NAME
XkbForceBell - Overrides user preference settings for audible bells to ring the bell on the default keyboard SYNOPSIS Bool XkbForceBell (Display *display, int percent); ARGUMENTS
- display connection to the X server
- percent
volume for the bell, which can range from -100 to 100 inclusive 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, dis‐ able 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 fol‐ lowing: · The default bell · Any bell on an input device that can be specified by a bellclass and bellid 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 con‐ figure 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 XkbBellNo‐ tify 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 Ta‐ ble 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 AXIndicatorOn Indicator turned off AXIndicatorOff More than one indicator changed state AXIndicatorChange Control turned on AXFeatureOn Control turned off AXFeatureOff More than one control changed state AXFeatureChange SlowKeys and BounceKeys about to be AXSlowKeysWarning turned on or off SlowKeys key pressed AXSlowKeyPress SlowKeys key accepted AXSlowKeyAccept SlowKeys key rejected AXSlowKeyReject Accepted SlowKeys key released AXSlowKeyRelease BounceKeys key rejected AXBounceKeyReject StickyKeys key latched AXStickyLatch StickyKeys key locked AXStickyLock StickyKeys key unlocked AXStickyUnlock 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 XkbBell‐ Notify 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 XkbAudible‐ BellMask 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 XkbForceDe‐ viceBell 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 gener‐ ate 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 bellclass and bellid parameters; set them as follows: Set bellclass to BellFeedbackClass or KbdFeedbackClass. A device can have more than one feedback of each type; set bellid to the particular bell feedback of bellclass type. Table 2 shows the conditions that cause a bell to sound or an XkbBell‐ NotifyEvent 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, Xkb‐ ForceBell calls XBell with the specified display and percent and returns False. Otherwise, XkbForceBell calls XkbForceDeviceBell with the specified display and percent, devicespec =XkbUseCoreKbd, bellclass = XkbDfltXIClass, bellid = XkbDfltXIId, window = None, and name = NULL, and returns what XkbForceDeviceBell returns. XkbForceBell does not cause an XkbBellNotify event. You can call XkbBell without first initializing the keyboard extension. RETURNS VALUES False The XkbForceBell function returns False when a compati‐ ble keyboard extension isn't present in the X server. 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 bitstochange and valuesforbits param‐ eters to XkbSelectEvents. The XkbBellNotify event has no event details. It is either selected or it is not. However, you can call XkbSelectEventDetails using XkbBell‐ Notify as the eventtype and specifying XkbAllBellNotifyMask in bitstochange and valuesforbits. 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 sendevent; /∗ True => synthetically generated */ Display * display; /∗ server connection where event generated */ Time time; /∗ server time when event generated */ int xkbtype; /∗ 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 bellclass; /∗ X input extension feedback class */ unsigned int bellid; /∗ X input extension feedback ID */ Atom name; /∗ "name" of requested bell */ Window window; /∗ window associated with event */
Bool eventonly; /∗ 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 XkbBell‐ NotifyEvent, if present. SEE ALSO XBell(3), XkbBell(3), XkbChangeEnabledControls(3), XkbForceDevice‐ Bell(3), XkbSelectEventDetails(3), XkbSelectEvents(3) X Version 11 libX11 1.6.5 XkbForceBell(3)