XtAppMainLoop()XtAppMainLoop()NameXtAppMainLoop - continuously process events.
Synopsis
void XtAppMainLoop(app_context)
XtAppContext app_context;
Inputs
app_context
Specifies the application context that identifies the appli‐
cation.
ReturnsXtAppMainLoop() enters an infinite loop and never returns.
DescriptionXtAppMainLoop() enters an infinite loop which calls XtAppNextEvent() to
wait for an events on all displays in app_context and XtDispatchEvent()
to dispatch that event to the appropriate code.
Usage
Most applications will call XtAppNextEvent() as the last line of their
main() procedure. Some applications may provide their own versions of
this loop, however. A custom event loop might test an application-
dependent global flag or other termination condition before looping
back and calling XtAppNextEvent(). If the number of top-level widgets
drops to zero, the application may be able to exit safely, for example.
Applications that use multiple application contexts or that use inter‐
nal event loops will have to build their own event loop.
BackgroundXtAppNextEvent() looks for X events in the input queue, and also han‐
dles timer events (see XtAppAddTimeOut()) and events from alternate
input sources (see XtAppAddInput()). If none of these events are pend‐
ing and a work procedure (see XtAppAddWorkProc()) is registered, XtApp‐
NextEvent() invokes that work procedure to do background processing,
otherwise it blocks waiting for an event. Note that XtAppNextEvent()
dispatches timer and input events directly, but returns any X events
that occur. Within XtAppMainLoop(), these X events are always passed
to XtDispatchEvent().
XtDispatchEvent() dispatches an event to the appropriate event handlers
(see XtAddEventHandler()). Note that the translation manager registers
an event handler, and that events that are dispatched to the transla‐
tion manager will be further dispatched through the translations-to-
actions mechanism.
ExampleXtAppMainLoop() is implemented as follows:
void XtAppMainLoop(app)
XtAppContext app;
{
XEvent event;
for (;;) {
XtAppNextEvent(app, &event);
XtDispatchEvent(&event);
}
}
See AlsoXtAddEventHandler(1), XtAppAddInput(1), XtAppAddTimeOut(1), XtAppAd‐
dWorkProc(1), XtAppNextEvent(1), XtAppProcessEvent(1), XtDis‐
patchEvent(1).
Xt - Event Handling XtAppMainLoop()
