XtAppAddSignal(3Xt)X Version 11 (Release 6.6) XtAppAddSignal(3Xt)
NAME
XtAppAddSignal, XtRemoveSignal, XtNoticeSignal - register
and remove a signal source
SYNTAX
XtSignalId XtAppAddSignal(app_context, proc, client_data)
XtAppContext app_context;
XtSignalCallbackProc proc;
XtPointer client_data;
void XtRemoveSignal(id)
XtSignalId id;
void XtNoticeSignal(id)
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
XtAppAddSignal 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
Page 1 (printed 7/20/06)
XtAppAddSignal(3Xt)X Version 11 (Release 6.6) XtAppAddSignal(3Xt)
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
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