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X11R7.4 - man page for xkbforcebell (x11r4 section 3)

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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, percent )
	     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, 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:

       o    The default bell

       o    Any bell on an input device that can be specified by a bell_class and bell_id pair

       o    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  dif-
       ferent 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  -  Xkb-
       ForceDeviceBell 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 repeat-
       ing, 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 gener-
       ate 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  receiv-
       ing 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 pre-
       defined	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 XkbBell-
       Notify 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  lis-
       ten  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 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 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, 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.

RETURNS VALUES
       False	      The  XkbForceBell  function returns False when a compatible keyboard exten-
		      sion 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  parame-
       ters to XkbSelectEvents.

       The  XkbBellNotify  event  has no event details. It is either selected or it is not.  How-
       ever, you can call XkbSelectEventDetails using XkbBellNotify as the event_type and  speci-
       fying  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(3X11),   XkbBell(3),   XkbChangeEnabledControls(3),   XkbForceDeviceBell(3),  XkbSe-
       lectEventDetails(3), XkbSelectEvents(3)

X Version 11				   libX11 1.2.1 			  XkbForceBell(3)
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