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XkbAllocDeviceLedInfo - Obtain an XkbDeviceLedInfoRec structure


Status XkbAllocDeviceLedInfo
(XkbDeviceInfoPtr device_info, int num_needed);


- device_info
structure in which to allocate LED space
- num_needed
number of indicators to allocate space for


XkbAllocDeviceLedInfo allocates space for an XkbDeviceLedInfoRec and places it in device_info. If num_needed is nonzero, num_needed XkbIndicatorMapRec structures are also allocated and linked into the XkbDeviceLedInfoRec structure. If you request XkbIndicatorMapRec structures be allocated using this request, you must initialize them explicitly. All other fields are initialized to zero.

To initialize an XkbDeviceLedInfoRec structure, use XkbAddDeviceLedInfo.


Information about X Input Extension devices is transferred between a client program and the Xkb extension in an XkbDeviceInfoRec structure:

    typedef struct {
        char *               name;          /* name for device */
        Atom                 type;          /* name for class of devices
        unsigned short       device_spec;   /* device of interest */
        Bool                 has_own_state; /* True=>this device has its
own state */
        unsigned short       supported;     /* bits indicating supported
capabilities */
        unsigned short       unsupported;   /* bits indicating unsupported
capabilities */
        unsigned short       num_btns;      /* number of entries in btn_acts
        XkbAction *          btn_acts;      /* button actions */
        unsigned short       sz_leds;       /* total number of entries
in LEDs vector */
        unsigned short       num_leds;      /* number of valid entries
in LEDs vector */
        unsigned short       dflt_kbd_fb;   /* input extension ID of default
(core kbd) indicator */
        unsigned short       dflt_led_fb;   /* input extension ID of default
indicator feedback */
        XkbDeviceLedInfoPtr  leds;          /* LED descriptions */
    } XkbDeviceInfoRec, *XkbDeviceInfoPtr;
    typedef struct {
        unsigned short      led_class;        /* class for this LED device*/
        unsigned short      led_id;           /* ID for this LED device
        unsigned int        phys_indicators;  /* bits for which LEDs physically
present */
        unsigned int        maps_present;     /* bits for which LEDs have
maps in maps */
        unsigned int        names_present;    /* bits for which LEDs are
in names */
        unsigned int        state;            /* 1 bit => corresponding
LED is on */
        Atom                names[XkbNumIndicators];   /* names for LEDs
        XkbIndicatorMapRec  maps;             /* indicator maps for each
LED */
    } XkbDeviceLedInfoRec, *XkbDeviceLedInfoPtr;
Each indicator has its own set of attributes that specify whether clients can explicitly set its state and whether it tracks the keyboard state. The attributes of each indicator are held in the maps array, which is an array of XkbIndicatorRec structures:
    typedef struct {
        unsigned char   flags;            /* how the indicator can be changed
        unsigned char   which_groups;     /* match criteria for groups
        unsigned char   groups;           /* which keyboard groups the
indicator watches */
        unsigned char   which_mods;       /* match criteria for modifiers
        XkbModsRec      mods;             /* which modifiers the indicator
watches */
        unsigned int    ctrls;            /* which controls the indicator
watches */
    } XkbIndicatorMapRec, *XkbIndicatorMapPtr;
This indicator map specifies for each indicator:

See Also

XkbAddDeviceLedInfo(3) , XkbSetControls(3)

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