Provided by: libx11-doc_1.8.7-1build1_all 
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)