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NAME

       XkbForceBell  - Overrides user preference settings for audible bells to
       ring the bell on the default keyboard

SYNOPSIS

       Bool XkbForceBell (Display *display, int percent);

ARGUMENTS

       - display
              connection to the X server

       - percent
              volume for the bell, which can range from -100 to 100 inclusive

DESCRIPTION

       The core X protocol allows only applications to  explicitly  sound  the
       system  bell with a given duration, pitch, and volume. Xkb extends this
       capability by allowing clients  to  attach  symbolic  names  to  bells,
       disable  audible bells, and receive an event whenever the keyboard bell
       is rung. For the purposes of this document, the audible bell is defined
       to  be the system bell, or the default keyboard bell, as opposed to any
       other audible sound generated elsewhere in the system.  You can ask  to
       receive  XkbBellNotify  events  when  any  client  rings any one of the
       following:

       ·    The default bell

       ·    Any bell on an input device that can be specified by a  bell_class
            and bell_id pair

       ·    Any  bell  specified only by an arbitrary name. (This is, from the
            server’s point of view, merely a name, and not connected with  any
            physical  sound-generating  device.  Some  client application must
            generate the sound, or visual feedback, if any, that is associated
            with the name.)

       You  can also ask to receive XkbBellNotify events when the server rings
       the default bell or if any client has requested  events  only  (without
       the bell sounding) for any of the bell types previously listed.

       You  can disable audible bells on a global basis. For example, a client
       that replaces the keyboard bell with some other audible cue might  want
       to  turn  off  the  AudibleBell control to prevent the server from also
       generating a sound and avoid cacophony. If you  disable  audible  bells
       and  request to receive XkbBellNotify events, you can generate feedback
       different from the default bell.

       You can, however, override the AudibleBell control by  calling  one  of
       the  functions that force the ringing of a bell in spite of the setting
       of the AudibleBell control - XkbForceDeviceBell  or  XkbForceBell.   In
       this case the server does not generate a bell event.

       Just  as some keyboards can produce keyclicks to indicate when a key is
       pressed or repeating, Xkb can provide  feedback  for  the  controls  by
       using  special  beep  codes.   The  AccessXFeedback  control is used to
       configure the specific types of operations that generate feedback.

       Bell Names

       You can associate a name to an act of ringing a bell by converting  the
       name  to  an  Atom and then using this name when you call the functions
       listed in this chapter. If an event is generated as a result, the  name
       is   then   passed   to  all  other  clients  interested  in  receiving
       XkbBellNotify events. Note that these  are  arbitrary  names  and  that
       there is no binding to any sounds. Any sounds or other effects (such as
       visual bells on the screen) must be generated by a  client  application
       upon receipt of the bell event containing the name. There is no default
       name for the default keyboard  bell.  The  server  does  generate  some
       predefined  bells for the AccessX controls. These named bells are shown
       in the Table 1; the name is included in any bell event sent to  clients
       that have requested to receive XkbBellNotify events.

                         Table 1 Predefined Bells
       --------------------------------------------------------------
       Action                                     Named Bell
       --------------------------------------------------------------
       Indicator turned on                        AX_IndicatorOn
       Indicator turned off                       AX_IndicatorOff
       More than one indicator changed state      AX_IndicatorChange
       Control turned on                          AX_FeatureOn
       Control turned off                         AX_FeatureOff
       More than one control changed state        AX_FeatureChange
       SlowKeys  and  BounceKeys  about  to  be   AX_SlowKeysWarning
       turned on or off
       SlowKeys key pressed                       AX_SlowKeyPress
       SlowKeys key accepted                      AX_SlowKeyAccept
       SlowKeys key rejected                      AX_SlowKeyReject
       Accepted SlowKeys key released             AX_SlowKeyRelease
       BounceKeys key rejected                    AX_BounceKeyReject
       StickyKeys key latched                     AX_StickyLatch
       StickyKeys key locked                      AX_StickyLock
       StickyKeys key unlocked                    AX_StickyUnlock

       Audible Bells

       Using Xkb you can generate bell events that do not necessarily ring the
       system bell.  This is useful if you need to use an audio server instead
       of the system beep. For example, when an audio client starts, it  could
       disable  the  audible  bell  (the  system  bell)  and  then  listen for
       XkbBellNotify events. When it receives a XkbBellNotify event, the audio
       client could then send a request to an audio server to play a sound.

