Tribblix: manual page: XkbDeviceBellEvent.3

XkbDeviceBellEvent(3) XKB FUNCTIONS XkbDeviceBellEvent(3)

NAME

XkbDeviceBellEvent - Creates a bell event for an X input extension
device or for the keyboard, without ringing the corresponding bell

SYNOPSIS

Bool XkbDeviceBellEvent (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 event window, or None

device_spec
device ID, or XkbUseCoreKbd

bell_class
input extension bell class for the event

bell_id
input extension bell ID for the event

percent
volume for the bell, 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 the 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 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.

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, XkbDeviceBellEvent immediately returns False. Otherwise,
XkbDeviceBellEvent causes an XkbBellNotify event to be sent to
all interested clients and returns True. Set percent to be the
volume relative to the base volume for the keyboard as described
for XBell.

In addition, XkbDeviceBellEvent may generate Atom protocol
errors as well as XkbBellNotify events. You can call XkbBell
without first initializing the keyboard extension.

RETURN VALUES

True The XkbDeviceBellEvent sends an XkbBellNotify event to
to all interested clients and returns True.

False If a compatible keyboard extension isn't present in
the X server, XkbDeviceBellEvent immediately returns
False

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