XkbGetKeyboardByName(3)
NAME
XkbGetKeyboardByName - Build a new keyboard description from a set of
named components, and to optionally have the server use the resulting
description to replace an active one
SYNOPSIS
XkbDescPtr XkbGetKeyboardByName (Display *dpy, unsigned int
device_spec, XkbComponentNamesPtr names, unsigned int want,
unsigned int need, Bool load);
ARGUMENTS
- dpy connection to X server
- device_spec
device ID, or XkbUseCoreKbd
- names
names of components to fetch
- want desired structures in returned record
- need mandatory structures in returned record
- load True => load into device_spec
DESCRIPTION
A client may request that the server fetch one or more components from
its database and use those components to build a new server keyboard
description. The new keyboard description may be built from scratch,
or it may be built starting with the current keyboard description for a
particular device. Once the keyboard description is built, all or part
of it may be returned to the client. The parts returned to the client
need not include all of the parts used to build the description. At the
time it requests the server to build a new keyboard description, a
client may also request that the server use the new description
internally to replace the current keyboard description for a specific
device, in which case the behavior of the device changes accordingly.
To build a new keyboard description from a set of named components, and
to optionally have the server use the resulting description to replace
an active one, use XkbGetKeyboardByName.
names contains a set of expressions describing the keyboard components
the server should use to build the new keyboard description. want and
need are bit fields describing the parts of the resulting keyboard
description that should be present in the returned XkbDescRec.
The individual fields in names are component expressions composed of
keyboard component names (no wildcarding as may be used in
XkbListComponents), the special component name symbol `%', and the
special operator characters `+' and `|'. A component expression is
parsed left to right, as follows:
* The special component name "computed" may be used in keycodes
component expressions and refers to a component consisting of a
set of keycodes computed automatically by the server as needed.
* The special component name "canonical" may be used in types
component expressions and refers to a partial component defining
the four standard key types: ALPHABETIC, ONE_LEVEL, TWO_LEVEL, and
KEYPAD.
* The special component name `%' refers to the keyboard description
for the device specified in device_spec or the keymap names
component. If a keymap names component is specified that does not
begin with `+' or `|' and does not contain `%', then `%' refers to
the description generated by the keymap names component.
Otherwise, it refers to the keyboard description for device_spec.
* The `+' operator specifies that the following component should
override the currently assembled description; any definitions that
are present in both components are taken from the second.
* The `|' operator specifies that the next specified component
should augment the currently assembled description; any
definitions that are present in both components are taken from the
first.
* If the component expression begins with an operator, a leading `%'
is implied.
* If any unknown or illegal characters appear anywhere in the
expression, the entire expression is invalid and is ignored.
For example, if names->symbols contained the expression "+de", it
specifies that the default member of the "de" class of symbols
should be applied to the current keyboard mapping, overriding any
existing definitions (it could also be written "+de(default)").
Here is a slightly more involved example: the expression
"acme(ascii)+de(basic)|iso9995-3" constructs a German (de) mapping
for the ASCII keyboard supplied by the "acme" vendor. The new
definition begins with the symbols for the ASCII keyboard for Acme
(acme(ascii)), overrides them with definitions for the basic
German keyboard (de(basic)), and then applies the definitions from
the default iso9995-3 keyboard (iso9995-3) to any undefined keys
or groups of keys (part three of the iso9995 standard defines a
common set of bindings for the secondary group, but allows
national layouts to override those definitions where necessary).
NOTE The interpretation of the above expression components (acme,
ascii, de, basic, iso9995-3) is not defined by Xkb; only the
operations and their ordering are.
Note that the presence of a keymap names component that does not
contain `%' (either explicit or implied by virtue of an expression
starting with an operator) indicates a description that is
independent of the keyboard description for the device specified
in device_spec. The same is true of requests in which the keymap
names component is empty and all five other names components
contain expressions void of references to `%'. Requests of this
form allow you to deal with keyboard definitions independent of
any actual device.
The server parses all non-NULL fields in names and uses them to
build a keyboard description. However, before parsing the
expressions in names, the server ORs the bits in want and need
together and examines the result in relationship to the
expressions in names. Table 1 identifies the components that are
required for each of the possible bits in want or need. If a
required component has not been specified in the names structure
(the corresponding field is NULL), the server substitutes the
expression "%", resulting in the component values being taken from
device_spec. In addition, if load is True, the server modifies
names if necessary (again using a "%" entry) to ensure all of the
following fields are non-NULL: types, keycodes, symbols, and
compat.
Table 1 Want and Need Mask Bits and Required Names Components
want or need mask bit Required names Components value
XkbGBN_TypesMask Types (1L<<0)
XkbGBN_CompatMapMask Compat (1L<<1)
XkbGBN_ClientSymbolsMask Types + Symbols + Keycodes (1L<<2)
XkbGBN_ServerSymbolsMask Types + Symbols + Keycodes (1L<<3)
XkbGBN_SymbolsMask Symbols (1L<<1)
XkbGBN_IndicatorMapMask Compat (1L<<4)
XkbGBN_KeyNamesMask Keycodes (1L<<5)
XkbGBN_GeometryMask Geometry (1L<<6)
XkbGBN_OtherNamesMask Types + Symbols + Keycodes + Compat + Geometry (1L<<7)
XkbGBN_AllComponentsMask (0xff)
need specifies a set of keyboard components that the server must
be able to resolve in order for XkbGetKeyboardByName to succeed;
if any of the components specified in need cannot be successfully
resolved, XkbGetKeyboardByName fails.
want specifies a set of keyboard components that the server should
attempt to resolve, but that are not mandatory. If the server is
unable to resolve any of these components, XkbGetKeyboardByName
still succeeds. Bits specified in want that are also specified in
need have no effect in the context of want.
