In VB6 - How to unload a form that is in the middle of having code executed on it due to a multi-threaded programming model (using timers)?
I have a program which there is a "CANCEL" button on a form which is supposed to unload the form in question and reactivate the form that called it. The problem is that a timer triggered event is updating picture boxes and while that occurs, this form (the one with the cancel button and picturboxes) will reappear even though I tried to unload it. How do I stop execution dead on a form before unloading it. ? Is this clear enough?
I tried to code an 'abort' global variable which I would set true when I'm about to unload the form (and the code in the timer would exit its loop if abort is set true (if abort then exit sub). Problem is that mostly this works but sometimes due to some timing constraint .. the form will disappear and reappear with a picturebox being updated nonetheless. Debugging shows the abort value to be true in all cases so I'm sure it's not a coding error (too simple to be coding error)
Please advise (p.s. I'm not a novice but programming multi-threaded apps in vb6 is something I'm not used to)
thanks
Mike
I tried to code an 'abort' global variable which I would set true when I'm about to unload the form (and the code in the timer would exit its loop if abort is set true (if abort then exit sub). Problem is that mostly this works but sometimes due to some timing constraint .. the form will disappear and reappear with a picturebox being updated nonetheless. Debugging shows the abort value to be true in all cases so I'm sure it's not a coding error (too simple to be coding error)
Please advise (p.s. I'm not a novice but programming multi-threaded apps in vb6 is something I'm not used to)
thanks
Mike
If it's in its own thread, why not just hide the form and put the unload code in the event that the timer triggered??
ASKER
you mean something like this
sub timerupdate_timer()
do while somethingwonderful
if not forminqustion.visible then exit do
...other stuff
loop
if not forminquestion.visible then unload me
end sub
would this work?
Leaving the form hidden (and having the thread run) takes up a lot of computing power. It's a high-res graphical app.
Mike
sub timerupdate_timer()
do while somethingwonderful
if not forminqustion.visible then exit do
...other stuff
loop
if not forminquestion.visible then unload me
end sub
would this work?
Leaving the form hidden (and having the thread run) takes up a lot of computing power. It's a high-res graphical app.
Mike
I think you're on the right track already. Disable the Timer and set your global variable. Then EVERYWHERE in the Timer event you need to check the globabl before you manipulate any controls on the form. You may have to spatter the code with multiple checks.
May we see the Timer code?
May we see the Timer code?
if the process is in the middle of a task then you won't be able to exit until all the code in the Timer procedure is finished. This is what idle_mind means by "You may have to spatter the code with multiple checks"
simply placing it at the top will stop it for the next time around, but won't stop it while its processing therefor you will have multiple checks going all the way down to the last line of your routine
simply placing it at the top will stop it for the next time around, but won't stop it while its processing therefor you will have multiple checks going all the way down to the last line of your routine
You could try this if your reference the object.
Set mtimer = nothing
Set mtimer = nothing
ASKER CERTIFIED SOLUTION
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1. make sure you don't have doevent inside the timer routine
2. worse case, use End (not recommended)
2. worse case, use End (not recommended)
ASKER
Thank you one and all for your input. The threading code is very similar to my actual structure so that's what I've tried ... and it worked!!
Now I also see a couple of other ways to do this. I really appreciate the help
Mike
Now I also see a couple of other ways to do this. I really appreciate the help
Mike