focal (3) XkbKeyTypesForCoreSymbols.3.gz
NAME
XkbKeyTypesForCoreSymbols - Determine the Xkb key types appropriate for the symbols bound to a key in a
core keyboard mapping
SYNOPSIS
int XkbKeyTypesForCoreSymbols (XkbDescPtr xkb, int map_width, KeySym *core_syms, unsigned int protected,
int *types_inout, KeySym *xkb_syms_rtrn);
ARGUMENTS
- xkb keyboard description in which to place symbols
- map_width
width of core protocol keymap in xkb_syms_rtrn
- core_syms
core protocol format array of KeySyms
- protected
explicit key types
- types_inout
backfilled with the canonical types bound to groups one and two for the key
- xkb_syms_rtrn
backfilled with symbols bound to the key in the Xkb mapping
DESCRIPTION
XkbKeyTypesForCoreSymbols expands the symbols in core_syms and types in types_inout, then chooses
canonical key types (canonical key types are defined The Canonical Key Types) for groups 1 and 2 using
the rules specified by the Xkb protocol and places them in xkb_syms_rtrn, which will be non-NULL.
The Canonical Key Types
Xkb allows up to XkbMaxKeyTypes (255) key types to be defined, but requires at least XkbNumRequiredTypes
(4) predefined types to be in a key map. These predefined key types are referred to as the canonical key
types and describe the types of keys available on most keyboards. The definitions for the canonical key
types are held in the first XkbNumRequiredTypes entries of the types field of the client map and are
indexed using the following constants:
XkbOneLevelIndex
XkbTwoLevelIndex
XkbAlphabeticIndex
XkbKeypadIndex
ONE_LEVEL
The ONE_LEVEL key type describes groups that have only one symbol. The default ONE_LEVEL key type has no
map entries and does not pay attention to any modifiers. A symbolic representation of this key type could
look like the following:
type "ONE_LEVEL" {
modifiers = None;
map[None]= Level1;
level_name[Level1]= "Any";
};
The description of the ONE_LEVEL key type is stored in the types[XkbOneLevelIndex] entry of the client
key map.
TWO_LEVEL
The TWO_LEVEL key type describes groups that consist of two symbols but are neither alphabetic nor
numeric keypad keys. The default TWO_LEVEL type uses only the Shift modifier. It returns shift level two
if Shift is set, and level one if it is not. A symbolic representation of this key type could look like
the following:
type "TWO_LEVEL" {
modifiers = Shift;
map[Shift]= Level2;
level_name[Level1]= "Base";
level_name[Level2]= "Shift";
};
The description of the TWO_LEVEL key type is stored in the types[XkbTwoLevelIndex] entry of the client
key map.
ALPHABETIC
The ALPHABETIC key type describes groups consisting of two symbols: the lowercase form of a symbol
followed by the uppercase form of the same symbol. The default ALPHABETIC type implements locale-
sensitive "Shift cancels CapsLock" behavior using both the Shift and Lock modifiers as follows:
• If Shift and Lock are both set, the default ALPHABETIC type yields level one.
• If Shift alone is set, it yields level two.
• If Lock alone is set, it yields level one, but preserves the Lock modifier so Xlib notices and
applies the appropriate capitalization rules. The Xlib functions are locale-sensitive and apply
different capitalization rules for different locales.
• If neither Shift nor Lock is set, it yields level one.
A symbolic representation of this key type could look like the following:
type "ALPHABETIC" {
modifiers = Shift+Lock;
map[Shift]= Level2;
preserve[Lock]= Lock;
level_name[Level1]= "Base";
level_name[Level2]= "Caps";
};
The description of the ALPHABETIC key type is stored in the types[XkbAlphabeticIndex] entry of the
client key map.
KEYPAD
The KEYPAD key type describes groups that consist of two symbols, at least one of which is a numeric
keypad symbol. The numeric keypad symbol is assumed to reside at level two. The default KEYPAD key
type implements "Shift cancels NumLock" behavior using the Shift modifier and the real modifier
bound to the virtual modifier named "NumLock," known as the NumLock modifier, as follows:
• If Shift and NumLock are both set, the default KEYPAD type yields level one.
• If Shift alone is set, it yields level two.
• If NumLock alone is set, it yields level two.
• If neither Shift nor NumLock is set, it yields level one.
A symbolic representation of this key type could look like the following:
type "KEYPAD" {
modifiers = Shift+NumLock;
map[None]= Level1;
map[Shift]= Level2;
map[NumLock]= Level2;
map[Shift+NumLock]= Level1;
level_name[Level1]= "Base";
level_name[Level2]= "Caps";
};
The description of the KEYPAD key type is stored in the types[XkbKeypadIndex] entry of the client
key map.
A core keymap is a two-dimensional array of keysyms. It has map_width columns and max_key_code rows.
XkbKeyTypesForCoreSymbols takes a single row from a core keymap, determines the number of groups
associated with it, the type of each group, and the symbols bound to each group. The return value
is the number of groups, types_inout has the types for each group, and xkb_syms_rtrn has the symbols
in Xkb order (that is, groups are contiguous, regardless of size).
protected contains the explicitly protected key types. There is one explicit override control
associated with each of the four possible groups for each Xkb key, ExplicitKeyType1 through
ExplicitKeyType4; protected is an inclusive OR of these controls. map_width is the width of the
core keymap and is not dependent on any Xkb definitions. types_inout is an array of four type
indices. On input, types_inout contains the indices of any types already assigned to the key, in
case they are explicitly protected from change.
Upon return, types_inout contains any automatically selected (that is, canonical) types plus any
protected types. Canonical types are assigned to all four groups if there are enough symbols to do
so. The four entries in types_inout correspond to the four groups for the key in question.