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NAME

       XkbBell - Rings the bell on the default keyboard

SYNOPSIS

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

ARGUMENTS

       - display
              connection to the X server

       - window
              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
       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
       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_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, XkbBell calls XBell with
       the   specified   display  and  percent,  and  returns  False.  Otherwise,  XkbBell  calls
       XkbDeviceBell 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
       True.

       If you have disabled the audible bell, the server does not ring the system bell,  although
       it does generate a XkbBellNotify event.

       You can call XkbBell without first initializing the keyboard extension.

RETURN VALUES

       FALSE          The XkbBell function returns FALSE if XlibDisplayNoXkb is set.

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), XkbUseCoreKbd(3)