二者的联系： QMetaTypeId<TYPE>的类中的成员包含对qRegisterMetaType的调用. qRegisterMetaType<FileNodePointer> ("FileNodePointer"); should be called once (in main, constructor etc. Can you show the code that's actually causing the. 2、在类型定义完成后，加入声明：Q_DECLARE_METATYPE (MyDataType); 3、在main ()函数中. A single QMetaObject instance is created for each QObject subclass that is used in an application, and this instance stores all the meta-information for the QObject subclass. ros. 2 Answers Sorted by: 3 You do not need to call qRegisterMetaType () to use a type with QVariant. Follow answered Jan 29, 2016 at 11:01. This topic has been deleted. 因为没有指定 connect的链接方向 Qt::DirectConnection. emit (statuses) Share. The Connection class holds either a QTcpSocket or QTcpServer (depends on the config). Nope, registering with qRegisterMetaType<std::vector<int>>() has same effect as not registering at all (using QVector<int> works without registration, but does not expose length, either). QObject::connect: Cannot queue arguments of type 'MyStruct'. To do this you first subclass logging. Currently I have a 2d array which represents the game board. To not see the message. MainWindow win; win. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. This maybe is not the nicest solution, but it works just fine: Add a property to the wizardpage which contains the QListView and let it return the pointer to the selectionmodel. SIGNAL(ueSignalTaskFinished(UePosCommProtocolArch::UeCommand&, // reference QByteArray&)), //dittoCustom types registered using qRegisterMetaType() that have operators for streaming to and from a QDataStream can be stored using QSettings. The. Make sure you call it from within a method. karensantana. MyEnum needs to be registered with qRegisterMetaType. ) I read about qRegisterMetaType() and try to implement it in the constructor of both classes, like this:. Use Q_DECLARE_OPAQUE_POINTER () to be able to register pointers to forward. Qt is complaining about QObject::connect: Cannot queue arguments of type 'QTextCursor' (Make sure 'QTextCursor' is registered using qRegisterMetaType(). Returns QPartialOrdering::Unordered if comparison is not supported or the values are unordered. If you use queued connections, you'll need to call qRegisterMetaType() too. Check if from PyQt5. e. Attention: Answers. Since Qt 5. 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. The actual values () are either single bit or. This requires the exchanged data to be of a type that is recognizable by the engine. QMetaType is Qt's way to have run-time dynamic information about your types. 3k 33 33 silver badges 58 58 bronze badges. See also. QObject::connect: Cannot queue arguments of type 'object' (Make sure 'object' is registered using qRegisterMetaType(). By convention, these files are given a . template<class T> QMetaObject::Connection connect_from_pointer ( const QSharedPointer<T>& sender,. I can override QObject's. 如果要使用单个全局类来访问QML或从QML访问. ) INFO:cfclient. But with the shared_ptr object, not a pointer to the shared pointer! You will have to register std::shared_ptr<yourclass> with the Qt meta object system before this can work, i. call qRegisterMetaType with the name specified, else reading properties. One of these plugins uses Q_DECLARE_METATYPE on some types that need to be stored in a QVariant. It seems that for a metatype that is a QList<MyClass::MyEnum> I must. #include <QObject> #include <QVariant> class Record : public QPair<qreal, qreal> {. 二者的联系： QMetaTypeId<TYPE>的类中的成员包含对qRegisterMetaType的调用. Constantin. In general, you only need Q_DECLARE_METATYPE (). If that is. And this should be used for each exe/dll instance. The. If I register QVector I can't dissconnect this signal and the signal is emited. ) I have Googled for eons trying to figure out a way how to use the qRegisterMetaType() in PySide, to no avail. So if you put the register in constructor, you have to instance your class once and then make the connection. 0. The signature of your signal does not match the signature of what you wrote in the SIGNAL macro -- those are non-const references:. QBluetoothDeviceInfo which provides similar information for remote devices. 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(). websocket. So I saw this in the documentation: typedef QString CustomString;. I am trying to learn Qt and I am attempting to do so by making a little titres game. (Make sure 'QVector<int>' is registered using qRegisterMetaType(). QObject::connect: Cannot queue arguments of type 'SomeUserDefinedType' (Make sure 'SomeUserDefinedType' is registered using qRegisterMetaType(). 1 Answer. Also you may need to use qRegisterMetaType function. 9 under OSX 10. Although I have not made clear the specific meaning, at least it can work well. Then, connect this signal to a slot that will do the actual update of the data. I'll take your word on that, because on my rig fixing the return type of area() and providing the empty template parameter list for the specialization leaves only get() failing to compile, and as near as I can tell it may be because of the order this was pasted into the question. " Currently I have no UI implemented (yet!). Doc states:. open(wsUrl); without threading the connection works fine. 9k 9 34 52. rep file extension, short for Replica. Read and abide by the Qt Code of Conduct. said, try to directly pass shared_ptr with your signal/slots. