Qwt and Qwtpolar : "Qwidget: Must construct a QApplication before a QWidget"

[plb29n]

Hi Uwe,

Thanks a lot for your reply. Following it, I checked with DepedencyWalker the dependencies of qwtpolard.dll and saw that
it depended on qwt.dll (instead of qwtd.dll). The reason is the following : Previously, in order to compile the qwtpolar libraries
under QtCreator I had to add qwt paths (lib and include) and library name to the qwtpolar/src/src.pro file and forgot to make
the distinction between release and debug mode.

When I do it in the right way (using CONFIG(debug, debug|release) ... ) it works perfectly : qwtpolard.dll depends on qwtd.dll
and my application runs in both modes.

The question is now : why do I have to add the dependencies to qwt (lib and include paths) when I try to compile qwtpolar
whereas I use the default .pro files delivered with qwtpolar1.1.1 ?

Thanks again.

[Uwe]

You didn't install qwtpolar properly - instead you are trying to build against something left over in the build directory. Once having qwtpolar installed, you will see, that qwtpolar.prf ( CONFIG += qwtpolar ) is the one for building applications.
Have a look at http://qwt.sourceforge.net/qwtinstall.html. The concepts are the same for qwtpolar then.

Putting the sources of qwt and qwtpolar and your application into one project is not the officially supported way and then you have to be able to ship around those issues yourself.

Uwe