However, you should verify its validity after construction. and another folder with the obj files. qRegisterMetaType<QAbstractSocket::SocketState>(); Share. qRegisterMetaType<QVector<int> > ("QVector<int>"); Once you make this call, you should be able to emit the QVector type over queued connections. template<class T> QMetaObject::Connection connect_from_pointer ( const QSharedPointer<T>& sender,. 我们知道类中的成员函数并不一定会被调用(即，该宏并不确保类型被注册到MetaType)。 通过qRegisterMetaType可以确保类型被注册; 两个qRegisterMetaType 的联系In part II of our Qt for Beginners Summer Webinar Series we will explore how Qt is so much more than just a GUI toolkit. [override virtual noexcept] QQmlEngine:: ~QQmlEngine Destroys the QQmlEngine. call qRegisterMetaType with the name specified, else reading properties. Here my test code and example: #include <QCoreApplication> #include <QDebug> #include <QMetaType> #include <QRect> #include <QMetaObject> class. Normally, you would only register the pointer form if your class cannot be copied, as in the case of QObject and derivatives, but. If you need a socket, you have two options: Instantiate QTcpSocket or QUdpSocket. Note: Since all expressions evaluated in QML are evaluated in a particular context, if the context is. qRegisterMetaType<QSqlDatabase>("QSqlDatabase"); Just changing the signal to this form: void dbConnected(QSqlDatabase *db); And, in the slot side I'll use something like this: void onDBConnected(QSqlDatabase * const db); I'm concerned with the usage of db (as in the beginning I've made the reference const), so I make it const here (in the slot. Otherwise, returns QPartialOrdering::Less, QPartialOrdering::Equivalent or QPartialOrdering::Greater if lhs is less than, equivalent to or. 2、使用 qRegisterMetaType，将对象注册为元类型 使用qRegisterMetaType对自. Hm. This class can tell the outside world that its state has changed by emitting a signal, valueChanged(), and it has a slot which other objects can send signals to. If the Microsoft compiler was not requiring this, then it was doing it wrong. QObject::connect: Cannot queue arguments of type 'SomeUserDefinedType' (Make sure 'SomeUserDefinedType' is registered using qRegisterMetaType(). QSignalSpy can connect to any signal of any object and records its emission. One or many threads can block waiting for a QWaitCondition to set a condition with wakeOne() or wakeAll(). ) You can read about how to call qml functions from c++. 在使用 qRegisterMetaType<int>("int&");注册一个自定义类型给线程后，就出现“启动程序失败,路径或者权限错误”的提示，之后程序就一直编译不过去。不管删除了相关的文件后，或者重新构建，都是一样的问题。 但是，在不断的摸索后，突然之间就可以了，后面实验. As soon as the first event arrives I got the errormessage: @QObject::connect: Cannot queue arguments of type 'QQuickChangeSet'. Hey Something I wanted to follow up as I noticed I'm not the only with the issue. text_changed. This way your metatype will be registered once at startup, and the registration is close by the implementation and does not require to modify <code>main</code>. QScriptEngine myEngine; QScriptValue three = myEngine. iii. This replaces the now-deprecated Q_ENUMS and will automatically register the metatype. See also Q_DECLARE_METATYPE() and qRegisterMetaType(). 4 x64, and PyQt5 using its binary provided on riverbankcomputiong. Finds signal and returns its index; otherwise returns -1. Normally it's done directly in the main () How: Just call qRegisterMetaType<QMap<QString,long long unsigned int> > (); It doesn't matter how you refer to MyClass in the template argument. My original script use this : from PyQt5. 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. No, everything is in separated folders. main. 0 and have problems registering my own class as a QMetaType. tag(); // prints MY_CUSTOM_TAG. ;. The QObject documentation states that the copy-constructor should be private, but the QMetaType documentation states that a type should have a public default constructor, a public copy constructor, and a public destructor. 1、自定MyDataType 类型，在这个类型的顶部包含：#include <QMetaType>. For pointer types, it also requires that the pointed to type is fully defined. cppuint64 is a typedef for 64 bit integers in VS: Qt Code: Switch view. In QML, the meta-type system is the only way that QML engine can access C++ structures from a QML environment. Read and abide by the Qt Code of Conduct. setContextProperty : Use setContextProperty, When you want to use a single global class to access to or from QML. layoutAboutToBeChanged. ) What I have done is, declare in the main the qRegisterMetatype but it still complaining. 