extended control of keyboard indicators (LEDs) and bells;
various new keyboard parameters (controls);
association of actions (of a particular kind) to keys.
XKB is composed of two parts: a server extension and a client library. Modern versions of Xlib contain XKB, which is active by default. Client programs not using this extension can deactivate it before connecting with the server, or can simply work normally as the extension simulates the core protocol by default.
XKB allows a modifier to be locked or latched, other than being in its regular state. Normally, a modifier is active exactly when it is pressed, like the Shift. However, a modifier may also be locked, like the Caps Lock modifier. When a modifier is locked, it remains active until it is explicitly deactivated. An intermediate condition between regular and locked is the latched state: When a modifier is latched, it remains active, but only until the next non-modifier key is pressed.
XKB allows a client application to explicitly latch or lock a modifier. Moreover, an application can bind a key press or release to a modifier state change. This way, a modifier may automatically become latched or locked whenever a key is pressed or released.
Key groupsEdit
XKB allows for the keyboard to switch between any of four different character groups. This is usually done for making a keyboard behave like a keyboard of a different language. In this context, the set of characters that is generated by the keyboard is called a group, and a keyboard can switch to a different group at any time.
XKB defines some group selectors (which are simply called groups in the specification). As with modifiers, a group selector can be associated with a key, but can also be latched or locked.
ControlsEdit
The behavior of the keyboard depends on a number of parameters that can be changed by the clients. These parameters are called controls. For example, the SlowKey control can be used to ignore short keypresses. Another control is the MouseKeys, which makes some keypresses to simulate mouse movements. The control only indicates whether this simulation is active or not; which keys produce the movement is not considered a part of the control, but is specified by attaching actions to these keys.
The above two controls are boolean: they are either active or not. The PerKeyRepeat is a control that is not boolean. Namely, it is a mask that says which keys are in autorepeat mode. According to the specification, non-boolean controls are "always active": that means that they always depends on a set of parameters (in this case, the mask), but that there is no single bit that can be used to deactivate the effects of the control completely.
Other than being boolean or non-boolean, controls also classifies as affecting the behavior of the server and affecting the behavior of the client library. The two above are server controls. Client library controls affect the translation of a keycode or a sequence of keycodes into a string (XLookupString) and event delivery.
ActionsEdit
XKB allows for associating actions with key presses, which moves some of the burden of input event processing from client applications to the X server. However, the actions that can be associated with keys are limited to the following:
Change the state of a modifier, making it active, inactive, latched or locked
Change the state of the group selectors (same as modifiers)
Simulate a mouse event (movement or button activity)
Change the active screen (this kind of action is optional, that is, not necessarily supported by the server)
Change the state of boolean controls
Generate a message event (that is, a packet that is sent to the client)
Generate a different keycode
Moreover, there are some actions related to devices that are available if the server supports the X Input extension.
Compatibility problemsEdit
The X keyboard extension is incompatible with core keyboard handling and as a result several modifier keys are not working or require workarounds inside emulated environments such as VNC or Xephyr.
OtherEdit
XKB allows better handling of the keyboard indicators (LEDs). In particular, XKB provides symbolic names for indicators, which allows binding indicators to keyboard activity and checking which indicators are actually present on the keyboard.
XKB also improves upon the core protocol's handling of bells; the core protocol only supports one bell, and the only action a client can perform is to ring the bell. XKB supports multiple named bells and allows a client to deactivate some of them and to be informed when a bell is rung.
XKB allows a client to query the physical shape of the keyboard, including the shapes of individual keys. In particular, keys are arranged into sections, possibly rotated (as an example, the numeric keypad is typically considered a section). Within a section, keys are arranged into rows. Keys and sections have a geometry, which comprise the approximate outline of the key, its bounding box, and the precise form. Other than keys, the geometry also includes doodads, which are elements on the keyboard that are not keys. The overall shape of the keyboard is a doodad. Information provided about doodads includes their color and any text printed on them (including the font used).
ReferencesEdit
X Consortium Inc. The X keyboard extension: library specification (1996). HTML, PDF.
X Consortium Inc. The X keyboard extension: protocol specification (1996). HTML, PDF.
X Consortium Inc. The XKB configuration guide (2010) HTML, PDF.
X Consortium Inc. How to further enhance XKB configuration (2002). HTML, PDF.
External linksEdit
On XKB
ArchWiki. X keyboard extension
Damiano Venturin. A simple, humble but comprehensive guide to XKB for linux (2016)
Michal Kosmulski. Creating custom keyboard layouts for X11 using XKB (2011)
— Detailed information on the various XKB Configuration files.