If load is True, the server updates its keyboard description for
device_spec to match the result of the keyboard description just
built. If load is False, the server's description for device
device_spec is not updated. In all cases, the parts specified by
want and need from the just-built keyboard description are
returned.
The names structure in an XkbDescRec keyboard description record
contains one field for each of the five component types used to
build a keyboard description. When a keyboard description is built
from a set of database components, the corresponding fields in
this names structure are set to match the expressions used to
build the component.
Building a New Keyboard Description from the Server Database
The information returned to the client in the XkbDescRec is
essentially the result of a series of calls to extract information
from a fictitious device whose description matches the one just
built. The calls corresponding to each of the mask bits are
summarized in Table 2, together with the XkbDescRec components
that are filled in.
Table 2 XkbDescRec Components Returned for Values of Want & Needs
Request (want+need) Fills in Xkb components Equivalent Function Call
XkbGBN_TypesMask map.types XkbGetUpdatedMap(dpy, XkbTypesMask, Xkb)
XkbGBN_ServerSymbolsMask server XkbGetUpdatedMap(dpy,
XkbAllClientInfoMask, Xkb)
XkbGBN_ClientSymbolsMask map, including map.types
XkbGetUpdatedMap(dpy, XkbAllServerInfoMask, Xkb)
XkbGBN_IndicatorMaps indicators XkbGetIndicatorMap(dpy,
XkbAllIndicators, Xkb)
XkbGBN_CompatMapMask compat XkbGetCompatMap(dpy, XkbAllCompatMask, Xkb)
XkbGBN_GeometryMask geom XkbGetGeometry(dpy, Xkb)
XkbGBN_KeyNamesMask names.keys XkbGetNames(dpy, XkbKeyNamesMask |
names.key_aliases XkbKeyAliasesMask, Xkb)
XkbGBN_OtherNamesMask names.keycodes XkbGetNames(dpy, XkbAllNamesMask &
names.geometry ~(XkbKeyNamesMask | XkbKeyAliasesMask),
names.symbols Xkb)
names.types
map.types[*].lvl_names[*]
names.compat
names.vmods
names.indicators
names.groups
names.radio_groups
names.phys_symbols
There is no way to determine which components specified in want
(but not in need) were actually fetched, other than breaking the
call into successive calls to XkbGetKeyboardByName and specifying
individual components.
XkbGetKeyboardByName always sets min_key_code and max_key_code in
the returned XkbDescRec structure.
XkbGetKeyboardByName is synchronous; it sends the request to the
server to build a new keyboard description and waits for the
reply. If successful, the return value is non-NULL.
XkbGetKeyboardByName generates a BadMatch protocol error if errors
are encountered when building the keyboard description.
STRUCTURES
The complete description of an Xkb keyboard is given by an XkbDescRec.
The component structures in the XkbDescRec represent the major Xkb
components outlined in Figure 1.1.
typedef struct {
struct _XDisplay * display; / connection to X server */
unsigned short flags; / private to Xkb, do not modify */
unsigned short device_spec; / device of interest */
KeyCode min_key_code; / minimum keycode for device */
KeyCode max_key_code; / maximum keycode for device */
XkbControlsPtr ctrls; / controls */
XkbServerMapPtr server; / server keymap */
XkbClientMapPtr map; / client keymap */
XkbIndicatorPtr indicators; / indicator map */
XkbNamesPtr names; / names for all components */
XkbCompatMapPtr compat; / compatibility map */
XkbGeometryPtr geom; / physical geometry of keyboard */
} XkbDescRec, *XkbDescPtr;
The display field points to an X display structure. The flags field is
private to the library: modifying flags may yield unpredictable
results. The device_spec field specifies the device identifier of the
keyboard input device, or XkbUseCoreKeyboard, which specifies the core
keyboard device. The min_key_code and max_key_code fields specify the
least and greatest keycode that can be returned by the keyboard.
Each structure component has a corresponding mask bit that is used in
function calls to indicate that the structure should be manipulated in
some manner, such as allocating it or freeing it. These masks and their
relationships to the fields in the XkbDescRec are shown in Table 3.
Table 3 Mask Bits for XkbDescRec
Mask Bit XkbDescRec Field Value
XkbControlsMask ctrls (1L<<0)
XkbServerMapMask server (1L<<1)
XkbIClientMapMask map (1L<<2)
XkbIndicatorMapMask indicators (1L<<3)
XkbNamesMask names (1L<<4)
XkbCompatMapMask compat (1L<<5)
XkbGeometryMask geom (1L<<6)
XkbAllComponentsMask All Fields (0x7f)
DIAGNOSTICS
BadMatch A compatible version of Xkb was not available in the
server or an argument has correct type and range, but is
otherwise invalid
SEE ALSO
XkbListComponents(3)
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