In the example's Message class, a static method is included to do this. no unexpected garbage. Therefore I want to use Q_DECLARE_METATYPE (My_Item) and from the documentation I learned that I need a public copy constructor. You pass around pointers instead. due to requirements at my job, I had to revert by build from Qt5. QVariant’s operator== now uses QMetaType::equals for the comparison. Make sure you call it from within a method. A separate point for your own benefit. It associates a type name to a type so that it can be created and destructed dynamically at run-time. This is by design. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. Make your own typedef and do the Q_DECLARE_METATYPE and qRegisterMetatype. Basically, I created a library containing a type: struct MyCustomType {. 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. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Q_DECLARE_METATYPE. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. 4] QString QWebSocket:: subprotocol const. 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. QtCore. More. qRegisterMetaType<signed long long>() - do nothing. Share Improve this answerWe 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. type() typeName() PySide6. call qRegisterMetaType with the name specified, else reading properties. For that, I want to declare a. When data values are exchanged between QML and C++, they are converted by the QML engine to have the correct data types as appropriate for use in QML or C++. Q_DECLARE_METATYPE ( blabla* ) Also qRegisterMetaType<T> () is only required for sending your object through queued signal/slot connections. 如果是指针类型他需要有完整的定义。使用Q_DECLARE_OPAQUE_POINTER()去注册指针用于转发数据类型。 使用Q_DECLARE_METATYPE()可以让这个数据类型T放到QVariant里面。如果想以队列的方式让T使用信号与槽，当第一次连接的时候就要调用qRegisterMetaType<T>()。Detailed Description. 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. Q_DECLARE_METATYPE(MyClass*); That's how Qt handles it with QObject and QWidget. Sorted by: 1. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. 5 is compiled with GCC 4. Read and abide by the Qt Code of Conduct. e. qRegisterMetaType 必须使用该函数的两种情况. However, I cannot figure out how to verify that the included parameter is FACE_UP or FACE_DOWN. [since 6. Returns the internal ID used by QMetaType. First of all you need to declare your custom object for Qt metatype system. Any class or struct that has a public default constructor, a public copy constructor, and a. } But you'll most likely need to abstract the Q_DECL_EXPORT part so it is a Q_DECL_IMPORT in right circumstances, as described in Creating Shared Libraries. Of course it's a bug and an odd mistake that Q_DECLARE_METATYPE(QList<QSslError>) is in qsslsocket. This function is typically used together with construct () to perform low-level management of the memory used by a type. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. Q_DECLARE_METATYPE, as pointed out by @SingerOfTheFall, would register template based type into QVariant (so it can be retrieved using qvariant_cast<T>()). 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. rep file extension, short for Replica. queued connections. My workround was to explicitly cast the enum values to int when passing them onto a function requiring a QVariant type, in my case. 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. . Q_DECLARE_METATYPE(shared_ptr<SomeClass> const &) qRegisterMetaType<shared_ptr<SomeClass> const&>(); 许多标准API都有 QString const & ，因此我认为从根本上来说是可能的，而我只是想不出语法。You actually need to do it once (i. Additional types can be registered using qRegisterMetaType() or by calling registerType(). Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. 步骤： (以自定义MyDataType类型为例）. Additionally Qt5 always refers to Q_DECLARE_METATYPE, saying that qRegisterMetaType is only when you want to. Also, to use type T with the QObject::property () API, qRegisterMetaType () must be. As G. Any class or struct that has a public default constructor, a public copy. We all have started by asking questions. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. QMetaType registerNormalizedTypedef normalizedTypeName, type: metaType ); return. There's also no need for that typedef, it only makes the code less readable. 0. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. To make the custom. I guess it's the qRegisterMetaType () call itself that's missing. 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。. g. e. Connect and share knowledge within a single location that is structured and easy to search. See also Thread Support in Qt, QObject::connect(), qRegisterMetaType(), and Q_DECLARE_METATYPE(). 基本理解. 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. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. By the way, Qt 4. This version of the function is to register alias types. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. 基本理解. Any class or struct that has a public default constructor, a public copy constructor, and a. If you ever wondered what does Q_DECLARE_META_TYPE or qRegisterMetaType do and when to use (or not to use) them, read on. 0. Note: it's also safe to call qRegisterMetaType () multiple times. append (QVariant::fromValue (l)); } return list; } The metatype system declaration and registration you have. 