XkbForceBell man page on Ubuntu

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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 *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:

       ·    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 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.

			 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 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.

		    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, 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(3),   XkbBell(3),	 XkbChangeEnabledControls(3),  XkbForceDevice‐
       Bell(3), XkbSelectEventDetails(3), XkbSelectEvents(3)

X Version 11			 libX11 1.3.2		       XkbForceBell(3)
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