[python-win32] ActiveX components with Events

[Neil Benn]

Hihn, Jason wrote:

>I will attempt to use my psychic powers and read into this situation
>more than you have told.
>
>
>That ActiveX is coded in VB, hence the OCX. The VB is calling
>form.show(). I bet (if all previous assumptiona are correct) that you
>could fix the subliminal message by calling form.load()
>
>I will stop now before people start thinking that I am proud of knowing
>VB.
>
>  
>
<snip>
Hello,

          I'm sorry but I'm having real trouble trying to get this 
across, please see the comment embedded in my original e-mail beneath :

<Last e-mail>
Sorry that was a bad explanation - the control _is_ an ActiveX exe - not 
an ocx - it simply brings up a form (which in actual fact I then hide 
immediately, I can't stop the form appearing in the first place - it has 
to appear for a few millisecs like a subliminal message).
</Last e-mail>

    The component is _not_ an ocx - I don't even know (or care) what the 
original programming language was, I guess its C++ but it doesn't (or 
shouldn't) concern me.  The component is an ActiveX exe which is an out 
of process exe - I didn't write it and I don't have the source code.  I 
have successfully interacted with the ActiveX component using Java and 
Jacob (a Java/COM bridge) using the interface supplied by the 
manufacturer.  The only reason that I'm quoting VB code is because I 
assumed that there would more people here who know VB than know Java/Jacob!

    Therefore the underlying component is trying to bring up a form, in 
order to give it the processor time to handle that I need to allow the 
OS to process the windows message (this is the bit that is written 
incorrectly in the ActiveX as they should be managing this themselves).  
The way to do this in VB is to use a method called DoEvents.  The 
DoEvents method basically calls PeekMessage and DispatchMessage for all 
messages waiting on the events queue and then returns into my process.  
Essentially this is what pythoncom.PumpWaitingMessages does.

    However this still doesn't work, I cannot get events.  Looking at 
the behavior in other code, an event is fired just before the form is 
shown, if this event is blocked in the EventHandkler then the ActiveX 
exe will hang on the completion.  Thereby stopping the code which 
displays the form from being executed in the component ActiveX.

    However upon inserted the pythomcom.PumpWaitingMessages, I still 
cannot capture any events from this ActiveX exe.  I even wrote a very 
very simple test case which creates an ActiveX dll with the following code :

public event Event1

public sub FireEvent()
    RaiseEvent Event1

the python code had

.>>>def class EventHandler:
.>>>   def Event1(self):
.>>>      print 'event fired'
.>>>objTest = DispatchWithEvents("TestDll.cTest", EventHandler)
.>>>objTest.FireEvent()

    This should have captured the event and displayed the test 'event 
fired' on the screen.  Nothing happened - I know I have a correct 
install because the IE6 example supplied in the docs in the source file 
for win32\client\__init__.py works fine.

    If there is any other information that could help to determine my 
problem then please let me know.  I appreciate your help - as I have 
managed to boil my problem down to a very simple test case then the fine 
details of the original ActiveX exe (__not__ an OCX) are by the by.  
This test case removes that element from the equation.

Cheers,

Neil

-- 

Neil Benn
Senior Automation Engineer
Cenix BioScience
BioInnovations Zentrum
Tatzberg 47
D-01307
Dresden
Germany

Tel : +49 (0)351 4173 154
e-mail : benn at cenix-bioscience.com
Cenix Website : http://www.cenix-bioscience.com