12. )@. Also, to use type T with the QObject::property() API, qRegisterMetaType<T>() must be called before it is used, typically in the constructor of the class that uses T, or in the main() function. 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++. the type name must be specified without the class, as in. 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. ) changing rowCount in the main thread or commenting out setRowCount call in change_row_count() makes those errors. ). qRegisterMetaType usage. Data Type Conversion Between QML and C++. QtCore import QObject works. stackexchange. Normally you would do this in main () or. Attention: Answers. queued connections. Your uint8_t is atomic and you don't need to register it, just use. For example, this registers a Python class ‘MySliderItem’ as a QML type named ‘Slider’ for version ‘1. . I'm not sure how to do this in python but probably you should add similar call with QTextCursor. @reddy9pp said in QObject::connect: Cannot queue arguments of type 'std::string' (Make sure 'std::string' is registered using qRegisterMetaType(). ChildAdded and ChildRemoved events are sent to objects when children are added or removed. Call qRegisterMetaType () to make types available to non-template based functions, such as the queued signal and slot connections. I can confirm the observed behaviour. connect(self. In general, you only need Q_DECLARE_METATYPE (). However, as you need the type to be. You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. Undeclared QMetaObject::SuperData. To enable creation of objects at run-time, call the qRegisterMetaType () template function to register it with the meta-object system. Note: This function is thread-safe. For example, setting to 150 results in all characters in the font being 1. call qRegisterMetaType() to register the data type before you call QMetaMethod::invoke(). And this should be used for each exe/dll instance. If I register QVector I can't dissconnect this signal and the signal is emited. The members of the class contain calls to qRegisterMetaType We can also use Q_DECLARE_METATYPE to declare custom variables, and package custom. 5 and Qt Version 5. All the resources I found online point to a C++ syntax/documentation. 31. 5] int qRegisterMetaType (QMetaType meta) Registers the meta type meta and returns its type Id. This requires the exchanged data to be of a type that is recognizable by the engine. You can safely remove the const, even if the real signature of SendData and ReceiveData is const u_char*. QBluetoothDeviceInfo which provides similar information for remote devices. qRegisterMetaType <Card::Orientation> ( "Card::Orientation" ); QSignalSpy. If the signal is being emitted, I get this error: @. ) QObject::connect: Cannot queue arguments of type 'QModelIndex' (Make sure 'QModelIndex' is registed using qRegisterMetaType(). Add a comment | 5 I believe the following is state is not defined in your MyThread class. From Qt documentation: Ideally, this macro should be placed below the declaration of the class or struct. newStatuses. The related type must provide a public default constructor, a public copy constructor and a public destructor to be eligible to be declared as a metatype. 11. (Parent is QTcpSocket (0x24a6ce8), parent's thread is ServiceSlots (0xea66488), current thread is QThread (0x2418a78) See also qRegisterMetaType(). Please visit robotics. The QSignalSpy class provides an elegant mechanism for capturing the list of signals emitted by an object. 2 @Alfredocubitos would it be possible to share an example of the threaded websocket. Using Q_ENUM () allows you to retrieve at run-time the name of an enum value: The class in Qt responsible for custom types is QMetaType. ) QObject::connect: Cannot queue arguments of type 'QVector' (Make sure 'QVector' is registered using qRegisterMetaType(). Even though qRegisterMetaType(). I created a. When these files are processed by repc, repc generates both Source and Replica header files. See also qRegisterMetaType(). It provides a safer and easier way to manage dynamic memory allocation and deallocation by automatically managing the reference counting of a shared object. Returns a list of child objects. adam-iris added a commit that referenced this issue Oct 10, 2017. runtime barfs if the signature for test in both headers and . tabs. org is deprecated as of August the 11th, 2023. By implementing a factory it is possible to create custom QNetworkAccessManager with specialized caching, proxy and cookie support. See also insertColumns (), insertRow (), and removeColumn (). Returns the internal ID used by QMetaType. The difference between Qt::QueuedConnection and Qt::AutoConnection is due to a difference in the. Each emission of the signal will append one item to the list, containing the arguments of the signal. You don't have to register your data type via qRegisterMetaType, and when you send your data as a reference it is not copied. ) QObject::connect: Cannot queue arguments of type 'QTextCursor' (Make sure 'QTextCursor' is registered using qRegisterMetaType(). What is the expected behavior. It is part of QMetaType, which is not implemented by PySide. Registers the type name typeName for the type T. 0. #pragma once #include <QObject> class MyClass : public QObject { Q_OBJECT public: static void initQML (); MyClass (); MyClass (const MyClass &myClass. QObject::connect: Cannot queue arguments of type 'QModbusDevice::State' (Make sure 'QModbusDevice::State' is registered using qRegisterMetaType (). Obviously then you would not do registerComparator (). M. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. The registrations must have happened after doing a foo::FooUsingClass *f = new foo::FooUsingClass();. on_click. Note that this only works for QObject subclasses which use the Q_OBJECT macro. It will look for the signature of methods using string matching. The Qt doc on qRegisterMetaType explicitly says : T must be declared with Q_DECLARE_METATYPE (). Detailed Description. 12. The central feature in this model is a very powerful mechanism for seamless object communication called signals and slots. The connection in question is queued. Also note that I have my sig/slots with a reference, but if I used a connect like this: @. QNativeSocketEngine::write () was not called in QAbstractSocket::ConnectedState. Section and Key Syntax. The QML engine provides built-in support for a. if the permission has been granted, it continues with the next permission in the list. I don't really know what I have to do in addition. an int and a std::string. show(); int functionIndex = win. beginGroup("references/"); QStringList keys = settings. Returns QPartialOrdering::Unordered if comparison is not supported or the values are unordered. Call qRegisterMetaType<std::string> (); in the initialization of your code. Note that if you intend to use the type in queued. The Qt doc on qRegisterMetaType explicitly says : T must be declared with Q_DECLARE_METATYPE (). For the moment, moc will extract and record all tags, but it will not handle any of them specially. Specifically, the function have to be called before using the struct in a queued signal/slot connection or before. You have to register your custom type for queued signals because by registering it, Qt can make a copy of it in its event loop (which certainly uses QVariant) and pass it as argument later (when the original passed value is long since out. QDBusArgument is the central class in the Qt D-Bus type system, providing functions to marshall and demarshall the primitive types. Sets the port on the local side of a connection to port. An alternative would be to wrap shared_ptr<int> in your own class and implement comparison the way you want. It is. new children are appended at. This function should only be used if this is a property of a Q_GADGET. 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++. When you think about, there are quite convincing reasons to disallow it implicitly happening. Consider the specific case of qRegisterMetaType. h file. ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. Problem: There is no update of the UI. com to ask a new question. Thanks a lot for that!. Data Type Conversion Between QML and C++. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. Usually, we call the macro right below the class/struct declaration in the header file. king_nak king_nak. 0. Use Q_DECLARE_METATYPE (std::string) in one of your headers. Returns true if the column is inserted; otherwise returns false. When sender and receiver objects do not live in the same thread, the Qt::QueuedConnection type is used. As the docs state: Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. [override virtual noexcept] QQmlEngine:: ~QQmlEngine Destroys the QQmlEngine. Then, connect this signal to a slot that will do the actual update of the data. That's probably there, as qRegisterMetaType () wouldn't compile otherwise. 使用此连接类型在同一线程中的对象之间进行. 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). 