Tribblix: manual page: XkbBell.3

XkbBell(3) XKB FUNCTIONS XkbBell(3)

NAME

XkbBell - Rings the bell on the default keyboard

SYNOPSIS

Bool XkbBell (Display *display, Window window, int percent, Atom
name);

ARGUMENTS

display
connection to the X server

window event window, or None

percent
relative volume, which can range from -100 to 100 inclusive

name a bell name, 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:

+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 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 Table 1 below; 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 turned on or off 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

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
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,
XkbBell calls XBell with the specified display and percent, and
returns False. Otherwise, XkbBell calls XkbDeviceBell with the
specified display, window, percent, and name, a device_spec of
XkbUseCoreKbd, a bell_class of XkbDfltXIClass, and a bell_id of
XkbDfltXIId, 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 XkbBell without first initializing the keyboard
extension.

RETURN VALUES

FALSE The XkbBell function returns FALSE if XlibDisplayNoXkb
is set.

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 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.

NAME

SYNOPSIS

ARGUMENTS

DESCRIPTION

RETURN VALUES

STRUCTURES

SEE ALSO