ActiveQt Com app example - COM server not registered in Windows registry (Qt4.7.4)

Question

I’m currently trying to use the example project Com App which is given with the Qt installation (Qt_folder\Examples\4.7\activeqt\comapp)

I’m using version 4.7.4 on Windows, Qt Creator 2.3.0 and MinGw compiler.

So the example project compiles and runs fine, but it seems the COM server informations are not registered into the registry because I’m not able to reach it from any scripts, and I also cannot find UID in the registry, meaning that the COM server is not registered.

I’m trying to find a solution from 3 days ago and I’m starting to be desperate. Any help is welcome.

p.s. Sorry for my english, it’s not my native language

How did you manage to get a Qt+MinGW COM ready (you claim you succeed in compiling the comapp project)? — menjaraz, Feb 21 '12 at 17:20
I have just opened the comapp example from Qt example folder, and then I compile it from Qt creator. I did nothing special. — Gojir4, Jul 03 '12 at 11:52

Matthew · Accepted Answer · 2012-07-03T13:16:08.407

0

Not sure if Qt looks after this under the hood but are you sure that your thread is being initialized for COM by calling CoInitializeEx?

I've been using some COM and Qt at work and this is sometimes something is overlooked.

CoInitializeEx Function

Here is an example of using the function.

MyClass::MyClass()
{
    // Make this call before attempting to access COM.
    if( SUCCEEDED( CoInitializeEx( 0, COINIT_APARTMENTTHREADED ) ) )
    {
         // This single thread has been initialized for COM usage.
         // Alternatively you can use COINIT_MULTITHREADED instead
         // of COINIT_APARTMENTTHREADED if you require threaded
         // support.
    }
    else
    {
         // Failed, still must call uninitialize.
         CoUninitialize();
    }
}

MyClass::~MyClass()
{
    CoUninitialize();
}

edited Jul 03 '12 at 13:16

answered Jul 02 '12 at 23:52

Matthew

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28

Thanks for reply. How can you verify that CoInitializeEx is called ? I thought that it is handled by Qt. Are you using MingGW or VS compiler ? I found that is working fine if I import the project in Visual Studio 2008 using the visual studio add-in. I didn't try another solution from last post because I put this issue on hold. But now I will restart it soon as I need to resolve it for my project. – Gojir4 Jul 03 '12 at 11:54
@Gojir4, edited my answer to include an example of initialization of COM in a class. I'm using VS2008, which is VC9. – Matthew Jul 03 '12 at 13:19
@Gojir4, no need to check if CoInitializeEx has been called. Just call it again and it will return S_FALSE, if the thread is already initialized. Just make sure to call CoUninitialize if you call CoInitializeEx regardless of its return value. – Matthew Jul 03 '12 at 16:09
Thanks for your suggestion. It helps me because I used the QAxObject to make a COM client and it was not working because CoInitializeEx was not called. – Gojir4 Jul 11 '12 at 11:26

score 0 · Answer 2 · edited May 23 '17 at 12:04

It seems the only way to make COM interface to work properly is to compile from VS using Qt VS add-in. It works for me, I used Visual Studio 2008. See this post : Building ActiveQt (COM) applications with MinGW

But anyway this does not fix the issue as it's necessary to have a Microsoft VS license to be able to compile Qt software using COM interface. (VS add-in is not compatible with VS express editions)

Thanks to all for your help.

ActiveQt Com app example - COM server not registered in Windows registry (Qt4.7.4)

2 Answers2