       You   can   control   the   audible   bells   feature  by  passing  the
       XkbAudibleBellMask   to   XkbChangeEnabledControls.    If    you    set
       XkbAudibleBellMask  on,  the  server  rings the system bell when a bell
       event occurs. This is the default. If you  set  XkbAudibleBellMask  off
       and  a  bell  event  occurs,  the  server does not ring the system bell
       unless you call XkbForceDeviceBell or XkbForceBell.

       Audible bells are also part of the per-client auto-reset controls.

       Bell Functions

       Use the functions described in  this  section  to  ring  bells  and  to
       generate bell events.

       The  input extension has two types of feedbacks that can generate bells
       - bell feedback and keyboard feedback. Some of the  functions  in  this
       section  have  bell_class  and bell_id parameters; set them as follows:
       Set bell_class to BellFeedbackClass or KbdFeedbackClass. A  device  can
       have more than one feedback of each type; set bell_id to the particular
       bell feedback of bell_class type.

       Table 2 shows  the  conditions  that  cause  a  bell  to  sound  or  an
       XkbBellNotifyEvent to be generated when a bell function is called.

                    Table 2 Bell Sounding and Bell Event Generating
       ---------------------------------------------------------------------------
       Function called      AudibleBell   Server sounds a bell   Server sends an
       XkbBellNotifyEvent
       ---------------------------------------------------------------------------
       XkbDeviceBell        On            Yes                    Yes
       XkbDeviceBell        Off           No                     Yes
       XkbBell              On            Yes                    Yes
       XkbBell              Off           No                     Yes
       XkbDeviceBellEvent   On or Off     No                     Yes
       XkbBellEvent         On or Off     No                     Yes
       XkbDeviceForceBell   On or Off     Yes                    No
       XkbForceBell         On or Off     Yes                    No

       If  a  compatible  keyboard  extension  isn’t  present in the X server,
       XkbForceBell calls XBell with the specified  display  and  percent  and
       returns  False.  Otherwise,  XkbForceBell calls XkbForceDeviceBell with
       the  specified  display  and   percent,   device_spec   =XkbUseCoreKbd,
       bell_class  = XkbDfltXIClass, bell_id = XkbDfltXIId, window = None, and
       name = NULL, and returns what XkbForceDeviceBell returns.

       XkbForceBell does not cause an XkbBellNotify event.

       You can call XkbBell without first initializing the keyboard extension.

RETURNS VALUES

       False          The   XkbForceBell   function   returns   False  when  a
                      compatible keyboard extension isn’t  present  in  the  X
                      server.

STRUCTURES

       Xkb  generates  XkbBellNotify  events  for  all  bells except for those
       resulting  from  calls  to  XkbForceDeviceBell  and  XkbForceBell.   To
       receive  XkbBellNotify  events  under  all  possible  conditions,  pass
       XkbBellNotifyMask  in  both  the  bits_to_change  and   values_for_bits
       parameters to XkbSelectEvents.

       The  XkbBellNotify event has no event details. It is either selected or
       it  is  not.   However,  you  can  call   XkbSelectEventDetails   using
       XkbBellNotify  as the event_type and specifying XkbAllBellNotifyMask in
       bits_to_change and values_for_bits.  This has the same effect as a call
       to XkbSelectEvents.

       The structure for the XkbBellNotify event type contains:

          typedef struct _XkbBellNotify {
              int            type;        /∗ Xkb extension base event code */
              unsigned long  serial;      /∗ X server serial number for event */
              Bool           send_event;  /∗ True => synthetically generated */
              Display *      display;     /∗ server connection where event generated */
              Time           time;        /∗ server time when event generated */
              int            xkb_type;    /∗ XkbBellNotify */
              unsigned int   device;      /∗ Xkb device ID, will not be XkbUseCoreKbd */
              int            percent;     /∗ requested volume as % of max */
              int            pitch;       /∗ requested pitch in Hz */
              int            duration;    /∗ requested duration in microseconds */
              unsigned int   bell_class;  /∗ X input extension feedback class */
              unsigned int   bell_id;     /∗ X input extension feedback ID */
              Atom           name;        /∗ "name" of requested bell */
              Window         window;      /∗ window associated with event */
              Bool           event_only;  /∗ False -> the server did not produce a beep */
          } XkbBellNotifyEvent;

       If  your  application  needs  to  generate  visual bell feedback on the
       screen when it receives  a  bell  event,  use  the  window  ID  in  the
       XkbBellNotifyEvent, if present.

SEE ALSO

       XBell(3),            XkbBell(3),           XkbChangeEnabledControls(3),
       XkbForceDeviceBell(3), XkbSelectEventDetails(3), XkbSelectEvents(3)