Running Qt Application from .dll
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If I may, you should avoid such naming, this can make reading errors and warnings confusing. Give your dll a proper name even if it's
foobarso it can be clearly identified with regards to the errors and related stuff. Same goes for the files you are using. -
@SGaist
Thanks for the advice, i changed the Mainwindow to mywidget and the name of the library to mylibrary. it seems more clear code now but still have the same errors in the moc_ file:1)moc_mylibrary.cpp:58: warning: C4273: 'mywidget::qt_static_metacall': inconsistent dll linkage
2)error: C2491: 'mywidget::staticMetaObject': definition of dllimport static data member not allowedIs it a problem that i create in QT a C++ Library? Do i need to make a QT Creator Plugin to load these type of QT objects in my new Qapplication? Maybe these errors indicate that i am in the wrong way?
Here is the code of the moc_mylibrary file where the errors exists:
**#include "../../WidgetAppforLibrary/mylibrary.h"
#include <QtCore/qbytearray.h>
#include <QtCore/qmetatype.h>
#if !defined(Q_MOC_OUTPUT_REVISION)
#error "The header file 'mylibrary.h' doesn't include <QObject>."
#elif Q_MOC_OUTPUT_REVISION != 67
#error "This file was generated using the moc from 5.12.1. It"
#error "cannot be used with the include files from this version of Qt."
#error "(The moc has changed too much.)"
#endifQT_BEGIN_MOC_NAMESPACE
QT_WARNING_PUSH
QT_WARNING_DISABLE_DEPRECATED
struct qt_meta_stringdata_mywidget_t {
QByteArrayData data[1];
char stringdata0[9];
};
#define QT_MOC_LITERAL(idx, ofs, len)
Q_STATIC_BYTE_ARRAY_DATA_HEADER_INITIALIZER_WITH_OFFSET(len,
qptrdiff(offsetof(qt_meta_stringdata_mywidget_t, stringdata0) + ofs
- idx * sizeof(QByteArrayData))
)
static const qt_meta_stringdata_mywidget_t qt_meta_stringdata_mywidget = {
{
QT_MOC_LITERAL(0, 0, 8) // "mywidget"}, "mywidget"};
#undef QT_MOC_LITERALstatic const uint qt_meta_data_mywidget[] = {
// content:
8, // revision
0, // classname
0, 0, // classinfo
0, 0, // methods
0, 0, // properties
0, 0, // enums/sets
0, 0, // constructors
0, // flags
0, // signalCount0 // eod};
void mywidget::qt_static_metacall(QObject *_o, QMetaObject::Call _c, int _id, void **_a)
{
Q_UNUSED(_o);
Q_UNUSED(_id);
Q_UNUSED(_c);
Q_UNUSED(_a);
}QT_INIT_METAOBJECT const QMetaObject mywidget::staticMetaObject = { {
&QMainWindow::staticMetaObject,
qt_meta_stringdata_mywidget.data,
qt_meta_data_mywidget,
qt_static_metacall,
nullptr,
nullptr
} };const QMetaObject *mywidget::metaObject() const
{
return QObject::d_ptr->metaObject ? QObject::d_ptr->dynamicMetaObject() : &staticMetaObject;
}void *mywidget::qt_metacast(const char _clname)
{
if (!_clname) return nullptr;
if (!strcmp(_clname, qt_meta_stringdata_mywidget.stringdata0))
return static_cast<void>(this);
return QMainWindow::qt_metacast(_clname);
}int mywidget::qt_metacall(QMetaObject::Call _c, int _id, void **_a)
{
_id = QMainWindow::qt_metacall(_c, _id, _a);
return _id;
}
QT_WARNING_POP
QT_END_MOC_NAMESPACEThanks again for replying!
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What is
@Theok said in Running Qt Application from .dll:DLLSHARED_EXPORT
?
Also, you seem to have a mix of header files which contain classes not having name matching the header file. Not that it is forbidden but it makes things unclear.
What does your .pro file look like ?
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Thanks for reply,
if i understand correct you need to define which classes,functions will be exported from the library so the user can use-call to his main app.#if defined(MYLIBRARY_LIBRARY) # define MYLIBRARYSHARED_EXPORT Q_DECL_EXPORT #else # define MYLIBRARYSHARED_EXPORT Q_DECL_IMPORT #endifThis is the code of the xxx_myglobal.h header file that is automatically created when i create a C++ library project (The names changed with your recommendation so instead of MYLIBRARYSHARED_EXPORT before was DLLSHARED_EXPORT ). The .pro file of the shared library project is :
#------------------------------------------------- # # Project created by QtCreator 2019-02-19T10:28:30 # #------------------------------------------------- QT += widgets TARGET = MyLibrary TEMPLATE = lib DEFINES += MYLIBRARY_LIBRARY # The following define makes your compiler emit warnings if you use # any feature of Qt which has been marked as deprecated (the exact warnings # depend on your compiler). Please consult the documentation of the # deprecated API in order to know how to port your code away from it. DEFINES += QT_DEPRECATED_WARNINGS # You can also make your code fail to compile if you use deprecated APIs. # In order to do so, uncomment the following line. # You can also select to disable deprecated APIs only up to a certain version of Qt. #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0 SOURCES += \ mylibrary.cpp HEADERS += \ mylibrary.h \ mylibrary_global.h \ ui_windowlibrary.h unix { target.path = /usr/lib INSTALLS += target }Do you think the problem is on the C++ library project? This project builds fine but when i try to call the library from another application then comes the errors i wrote in the top...
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The .pro file looks correct.
However, as suggested before, use consistent file naming. You have a widget called MainWindow, then you should have kept the original file name generated for you by Qt Creator. There's no need for any special naming because you are creating a library.
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After your recommendation i changed the names:
so the first code uploaded is not the same as the latest.
Named my library project mylibrary instead of dll and mainwindow class (Qt's default) -> mywidget class.So my library builds correct,
But why i 'm having these errors when i try to build my app including my library?#include "mylibrary.h" #include <QApplication> int main(int argc, char *argv[]) { QApplication a(argc, argv); mywidget b; b.show(); return a.exec(); }This is the main.cpp file of my app. Just replacing with mywidget from the dll...
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Can you show the .pro file of your application ?
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What is it ?
