While reviewing the code for WindowResizerClass (in an attempt to get more agreeable resizing behavior for ClarionTest) I came across a usage of RegisterEvent that I hadn't noticed before:
...
But RegisterEvent is part of the Clarion runtime, and it's smart enough to handle a method if that's what you throw at it.
Here's a small sample program to demonstrate:
| Code Block |
|---|
PROGRAM
MAP
END
EventQueue queue,type
EventTime long
end
EventHandler class
EventQ &EventQueue
Construct procedure
Destruct procedure
TakeEvent procedure,byte
end
Window WINDOW('Timer event callback'),AT(,,177,129),GRAY,FONT('Microsoft Sans Serif',8), |
TIMER(100)
LIST,AT(3,2,171,124),USE(?LIST1),VSCROLL,FROM(EventHandler.EventQ), |
FORMAT('20L(2)|M@t4@')
END
CODE
open(window)
accept
case event()
of EVENT:OpenWindow
RegisterEvent(event:timer,address(EventHandler.TakeEvent),address(EventHandler))
end
end
UnRegisterEvent(event:timer,address(EventHandler.TakeEvent),address(EventHandler))
close(window)
EventHandler.Construct procedure
code
self.EventQ &= new EventQueue
EventHandler.Destruct procedure
code
free(self.EventQ)
dispose(self.EventQ)
EventHandler.TakeEvent procedure
code
self.EventQ.EventTime = clock()
add(self.EventQ,-self.EventQ.EventTime)
return level:benign
|
...
The return value can be one of the following:
Level:Benign | Calls any other handlers and the ACCEPT loop, if available. |
Level:Notify | Doesn't call other handlers or the ACCEPT loop. This is like executing CYCLE when processing the event in an ACCEPT loop. |
Level:Fatal | Doesn't call other handlers or the ACCEPT loop. This is like executing BREAK when processing the event in an ACCEPT loop. |
On further experimentation I found that I could reduce the program code to just four lines:
...