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. ui). Hello, i have the following warning and i would like to ask how can i fix it. 1. 04 with anaconda distribution of python 3. struct StandardData { int EmpId; QString Name; }; Q_DECLARE_METATYPE (StandardData) Additionally, you might need to call qRegisterMetaType. Instead, the following lines have been added to the adding. setContextProperty qmlRegisterType qRegisterMetaType等区别. (Make sure 'QTextCursor' is registered using qRegisterMetaType (). QMetaType:: 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(). In general, you only need Q_DECLARE_METATYPE (). 14. )" caused by working in threads. The application may need to relay this clicking event to other applications. The following code allocates and destructs an instance of MyClass: 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. Following this logic, the following code may not work: connect (senderObject. You should use qmlRegisterType function for that. One of the overloads is a function template that can be used to create an alias for a type and the form is:. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. ) The text was updated successfully, but these errors were encountered: QObject::connect: Cannot queue arguments of type 'object' (Make sure 'object is registered using qRegisterMetaType(). e. However documentation of qRegisterMetaType() says: "Call this function to. Detailed Description. qRegisterMetaType<geometry_msg::msg::Pose>(); // In MainWindow's constructor. Warning. uint8_t is the typedef for unsigned char . There is no use case for implementing qRegisterMetaType, because PyObject. I'm introducing myself to PyQt5 through one of its included examples. karensantana. (Make sure 'uint64' is registered using. Make sure 'QTextCursor' is registered using qRegisterMetaType(). button. Since Qt 5. What worries me is that. It will return correct type value like 1230 for type in function SomethingElse of class C. Q_DECLARE_METATYPE与qRegisterMetaType学习. Where: before using any of the above. 步骤： (以自定义MyDataType类型为例）. Reply Quote 0. This requires the exchanged data to be of a type that is recognizable by the engine. To do this you first subclass logging. QtGui import * from PyQt5. In C++ if you wan't to use some type in queued connection type you should call qRegisterMetaType<MyType> ("MyType"). QObject::connect: Cannot queue arguments of type 'my_enum' (Make sure 'my_enum' is registered using qRegisterMetaType(). – Kamil Klimek. Data Type Conversion Between QML and C++. So I don't stream the pointer itself just copy the properties and set them to a new created pointer object. Note: Signals are always public, but you should regard that as an implementation detail. Improve this answer. We strongly advise against using it in new code. Before emitting a signal across a thread boundary with a non-trivial argument type (like QModelIndex ), you must first call this: qRegisterMetaType<QModelIndex> ("QModelIndex"); That prepares Qt to be able to emit the signal across a thread boundary. Returns true if the write succeeded; otherwise returns false. ) I read about qRegisterMetaType() and try to implement it in the constructor of both classes, like this:. 0’ of a module called ‘com. emit (statuses) Share. layoutChanged. 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 Qt doc on qRegisterMetaType explicitly says : T must be declared with Q_DECLARE_METATYPE (). 2. When a signal is emitted, the corresponding signal handler is invoked. complains that the metatype isn't registered. Q&A for work. the connect () call returns true, but when the signal is emitted, Qt outputs this: QObject::connect: Cannot queue arguments of type 'uint64'. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. QWaitCondition allows a thread to tell other threads that some sort of condition has been met. Debugging signals and slots connections. adam-iris added a commit that referenced this issue Oct 11, 2017. In C++ if you wan't to use some type in queued connection type you should call qRegisterMetaType<MyType> ("MyType"). ; Create a native socket descriptor, instantiate QAbstractSocket, and call setSocketDescriptor() to wrap the native socket. Nejat Nejat. However Q_DECLARE_METATYPE () is a bit more complicated. It's a bit tricky thing. Not sure yet. ) My application is an image viewer. goocreations 12 Mar 2013, 07:22. The default value is Data8, i. you don't call qRegisterMetaType multiple times, even with the same type and the same string. 