path: root/libX11/man/xkb/XkbForceBell.man

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.TH XkbForceBell __libmansuffix__ __xorgversion__ "XKB FUNCTIONS"
.SH NAME
XkbForceBell \- Overrides user preference settings for audible bells to ring the 
bell on the default keyboard
.SH SYNOPSIS
.HP
.B Bool XkbForceBell
.BI "(\^Display *" "display" "\^,"
.BI "int " "percent" "\^);"
.if n .ti +5n
.if t .ti +.5i
.SH ARGUMENTS
.TP
.I \- display
connection to the X server
.TP
.I \- percent
volume for the bell, which can range from -100 to 100 inclusive
.SH DESCRIPTION
.LP
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 
.I 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:

.IP \(bu 5
The default bell
.IP \(bu 5
Any bell on an input device that can be specified by a bell_class and bell_id pair
.IP \(bu 5
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.)

.LP
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 - 
.I XkbForceDeviceBell 
or 
.I 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.

.B 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.

.TS
c s
l l
lW(4i) l.
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
.TE

.B 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
.I 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 
.I XkbForceDeviceBell 
or 
.I 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
.I bell_class 
and 
.I bell_id 
parameters; set them as follows: Set 
.I bell_class 
to BellFeedbackClass or KbdFeedbackClass. A device can have more than one feedback 
of 
each type; set 
.I bell_id 
to the particular bell feedback of 
.I 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.

.TS
c s s s
l l l l
l l l l.
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
.TE


If a compatible keyboard extension isn't present in the X server, 
.I XkbForceBell 
calls 
.I XBell 
with the specified 
.I display 
and 
.I percent 
and returns False. Otherwise, 
.I XkbForceBell 
calls 
.I XkbForceDeviceBell 
with the specified 
.I display 
and 
.I percent, device_spec 
=XkbUseCoreKbd, 
.I bell_class 
= XkbDfltXIClass, 
.I bell_id 
= XkbDfltXIId, 
.I window 
= None, and 
.I name 
= NULL, and returns what 
.I XkbForceDeviceBell 
returns.

.I XkbForceBell 
does not cause an XkbBellNotify event.

You can call 
.I XkbBell 
without first initializing the keyboard extension.
.SH "RETURNS VALUES"
.TP 15
False
The 
.I XkbForceBell 
function returns False when a compatible keyboard extension isn't present in the X server.
.SH STRUCTURES
.LP
Xkb generates XkbBellNotify events for all bells except for those resulting from 
calls to 
.I XkbForceDeviceBell 
and 
.I XkbForceBell. 
To receive XkbBellNotify events under all possible conditions, pass 
XkbBellNotifyMask in 
both the 
.I bits_to_change 
and 
.I values_for_bits 
parameters to 
.I XkbSelectEvents.

The XkbBellNotify event has no event details. It is either selected or it is not. 
However, you can call 
.I XkbSelectEventDetails 
using XkbBellNotify as the 
.I event_type 
and specifying XkbAllBellNotifyMask in 
.I bits_to_change 
and 
.I values_for_bits. 
This has the same effect as a call to 
.I XkbSelectEvents.

The structure for the XkbBellNotify event type contains:
.nf

   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;
   
.fi   
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.

.SH "SEE ALSO"
.BR XBell (__libmansuffix__),
.BR XkbBell (__libmansuffix__),
.BR XkbChangeEnabledControls (__libmansuffix__),
.BR XkbForceDeviceBell (__libmansuffix__),
.BR XkbSelectEventDetails (__libmansuffix__),
.BR XkbSelectEvents (__libmansuffix__)