: Q_DECLARE_METATYPE(MyClass*); That's how Qt handles it with QObject and QWidget. Obviously, a call to qRegisterMetaType<T>(. Re: How to use Q_DECLARE_METATYPE. Mixing doesn't work but if you always use one or the other it works. You may have to register before you can post: click the register link above to proceed. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. 3 Answers Sorted by: 13 "qRegisterMetaType" is a function. the type name must be specified without the class, as in. What is the point of emitting a QSharedPointer? The worker thread reads the files computes the data allocates and fills the memory with data, wraps it in QSharedPointer and passes it to the mainThread, which is used for plotting. The QMetaType class manages named types in the meta-object system. There's no need to call qRegisterMetaType that many times, once is enough. hpp which is included in Class1. Note that if you intend to use the type in queued signal and slot connections or in QObject's property system, you also have to call qRegisterMetaType() since the names are resolved at runtime. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Actually, they are declared, but in a private section with the macro Q_DISABLE_COPY(). Q_DECLARE_METATYPE. Qt has to stay free or it will die. complains that the metatype isn't registered. I have a problem with a class that exchanges data using TCP/IP socket. Similarly you can create a mutable view of type QAssociativeIterable on any container registered with Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE(). This now makes it possible for Message values to be stored in QVariant objects and retrieved later. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. . Type is declared with Q_DECLARE_METATYPE and registered with qRegisterMetaType. Passing across threads (queued connection) will copy the QVector in either case, but the const will remind you that you cannot alter the original QVector in. QML_DECLARE_TYPE. Q_DECLARE_METATYPE(MyStruct) Q_DECLARE_METATYPE(MyList) QDBusArgument &operator<<(QDBusArgument &, const MyStruct&);. This allows us to use the Enum as a custom-type of a QVariant, to pass it between QML and Qt, to use it in synchronous signal-slot connections, and to print the symbolic enums (instead of a magic number) with qDebug(). private: AnotherQGadgetClass test_; } Q_DECLARE_METATYPE(QGadgetClass) I am trying to access Q_GADGET from QML classic way like accessing a Q_OBJECT , but the setters are not called. container. See also state() and Creating Custom Qt Types. qRegisterMetaType usage. So I don't stream the pointer itself just copy the properties and set them to a new created pointer object. See full list on doc. Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. To register. 3 to Qt4. Is your Q_DECLARE_METATYPE in a header file or an implementation file? Incidentally, there is a mistake in TreeItem. To enable creation of objects at run-time, call the qRegisterMetaType() template function to register it with the meta-object system. We will still need to register it with the meta-object system at run-time by calling the qRegisterMetaType() template function before we make any signal-slot connections that use this type. You can create Q_GADGETS in QML using a C++ factory object registered to be accessible in QML, and a Q_INVOKABLE function in this factory which returns an instance of the Q_GADGET object. If the type was not declared with Q_DECLARE_METATYPE (), compilation will fail. qRegisterMetaType<FileNodePointer> ("FileNodePointer"); should be called once (in main, constructor etc. If you want both, then register both. @kshegunov said: you're doing it wrong. We will still need to register it with the meta-object system at run-time by calling the qRegisterMetaType() template function before we make any signal-slot connections that use this type. without providing the Q_DECLARE_METATYPE macro in the class header, but one could provide a macro where registration is automatically performed (more or less along with meta type declaration). As a workaround you can call the Q_DECLARE_METATYPE macro from the implementation files that need it instead of calling it from the header files, or as the documentation suggests, call it from private headers in each library. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. See also Thread Support in Qt, QObject::connect(), qRegisterMetaType(), and Q_DECLARE_METATYPE(). To make the custom type. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. I read on documentation that Q_DECLARE_METATYPE makes available type to QVariant, for example (I got it from documentation): @ struct MyStruct { int i;. Connect and share knowledge within a single location that is structured and easy to search. typedef QVector<QSharedPointer<Tester> > TestPointerVector;. Step 1 (mark for MOC), build some QObjects That pattern uses Q_PROPERTY and Q_OBJECT and the MoC tool. hpp and qRegisterMetaType<quint32>("quint32"); in both the Constructors of Class1 and Class2. Macros Detailed Description The QMetaType class manages named types in the meta-object system. