I am trying to create a shared library for a part of my project that
contains a class derived from QFrame called QFilterWidget. If I build
the code as a shared library I am getting link errors with the
following output.
19>QLeeMarchingCubesWidget.obj : error LNK2001: unresolved external
symbol "public: static struct QMetaObject const
QFilterWidget::staticMetaObject"
(?staticMetaObject@QFilterWidget@@2UQMetaObject@@B)
19>QSMVtkPolyDataWriterWidget.obj : error LNK2001: unresolved external
symbol "public: static struct QMetaObject const
QFilterWidget::staticMetaObject"
(?staticMetaObject@QFilterWidget@@2UQMetaObject@@B)
I am running moc on the class which generates my moc_QFilterWidget.cxx
file and I have the necessary __declspec(dllexport)/(dllimport) stuff
defined in another header.
#if defined (PipelineBuilderLib_EXPORTS) /* Compiling the DLL/Dylib */
#if defined (_MSC_VER) /* MSVC Compiler Case */
#define PipelineBuilderLib_EXPORT __declspec(dllexport)
#elif (__GNUC__ >= 4) /* GCC 4.x has support for visibility options */
#define PipelineBuilderLib_EXPORT __attribute__ ((visibility("default")))
#endif
#else /* Importing the DLL into another project */
#if defined (_MSC_VER) /* MSVC Compiler Case */
#define PipelineBuilderLib_EXPORT __declspec(dllimport)
#elif (__GNUC__ >= 4) /* GCC 4.x has support for visibility options */
#define PipelineBuilderLib_EXPORT __attribute__ ((visibility("default")))
#endif
#endif
This is the top part of the class declaration for QFilterWidget:
class PipelineBuilderLib_EXPORT QFilterWidget : public QGroupBox
{
Q_OBJECT;
public:
QFilterWidget(QWidget* parent = NULL);
virtual ~QFilterWidget();
....
};
The link errors occur when I am creating a plugin library
(SurfaceMeshPlugin) which uses the library that the QFilterWidget is
compiled into (PipelineLib). I'm not really sure what I am missing at
this point. I am mostly an OS X guy so I may just be missing something
about building Qt based DLL's on windows. Building as a static library
is NOT possible because of a singleton class that is in the
PipelineLib. If I build as a static library then I get 2 distinct
instances of a "singleton" which is odd but understandable if the
plugin links a static lib and the Application links a static lib.
If anyone might be able to shed some light on how to create a DLL that
has QtWidgets with their signals/slots that would be awesome.
Thanks
--
Mike Jackson
imikejackson _at_ gee-mail dot com
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