总之，有时候，我们多么希望信号能发送自定义数据类型。. G. Returns the metatype of the parameter at the given index. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. One way to work around this is for example having a helper class (singleton or context property) with. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. I'm confused by this error, as the documentation states (emphasis mine): Returns the meta type id of type T at compile time. 5 is compiled with GCC 4. cpp I have to do: qRegisterMetaType<Pkg>("Pkg"); and this does not give errors too, but when I try to create a QVariant(Pkg) I get lots of errors like:cardio63 26 Jan 2016, 10:19. So, if you had a custom type FooType, you'd put the Q_DECLARE_METATYPE directly after the declaration, and in. Call qRegisterMetaType () to make types available to non-template based functions, such as the queued signal and slot connections. When I try to simply connect signalslot with such QVector as argument programm tells during run that this metatype should be registered (though QVector, QSharedPointer and class inherited from QObject should be registered automatically. const EventExport& in signal and slot profiles; Sending empty EventExport in prepareExport() so emit has no/low data amount; Checking connect statement (always returns true) Having qDebug() in prepareExport() and signal always appears to be emitted; Calling emit right. The class is used as a helper to marshall types in QVariant and in queued. # In the class MainWindow declaration #ifndef Q_MOC_RUN # define the tag text as empty,. The ENUM type. +50. Enumerations that are declared with Q_ENUM have their QMetaEnum registered in the enclosing QMetaObject. . Equivalent to Q_DECLARE_METATYPE(TYPE *) and Q_DECLARE_METATYPE(QQmlListProperty<TYPE>) QML_DECLARE_TYPEINFO (Type, Flags) Declares additional properties of the given Type as described by the specified Flags. Qt Remote Objects Compiler. 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. Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template. 2）添加声明：利用宏 Q_DECLARE_METATYPE. qRegisterMetaType() docs say: Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. I have registered an enumeration type "ClefType" within my header file - this enum is registered with the MetaObject system using the Q_DECLARE_METATYPE and Q_ENUMS macros. It associates a type name to a type so that it can be created and destructed dynamically at run-time. 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. See also Thread Support in Qt, QObject::connect(), qRegisterMetaType(), and Q_DECLARE_METATYPE(). 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. @kshegunov said: you're doing it wrong. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. Re: How to use Q_DECLARE_METATYPE. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. One of these plugins uses Q_DECLARE_METATYPE on some types that need to be stored in a QVariant. h. 11. 4 which does not support all C++11 features. I tried to write one, but I failed. fromValue <QList<double> > ( x1); To copy to clipboard, switch view to plain text mode. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. e. 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_METATYPE accepts objects with public constructor, copy constructor and destructor. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. So using qRegisterMetaType () you will just trade Q_ENUM () for Q_DECLARE_METATYPE (). See the Qt D-Bus Type System page for more information on the type system. You should use Q_DECLARE_METATYPE macro for this. 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. If you have to use Q_DECLARE_METATYPE yourself, the id is not constexpr. You can make them known ( Q_DECLARE_METATYPE ), however you can't register them as QML type. 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. 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. 0. 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. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. 0. QMetaType::type () returns the same ID as qMetaTypeId (), but does a lookup at runtime based on the name of the type. See also. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. You may have to register before you can post: click the register link above to proceed. Using the following required me to use Q_DECLARE_METATYPE. 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. ) 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. Share. jsulm Lifetime Qt Champion @shivaVMC last edited by . The code compiles and runs ok. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. 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. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system. You should use Q_DECLARE_METATYPE macro for this. Detailed Description. ) summary refs log tree commit diff stats Foo and Foo* are different types and need to be registered separately. no unexpected garbage data or the like). The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. 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). Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. When the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. . Hope it. Your code should look like this: Q_ENUM (StateEnum) //note the missing 'S' here Q_PROPERTY (StateEnum state READ state NOTIFY stateChanged) Share. Q_DECLARE_METATYPE. It associates a type name to a type so that it can be created and destructed dynamically at run-time. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. See also Q_DECLARE_METATYPE() and. Sorted by: 5. This makes them suitable for use with both static properties declared using the Q_PROPERTY() macro in class definitions and dynamic properties created at run-time. All I want to do is be able to convert this to a byte array in order to send on a socket, and get the object back (deserialize) on the other end. Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. waitForConnected ([msecs=30000]) # Parameters: msecs – int. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. The issue here is that Q_OBJECT forbids the copy and assignment constructors. The Custom Type and Queued Custom Type examples show how to implement a custom type with the features outlined in this document. See also state() and Creating Custom Qt Types. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. cpp I have to do: qRegisterMetaType<Pkg>("Pkg"); and this does not give errors too, but when I try to create a QVariant(Pkg) I get lots of errors like:cardio63 26 Jan 2016, 10:19. Q_DECLARE_METATYPE(MyStruct) Q_DECLARE_METATYPE(MyList) QDBusArgument &operator<<(QDBusArgument &, const MyStruct&);. " 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. qRegisterMetaType is also called in the class constructor. Here you can see that the macro expands to nothing. 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. SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). staticMetaObject is of type QMetaObject and provides access to the enums declared with Q_ENUMS. 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。. The logical equivalent of a const T &r (reference to const T) is a const T * const p (const pointer to const T). Using Qt 3D with QCustomPlot. cpp. To start viewing messages, select the forum that you want to visit from the selection below. qRegisterMetaType () is called to register the TYPE and generate a TYPE ID. @Mark81 Actually you'll probably need only Q_DECLARE_METATYPE as this is done at compile time - exposing the type to the metatype system (I know it is an enum but it's needed for the QVariant and the like). QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). I also don't want to use qRegisterMetaType, since it is run-time bound. . But I really would like to know the correct way to solve this problem; one where it is not possible to modify. Registers the type name . Call qRegisterMetaType() to register the data type before you establish the connection. (Make sure 'QVector<int>' is. It does not say anything about registering the type. In my own code, I use Q_DECLARE_METATYPE for classes I want to store. Teams. 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(). qRegisterMetaType<Subclass> ("Subclass") also doesn't work. There's no such thing as a "const reference" because references are always const -- you can't reseat them. Thus you need to use the runtime check QMetaType::type (). 1 Answer. Note that you are technically lying to the meta type system. Now you have a valid QObject. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. 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. The class in Qt responsible for custom types is QMetaType . See also state(). hpp and qRegisterMetaType<quint32>("quint32"); in both the Constructors of Class1 and Class2. Your Matrix type is not copiable, thus you can't use Q_DECLARE_METATYPE on it. That's created by this macro. 4. Although I'm. 1. My workround was to explicitly cast the enum values to int when passing them onto a function requiring a QVariant type, in my case when adding a QComboBox item, and then casting it back to my enum class type at value retrieval. This example is meant to declare and register only the pointer type of a given class: In conclusion: Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. 如果非QMetaType内置类型要. 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. Since \c{MyStruct} is now known to QMetaType, it can be used in QVariant: Some types are registered automatically and do not need this macro: /*! This macro makes the container \a Container known to QMetaType as a sequential. Here’s the list of what changed: QVariant used to forward isNull () calls to its contained type – but only for a limited set of Qt’s own types. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit. See also isRegistered () and Q_DECLARE_METATYPE (). QVariant v = QVariant::fromValue<cMyClass>(MyObject); However, as soon as I use Q_DECLARE_METATYPE, I get errors about using a deleted function. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. Using Q_ENUM () allows you to retrieve at run-time. h" class B : public QObject { Q_OBJECT Q_PROPERTY(A* A1 READ getA1 WRITE setA1) Q_PROPERTY(A* A2 READ getA2 WRITE setA2) public: static A A1;. Re: How to use Q_DECLARE_METATYPE. There's no compile time error, but when I run. You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. The fix is probably to include qsslsocket. 