The documentation for exposing C++ properties to QML says that: "Note: Do not use typedef or using for Q_PROPERTY types as these will confuse moc. 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. However, I cannot figure out how to verify that the included parameter is FACE_UP or FACE_DOWN. 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. g. This object can then be passed from QML to C++ via. 2、在类型定义完成后，加入声明：Q_DECLARE_METATYPE (MyDataType); 3、在main ()函数中. This function was introduced in Qt 4. by using qRegisterMetaType(). 1 Answer. To call qRegisterMetaType (), you still need to use Q_DECLARE_METATYPE (). So you can call it from your constructor. Situation. See the Custom Type Example for code. But because QUuid stores its content as a QByteArray which is already supported by QVariant, you. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. I tested your code on Qt 5. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. void QAbstractSocket:: abort ()2 Answers. 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. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. The default access for a class is private, so that Container* data(); declares a private member function, but it looks like you expect it to be public. Then after some time, we can begin answering them. 2. That. no unexpected garbage. 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. Constantin. Any errors from Qt's metatype systems are usually due to MOC (the "meta-object compiler"), which reads your header files and generates a "moc" file with metatype information for every class where the Q_OBJECT macro is declared. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. [since 6. Update. 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. Sorted by: 2. If you want to pass IBase * between different threads, you need to register class with qRegisterMetaType<IBase *> () call; It is bad practice to pass pointers throught singals, because it is hard to control lifetime of passed objects. Step 1 (mark for MOC), build some QObjects That pattern uses Q_PROPERTY and Q_OBJECT and the MoC tool. ), or any other callable, cannot declare a type for use outside of the call site. Enumerations that are declared with Q_ENUM have their QMetaEnum registered in the enclosing QMetaObject. SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). It associates a type name to a type so that it can be created and destructed dynamically at run-time. I want to use drag-and-drop to drag a QTreeWidgetItem that has std::shared_ptr user data. You don't pass around copies of QObject derived types because it is not copyable. Note: This function is thread-safe. qRegisterMetaType() requires also a Q_DECLARE_METATYPE() – dtech. This article will. The code compiles and runs ok. F. Labels: meta system, Meta type, qt. So, if you had a custom type FooType, you'd put the Q_DECLARE_METATYPE directly after the declaration, and in. But I couldn't register the type because it's a QObject and I don't have access to the implementation to change it. 1. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. In my own code, I use Q_DECLARE_METATYPE for classes I want to store. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. An alternative would be to wrap shared_ptr<int> in your own class and implement comparison the way you want. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. Per Qt documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. If the type was not declared with Q_DECLARE_METATYPE (), compilation will fail. int videoSourceMetaTypeId = qRegisterMetaType< VideoSource > ();Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. Additionally Qt5 always refers to Q_DECLARE_METATYPE, saying that qRegisterMetaType is only when you want to. I read a bit and it seems that Q_DECLARE_SMART_POINTER_METATYPE is supposed to allow this to work. 9k 9 34 52. To enable creation of objects at run-time, call the qRegisterMetaType() template function to register it with the meta-object system. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Sorted by: 1. 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. 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. Note that you are technically lying to the meta type system. As a result, if the library connects a D-Bus signal to a slot with a signature "void mySlot (MyType)", it is. 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. // This primary template calls the -Implementation, like all other specialisations should. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. qRegisterMetaType vs. You had to use QMetaType::registerComparators () and the other static register functions in QMetaType to actually make use of that functionality, though. You should use qmlRegisterType function for that. To start viewing messages, select the forum that you want to visit from the selection below. namespace CCS { Q_DECL_EXPORT Q_NAMESPACE. Posted by Unknown at 2:06 AM. I placed Q_DECLARE_METATYPE (DataPoint) after the class definition. Detailed Description. 5 is compiled with GCC 4. 2. 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. See also state() and Creating Custom Qt Types. }; Q_DECLARE_METATYPE (MyCustomType); Then in my application, I have a signal "void sendMsg (MyCustomType)" and I qRegisterMetaType (). You may have to register before you can post: click the register link above to proceed. 1 Answer Sorted by: 21 Objects are copied when put into a QVariant, but QObject derived classes cannot be copied, so the solution is to use a pointer to your. nyaruko. I'm using Qt 5. e. Qt has to stay free or it will die. To make the custom type. Q_DECLARE_METATYPE(MyObject*) somewhere in your code. I read a bit and it seems that Q_DECLARE_SMART_POINTER_METATYPE is supposed to allow this to work. Similarly you can create a mutable view of type QAssociativeIterable on any container registered with Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE(). I read on documentation that Q_DECLARE_METATYPE makes available type to QVariant, for example (I got it from documentation): @ struct MyStruct { int i;. Q_DECLARE_METATYPE (std::string) Quoting Qt Doc. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. If you have to use Q_DECLARE_METATYPE yourself, the id is not constexpr. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. Remember that Q_DECLARE_METATYPE merely defines a specialization of QMetaTypeId for your type. 2. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. This function is useful to register typedefs so they can be used by QMetaProperty, or in QueuedConnections. If you want both, then register both. Mixing doesn't work but if you always use one or the other it works. So in your case you need to declare. Your Matrix type is not copiable, thus you can't use Q_DECLARE_METATYPE on it. Do do you register the meta type with the call qRegisterMetaType("your custom meta type")? 1 Reply Last reply Reply Quote 0. @Q_DECLARE_METATYPE (std::unique_ptr<Thing>);@. private: AnotherQGadgetClass test_; } Q_DECLARE_METATYPE(QGadgetClass) I am trying to access Q_GADGET from QML classic way like accessing a Q_OBJECT , but the setters are not called. Registered enumerations are automatically registered also to the Qt meta type system, making them known to QMetaType without the need to use. It is not safe to make a QObject's copy constructor public. The. There's also no need for that typedef, it only makes the code less readable. 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. 16. I have an application that requires use of both Qt 3D and the QCustomPlot library. QObject can't be copied and all its descendants can't be copied also. It is a static method, it does not (cannot) change x2. Adding a Q_DECLARE_METATYPE () makes the type known to all template based functions, including QVariant. Additional types can be registered using qRegisterMetaType() or by calling registerType(). 3. 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. Any class or struct that has a public default constructor, a public copy. The class is used as a helper to marshall types in QVariant and in queued. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. 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。. The following should work: Note that you also have to call qRegisterMetaType<MyMpiMessage> (); before you use the function the first time. Inheritance diagram of PySide6. io Please note that I do not use Q_DECLARE_METATYPE on purpose because I don't actually need its features (QVariant expansion) right now. hpp which is included in Class1. Qt is throwing an exception because it doesn't know how to store the shared_ptr onto a QDataStream. I only care about runtime instantiation. 1 Answer. 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(). 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 (). 0. qRegisterMetaType<Subclass> ("Subclass") also doesn't work. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. See also state() and Creating Custom Qt Types. 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. Call qRegisterMetaType () to make types available to non-template based functions, such as the queued signal and slot connections. no unexpected garbage. That would allow you to use. Even though we do not intend. 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. Note: it's also safe to call qRegisterMetaType () multiple times. 1. I believe this is related to the fact that. qRegisterMetaType usage. qRegisterMetaType vs. The problem of owner ship of the memory is avoided. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. 0. qRegisterMetaType<signed long long>() - do nothing. You should use Q_DECLARE_METATYPE macro for this. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. Qt Base (Core, Gui, Widgets, Network,. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. Q_DECLARE_METATYPE. Hello Ladies and Gentlemen. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. Q_DECLARE_METATYPE accepts objects with public constructor, copy constructor and destructor. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. queued connections. 1. // This primary template calls the -Implementation, like all other specialisations should. Of course it's a bug and an odd mistake that Q_DECLARE_METATYPE(QList<QSslError>) is in qsslsocket. Trying to register std::map<non_template_type_1,non_template_type_2> with Q_DECLARE_METATYPE() results in compilation failure and apparently is not supported. The ENUM type. –To copy to clipboard, switch view to plain text mode. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). Re: Qt warning of type conversion already registered Originally. 0. Re: How to use Q_DECLARE_METATYPE. canConvert<x> (); } and. See also. h. state() Creating Custom Qt Types. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. void QAbstractSocket:: abort ()Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. void Message:: registerMetaType {qRegisterMetaType < Message >. 0. g. Note that you are technically lying to the meta type system. To start viewing messages, select the forum that you want to visit from the selection below. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). As said in int qRegisterMetaType () documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. QVariant’s operator== now uses QMetaType::equals for the comparison. Yes I tried with qRegisterMetaType, it. Franzk 26 May 2011, 06:59. Share. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. In the header, after the class declaration, outside the namespace, I've included. cpp. I have declared all the types with Q_DECLARE_METATYPE, Q_OBJECT and the properties with Q_PROPERTY with the proper getters and setters. Add qRegisterMetaType and qDBusRegisterMetaType calls to enable the framework to work with the custom type. Enum has been moved from outside of the class to inside of it. 4 which does not support all C++11 features. QtCore. 