Lets Dialog with Qt

[qtoptus]

Hello,

Is there a way that I can create a dialog application without using main() function? I want to call the dialog function from another application function instead that uses a different toolkit/framework. In other words I'm launching the dialog from within the same process of the main program.

Thanks.

[wysota]

Yes. Libraries do not need a main() function. Just export a function that you will call from within the main program. Note however that an instance of QApplication needs to exist to use Qt widgets so either the main application will have to create it or you need to do that yourself in your library function.

[qtoptus]

Great! So this implies a different process will be instantiated for the QApplication.

Thanks.

[qtoptus]

I'm writing a plugin for Lightwave3D which uses Qt for GUI instead of the LW native GUI. However I get this when I start LW:

msg.jpg

[wysota]

Most likely you have taken an incorrect version of Qt libraries (the ones for QtCreator instead of those for your apps) when deploying the plugin.

[qtoptus]

I don't use QtCreator. I copied the Qt dlls: QtCore4.dll, QtGui4.dll, and QtOpenGL4.dll from Qt bins to the plugin directory. However when I compile as Debug, and use the debug dll versions I get another error complaining about the MSVCP100d.dll not found...This file does not even look installed in my system.
My platform is Windows 7, VS 2008, and Qt 4.8.1 SDK.

[amleto]

you should take it as a hint that copy/pasting dlls all over the shop isn't the correct thing to do

[qtoptus]

Nothing Qt code related as I'm not using it. just trying to get the plugin loaded properly first. I could upload the project but first I need a confirmation that someone who willing to test it has access to Lightwave 3D 9.6. Otherwise it's useless. The code I have is only LW SDK plugin initialization, nothing more.

you should take it as a hint that copy/pasting dlls all over the shop isn't the correct thing to do

Correct when the DLLs are installed in the proper system directory

Otherwise we are all guessing the problem from a fabrication where relevant details are often missing.

As I mentioned not much details. The problem is very clear, a third party application loading a dll that depends on Qt dlls is failing to load. Clearly something has to do with Qt DLLs. I will try statically link to the Qt libs instead.

[amleto]

That's my sig you are responding to, but thanks for reading

[qtoptus]

LoL, sorry! I did not see that.

Anyway I hope it's something I can solve on my end, cause working with LW GUI is a pain...

[wysota]

I copied the Qt dlls: QtCore4.dll, QtGui4.dll, and QtOpenGL4.dll from Qt bins to the plugin directory.

What is the exact path to the files you copied?

[qtoptus]

Copied from C:\Qt\4.8.1\bin

[ChrisW67]

I get another error complaining about the MSVCP100d.dll not found...This file does not even look installed in my system.

This is the Microsoft Visual C 10 runtime debug version. It will be installed on any machine that has a recent enough Windows SDK/Visual Studio of some sort installed (I don't know if that is VS 2008 or 2010) as a SxS assembly and also redist file. If you are deploying your release application then you can use the redist package to ensure the release version of the runtime is present. You are not permitted to redistribute the debug library IIRC.

[qtoptus]

I could fix the problem, using a release build only, and a dialog based Qt application rather than a frame window. The plugin loads fine until I create the dialog instance, it crashes. I cannot debug the plugin since I cannot use a Debug version.

[qtoptus]

More details:

extern "C" void plugin_starter(...)
{
//Qt-main-code copied here

// Instantiate dialog class, CRASH!

}

[qtoptus]

Finally this worked! I have the dialog shows within the main program and no problem. After I added a tabbed widget to the dialog, the plugin fails to load again. And I got this message:

msg2.jpg

I have the correct DLLs QtCore4.dll, QtGui4.dll QtOpenGL4.dll version 4.8.2 and all copied from Qt\4.8.2\bin\

Any idea?

[qtoptus]

Any suggestions?

I'm suspecting it's a problem with Qt build itself since the module is aware of the dependency DLL, QtGui4.dll, but it cannot link to the function, which means a different signature/name mangling...

Should I build Qt from the source?

Can I link to static version of Qt libs?

[amleto]

do you have qt built with the same compiler as your app?

[qtoptus]

I installed the binary version 4.8.2 for the same compiler VS 2008.

[amleto]

how do you build your app, how do you link it with qt?

you will not be able to statically link since you have not built static qt libraries.

and you say you use sdk 4.8.1 earlier in the thread, but now you have installed 4.8.2 binaries? They should be compatible anyway, if built with same compiler.