/wayland/libinput/tree/tools/libinput-debug-events.c
- A GTK application that draws cursor/touch/tablet positions: https://cgit.freedesktop.org/wayland/libinput/tree/tools/libinput-debug-gui.c
License
libinput is licensed under the MIT license.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: [...]
See the COPYING file for the full license information.