XkbAllocDeviceLedInfo(3)

NAME

   XkbAllocDeviceLedInfo - Obtain an XkbDeviceLedInfoRec structure

SYNOPSIS

   Status   XkbAllocDeviceLedInfo   (XkbDeviceInfoPtr   device_info,   int
          num_needed);

ARGUMENTS

   - device_info
          structure in which to allocate LED space

   - num_needed
          number of indicators to allocate space for

DESCRIPTION

   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.

STRUCTURES

   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:

   *    The conditions under which the keyboard modifier state affects the
        indicator

   *    The  conditions  under  which the keyboard group state affects the
        indicator

   *    The conditions under which  the  state  of  the  boolean  controls
        affects the indicator

   *    The  effect (if any) of attempts to explicitly change the state of
        the   indicator   using   the    functions    XkbSetControls    or
        XChangeKeyboardControl

SEE ALSO

   XkbAddDeviceLedInfo(3), XkbSetControls(3)

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