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NAME

       XkbDeviceBellEvent  -  Creates  a  bell  event  for an X input extension device or for the
       keyboard, without ringing the corresponding bell

SYNOPSIS

       Bool XkbDeviceBellEvent  (Display  *display,  Window  window,  unsigned  int  device_spec,
              unsigned int bell_class, unsigned int bell_id, int percent, Atom name);

ARGUMENTS

       - display
              connection to the X server

       - window
              event window, or None

       - device_spec
              device ID, or XkbUseCoreKbd

       - bell_class
              input extension bell class for the event

       - bell_id
              input extension bell ID for the event

       - percent
              volume for the bell, 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 the Table 1 below; 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,  XkbDeviceBellEvent
            immediately  returns  False.  Otherwise,  XkbDeviceBellEvent  causes an XkbBellNotify
            event to be sent to all interested clients and returns True. Set percent  to  be  the
            volume relative to the base volume for the keyboard as described for XBell.

            In  addition,  XkbDeviceBellEvent  may  generate  Atom  protocol  errors  as  well as
            XkbBellNotify events. You can call XkbBell without first  initializing  the  keyboard
            extension.

RETURN VALUES

       True           The  XkbDeviceBellEvent  sends  an XkbBellNotify event to to all interested
                      clients and returns True.

       False          If  a  compatible  keyboard  extension  isn't  present  in  the  X  server,
                      XkbDeviceBellEvent immediately returns False

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),       XkbBellNotify(3),      XkbChangeEnabledControls(3),      XkbDeviceBell(3),
       XkbForceBell(3),  XkbForceDeviceBell(3),   XkbSelectEvents(3),   XkbSelectEventDetails(3),
       XkbUseCoreKbd(3)