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XkbKeyNumActions(3) XKB FUNCTIONS XkbKeyNumActions(3) NAME XkbKeyNumActions - Computes the number of actions associated with the key corresponding to keycode SYNOPSIS int XkbKeyNumActions (XkbDescPtr xkb, KeyCode keycode); ARGUMENTS xkb Xkb description of interest keycode keycode of interest DESCRIPTION A key action defines the effect key presses and releases have on the internal state of the server. For example, the expected key action as- sociated with pressing the Shift key is to set the Shift modifier. There is zero or one key action associated with each keysym bound to each key. Just as the entire list of key symbols for the keyboard mapping is held in the syms field of the client map, the entire list of key actions for the keyboard mapping is held in the acts array of the server map. The total size of acts is specified by size_acts, and the number of entries is specified by num_acts. The key_acts array, indexed by keycode, describes the actions associ- ated with a key. The key_acts array has min_key_code unused entries at the start to allow direct indexing using a keycode. If a key_acts entry is zero, it means the key does not have any actions associated with it. If an entry is not zero, the entry represents an index into the acts field of the server map, much as the offset field of a KeySymMapRec structure is an index into the syms field of the client map. The reason the acts field is a linear list of XkbActions is to reduce the memory consumption associated with a keymap. Because Xkb allows in- dividual keys to have multiple shift levels and a different number of groups per key, a single two-dimensional array of KeySyms would poten- tially be very large and sparse. Instead, Xkb provides a small two-di- mensional array of XkbActions for each key. To store all of these indi- vidual arrays, Xkb concatenates each array together in the acts field of the server map. The key action structures consist only of fields of type char or un- signed char. This is done to optimize data transfer when the server sends bytes over the wire. If the fields are anything but bytes, the server has to sift through all of the actions and swap any nonbyte fields. Because they consist of nothing but bytes, it can just copy them out. XkbKeyNumActions computes the number of actions associated with the key corresponding to keycode. This should be the same value as the result of XkbKeyNumSyms. STRUCTURES The KeySymMapRec structure is defined as follows: #define XkbNumKbdGroups 4 #define XkbMaxKbdGroup (XkbNumKbdGroups-1) typedef struct { /* map to keysyms for a single keycode */ unsigned char kt_index[XkbNumKbdGroups]; /* key type index for each group */ unsigned char group_info; /* # of groups and out of range group handling */ unsigned char width; /* max # of shift levels for key */ unsigned short offset; /* index to keysym table in syms array */ } XkbSymMapRec, *XkbSymMapPtr; SEE ALSO XkbKeyNumSyms(3) X Version 11 libX11 1.8.12 XkbKeyNumActions(3)
NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | STRUCTURES | SEE ALSO
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