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. I created a. Additionally Qt5 always refers to Q_DECLARE_METATYPE, saying that qRegisterMetaType is only when you want to. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. QVariant x2 = QVariant::fromValue( x1); To copy to clipboard, switch view to plain text mode. Re: Qt warning of type conversion already registered Originally. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. Q_DECLARE_METATYPE only registers a type in meta type system. PySide6. I want to use drag-and-drop to drag a QTreeWidgetItem that has std::shared_ptr user data. Returns the internal ID used by QMetaType. When the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. I tested your code on Qt 5. To start viewing messages, select the forum that you want to visit from the selection below. Registers the type name . In fact, all Qt classes derived from QObject (direct or indirect) use this macro to declare their copy constructor and assignment operator to be private. 幸哉~ Qt是支持自定义信号，且自定义信号可以发送自定义数据类型的对象。. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE() and qRegisterMetaType(). QVariant::fromValue () returns a QVariant. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. See also. In. By convention, these files are given a . Returns true if convert can convert from fromType to toType. ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. If the pointer stored in the QVariant can be qobject_cast to T, then that result is returned. You may have to register before you can post: click the register link above to proceed. " Yet types like QVariantMap are themself typedefs. 1 Answer. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. F. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. Use it if you want to use it as a global enumerator and then you need to call the meta-type runtime registration from the library, not from the application. Qt Base (Core, Gui, Widgets, Network,. 0. // to be declared somewhere Q_DECLARE_METATYPE(std::string); // to be invoked at the beginning of program qRegisterMetaType<std::string>(); Without type registration Qt doesn't know how to do. The QMetaType class manages named types in the meta-object system. Your Matrix type is not copiable, thus you can't use Q_DECLARE_METATYPE on it. Sorted by: 5. Alt. QtCore. 23k 10 10 gold. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. // This primary template calls the -Implementation, like all other specialisations should. An alternative would be to wrap shared_ptr<int> in your own class and implement comparison the way you want. You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. Detailed Description The QMetaType class manages named types in the meta-object system. g. state() Creating Custom Qt Types. By the way, Qt 4. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. We will still need to register it with the meta-object system at run-time by calling the qRegisterMetaType() template function before we make any signal-slot connections that use this type. Here you can see that the macro expands to nothing. Greetings. ) What I'm trying to do is send a signal containing two cv::Mat images from a QThread to the main thread, so that I can display the output. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. Current the only supported type info is QML_HAS_ATTACHED_PROPERTIES. . io Please note that I do not use Q_DECLARE_METATYPE on purpose because I don't actually need its features (QVariant expansion) right now. QMetaType registerNormalizedTypedef normalizedTypeName, type: metaType ); return. nyaruko. The class is used to send arguments over D-Bus to remote applications and to receive them back. It is not safe to make a QObject's copy constructor public. However, I cannot figure out how to verify that the included parameter is FACE_UP or FACE_DOWN. There's no such thing as a "const reference" because references are always const -- you can't reseat them. To start viewing messages, select the forum that you want to visit from the selection below. Use Q_DECLARE_METATYPE (std::string) in one of your headers. The default access for a class is private, so that Container* data();. Read and abide by the Qt Code of Conduct. e. QMetaType registerNormalizedTypedef normalizedTypeName, type: metaType ); return. 2. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. At the point where I want to read the list, I only care about (and know) the fact that the list contains pointers to objects, which have been derived. To start viewing messages, select the forum that you want to visit from the selection below. This also makes the type available for queued. due to requirements at my job, I had to revert by build from Qt5. ) QObject::connect: Cannot queue arguments of type 'QVector<int>'. Gerald Gerald. Add qRegisterMetaType and qDBusRegisterMetaType calls to enable the framework to work with the custom type. . There's also no need for that typedef, it only makes the code less readable. QObject::connect: Cannot queue arguments of type 'MyStruct'. By convention, these files are given a . This won't work because you can't use qMetaTypeId<> () before Q_DECLARE_METATYPE<>. By the way, Qt 4. I've registered my class with: @Q_DECLARE_METATYPE(MyClass);@ and. Q_DECLARE_METATYPE(MyClass); qRegisterMetaType<MyClass>(); I can use the type in queued connection with signals like this one: void MySignal(MyType o); Now I also would like to use the type with signals like this: void MyVectorSignal(QVector<MyType> v);Qt 5. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. g. It associates a type name to a type so that it can be created and destructed dynamically at run-time. All Qt Overviews. 0. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. 4 and it seems to work. It associates a type name to a type so that it can be created and destructed dynamically at run-time. G. Share. Execute qRegisterMetaType<QItemSelection> (); before it is used as such, e. QList<AnotherObject*> has of course been registered with Q_DECLARE_METATYPE and qRegisterMetaType(). QMetaType. As said in int qRegisterMetaType () documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. So in your case you need to declare. What worries me is that. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. no unexpected garbage. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. When these files are processed by repc, repc generates both Source and Replica header files. Q_DECLARE_METATYPE(MyClass*); That's how Qt handles it with QObject and QWidget. Jun 13, 2021 at 19:37. It's a bit convoluted to follow, and definitely depends on which Qt modules have been included (the meta type system is designed to be expandable this way -- eg. Obviously then you would not do registerComparator (). With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. Franzk 26 May 2011, 06:59. Also Q_DECLARE_METATYPE does not register a type, but declares it. Yes I tried with qRegisterMetaType, it. In practice, both the Q_DECLARE_METATYPE() macro and the qRegisterMetaType() template function can be used to register custom types, but qRegisterMetaType() is only required if you need to perform signal-slot communication or need to create and destroy objects of the custom type at run-time. The id is constexpr in the special case of Qt built-in types only. Q_DECLARE_METATYPE. 手册中告诉我们，执行这个的时候，模板参数T必须用 Q_DECLARE_METATYPE() 声明过 能猜到原因吗？注意看前面 Q_DECLARE_METATYPE() 代码， 对了。类中的成员函数qt_metatype_id中包含对qRegisterMetaType(typeName)的调用 这儿就是辗转调用了这个带参数. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. I. I my real world application Context holds a large number of physical quantities (masses, forces, velocities,. 2. 1. Remember that Q_DECLARE_METATYPE merely defines a specialization of QMetaTypeId for your type. I think you need to add an explicit export/import directive to the QT_NAMESPACE macro. Hope it. qRegisterMetaType () is called to register the TYPE and generate a TYPE ID. The fix is probably to include qsslsocket. QLocalSocket. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). qRegisterMetaType vs. It would look something like this: Q_DECLARE_METATYPE (MyNamespace::MyClass::MyEnum) However, the Q_DECLARE_METATYPE macro would expand to the following call to qRegisterMetaType: qRegisterMetaType< MyNamespace::MyClass::MyEnum > ("MyNamespace::MyClass::MyEnum",. It's not enough to get reflection features out of a type this way (it does not create a QMetaObject), so for the thing to be useful at all you need at least Q_GADGET in both base and derived classes. Q_DECLARE_OPAQUE_POINTER (PointerType) This macro enables pointers to forward-declared types (PointerType) to be registered with QMetaType using either Q_DECLARE_METATYPE() or qRegisterMetaType(). The following should work: Note that you also have to call qRegisterMetaType<MyMpiMessage> (); before you use the function the first time. But at run time, I got below error:1 Answer. Q_GADGET makes a class member, staticMetaObject, available. Detailed Description. qRegisterMetaType<cv::Mat>(); Modified: qRegisterMetaType< Mat >("Mat");The code generated by repc creates a Q_GADGET class for each POD, with corresponding Q_PROPERTY members for each type defined for the POD. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. Avoid having to qRegisterMetaType (pointer. To achieve this you need Q_DECLARE_METATYPE macro and qRegisterMetaType () function. It manages an insane amount of static variables and sets a static global pointer of. When using signals and slots with multiple threads, see Signals and Slots Across Threads. Q_DECLARE_META_TYPE (Fruit) and qRegisterMetaType were redundant: #define PluginInterface_iid "pluginInterface" Q_DECLARE_INTERFACE (PluginInterface, PluginInterface_iid) //Actual plugin implementing PluginInterface class. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. I just tried. You can create Q_GADGETS in QML using a C++ factory object registered to be accessible in QML, and a Q_INVOKABLE function in this factory which returns an instance of the Q_GADGET object. Firstly, you shouldn't need to use Q_DECLARE_METATYPE (or qRegisterMetaType) with the enum at all, this is handled by the moc. " and: "Warning: This function is useful only for registering an alias (typedef) for every other use case Q_DECLARE_METATYPE and qMetaTypeId() should be used instead. Got a similar example working without explicitly calling qRegisterMetaType() just by removing the semicolon from the line Q_DECLARE_METATYPE(StateMachine::state) – user666412 Sep 21, 2015 at 14:17Additional types can be registered using qRegisterMetaType() or by calling registerType(). That always worked in Qt4, but in Qt5 I get the following error: @error: specializing member ‘::qRegisterMetaType<Subclass>’ requires ‘template<>’ syntax@. e. Use it if you want to use it as a global enumerator and then you need to call the meta-type runtime registration from the library, not from the application. The correct syntax is Q_DECLARE_METATYPE (std::string) without the ;. complains that the metatype isn't registered. h" class Context : public QObject { Q_OBJECT Q_PROPERTY (MyGadget* gadget READ gadget CONSTANT) public: explicit Context () : QObject {nullptr} { } MyGadget* gadget () { return &_gadget; } private. Returns the internal ID used by QMetaType. Q_DECLARE_METATYPE. Without this reference, it compiles just fine. @Q_DECLARE_METATYPE (std::unique_ptr<Thing>);@. g. See also Thread Support in Qt, QObject::connect(), qRegisterMetaType(), and Q_DECLARE_METATYPE(). To make the type known to this class, we invoke the Q_DECLARE_METATYPE() macro on the class in the header file where it is defined: Q_DECLARE_METATYPE (Message). QMetaType::type () is a bit slower, but compilation succeeds if a type is not registered. 如果要使自定义类型或其他非QMetaType内置类型在QVaiant中使用，必须使用该宏。. To register a type, it must be declared as a meta-type with the Q_DECLARE_METATYPE() macro, and then registered as in the following example:. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. Qt Code: Switch view. // This primary template calls the -Implementation, like all other specialisations should. Note that you are technically lying to the meta type system. Some structure need to be registered to be queued in asynchronous signals using qRegisterMetaType<T>(name), such as signal which passes QVector<int>. # In the class MainWindow declaration #ifndef Q_MOC_RUN # define the tag text as empty,. 1 Answer. Call qRegisterMetaType () to make type available to non-template based. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. 8. enum Qt:: ContextMenuPolicycall qRegisterMetaType() to register the data type before you call QMetaMethod::invoke(). What you made is a const pointer to a non-const T; but top-level consts in function signatures are not part of the function. Re: Q_DECLARE_METATYPE problem. The logical equivalent of a const T &r (reference to const T) is a const T * const p (const pointer to const T). One of the overloads is a function template that can be used to create an alias for a type and the form is: qRegisterMetaType<Type> ("alias"); That is, it wants to know the type for which you are declaring something. The following should work: Note that you also have to call qRegisterMetaType<MyMpiMessage> (); before you use the function the first time. Q_DECLARE_METATYPE(TYPEDEF) Q_DECLARE_METATYPE(TYPEDEF) mainwindow. You can make them known ( Q_DECLARE_METATYPE ), however you can't register them as QML type. no unexpected garbage. For those who follow. In general, you can only export two kinds of C++ types to QML: QObject-derived classes and some build-in value types, see this documentation page. You should use Q_DECLARE_METATYPE macro for this. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Than I did read this copy constructor of derived QT class and the answer by BЈовић. I explicitly don't want to update it on every change to one of the quantities, so they don't. I think it would be great if we could run requests in a QThread, but right now it's not possible because the r. That was it for Q_DECLARE_METATYPE, but you would still need to call qRegisterMetaType to use these type in a Q_PROPERTY or as a parameter in a signal/slot queued connection. Q_OBJECT derived class, inheritance. call qRegisterMetaType with the name specified, else reading properties. To use the type T in queued signal and slot connections,. J 1 Reply Last reply Reply Quote 0. That was it for Q_DECLARE_METATYPE, but you would still need to call qRegisterMetaType to use these type in a Q_PROPERTY or as a parameter in a signal/slot queued connection. void QAbstractSocket:: abort ()2 Answers. Believing an Question from 2010 and the Qt Documentation, the operator==() doesn't work with custom types. type() typeName() PySide6. このケースでも、Q_DECLARE_METATYPE(QSharedPointer<MyObject>)の宣言と、qRegisterMetatype<QSharedPointer<MyObject>>()の呼び出しが必要になる。 上のサンプルでは、同じsignalに対して2回connectを実行している。 The correct syntax is Q_DECLARE_METATYPE (std::string) without the ;. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. 8 and it all went well with a few function changes, except I got QMetaProperty::read: Unable to handle unregistered datatype errors all over. The third without Q_DECLARE_METATYPE. Re: Q_DECLARE_METATYPE vs qRegisterMetaType for non global namespace classes (QTest) The reason for this behavior might be caused by the fact that runtime signal/slot connections are checked by string manipulation - both Q_DECLARE_METATYPE, SIGNAL, SLOT macros and 'moc' are (among other things) converting type-names to text and pass it along. Actually, they are declared, but in a private section with the macro Q_DISABLE_COPY(). Q_DECLARE_METATYPE (std::string) Quoting Qt Doc. You may have to register before you can post: click the register link above to proceed. According to the Qt docs for qRegisterMetaType "Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. (Make sure 'MyStruct' is registered using qRegisterMetaType (). 被 Q_DECLARE_METATYPEQ 标记的类型可以让Q MetaType 查询到类型，也可以让QVariant识别到。 struct MyStruct { QString name; }; Q_DECLARE_METATYPE(MyStruct) 若对象包含在自定义的命名空间中时，注册时要带上完整的命令空间. e. [since 6. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. Make sure you call it from within a method. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. cpp. To register VideoMeta you need to call qRegisterMetaType<VideoMeta>(). Also you may need to use qRegisterMetaType function. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). Read and abide by the Qt Code of Conduct. I guess it's the qRegisterMetaType () call itself that's missing. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. I tried to write one, but I failed. If you need the functionality provided by Q_DECLARE_METATYPE, you will have to use it. Q_DECLARE_METATYPE, as pointed out by @SingerOfTheFall, would register template based type into QVariant (so it can be retrieved using qvariant_cast<T>()). Otherwise your signals and slots connected used the old mechanism (with macros SIGNAL and SLOT) that require queueing of the parameters won't know how to do so. Also, to use type T with the QObject::property () API, qRegisterMetaType () must be. 能猜到原因吗？注意看前面 Q_DECLARE_METATYPE() 代码， 对了。类中的成员函数qt_metatype_id中包含对qRegisterMetaType(typeName)的调用: 这儿就是辗转调用了这个带参数的qRegisterMetaType函数: unregisterType(const char *typeName) 函数的作用是取消自己先前注册的某个metatype类型。 and a Context class that holds an instance of MyGadget and exposes a pointer to it to QML via a Q_PROPERTY: #include <QObject> #include "mygadget. This replaces the now-deprecated Q_ENUMS and will automatically register the metatype. The Rep lica C ompiler (repc) generates QObject header files based on an API definition file. Do do you register the meta type with the call qRegisterMetaType("your custom meta type")? 1 Reply Last reply Reply Quote 0. Registered enumerations are automatically registered also to the Qt meta type system, making them known to QMetaType without the need to use. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. Question: Is there a way to check at compile-time if qRegisterMetaType<T> () was called for a custom type T? The custom type T needs to be registered in Qt meta-type system in order to be used in e. The Custom Type, Custom Type Sending and Queued Custom Type examples show how to implement a custom type with the features outlined in this document. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. I have a const pointer to a class derived from qobject and want to put into QVariant like below: QVariant::fromValue(objectPointer) I have declared the meta type of derived class using: Q_DECLARE_METATYPE(const QDrivedClass *) in the header file (. D-Bus offers an extensible type system, based on a few primitive types and associations of them. Is your feature request related to a problem? No, it's an improvement Please describe. So in both cases qRegisterMetaType isn't required for the slot to be called and the custom type to be accessible within the slot (i. Inheritance diagram of PySide6. ), or any other callable, cannot declare a type for use outside of the call site. ) summary refs log tree commit diff statsFoo and Foo* are different types and need to be registered separately. The reason to need this is usually that Q_PROPERTY is used with a metatype which is not built-in (types such as int and QString are built-in and don’t. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. 11. h in the translation unit where you have that line. pro file, several errors appear referencing the QMouseEvent and QWheelEvent classes. To call qRegisterMetaType (), you still need to use Q_DECLARE_METATYPE (). Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. 5 is compiled with GCC 4. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). 7. You don't pass around copies of QObject derived types because it is not copyable. Q_DECLARE_METATYPE ( blabla* ) Also qRegisterMetaType<T> () is only required for sending your object through queued signal/slot connections. In Qt, you can declare a variable in two ways: 1. 4 which does not support all C++11 features. There's no need to call qRegisterMetaType that many times, once is enough. no unexpected garbage. In the header, after the class declaration, outside the namespace, I've included. The issue here is that Q_OBJECT forbids the copy and assignment constructors. Compares this QVariant with v and returns true if they are equal;. 16. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. Share Follow edited Apr 29, 2013 at 7:21 We will still need to register it with the meta-object system at run-time by calling the qRegisterMetaType () template function before we make any signal-slot connections that use this type. This function was introduced in Qt 4. M. So, whatever Q_DECLARE_METATYPE is doing cannot be done by writing a function call. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. The class in Qt responsible for custom types is QMetaType . The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. qRegisterMetaType vs. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. The following code will work as well: using namespace foo; Q_DECLARE_METATYPE (MyClass) Teams. JulienMaille @kshegunov last edited by JulienMaille . Secondly, your linker (MSVC) complains that it can't find the metaObject for your ErrorHandler enum, which is normal as it is not exported from the. Even though we do not intend to use the type with QVariant in this example, it is good practice to also declare the new type with Q_DECLARE_METATYPE (). Well, I certainly overplayed this particular point, but the statement I believe is valid in principle. 2）添加声明：利用宏 Q_DECLARE_METATYPE. In my project, MyClass is a cache for multi-dimensional data "point", and it looks like: class MyClass { public: MyClass(); /* Some functions */ private: int m_index; double m_time; QList<int> *m_data; };Firstly, you shouldn't need to use Q_DECLARE_METATYPE (or qRegisterMetaType) with the enum at all, this is handled by the moc. . // But the split allows to. 0. Workaround: use a class. ) summary refs log tree commit diff stats Foo and Foo* are different types and need to be registered separately. There's no such thing as a "const reference" because references are always const -- you can't reseat them. Posted by Unknown at 2:06 AM. Q_DECLARE_METATYPE(NSP::MyStruct) qRegisterMetaTypeIt associates a type name to a type so that it can be created and destructed dynamically at run-time. 1. Any class or struct that has a public default constructor, a public copy. The same plugin may be loaded multiple times during the application's lifetime. 2 Answers. // But the split allows to. qRegisterMetaType vs. This has been changed, and isNull () now only returns true if the QVariant is empty or contains a nullptr. So I played around, copied the original macro and adapted it a bit: @. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit initialization. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. But this is all useless if you are not using templates. Update. enum Qt:: ContextMenuPolicyQObject has neither a copy constructor nor an assignment operator. 基本理解. 1. Then you should register your object to use it with QML. I only care about runtime. The "traditional" way of doing this is to convert each element to a QVariant, and pass collection as a QVariantList. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. 1 Answer. 1. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). [edit] forgot to mention that you also have to use a worker object. It is still giving the error"QObject::connect: Cannot queue arguments of type 'quint32&' (Make sure 'quint32&' is registered using. qRegisterMetaType vs.