XkbDeviceBell(3)
NAME
XkbDeviceBell - Rings the bell on an X input extension device or the default keyboard
SYNOPSIS
Bool XkbDeviceBell (Display *display, Window window, unsigned int
device_spec, unsigned int bell_class, unsigned int bell_id, int
percent, Atom name);
ARGUMENTS
- display
connection to the X server
- window
window for which the bell is generated, or None
- device_spec
device ID, or XkbUseCoreKbd
- bell_class
X input extension bell class of the bell to be rung
- bell_id
X input extension bell ID of the bell to be rung
- percent
bell volume, from -100 to 100 inclusive
- name a name for the bell, 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 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.
The 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
Set percent to be the volume relative to the base volume for the
keyboard as described for .I XBell.
Note that bell_class and bell_id indicate the bell to physically
ring. name is simply an arbitrary moniker for the client
application's use.
To determine the current feedback settings of an extension input
device, use XGetFeedbackControl. See the X input extension
documentation for more information on XGetFeedbackControl and
related data structures.
If a compatible keyboard extension is not present in the X server,
XkbDeviceBell immediately returns False. Otherwise, XkbDeviceBell
rings the bell as specified for the display and keyboard device
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 XkbDeviceBell without first initializing the keyboard
extension.
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), XGetFeedbackControl(3), XkbSelectEvents(3)
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