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. Your code should look like this: Q_ENUM (StateEnum) //note the missing 'S' here Q_PROPERTY (StateEnum state READ state NOTIFY stateChanged) Share. For a signal-functor connection without a context object, it is the only way to selectively disconnect that connection. uint8_t is the typedef for unsigned char . 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. 这里您需要在使用setContextProperty ()之前创建此类对象。. karensantana. adam-iris added a commit that referenced this issue Oct 11, 2017. qmlRegisterUncreatableType# qmlRegisterUncreatableType (pytype: type, uri: str, versionMajor. I'm writing python library for very simple text output to Qt's QTextBrowser window (stored in window. [quote author="Andre" date="1306394817"]In that case, I think you need to register them. But Q_OBJECT macro handles this automatically. By implementing a factory it is possible to create custom QNetworkAccessManager with specialized caching, proxy and cookie support. E. no unexpected garbage. The habit of passing shared_ptr by ref should not be followed in lambdas. (Make sure 'uint64' is registered using. Reply Quote 0. 0 and have problems registering my own class as a QMetaType. 它的作用是将自定义的数据类型转换为Qt元对象系统中的类型，使得这些类型可以在不同线程之间进行信号槽的传递。. 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. The Rep lica C ompiler (repc) generates QObject header files based on an API definition file. If such a connection is made, and a signal triggered, the runtime warning will be shown: QObject::connect: Cannot queue arguments of type 'T' (Make sure 'T' is registered using qRegisterMetaType (). It will return correct type value like 1230 for type in function SomethingElse of class C. Problem: There is no update of the UI. I have a class that is a subclass of QObject that I would like to register as a meta-type. Qt documentation specifically states that qRegisterMetaType<T>() must be called for a type to work in the Qt property system. Detailed Description. QObject::connect: Cannot queue arguments of type 'QModbusDevice::State' (Make sure 'QModbusDevice::State' is registered using qRegisterMetaType (). In QML, the meta-type system is the only way that QML engine can access C++ structures from a QML environment. What is the expected behavior. As explained in this thread you can try using a typedef, including the QMetaType header and then using both Q_DECLARE_METATYPE macro and the qRegisterMetaType function (as implied by this thread on a similar issue). Thanks for replying! I'm using Qt 5. (Make sure 'QTextCursor' is registered using qRegisterMetaType(). close file : AnaEx01. evaluate("1 + 2"); evaluate () returns a QScriptValue that holds the result of the evaluation. Otherwise you might be adding duplicate entries to the metatype database each time. Did you try to use qRegisterMetaType function? The official manual says: The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. e. 0’ of a module called ‘com. Note that the signal has to be in normalized form, as returned by normalizedSignature (). ) What I have done is, declare in the main the qRegisterMetatype but it still complaining. Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. qRegisterMetaType () is called to register the TYPE and generate a TYPE ID. 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); This now makes it possible for Message values to be stored in QVariant objects and retrieved later. Detailed Description. Execute qRegisterMetaType<QItemSelection> (); before it is used as such, e. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. It contains a bin folder with the exe file and batch launchers, an include folder with the headers, a source folder with the source files and the moc file (cpp). Any class or struct that has a public default. e. QObject::connect: Cannot queue arguments of type 'QModbusDevice::State' (Make sure 'QModbusDevice::State' is registered using qRegisterMetaType (). Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. As soon as the first event arrives I got the errormessage: @QObject::connect: Cannot queue arguments of type 'QQuickChangeSet'. This replaces the now-deprecated Q_ENUMS and will automatically register the metatype. QPushButton(self. If you need a socket, you have two options: Instantiate QTcpSocket or QUdpSocket. Any class or struct that has a public default constructor, a public copy constructor and a public destructor can be registered in QMetaType. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. qRe terMetaType 是Qt框架中的一个函数，用于在Qt元对象系统中注册自定义的数据类型。. Custom types registered using qRegisterMetaType() that have operators for streaming to and from a QDataStream can be stored using QSettings. Also note that I have my sig/slots with a reference, but if I used a connect like this: @. This results in access violations. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit initialization call from application code. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. The following code allocates and destructs an instance of MyClass:The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. uint8_t is the typedef for unsigned char . . otherwise. rep file extension, short for Replica. Registers the type name typeName for the type T. The custom type T needs to be registered in Qt meta-type system in order to be used in e. The connection in question is queued. 1. So I don't stream the pointer itself just copy the properties and set them to a new created pointer object. g. See also convert(). py that implements a customwidget class it would look something like: from customwidgetscript import customwidget. ); RealTimeHistogram: the main widget, a user interface; DataGeneratorThread class DataGeneratorThread. Share. cppuint64 is a typedef for 64 bit integers in VS: Qt Code: Switch view. If you are using queued connections, you need to register std::string as meta type. metaObject()->method(functionIndex); qDebug() << mm. 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. 2. I realize that this actually works when more than one signal of different types is sent, e. That is sad. If I register QVector I can't dissconnect this signal and the signal is emited. queued connections. You need to create your own factory that will register functors that will call qRegisterMetaType in runtime. Then you should register your object to use it with QML. The physical memory sizes returned include the memory from all nodes. Data Type Conversion Between QML and C++. And then Python crashes. Object::connect: No such slot main_application::input_handler(button_back) Of course, there is, because signature is main_application::input_handler(button_type), and button_back is a value, not type. I have gave you below the basic process for a deletion for example. rows += self. QSharedPointer is a smart pointer class in the Qt library. In C++ if you wan't to use some type in queued connection type you should call qRegisterMetaType<MyType> ("MyType"). 子线程中：QMap<QString, QString> testMap; emit testSignal(testMap);Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. The following code: self. It enables things such as QVariant wrapping of custom types, copy of queued connection arguments, and more. Each emission of the signal will append one item to the list, containing the arguments of the signal. If the Microsoft compiler was not requiring this, then it was doing it wrong. h file. Using qRegisterMetaType() is actually registering a certain type to QMetaType. Warning. (异步调用) Qt::BlockingQueuedConnection，则将以与Qt :: QueuedConnection相同的方式调用该方法，除了当前线程将阻塞直到事件被传递。. I'm not sure how to do this in python but probably you should add similar call with QTextCursor. Notice that with this approach you will only be able to check the value of the passed. Now you have a valid QObject. However, as you need the type to be. 12. 11. When sender and receiver objects do not live in the same thread, the Qt::QueuedConnection type is used. Any class or struct that has a public default. You should use qmlRegisterType function for that. Improve this answer. king_nak king_nak. QObject. " 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. This function should only be used if this is a property of a Q_GADGET. The application may need to relay this clicking event to other applications. #include<QMetaType> typedef QList<int> IntList; qRegisterMetaType<IntList> ("IntList"); error C2909: 'qRegisterMetaType': explicit. A connection defines an interface for sending/receiving data independent of the protocol. It is more or less explained in the manual for int qRegisterMetaType (const char *typeName) This function requires that T is a fully defined type at the point where the function is called. 1 Answer. g. QObject::connect: Cannot queue arguments of type 'uint32_t' (Make sure 'uint32_t' is registered using qRegisterMetaType(). h which looks like: #ifndef ENUMS_H #define ENUMS_H #include <QtDBus> #include "enumDBus. Debugging signals and slots connections. QPainter supports drawing lines, polygons, vector paths, images, and text. Handler. call qRegisterMetaType with the name specified, else reading properties. Haven't tried it yet but it appears to check the permissions established in the manifest(?). 12. Sets the factory to use for creating QNetworkAccessManager (s). You can call this function in a subclass of QAbstractSocket to change the return value of the localPort () function after a connection has been established. Warning: To make this function work with a custom type registered with qRegisterMetaType(), its comparison operator must be registered using QMetaType::registerComparators(). Any class or struct that has a. (Make sure 'QTextCursor' is registered using qRegisterMetaType (). You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. complains that the metatype isn't registered. connect(self. #define. You could also Q_DECLARE_METATYPE to register your custom type and then use qMetaTypeId () to get the metaType id. 3. Nov 30, 2012 at 8:31. Call qRegisterMetaType () to make types available to non-template based functions, such as the queued signal and slot connections. template <typename T> int qRegisterMetaType (const char *typeName) This function is deprecated. Now the above code compiles and runs just fine. qRegisterMetaType<QAbstractSocket::SocketState>(); Share. When you think about, there are quite convincing reasons to disallow it implicitly happening. Improve this answer. I don't really know what I have to do in addition. This fully updated, classroom-tested book teaches C++ “The Qt Way,” emphasizing design patterns and efficient reuse. I created a. ) @. It works only in this case int qmlTypeId = qRegisterMetaType<namespace::MenuModel*> ("MenuModel*"); You return a pointer in the property, so Qt Meta Object system needs to know about it. Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this siteThis macro is used to specialise the template class QMetaTypeId with typename TYPE, in which, a static member function qt_metatype_id () is defined. To enable creation of objects at run-time, call the qRegisterMetaType () template function to register it with the meta-object system. setContextProperty : Use setContextProperty, When you want to use a single global class to access to or from QML. Returns the access specification of this method (private, protected, or public). You can try it:This function registers the Python type in the QML system with the name qmlName, in the library imported from uri having the version number composed from versionMajor and versionMinor. int QMetaObject:: indexOfSignal (const char * signal) const. 5. ) QObject::connect: Cannot queue arguments of type 'QTextCursor'. It just allows you to queue types that. ) QObject::connect: Cannot queue arguments of type 'QVector' (Make sure 'QVector' is registered using qRegisterMetaType(). Data Type Conversion Between QML and C++. If the signal is being emitted, I get this error: @. Share. 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++. self. The compound types are then created by association of one or more of the primitive types in arrays, dictionaries or structures. 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. connect (thread, SIGNAL (ShowData (QList<QString>)), this, SLOT (ev. When a new folder is selected I load the thumbnails and. QDBusArgument is the central class in the Qt D-Bus type system, providing functions to marshall and demarshall the primitive types. main. And once all of them are updated I'd like the Context object to inform QML to update the view. Detailed Description. The syntax gets especially interesting when specializing a template function of a. @reddy9pp said in QObject::connect: Cannot queue arguments of type 'std::string' (Make sure 'std::string' is registered using qRegisterMetaType(). Here is the list of information kept for each type in the meta-type system: The Type Name as registered. You need to create your own factory that will register functors that will call qRegisterMetaType in runtime. You should place Q_DECLARE_METATYPE (QSqlRecord) in only one header and then just include it everywhere it is needed. call qRegisterMetaType() to register the data type before you establish the connection. Section and Key Syntax# Setting keys can contain any Unicode characters. newStatuses. tab) self. Any class or struct that has a public default constructor, a public copy constructor and a public destructor can be registered in QMetaType. For the moment, moc will extract and record all tags, but it will not handle any of them specially. The operating system can enlarge the paging file up to the maximum size set by the administrator. launch" and then "roslaunch velo2cam_calibration laser_pattern. Call this function if you need QLocalSocket to start sending buffered data immediately. ; Create a native socket descriptor, instantiate QAbstractSocket, and call setSocketDescriptor() to wrap the native socket. clicked. Then the TYPE ID is saved in local static vairable metatype_id. Jun 13, 2021 at 19:37. on_click) binds signal of a button (clicked) to a slot self. 138: 139: This example shows a typical use case of Q_DECLARE_METATYPE(): 140: 141 snippet code/src_corelib_kernel_qmetatype. The type and its values must start with a capital letter but otherwise follow rules for naming a variable (e. 2D Graphics #. Obviously then you would not do registerComparator (). ) 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. #include <QObject> #include <QVariant> class Record : public QPair<qreal, qreal> {. However, I cannot figure out how to verify that the included parameter is FACE_UP or FACE_DOWN. mycompany. 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 的联系如果还希望使用这种类型的引用，可同样要注册：qRegisterMetaType<TextAndNumber>("TextAndNumber&"); 版权声明：本文为wangzhiqian7hao原创文章，遵循 CC 4. The QML engine provides built-in support for a. setContextProperty qmlRegisterType qRegisterMetaType等区别. Data Type Conversion Between QML and C++. 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QObject::connect: Cannot queue arguments of type 'QHostAddress' (Make sure 'QHostAddress' is registered using qRegisterMetaType(). ) The image I am trying to pass is a cv::Mat which I converted to a QImage which I afterwards converted to a QString. ) 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. Where are you getting this from? qRegisterMetaType is not a member function of QSettings or any other class. If it is a partial specialization it might be template<class X> instead. by using qRegisterMetaType(). (Make sure 'QVector<int>' is registered using qRegisterMetaType(). Note that, as far as the meta-type system is concerned, MyClass, MyClass *, QVector<MyClass>, shared_ptr<MyClass> and so on are all different types, and as such, each one may need its own registration. ) 1 stopped. 