Re: ActiveX control blocking the GUI

Hello,

I am developing a simple dialog based MFC application which contains
one ActiveX control that performs some image aquistion from external
devices and displays the image in its window (live preview).
Besides this control, the dialog has two buttons: one that starts the
image aquistion with this controls and the other that stops/aborts it
(by sending an "ESC" keypress message to this control's window).
The actual aqusition process is started in the first button's
BN_CLICKED notification message handler with a call to this control's
appropriate interface method, and this is where the main problem lies.
This method is a long lasting blocking method, and since its called
from a buttom message handler, the dialog's message dispatcher gets
blocked and the entire application becomes unresponsive.

My question: is there a way in MFC to circumvent this issue?

I tried one simple and vey dirty (naive) way to solve this by creating
a worker thread from the button's message handler, passing the thread a
pointer to this ActiveX control's object (an instance of MFC-generated
wrapper class) and then calling the objects method from the thread. The
result was miserable ofcourse, the application crashed with an access
violation exception somwhere in MSVBVM60.

Since I am quite a newbie in MFC/ActiveX development, I am out of ideas
what to do next so any help on this matter would be greatly
appreciated.

Best regards.

Bila