110 lines
4.5 KiB
Markdown
110 lines
4.5 KiB
Markdown
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# libxkbcommon
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xkbcommon is a keymap compiler and support library which processes a
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reduced subset of keymaps as defined by the XKB specification. Primarily,
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a keymap is created from a set of Rules/Model/Layout/Variant/Options names,
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processed through an XKB ruleset, and compiled into a struct xkb_keymap,
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which is the base type for all xkbcommon operations.
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From an xkb_keymap, an xkb_state object is created which holds the current
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state of all modifiers, groups, LEDs, etc, relating to that keymap. All
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key events must be fed into the xkb_state object using xkb_state_update_key().
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Once this is done, the xkb_state object will be properly updated, and the
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keysyms to use can be obtained with xkb_state_key_get_syms().
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libxkbcommon does not distribute a dataset itself, other than for testing
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purposes. The most common dataset is xkeyboard-config, as used by all
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current distributions for their X11 XKB data. More information on
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xkeyboard-config is available here:
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http://www.freedesktop.org/wiki/Software/XKeyboardConfig
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## Quick Guide
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See [Quick Guide](doc/quick-guide.md).
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## API
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While xkbcommon's API is somewhat derived from the classic XKB API as found
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in X11/extensions/XKB.h and friends, it has been substantially reworked to
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expose fewer internal details to clients. The supported API is available
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in the xkbcommon/xkbcommon-*.h files. Additional support is provided for
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X11 (XCB) clients, in the xkbcommon-x11 library, xkbcommon/xkbcommon-x11.h.
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The xkbcommon API and ABI are stable. We will attempt to not break ABI during
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a minor release series, so applications written against 0.1.0 should be
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completely compatible with 0.5.3, but not necessarily with 1.0.0. However, new
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symbols may be introduced in any release. Thus, anyone packaging xkbcommon
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should make sure any package depending on it depends on a release greater than
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or equal to the version it was built against (or earlier, if it doesn't use
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any newly-introduced symbols), but less than the next major release.
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## Relation to X11
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Relative to the XKB 1.1 specification implemented in current X servers,
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xkbcommon has removed support for some parts of the specification which
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introduced unnecessary complications. Many of these removals were in fact
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not implemented, or half-implemented at best, as well as being totally
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unused in the standard dataset.
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Notable removals:
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- geometry support
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+ there were very few geometry definitions available, and while
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xkbcommon was responsible for parsing this insanely complex format,
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it never actually did anything with it
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+ hopefully someone will develop a companion library which supports
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keyboard geometries in a more useful format
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- KcCGST (keycodes/compat/geometry/symbols/types) API
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+ use RMLVO instead; KcCGST is now an implementation detail
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+ including pre-defined keymap files
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- XKM support
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+ may come in an optional X11 support/compatibility library
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- around half of the interpret actions
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+ pointer device, message and redirect actions in particular
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- non-virtual modifiers
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+ core and virtual modifiers have been collapsed into the same
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namespace, with a 'significant' flag that largely parallels the
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core/virtual split
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- radio groups
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+ completely unused in current keymaps, never fully implemented
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- overlays
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+ almost completely unused in current keymaps
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- key behaviors
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+ used to implement radio groups and overlays, and to deal with things
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like keys that physically lock; unused in current keymaps
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- indicator behaviours such as LED-controls-key
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+ the only supported LED behaviour is key-controls-LED; again this
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was never really used in current keymaps
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Notable additions:
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- 32-bit keycodes
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- extended number of modifiers
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- extended number of groups
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- multiple keysyms per level
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+ this requires incompatible dataset changes, such that X11 would
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not be able to parse these
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## Development
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An extremely rudimentary homepage can be found at
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http://xkbcommon.org
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xkbcommon is maintained in git at
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https://github.com/xkbcommon/libxkbcommon
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Patches are always welcome, and may be sent to either
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<xorg-devel@lists.x.org> or <wayland-devel@lists.freedesktop.org>
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Bugs are also welcome, and may be reported either at
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Bugzilla https://bugs.freedesktop.org/describecomponents.cgi?product=libxkbcommon
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or
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Github https://github.com/xkbcommon/libxkbcommon/issues
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The maintainers are
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- Daniel Stone <daniel@fooishbar.org>
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- Ran Benita <ran234@gmail.com>
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## Credits
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Many thanks are due to Dan Nicholson for his heroic work in getting xkbcommon
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off the ground initially.
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