048771190]: Out drawPath [ INFO] [1432901455. The ones I am registering for are mostly structs for storing data and just a few simple classes. akshatrai91 7 Jan 2021, 06:21. QModbusDataUnit can be used for read and write operations. I explicitly don't want to update it on every change to one of the quantities, so they don't. Make sure 'QTextCursor' is registered using qRegisterMetaType(). Wrong code @ QSettings settings; settings. The errors you are getting are making it clear that it wouldn't work with const anyway you twist it, because that's not how the API is designed, because while you can pass non-const objects to const functions, you cannot do the opposite for reasons that should be obvious. childEvent (event) # Parameters:. I searched the Doc but I could not find a documentation to. . The qRegisterMetaType function essentially allows a typedef or alias to be assigned to a QVariant. 16. If you need a socket, you have two options: Instantiate QTcpSocket or QUdpSocket. QtCore. I have a class that is a subclass of QObject that I would like to register as a meta-type. Make sure you call it from within a method. You are looking for the Q_ENUM () macro. Any class or struct that has a public default constructor, a public copy constructor and a public destructor can be registered in QMetaType. The signature of your signal does not match the signature of what you wrote in the SIGNAL macro -- those are non-const references:. 4. ) summary refs log tree commit diff statsHello! Thanks for the package. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). 用qRegisterMetaType对自定义的类型进行注册，就是为了告诉Qt如何去做这些事情。. constData ()), " qRegisterNormalizedMetaType ", " qRegisterNormalizedMetaType was called with a not normalized type name, please call qRegisterMetaType instead. connect(self. childKeys();@J. 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. Although you can just create QBluetoothDeviceInfo objects on your own and fill them with data, the easier way is to use the QBluetoothDeviceDiscoveryAgent to start an automated search for visible Bluetooth devices within the connectable range. You could also Q_DECLARE_METATYPE to register your custom type and then use qMetaTypeId () to get the metaType id. // 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 a copy and provides a warning in logs. But the problem comes up when I try to send it to C++ slot, that have my enum as parameter. Step 2 (meta type Declare macro), if needed, describe your custom type/class to things like QVariant, QDebug and other "support" systems used everywhere on QObjects. ui. To enable creation of objects at run-time, call the qRegisterMetaType () template function to register it with the meta-object system. ) Is this a reminder t. I provide a minimal working example for int reference arguments. Improve this answer. However, you shouldn't rely on Qt::QueuedConnection without registering the arguments types using qRegisterMetaType. You can use Qt's typedef for unsigned char: quint8 and you don't need to register it. The QScriptValue class provides functions for converting the result. MyEnum needs to be registered with qRegisterMetaType. Note: If you want to use your custom metatypes also in queued slot connections or with QMetaMethod, you have to call qRegisterMetaType<QPushButton*>() Share. A more complex program sending QSharePointer objects using slots has a similar situation with GDB, that can be reproduced with the previous example. If a field is empty, don't include it in the result. metaObject()->indexOfSlot("testFunc ()"); QMetaMethod mm = win. qRegisterMetaType 将某类型注册中 MetaType 系统中. (Parent is QTextDocument (0x5a28e48), parent's thread is QThread (0x8dbcc0), current thread is QThread. QtGui. Returns the access specification of this method (private, protected, or public). QTextCursor contains information about both the cursor's position within a QTextDocument and any selection that it has made. ) I register my class like this after it's declaration: Q_DECLARE_METATYPE(taservices::ProcessHandle*); I also added this static method which I call from constructor: QObject::connect: Cannot queue arguments of type 'QProcess::ProcessError' (Make sure 'QProcess::ProcessError' is registered using qRegisterMetaType(). So the image buffer is maintained internally and thus implicitely shared. Hello, Can someone tell me about how to register a metatype in pyqt5. #include <QObject> #include <QVariant> class Record : public QPair<qreal, qreal> {. If you are using queued connections, you need to register std::string as meta type. Use Q_DECLARE_OPAQUE_POINTER () to be able to register pointers to forward. The stretch factor changes the width of all characters in the font by factor percent. ) So it seems to be a multi-threading issue caused by this instruction connect (process,&QProcess::started, [this. E. . Make a typedef for QSharedPointer<UserDataType>, and use both Q_DECLARE_METATYPE as well as qRegisterMetaType () to register it for use. PySide6. It can be done with some global container, but because in C++ order of initializing variables is not defined - it may be not trivial. The following code allocates and destructs an instance of MyClass: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>()。 