XtAppAddSignal(3)
NAME
XtAppAddSignal, XtRemoveSignal, XtNoticeSignal - register and remove a
signal source
SYNTAX
- XtSignalId XtAppAddSignal(XtAppContext app_context, XtSignalCallback
- Proc proc, XtPointer client_data);
- void XtRemoveSignal(XtSignalId id);
- void XtNoticeSignal(XtSignalId id);
ARGUMENTS
- app_context
- Specifies the application context.
- client_data
- Specifies the argument that is to be passed to the specified procedure when a signal has been raised.
- id Specifies the ID returned from the corresponding XtAppAdd
- Signal call.
- proc Specifies the procedure that is to be called when the signal
- has been raised.
DESCRIPTION
The XtAppAddSignal function initiates a mechanism for handling signals
within the context of the Intrinsics. Prior to establishing an operating system dependent signal handler the application may call XtAppAddSignal and store the returned id in a place accessible to the signal
handler.
Upon receipt of a signal from the operating system, the application may
call XtNoticeSignal passing the id returned by the call to XtAppAddSignal.
XtNoticeSignal is the only Intrinsics function that can safely be
called from a signal handler. If XtNoticeSignal is called multiple
times before the Intrinsics are able to invoke the registered callback,
the callback is only called once. Logically the Intrinsics maintain
``pending'' for each registered callback. This flag is initially False
and is set to True by XtNoticeSignal; the Intrinsics invoke the callback whenever the flag is True, and the flag is set to False just
before the callback is invoked.
The XtRemoveSignal function is called to remove the specified Intrinsics signal handler. The client should disable the source of the signal
before calling XtRemoveSignal.
SEE ALSO
- XtAppAddTimeOut(3Xt),XtAppAddInput(3Xt),XtAppAddWorkProc(3Xt)
X Toolkit Intrinsics - C Language Interface Xlib - C Language X Interface