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


       Bool XkbForceBell (Display *display, int percent);


       - display
              connection to the X server

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


       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

       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
       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.


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


       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.


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