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NAME

       XkbBellEvent  -  Provides  a function that initiates a bell event for the keyboard without
       ringing the bell

SYNOPSIS

       Bool XkbBellEvent (Display *display, Window window, int percent, Atom name);

ARGUMENTS

       - display
              connection to the X server

       - window
              the event window, or None

       - percent,
              relative volume, which can range from -100 to 100 inclusive

       - name a bell name, or NULL

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  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, XkbBellEvent
            immediately returns False. Otherwise, XkbBellEvent calls XkbDeviceBellEvent with  the
            specified  display,  window,  percent,  and  name,  a device_spec of XkbUseCoreKbd, a
            bell_class of  XkbDfltXIClass,  and  a  bell_id  of  XkbDfltXIId,  and  returns  what
            XkbDeviceBellEvent returns.

            XkbBellEvent generates a XkbBellNotify event.

            You can call XkbBellEvent without first initializing the keyboard extension.

RETURN VALUES

       False          The  XkbBellEvent  immediately  returns  False,  if  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  XkbAllBellEventsMask 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

       XkbChangeEnabledControls(3),            XkbDeviceBellEvent(3),            XkbForceBell(3),
       XkbForceDeviceBell(3), XkbSelectEventDetails(3), XkbSelectEvents(3)