XkbAllocDeviceInfo - Man Page

XkbDeviceInfoPtr XkbAllocDeviceInfo (unsigned int device_spec, unsigned int n_buttons, unsigned int sz_leds);

device_spec

device ID with which structure will be used

n_buttons

number of button actions to allocate space for

sz_leds

number of LED feedbacks to allocate space for

XkbAllocDeviceInfo allocates space for an XkbDeviceInfoRec structure and initializes that structure's device_spec field with the device ID specified by device_spec. If n_buttons is nonzero, n_buttons XkbActions are linked into the XkbDeviceInfoRec structure and initialized to zero. If sz_leds is nonzero, sz_leds XkbDeviceLedInfoRec structures are also allocated and linked into the XkbDeviceInfoRec structure. If  you request XkbDeviceLedInfoRec structures be allocated using this request, you must initialize them  explicitly, by using XkbAddDeviceLedInfo(3).

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;

XkbAddDeviceLedInfo(3)

XkbGetDeviceInfo(3).