QObject::property()要和类型T一起使用，这个时候qRegisterMetaType<T>()要提前调用。This enum specifies how the split () functions should behave with respect to empty strings. Instead, we should pass weak_ptr to a shared_ptr. 12. by using qRegisterMetaType(). Hello, Can someone tell me about how to register a metatype in pyqt5. This feature is commonly used by proxy connections for virtual connection settings. e. ) Bug is reproducable only if a queued connection is used (when objects are in different threads or explicit Qt::QueuedConnection is used) and MyType is declared inside a namespace. 1 Reply Last reply 0. ) I read on some forum, that this may be caused by calling qt-functions from another Thread, and that using signals & slots instead of plain function calling may fix the issue, but i have tried signals aswell, and i. Now, this simple class holds small samples of. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. That is, only Predefined C++ Types and custom objects that have Q_PROPERTY declarations could access from QML environment. ) QObject: Cannot create children for a parent that is in a different thread. There's no compile time error, but when I run. 2] enum QLocalSocket:: SocketOption flags QLocalSocket:: SocketOptions This enum describes the possible options that can be used to connect to a server. Nov 30, 2012 at 8:31. Turns out this was caused by the ipython magic "%matplotlib qt" in my startup script, which would try to use qt4. ) What I have done is, declare in the main the qRegisterMetatype but it still complaining. h. 因为没有指定 connect的链接方向 Qt::DirectConnection. My Thread is as. 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(). This results in access violations. registerType () determines which register is used for the operations. This function was introduced in Qt 5. Detailed Description. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. QObject::connect: Cannot queue arguments of type 'QVector<QVector<int> >'. Solution 1: somewhere. The Qt Meta-Object System in Qt is responsible for the signals and slots inter-object communication mechanism, runtime type information, and the Qt property system. e. bool QAbstractItemModel:: insertColumn ( int column, const QModelIndex & parent = QModelIndex ()) Inserts a single column before the given column in the child items of the parent specified. When these files are processed by repc, repc generates both Source and Replica header files. Note: This function is thread-safe. Note following line #include. 150%) wider. In my module tests, I turn the card up and down, and can verify that the number of signals are increasing using QSignalSpy. qRegisterMetaType<B_Custom::B_Enum>() before call A::DoSomething(), the type value of function SomethingElse will not be QMetaType::UnknownType. C++ (Cpp) qmlRegisterUncreatableMetaObject - 2 examples found. This function was introduced in Qt 5. 4. 5 times (ie. The QMetaType class manages named types in the meta-object system. metaObject()->method(functionIndex); qDebug() << mm. This object can then be passed from QML to C++ via. So using qRegisterMetaType () you will just trade Q_ENUM () for Q_DECLARE_METATYPE (). Asking for help, clarification, or responding to other answers. 1. ) QObject: Cannot create children for a parent that is in a different thread. Can you show the code that's actually causing the error? The. uint8_t is the typedef for unsigned char . QObject: Cannot create children for a parent that is in a different thread. Placing logic such as a script or other operations in the handler. multithreaded software and I am getting the warning says: (Make sure 'QVector<int>' is registered using qRegisterMetaType (). However, if I add the const qualifier in front of Person* p in the argument list of test () I get errors from QML at run-time! (i. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit initialization call from application code.