Custom Widgets loading in Designer, but unable to find headers in Creator

[wysota]

Well I simply ran build from the QT Creator.

Creator runs "make", not "make install".

From a bit of research, I found that it may have to do with adding libs to my project...unsure though, currently I just add the includepath for the headers.

That's not enough. You need to link the project against the actual code of the widget, either by compiling the widget files directly with your project or by linking to a library containing the widget implementation (like the plugin library). The plugin itself is only meant for Designer.

[Polnareff]

That's not enough. You need to link the project against the actual code of the widget, either by compiling the widget files directly with your project or by linking to a library containing the widget implementation (like the plugin library). The plugin itself is only meant for Designer.

By adding the header files and including it via the INCLUDEPATH, isn't that what I'm doing?

[wysota]

No. Header files only contain declarations of functions and classes. When you use Qt it is not enough to include Qt headers in your project, you need to link to actual Qt libraries (dlls), right? That's the same case here.

[Polnareff]

Ah, that makes sense. Okay well I've re-compiled my widget with mvsc (mostly because I want to be able to add the widgets from QT Creator's designer), and copied the lib into a folder called lib in my project root. So I have

/include/punitspinbox.h (there are others, but this is the only one I'm using at the moment)
/lib/PCustomWidgetGroup.lib

I've added the following lines to my project file:
INCLUDEPATH += ./include
LIBS += -lib -PCustomWidgetGroup

The first problem I have is with the LIBS line...which I followed from tutorials. Either way, upon replacing it with an actual direct path to the lib file, it finds the lib file, but I get the following error:

C:/Documents and Settings/amaior/Desktop/Projects/IntegratedCustomWidgets/ui_mainwindow.h:49: undefined reference to `_imp___ZN12PUnitSpinBoxC1EP7QWidget'

[wysota]

Your LIBS line is surely incorrect. It should say LIBS += -lnameofthelibrary, i.e. -lmyplugin (if your lib is called myplugin.dll).

[Polnareff]

Your LIBS line is surely incorrect. It should say LIBS += -lnameofthelibrary, i.e. -lmyplugin (if your lib is called myplugin.dll).

Thanks. I've fixed that, but the other error persists =/

[wysota]

Did you build the plugin with the same compiler you are using for compiling your projects? Also make sure you actually implemented the UnitSpinBox constructor taking a QWidget parameter. Remember about exporting the class from the DLL! In doubt, consult the documentation for Windows specifics.

[Polnareff]

I've decided to stop building with the mvsc compiler, and just stick to the one that QT Creator uses. And yes, the UnitSpinBox constructor takes a QWidget parameter.

Now I have two questions...

1. I made a macro to export my classes to DLL, and want to put it in the class definition. Except since my classes are also exported to designer, I need to have both macros in the class definition. Unfortunately, the following doesn't seem to work:

class SHAREDLIB_EXPORT QDESIGNER_WIDGET_EXPORT PUnitSpinBox : public PUnitWidget  {

class SHAREDLIB_EXPORT QDESIGNER_WIDGET_EXPORT PUnitSpinBox : public PUnitWidget  {

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I also tried separating the macros by comma, with no success. What's the correct syntax for this?

2. Currently building doesn't ever produce a *.lib file. Is that normal? What am I supposed to link against without it? (please excuse my lack of knowledge on this stuff, I'm still learning)

[wysota]

You only need one macro, they both probably have the same contents.

2. Currently building doesn't ever produce a *.lib file. Is that normal?

If you don't have export macros then yes. That's why you need them

[Polnareff]

Shortly before your reply I realized the macros were doing the same thing :P

But that's just it, I've had the QDESIGNER_WIDGET_EXPORT macro in there the whole time, and I still don't have any lib file. Incase it's important, my .pro file is:

CONFIG += designer \
    plugin \
    release
TEMPLATE = lib
DEFINES += SHAREDLIB_LIBRARY
 
HEADERS += pcustomwidgetgroupplugin.h \
include(CustomWidgets.pri)
 
target.path = $$[QT_INSTALL_PLUGINS]/designer
INSTALLS += target

CONFIG += designer \
    plugin \
    release
TEMPLATE = lib
DEFINES += SHAREDLIB_LIBRARY

HEADERS += pcustomwidgetgroupplugin.h \
include(CustomWidgets.pri)

target.path = $$[QT_INSTALL_PLUGINS]/designer
INSTALLS += target

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Am I missing something to create the lib file?

[wysota]

What's in CustomWidgets.pri?

[Polnareff]

HEADERS += pframe.h \
    punitspinbox.h \
    punitslider.h \
    punitwidget.h \
    sharedlib_global.h
SOURCES += pframe.cpp \
    punitspinbox.cpp \
    punitslider.cpp \
    punitwidget.cpp
FORMS += pframe.ui \
    punitspinbox.ui \
    punitslider.ui

HEADERS += pframe.h \
    punitspinbox.h \
    punitslider.h \
    punitwidget.h \
    sharedlib_global.h
SOURCES += pframe.cpp \
    punitspinbox.cpp \
    punitslider.cpp \
    punitwidget.cpp
FORMS += pframe.ui \
    punitspinbox.ui \
    punitslider.ui

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I only just introduced that. Those were originally in the pro file. It's just to clean it up a bit.