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. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. I read on documentation that Q_DECLARE_METATYPE makes available type to QVariant, for example (I got it from documentation): @ struct MyStruct { int i;. ) summary refs log tree commit diff stats Foo and Foo* are different types and need to be registered separately. What is the point of emitting a QSharedPointer? The worker thread reads the files computes the data allocates and fills the memory with data, wraps it in QSharedPointer and passes it to the mainThread, which is used for plotting. and Q_DECLARE_METATYPE uses qRegisterMetaType() internally. It does not say anything about registering the type. 1）引入头文件：#include<QMetaType>. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. Detailed Description. However Q_DECLARE_METATYPE () is a bit more complicated. pro file, several errors appear referencing the QMouseEvent and QWheelEvent classes. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). The file (called a "rep" file) uses a specific (text) syntax to describe the API. Declare new types with Q_DECLARE_METATYPE () to make them available. QVariant v = QVariant::fromValue<cMyClass>(MyObject); However, as soon as I use Q_DECLARE_METATYPE, I get errors about using a deleted function. You can also use QMetaEnum::fromType() to get the QMetaEnum. G. You may have to register before you can post: click the register link above to proceed. Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. cpp. First of all you need to declare your custom object for Qt metatype system. Compares this QVariant with v and returns true if they are equal;. qt. So using qRegisterMetaType () you will just trade Q_ENUM () for Q_DECLARE_METATYPE (). Yes, templated types can be used in Qt signal/slots. Q_DECLARE_METATYPE only registers a type in meta type system. Read and abide by the Qt Code of Conduct. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. When using signals and slots with multiple threads, see Signals and Slots Across Threads. 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. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. When these files are processed by repc, repc generates both Source and Replica header files. Share. # In the class MainWindow declaration #ifndef Q_MOC_RUN # define the tag text as empty,. Otherwise your signals and slots connected used the old mechanism (with macros SIGNAL and SLOT) that require queueing of the parameters won't know how to do so. Q&A for work. Then the TYPE ID is saved in local static vairable metatype_id. It does not say anything about registering the type. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. @Wieland Thanks. I've registered my class with: @Q_DECLARE_METATYPE(MyClass);@ and. Using the Q_DECLARE_METATYPE () macro 2. qRegisterMetaType () is called to register the TYPE and generate a TYPE ID. This is by design. 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. Here you can see that the macro expands to nothing. so that was all, but remember to use Q_DECLARE_METATYPE, qRegisterMetaType macros for registering your custom type with Qt meta object system. The reasoning is found in the. 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. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. Got a similar example working without explicitly calling qRegisterMetaType() just by removing the semicolon from the line Q_DECLARE_METATYPE(StateMachine::state) – user666412 Sep 21, 2015 at 14:17Additional types can be registered using qRegisterMetaType() or by calling registerType(). Also you may need to use qRegisterMetaType function. complains that the metatype isn't registered. As a workaround, I'm using QVariantMap instead of std::map. See also isRegistered () and Q_DECLARE_METATYPE (). In the example's Message class, a static method is included to do this. hi, I always after application running, receive debug text of: QObject::connect: Cannot queue arguments of type 'MyStruct'. 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;. A separate point for your own benefit. Consider the specific case of qRegisterMetaType. 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. Make your own typedef and do the Q_DECLARE_METATYPE and qRegisterMetatype. int videoSourceMetaTypeId = qRegisterMetaType< VideoSource > ();QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). 文章目录 Q_DECLARE_METATYPE qRegisterMetaType Q_DECLARE_METATYPE 使用Q_DECLARE_METATYPE标记自定义类型，可以让QMetaType查询到类型，也可以让QVariant识别。 qRegisterMetaType 在main函数中使用qRegisterMetaType注册自定义类型到元对象系统中,可在跨线程的信号槽中进行参数传递。I'm using Qt5 and qRegisterMetaType is not documented anymore, so I'm not sure if it's deprecated. The class is used to send arguments over D-Bus to remote applications and to receive them back. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. 手册中告诉我们，执行这个的时候，模板参数T必须用 Q_DECLARE_METATYPE() 声明过 能猜到原因吗？注意看前面 Q_DECLARE_METATYPE() 代码， 对了。类中的成员函数qt_metatype_id中包含对qRegisterMetaType(typeName)的调用 这儿就是辗转调用了这个带参数. QList<AnotherObject*> has of course been registered with Q_DECLARE_METATYPE and qRegisterMetaType(). in your main function or in the constructor of AudioGuiApplication. . But I really would like to know the correct way to solve this problem; one where it is not possible to modify. 12. ) QObject::connect: Cannot queue arguments of type 'QVector<int>'. Then you should register your object to use it with QML. See also. qRegisterMetaType vs. M. I want to use my objects as QVariants and for queued connections. There's no need to call qRegisterMetaType that many times, once is enough. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Qt5でシグナルの引数としてユーザー定義型を指定する場合は、Q_DECLARE_METATYPEとqRegisterMetaType()を使って方の登録を行う必要がある。Trying to register std::map<non_template_type_1,non_template_type_2> with Q_DECLARE_METATYPE() results in compilation failure and apparently is not supported. By the way, Qt 4. 8. 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. 