Table of Contents
XtAppAddSignal, XtRemoveSignal, XtNoticeSignal
- register and remove a signal source
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)
- 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.
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.
XtAppAddTimeOut(3Xt)
,XtAppAddInput(3Xt)
,XtAppAddWorkProc(3Xt)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
Table of Contents