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XkbForceBell(3)                  XKB FUNCTIONS                 XkbForceBell(3)



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

SYNOPSIS
       Bool XkbForceBell ( display, percent )
             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,  dis-
       able  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 fol-
       lowing:


       o    The default bell

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

       o    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 con-
       figure 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 XkbBellNo-
       tify 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 Ta-
       ble 1; the name is included in any bell event sent to clients that have
       requested to receive XkbBellNotify events.


       c  s  l  l lW(4i) l.  Table 1 Predefined Bells _ Action    Named Bell _
       Indicator turned on    AX_IndicatorOn Indicator turned off     AX_Indi-
       catorOff  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 T{ SlowKeys and
       BounceKeys  about  to  be  turned  on  or  off  T}   AX_SlowKeysWarning
       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_Stick-
       yUnlock

       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 XkbBell-
       Notify 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 XkbAudible-
       BellMask 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 XkbForceDe-
       viceBell 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 gener-
       ate 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  XkbBell-
       NotifyEvent to be generated when a bell function is called.


       c s s s l l l l l l l l.  Table 2 Bell Sounding and Bell Event Generat-
       ing    _    Function    called     AudibleBell    Server    sounds    a
       bell     Server    sends    an    XkbBellNotifyEvent    _    XkbDevice-
       Bell  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   XkbDeviceForce-
       Bell  On or Off    Yes  No XkbForceBell   On or Off Yes  No


       If  a compatible keyboard extension isn't present in the X server, Xkb-
       ForceBell 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  compati-
                      ble 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 param-
       eters to XkbSelectEvents.

       The  XkbBellNotify event has no event details. It is either selected or
       it is not.  However, you can call XkbSelectEventDetails using  XkbBell-
       Notify   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 XkbBell-
       NotifyEvent, if present.


SEE ALSO
       XBell(3X11),  XkbBell(3),  XkbChangeEnabledControls(3), XkbForceDevice-
       Bell(3), XkbSelectEventDetails(3), XkbSelectEvents(3)



X Version 11                     libX11 1.1.5                  XkbForceBell(3)