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:. 4. Can it be Done for a Custom Type? If you really need the qMetatypeId<Type>() to be constexpr, you have to take the responsibility for making it so by specializing struct QMetaTypeId<Type> (or. struct StandardData { int EmpId; QString Name; }; Q_DECLARE_METATYPE (StandardData) Additionally, you might need to call qRegisterMetaType. cpp. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. PySide6. QML Qvariant from custom class. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. However, if you want to use a type in a pure runtime context, for example in a QML document, the Qt runtime doesn't know the type declared with Q_DECLARE_METATYPE. h" class Context : public QObject { Q_OBJECT Q_PROPERTY (MyGadget* gadget READ gadget CONSTANT) public: explicit Context () : QObject {nullptr} { } MyGadget* gadget () { return &_gadget; } private. From the docs: int qRegisterMetaType ( const char * typeName ) Registers the type name typeName to the type T. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. ", which suggests it is only for classes and structs. So I am doing this: Qt Code: Switch view. Since Qt 5. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). I just found multiple examples showing the usage of Q_ENUM and Q_ENUMS and looking into the definition of Q_ENUM showed me that it includes Q_ENUMS and other definitions. The Rep lica C ompiler (repc) generates QObject header files based on an API definition file. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. I want to use drag-and-drop to drag a QTreeWidgetItem that has std::shared_ptr user data. If such a connection is made, and a signal triggered, the runtime warning will be shown: QObject::connect: Cannot. 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. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. There's also no need for that typedef, it only makes the code less readable. g. // - in a header: // - define a specialization of this template calling an out-of. qRegisterMetaType<FileNodePointer> ("FileNodePointer"); should be called once (in main, constructor etc. Then after some time, we can begin answering them. Adding a Q_DECLARE_METATYPE () makes the type known to all template based functions, including QVariant. A. Q_DECLARE_METATYPE. Qt. This function was introduced in Qt 4. E. 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. complains that the metatype isn't registered. See also disconnect(), sender(), qRegisterMetaType(), Q_DECLARE_METATYPE(), and Differences between String-Based and. The QMetaType class manages named types in the meta-object system. See also. 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. I have a problem with a class that exchanges data using TCP/IP socket. } But you'll most likely need to abstract the Q_DECL_EXPORT part so it is a Q_DECL_IMPORT in right circumstances, as described in Creating Shared Libraries. It will return the same result if it was called before. 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. ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. 4 which does not support all C++11 features. By the way, Qt 4. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. 14 vs 5. 1. Detailed Description. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. I created a. QML_DECLARE_TYPE. However, when attempting to compile QCustomPlot in a project using "QT += 3dinput" in its . 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. 2、在类型定义完成后，加入声明：Q_DECLARE_METATYPE (MyDataType); 3、在main ()函数中. 3 Answers Sorted by: 13 "qRegisterMetaType" is a function. If you are using queued connections, you need to register std::string as meta type. There is no way to add support for more of these value types like std::string (*). your custom type definition. Add qRegisterMetaType and qDBusRegisterMetaType calls to enable the framework to work with the custom type. Declare new types with Q_DECLARE_METATYPE () to make them available. qRegisterMetaType vs. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Detailed Description. [override virtual] bool QAbstractSocket:: waitForBytesWritten (int msecs = 30000) Reimplements: QIODevice::waitForBytesWritten(int. By convention, these files are given a . Also, to use type T with the QObject::property () API,. 1）引入头文件：#include<QMetaType>. I'm trying to use custom classes in QAbstractListModel, and the Q_DECLARE_METATYPE doesn't work at all! To test where the problem is, I've simplified the code as the following: #include <QMetaType> #include <QVariant> #include <QDebug> typedef int x; Q_DECLARE_METATYPE (x) void main () { QVariant v; qDebug () << v. I tried with and without the qRegisterMetaType<Schedule::TimePairMap>(), with and without Q_DECLARE_METATYPE(Schedule::TimePairMap). 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(). Q_DECLARE_METATYPE(TYPEDEF) Q_DECLARE_METATYPE(TYPEDEF) mainwindow. 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 ;. You could also Q_DECLARE_METATYPE to register your custom type and then use qMetaTypeId() to get the metaType id. Does your code ever call qRegisterMetatype() or use Q_DECLARE_METATYPE()? 10th November 2014, 05:23 #3. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). qRegisterMetaType vs. Q_DECLARE_METATYPE与qRegisterMetaType学习. Output:Additionally Q_DECLARE_METATYPE and qRegisterMetaType are not purposed to be used for QObject derived classes. qRegisterMetaTypeしているにもかかわらずQObject::connectでランタイムエラーが出る場合の回避策. For pointer types, it also requires that the pointed to type is fully defined. 1、自定MyDataType 类型，在这个类型的顶部包含：#include <QMetaType>. 2 Answers. It is often easier and cleaner to define an ENUM inside a class (see ENUM), but if you need a standalone enum type, using the ENUM keyword outside of a class definition can be. e. To enable creation of objects at run-time, call the qRegisterMetaType() template function to register it with the meta-object system. Obviously, a call to qRegisterMetaType<T>(. For this, a function call (evaluated during runtime) needs to be made, and qRegisterMetatype is the tool for this: qRegisterMetaType<Area>("Area");@julio. Jun 13, 2021 at 19:37. QMetaType::type () returns the same ID as qMetaTypeId (), but does a lookup at runtime based on the name of the type. That's probably there, as qRegisterMetaType () wouldn't compile otherwise. You may have to register before you can post: click the register link above to proceed. It does not say anything about registering the type. the type name must be specified without the class, as in. 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。. M. S 1 Reply Last reply Reply Quote 0. That always worked in Qt4, but in Qt5 I get the following error: @error: specializing member ‘::qRegisterMetaType<Subclass>’ requires ‘template<>’ syntax@. See the Custom Type Example for code. The "traditional" way of doing this is to convert each element to a QVariant, and pass collection as a QVariantList. Is your Q_DECLARE_METATYPE in a header file or an implementation file? Incidentally, there is a mistake in TreeItem. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. : Q_DECLARE_METATYPE(MyClass*); That's how Qt handles it with QObject and QWidget. So my first idea:. Follow. Q_DECLARE_METATYPE () doesn't actually register the type; you must still use qRegisterMetaType () for that, particularly if you intend to use the type in signal and slot connections. [quote author="Andre" date="1306394817"]In that case, I think you need to register them. . 2 Answers. 2. The struct is declared in my worker class, which is inside a namespace. The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. To make the custom type generally usable with the signals and slots mechanism, we need to perform some extra work. I have added Q_DECLARE_METATYPE(quint32) in Class2. It is still giving the error"QObject::connect: Cannot queue arguments of type 'quint32&' (Make sure 'quint32&' is registered using. Assuming base and derived are Q_GADGETs you want to get a static member. Obviously then you would not do registerComparator (). By the way, Qt 4. Usually it goes in a pair: Q_DECLARE_METATYPE(TypeName) goes in the header, and then in the source at runtime registration is done with: qRegisterMetaType<TypeName>();answered May 10, 2013 at 2:25. To enable creation of objects at run-time, call the qRegisterMetaType() template function to register it with the meta-object system. To start viewing messages, select the forum that you want to visit from the selection below. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. I'd understood if i want to pass my custom type like struct or so, but it is essential type. Assuming base and derived are Q_GADGETs you want to get a static member. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). To call qRegisterMetaType (), you still need to use Q_DECLARE_METATYPE (). I think it would be great if we could run requests in a QThread, but right now it's not possible because the r. QVariantList MyClass::getFooCollection (void) const { QVariantList list; for (const auto& l: fooCollection_) { list. I want to use my objects as QVariants and for queued connections. no I didn't, do I need to put in the file generated by repc or I can put it anywhere ? – Houss_gc. no unexpected garbage. class Test : public QWidget { Q_OBJECT public: Test(); signals: public slots: void setAppData(QList<QIcon> icons, QStringList names, QStringList versions, QStringList publishers, QString installLocation, QStringList uninstallLocations); private: }; Q_DECLARE_METATYPE(QIcon) The same issue is still present. To use the type T in queued signal and slot connections,. Read and abide by the Qt Code of Conduct. Current the only supported type info is QML_HAS_ATTACHED_PROPERTIES. qRegisterMetaType vs. 8. The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. QVariant x2 = QVariant::fromValue( x1); To copy to clipboard, switch view to plain text mode. The QML engine provides built-in support for a. " Yet types like QVariantMap are themself typedefs. To start viewing messages, select the forum that you want to visit from the selection below. This is not the case, since the following succeeded: @QMetaType::type("MyClass"); // success@. qRegisterMetaType 必须使用该函数的两种情况. void QAbstractSocket:: abort ()2 Answers. Constantin. qRegisterMetaType() requires also a Q_DECLARE_METATYPE() – dtech. This requires the exchanged data to be of a type that is recognizable by the engine.