Doug Palmer. An unreliable guide to XKB configuration (2004)
October 20, 2023
keyboard, extension, human, computer, interfaces, part, window, system, that, extends, ability, control, keyboard, over, what, offered, window, system, core, protocol, allows, multiple, keyboard, layouts, original, author, foundationstable, release1, 1996, yea. In human computer interfaces the X keyboard extension or XKB is a part of the X Window System that extends the ability to control the keyboard over what is offered by the X Window System core protocol and allows to use multiple keyboard layouts X keyboard extensionOriginal author s X Org FoundationStable release1 0 1996 27 years ago 1996 Websitewww wbr x wbr org wbr wiki wbr XKB wbr Its main features are enhanced support for modifiers Alt Shift etc better treatment of key groups typically keyboard layouts extended control of keyboard indicators LEDs and bells various new keyboard parameters controls association of actions of a particular kind to keys XKB is composed of two parts a server extension and a client library Modern versions of Xlib contain XKB which is active by default Client programs not using this extension can deactivate it before connecting with the server or can simply work normally as the extension simulates the core protocol by default XKB is also used by Wayland compositors and kmscon Contents 1 Latched and locked modifiers 2 Key groups 3 Controls 4 Actions 5 Compatibility problems 6 Other 7 References 8 External linksLatched and locked modifiers EditXKB allows a modifier to be locked or latched other than being in its regular state Normally a modifier is active exactly when it is pressed like the Shift However a modifier may also be locked like the Caps Lock modifier When a modifier is locked it remains active until it is explicitly deactivated An intermediate condition between regular and locked is the latched state When a modifier is latched it remains active but only until the next non modifier key is pressed XKB allows a client application to explicitly latch or lock a modifier Moreover an application can bind a key press or release to a modifier state change This way a modifier may automatically become latched or locked whenever a key is pressed or released Key groups EditXKB allows for the keyboard to switch between any of four different character groups This is usually done for making a keyboard behave like a keyboard of a different language In this context the set of characters that is generated by the keyboard is called a group and a keyboard can switch to a different group at any time XKB defines some group selectors which are simply called groups in the specification As with modifiers a group selector can be associated with a key but can also be latched or locked Controls EditThe behavior of the keyboard depends on a number of parameters that can be changed by the clients These parameters are called controls For example the SlowKey control can be used to ignore short keypresses Another control is the MouseKeys which makes some keypresses to simulate mouse movements The control only indicates whether this simulation is active or not which keys produce the movement is not considered a part of the control but is specified by attaching actions to these keys The above two controls are boolean they are either active or not The PerKeyRepeat is a control that is not boolean Namely it is a mask that says which keys are in autorepeat mode According to the specification non boolean controls are always active that means that they always depends on a set of parameters in this case the mask but that there is no single bit that can be used to deactivate the effects of the control completely Other than being boolean or non boolean controls also classifies as affecting the behavior of the server and affecting the behavior of the client library The two above are server controls Client library controls affect the translation of a keycode or a sequence of keycodes into a string XLookupString and event delivery Actions EditXKB allows for associating actions with key presses which moves some of the burden of input event processing from client applications to the X server However the actions that can be associated with keys are limited to the following Change the state of a modifier making it active inactive latched or locked Change the state of the group selectors same as modifiers Simulate a mouse event movement or button activity Change the active screen this kind of action is optional that is not necessarily supported by the server Change the state of boolean controls Generate a message event that is a packet that is sent to the client Generate a different keycodeMoreover there are some actions related to devices that are available if the server supports the X Input extension Compatibility problems EditThe X keyboard extension is incompatible with core keyboard handling and as a result several modifier keys are not working or require workarounds inside emulated environments such as VNC or Xephyr Other EditXKB allows better handling of the keyboard indicators LEDs In particular XKB provides symbolic names for indicators which allows binding indicators to keyboard activity and checking which indicators are actually present on the keyboard XKB also improves upon the core protocol s handling of bells the core protocol only supports one bell and the only action a client can perform is to ring the bell XKB supports multiple named bells and allows a client to deactivate some of them and to be informed when a bell is rung XKB allows a client to query the physical shape of the keyboard including the shapes of individual keys In particular keys are arranged into sections possibly rotated as an example the numeric keypad is typically considered a section Within a section keys are arranged into rows Keys and sections have a geometry which comprise the approximate outline of the key its bounding box and the precise form Other than keys the geometry also includes doodads which are elements on the keyboard that are not keys The overall shape of the keyboard is a doodad Information provided about doodads includes their color and any text printed on them including the font used References EditX Consortium Inc The X keyboard extension library specification 1996 HTML PDF X Consortium Inc The X keyboard extension protocol specification 1996 HTML PDF X Consortium Inc The XKB configuration guide 2010 HTML PDF X Consortium Inc How to further enhance XKB configuration 2002 HTML PDF External links EditOn XKBArchWiki X keyboard extension Damiano Venturin A simple humble but comprehensive guide to XKB for linux 2016 Michal Kosmulski Creating custom keyboard layouts for X11 using XKB 2011 Ivan Pascal X keyboard extension Detailed information on the various XKB Configuration files Doug Palmer An unreliable guide to XKB configuration 2004 Retrieved from https en wikipedia org w index php title X keyboard extension amp oldid 1042138395, wikipedia, wiki, book, books, library,