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. Q_DECLARE_METATYPE. See also. You may have to register before you can post: click the register link above to proceed. your custom type definition. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). So my first idea:. The ones I am registering for are mostly structs for storing data and just a few simple classes. Believing an Question from 2010 and the Qt Documentation, the operator==() doesn't work with custom types. Qt Base (Core, Gui, Widgets, Network,. waitForConnected ([msecs=30000]) # Parameters: msecs – int. Detailed Description The QMetaType class manages named types in the meta-object system. Now I want to read this property with Qt's meta object system. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Q_DECLARE_METATYPE(TYPEDEF) Q_DECLARE_METATYPE(TYPEDEF) mainwindow. Q_DECLARE_METATYPE on the other hand is (as far as I know) preprocessor bound. ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. QMetaType::type () is a bit slower, but compilation succeeds if a type is not registered. Also you may need to use qRegisterMetaType function. There's no need to call qRegisterMetaType that many times, once is enough. This function was introduced in Qt 6. 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. wysota. Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template. I have a problem with a class that exchanges data using TCP/IP socket. Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system. 1. 被 Q_DECLARE_METATYPEQ 标记的类型可以让Q MetaType 查询到类型，也可以让QVariant识别到。 struct MyStruct { QString name; }; Q_DECLARE_METATYPE(MyStruct) 若对象包含在自定义的命名空间中时，注册时要带上完整的命令空间. Since Qt 5. . I think it would be great if we could run requests in a QThread, but right now it's not possible because the r. Q_DECLARE_METATYPE. In that case, I think you need to register them. Workaround: use a class. Read and abide by the Qt Code of Conduct. the type name must be specified without the class, as in. no unexpected garbage. Unsure if my idea would work, I created a DataPoint class marked with Q_GADGET with three properties defined using Q_PROPERTY. Follow answered Jun 5, 2009 at 15:14. QVariantList , QString (if the list contains exactly one item) Casting between primitive type (int, float, bool etc. You may have to register before you can post: click the register link above to proceed. There's no such thing as a "const reference" because references are always const -- you can't reseat them. 0. This replaces the now-deprecated Q_ENUMS and will automatically register the metatype. 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. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. The Qt docs make it clear that to use a custom type with Queued Connections, I need to use both Q_DECLARE_METATYPE and qRegisterMetaType. You may have to register before you can post: click the register link above to proceed. If \c MyStruct is in a namespace, the Q_DECLARE_METATYPE () macro. 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++. 该类型必须有公有的 构造、析构、复制构造 函数. ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. This worked very well. Join Date Mar 2010 Posts 69 Thanks 8 Thanked 1 Time in 1 Post Qt products Platforms} Q_DECLARE_METATYPE(Topic) In main, I have included this: qRegisterMetaType<Topic>("Topic"); When propagating these elements from c++ to QML, everything is working. I also added qRegisterMetaType<DataPoint> () to the initialisation method of my main. To register VideoMeta you need to call qRegisterMetaType<VideoMeta>(). 8 and it all went well with a few function changes, except I got QMetaProperty::read: Unable to handle unregistered datatype errors all over. There's also no need for that typedef, it only makes the code less readable. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE() and qRegisterMetaType(). Your code should look like this: Q_ENUM (StateEnum) //note the missing 'S' here Q_PROPERTY (StateEnum state READ state NOTIFY stateChanged) Share. 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:. 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. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. @Q_DECLARE_METATYPE (std::unique_ptr<Thing>);@. Couple of points: 1) I would use QScriptEngine::newObject() instead of newQObject() for the namespace 2) I would not use a QObject subclass for the data entry if possible, only the prototype has to be. See the Custom Type Example for code that demonstrates this. See also state(). Data Type Conversion Between QML and C++. You are looking for the Q_ENUM () macro. There is no contradiction, because you can't register QObject descendants with Q_DECLARE_METATYPE. You should use Q_DECLARE_METATYPE macro for this. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). In fact, all Qt classes derived from QObject (direct or indirect) use this macro to declare their copy constructor and assignment operator to be private. As the docs state: Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. 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. You could also Q_DECLARE_METATYPE to register your custom type and then use qMetaTypeId() to get the metaType id. J. QMetaType::type () returns the same ID as qMetaTypeId (), but does a lookup at runtime based on the name of the type. Q_DECLARE_METATYPE (T) requires the type T to be default-constructable, copiable and destructable. You may have to register before you can post: click the register link above to proceed. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit initialization. . genC last edited by . 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: This now makes it possible for Message values to be stored in QVariant objects and retrieved later. You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. Passing across threads (queued connection) will copy the QVector in either case, but the const will remind you that you cannot alter the original QVector in.