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(). 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. You can use the tags to annotate your methods. ) 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(). Hello, Can someone tell me about how to register a metatype in pyqt5. Thanks for the code snippet. Detailed Description. Originally I was passing a pointer to a type to signals which worked, the slots obviously had to returned the same pointer, again this worked. Use Q_DECLARE_METATYPE (std::string) in one of your headers. com. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. The QML engine provides built-in support for a. step self. QAbstractSocket is the base class for QTcpSocket and QUdpSocket and contains all common functionality of these two classes. Any ideas? Nope, registering with qRegisterMetaType<std::vector<int>>() has same effect as not registering at all (using QVector<int> works without registration, but does not expose length, either). error C2059: syntax error : 'string' warning C4667: 'int qRegisterMetaType (void)' : no function template defined that matches forced. In C++ if you wan't to use some type in queued connection type you should call qRegisterMetaType<MyType> ("MyType"). (Make sure 'QTextBlock' is registered using qRegisterMetaType (). QAbstractSocket is the base class for QTcpSocket and QUdpSocket and contains all common functionality of these two classes. In addition to the limitations of the variadic invoke() overload, the arguments must have the same type as the ones expected by the method, else, the behavior is. You can use Qt's typedef for unsigned char: quint8 and you don't need to register it. As said in int qRegisterMetaType () documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. Following this logic, the following code may not work: connect (senderObject. ) QObject::connect: Cannot queue arguments of. metaObject()->indexOfSlot("testFunc ()"); QMetaMethod mm = win. ) QObject::connect: Cannot queue arguments of type 'QTextCursor' (Make sure 'QTextCursor' is registered using qRegisterMetaType(). 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. Even though qRegisterMetaType(). ChildAdded and ChildRemoved events are sent to objects when children are added or removed. text_changed. Make sure 'QTextCursor' is registered using qRegisterMetaType(). ) I have defined MyStruct in an accessible header file: myheader. Replacing it with "%matplotlib qt5" (or deleting it entirely) worked for me. 048771190]: Out drawPath [ INFO] [1432901455. 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(). It is. ;. The qRegisterMetaType function essentially allows a typedef or alias to be assigned to a QVariant. ", which suggests it is only for classes and structs. I searched the Doc but I could not find a documentation to. 11. Selected questions and answers have been migrated, and redirects have been put in place to direct users to the. If you are using those metatypes during. @reddy9pp said in QObject::connect: Cannot queue arguments of type 'std::string' (Make sure 'std::string' is registered using qRegisterMetaType(). Share. In this case the slot is executed as a normal function call. See moreqRegisterMetaType usage. Not sure yet. Specifically, the function have to be called before using the struct in a queued signal/slot connection or before. 5 times (ie. I'm using Qt 5. It's a bit tricky thing. 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. Occurs during "normal" usage (simply adding and downloading. Saved searches Use saved searches to filter your results more quicklyI get a solution to the problem of "Qmqtt QObject::connect: Cannot queue arguments of type 'ClientState' (Make sure 'ClientState' is registered using qRegisterMetaType(). But the thing is, I have. a copy of a cv::Mat object will point to the same data as the copied from item). Please visit robotics. ) I believe this is because I am updating the text box from threads other than the ma. the type name must be specified without the class, as in. TEST_VIEW4 contains a QML folder with a specific folder for this QML code. g. Improve this answer. @RIJIK "very unlikely" doesn't mean never ever. 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. When a signal is emitted, the corresponding signal handler is invoked. It is part of QMetaType, which is not implemented by PySide. cppWe 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. In that case, I think you need to register them. QPainter::begin: Paint device returned engine == 0, type: 3 QPainter::setFont: Painter not active QPainter::setPen: Painter not active [ INFO] [1432901455. runBtn = QtWidgets. Its probably something about Qt, but how can i fix it ?Member Function Documentation [explicit] QQmlEngine:: QQmlEngine (QObject *parent = nullptr) Create a new QQmlEngine with the given parent.