Conference bulova::decw_jan-89_to_nov-90

2714.0. "Client Application wants to update its windows?" by HILLST::KHALL (Wait till they get a load of me!) Fri May 04 1990 09:27

As I understand it X and DECwindows applications usually sit and loop, 
waiting for an event to occure.  This event is usually initiated by the 
user.  I've got a customer, however, that wants to be constantly updating 
the values within his windowed application.  The application might need 
to update as many as 100 displayed integer or floating point values per 
second.  What mechanisms are provided within X and DECwindows to 
accomplish this sort of thing?

Thanks for any help you can give,
Kyle

PS: Cross posted in X and DECwindows Conferences

    Your first statement is correct that application usually wait for an
    event to occur. For your situation you can use "work procedures". Work
    procedures get executed between checking for events. Thus work
    procedure should do short computation and display your number and
    return to the caller. This way application responses to user requests
    AND it does the display update same time.
    
    Robert
    

Also see XtAddInput and XtAddTimeout.  You can also service the queue 
within a long callback with XtPending/XtNextEvent/XtDispatchEvent, but 
watch for reentrancy.