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:
- •
- 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
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 |
| 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 |
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 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),
XkbUseCoreKbd(3)
