| background processing and widget_event [message #12417] |
Wed, 29 July 1998 00:00 |
Ray
Messages: 8
Registered: July 1998
|
Junior Member |
|
|
I'd like to put some low-priority, background processing into a widget
application.
I'd like the background processing to be interruptable - it bails if the
user generates
any events while the background processing is occurring. (At a later
point background
processing could be started again but it would have to start at the
beginning - at this
point I am not concenred about using partial results obtained when it
was interrupted.) Finally, I'd like this to be workable without
straying too far from using xmanager to manage the widgets.
It seems to me that I should be able to sprinkle widget_event calls
throught the
background processing procedure and to have the procedure bail if any
user events
have been generated. Of course, the process of checking for user events
using
widget_event should not result in any loss or change in the order of
queued events.
Below is my current attempt. (.run test & test). I am puzzled. I
click on "the long event"
and processing commences as expected. However, when I click on "the
short event"
while the long event is processing, I see that the short event gets
processed and then
the long event processing continues where it left off. It seems the me
that
the widget_event(/nowait) call initiates the short event processing.
Based on
my interpretation of the IDL docs, I expected widget_event would simply
return the next
event and not actually process it. What have I missed?
Ray Muzic
-
8>< on the dotted line
---------------------test.pro--------------------------
; example to test method for simulating multi-threading
; 1. create base widget, start event processing
; 2. while "the long event" processing, occasionally check for pending
events.
; if one is found, bail out of long event routine and process the
event.
; this should require re-queueing events to not alter the order of
event
; processing.
function LongEvent, event
common test, count, base
; function needed to enable event re-queueing
l=0L
print,'Long Event'
for i=0,9 do begin
print,'Inside LongEvent, i=',i
; check for queued events
we=widget_event(base, /nowait)
print,'we=',we.id,we.top,we.handler
if (we.id ne 0L) then begin
; bail if there is a queued event
print,'Bailing'
return, we
endif
for j=0L,500000L do begin
l=l+j
endfor ; j
endfor ; i
return,0L ; swallow event - LongEvent has completed
;
end
pro ShortEvent, event
common test, count, base
; print sequence of numbers. if re-queueing is done properly, no
; events should be lost
print,'Short Event'
print, 'Count=',count
count=count+1
end
pro DoneEvent, event
widget_control, event.top, /DESTROY
end
pro test
common test, count, base
count=0L
; create simple base
base=widget_base(/column)
button0=widget_button(base, value='the long event',
event_func='LongEvent')
button1=widget_button(base, value='the short event',
event_pro='ShortEvent')
button2=widget_button(base, value='Done', event_pro='DoneEvent')
widget_control, base, /REALIZE
xmanager, 'test', base
end
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
