xtappmainloop(1) [hpux man page]
XtAppMainLoop() XtAppMainLoop() Name XtAppMainLoop - continuously process events. Synopsis void XtAppMainLoop(app_context) XtAppContext app_context; Inputs app_context Specifies the application context that identifies the application. Returns XtAppMainLoop() enters an infinite loop and never returns. Description XtAppMainLoop() enters an infinite loop which calls XtAppNextEvent() to wait for an events on all displays in app_context and XtDis- patchEvent() 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 exam- ple. Applications that use multiple application contexts or that use internal event loops will have to build their own event loop. Background XtAppNextEvent() looks for X events in the input queue, and also handles timer events (see XtAppAddTimeOut()) and events from alternate input sources (see XtAppAddInput()). If none of these events are pending and a work procedure (see XtAppAddWorkProc()) is registered, XtAppNextEvent() invokes that work procedure to do background processing, otherwise it blocks waiting for an event. Note that XtAppNex- tEvent() 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 reg- isters an event handler, and that events that are dispatched to the translation manager will be further dispatched through the transla- tions-to-actions mechanism. Example XtAppMainLoop() is implemented as follows: void XtAppMainLoop(app) XtAppContext app; { XEvent event; for (;;) { XtAppNextEvent(app, &event); XtDispatchEvent(&event); } } See Also XtAddEventHandler(1), XtAppAddInput(1), XtAppAddTimeOut(1), XtAppAddWorkProc(1), XtAppNextEvent(1), XtAppProcessEvent(1), XtDis- patchEvent(1). Xt - Event Handling XtAppMainLoop()
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XtAppProcessEvent() XtAppProcessEvent() Name XtAppProcessEvent - get and process one input event of a specified type. Synopsis void XtAppProcessEvent(app_context, mask) XtAppContext app_context; XtInputMask mask; Inputs app_context Specifies the application context for which to process events. mask Specifies what types of events to process. Description XtAppProcessEvent() processes one X event, alternate input source event or timer event in app_context. The mask argument specifies which types of events are to be processed; it is the bitwise inclusive OR ( ) of any of the values XtIMXEvent, XtIMTimer, or XtIMAlternateInput, or the value XtIMAll which specifies all three event types. If there is no event or input of the appropriate type to process, if there is a background work procedure registered (see XtAppAd- dWorkProc()) XtAppProcessEvent() calls that procedure and checks again for input from all specified sources. If there are no pending events and no work procedures registered, XtAppProcessEvent() blocks until an event of one of the specified types occurs. If X events are specified in mask, and no events are immediately available, XtAppProcessEvent() flushes the output buffer of each of the Displays in app_context. If there is more than one of the requested types of input available, it is undefined which will be processed. XtAppProcessEvent() handles timer and alternate input events by calling the callback procedures registered for those events (see XtAppAd- dTimeOut() and XtAppAddInput()). It handles X events by passing them to XtDispatchEvent(). XtDispatchEvent() handles an event by passing it to the appropriate event handlers (see XtAddEventHandler()) or to the Translation Manager (which is itself an event handler). Usage Programs rarely need this much control over the event dispatching mechanism. Most programs use XtAppMainLoop(). Structures The XtInputMask type and its possible values are defined as follows: typedef unsigned long XtInputMask; #define XtIMXEvent 1 #define XtIMTimer 2 #define XtIMAlternateInput 4 #define XtIMAll (XtIMXEvent XtIMTimer XtIMAlternateInput) See Also XtAppAddInput(1), XtAppAddTimeOut(1), XtAppAddWorkProc(1), XtAppMainLoop(1), XtAppNextEvent(1), XtAppPeekEvent(1), XtAppPending(1), XtDis- patchEvent(1). Xt - Event Handling XtAppProcessEvent()