I meet a qt metatype issue. 0. The following should work: Note that you also have to call qRegisterMetaType<MyMpiMessage> (); before you use the function the first time. h) of the derived class. Re: Q_DECLARE_METATYPE problem. I believe this is related to the fact that. Per Qt documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. Note: it's also safe to call qRegisterMetaType () multiple times. QVariantList MyClass::getFooCollection (void) const { QVariantList list; for (const auto& l: fooCollection_) { list. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). I read a bit and it seems that Q_DECLARE_SMART_POINTER_METATYPE is supposed to allow this to work. See QMetaType docs for more information. The issue here is that Q_OBJECT forbids the copy and assignment constructors. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. Also, to use type T with the QObject::property () API, qRegisterMetaType () must be. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. on top of main. There's no need to call qRegisterMetaType that many times, once is enough. x however, the code generated by moc will call qRegisterMetaType for you if moc can determine that the type may be registered as a meta-type. 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. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. It associates a type name to a type so that it can be created and destructed dynamically at run-time. Thank you Volker, I had a couple of problems I forgot about the Q_DECLARE_METATYPE(myType); and I don't' think I was never consistent with the global scope specifier. See full list on doc. Q_DECLARE_META_TYPE (Fruit) and qRegisterMetaType were redundant: #define PluginInterface_iid "pluginInterface" Q_DECLARE_INTERFACE (PluginInterface, PluginInterface_iid) //Actual plugin implementing PluginInterface class. See also state() and Creating Custom Qt Types. 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(). no I didn't, do I need to put in the file generated by repc or I can put it anywhere ? – Houss_gc. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). Execute qRegisterMetaType<QItemSelection> (); before it is used as such, e. 1. As a workaround, I'm using QVariantMap instead of std::map. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. 1. statement to the header file containing. This allows us to use the Enum as a custom-type of a QVariant, to pass it between QML and Qt, to use it in synchronous signal-slot connections, and to print the symbolic enums (instead of a magic number) with qDebug(). Did you also check the Q_DECLARE_METATYPE macro ?我发现qt5怎么不需要通过q_declare_metatype声明自定义的结构体，也能编译通过，使用正常啊？！！ 估计是多线程传递时，才需要使用q_declare_metatype。另外，看样子q_declare_metatype和qvariant要搭配使用。1 Answer. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE() and qRegisterMetaType(). The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. 1. Teams. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. 1）引入头文件：#include<QMetaType>. @Q_DECLARE_METATYPE (std::unique_ptr<Thing>);@. Any class or struct that has a public default constructor, a public copy. See also state() and Creating Custom Qt Types. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. void QLocalSocket:: abort ()The signal "orientationChanged" includes an enum of type "Orientation" to indicate if the card has been turned up or down. qRegisterMetaType<FileNodePointer> ("FileNodePointer"); should be called once (in main, constructor etc. Without this reference, it compiles just fine. Connect and share knowledge within a single location that is structured and easy to search. 5 is compiled with GCC 4. @Daddedebad As @Bonnie says qRegisterMetaType. Believing an Question from 2010 and the Qt Documentation, the operator==() doesn't work with custom types. I can access the property. Actually, they are declared, but in a private section with the macro Q_DISABLE_COPY(). 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. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Using Q_ENUM () allows you to retrieve at run-time the name of an enum value: Q_GADGET makes a class member, staticMetaObject, available. It associates a type name to a type so that it can be created and destructed dynamically at run-time. The reasoning is found in the. But I really would like to know the correct way to solve this problem; one where it is not possible to modify the template classes. Question: Is there a way to check at compile-time if qRegisterMetaType<T> () was called for a custom type T? The custom type T needs to be registered in Qt meta-type system in order to be used in e. Last updated at 2016-07-08 Posted at 2015-11-16. 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. since it is a runtime registration. It does not say anything about registering the type. To start viewing messages, select the forum that you want to visit from the selection below. ) is supported. Then the TYPE ID is saved in local static vairable metatype_id. When the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. F. qRegisterMetaType usage. The struct is declared in my worker class, which is inside a namespace. 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. QList<AnotherObject*> has of course been registered with Q_DECLARE_METATYPE and qRegisterMetaType(). c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. So in your case you need to declare. your custom type definition. I am also using some in queued signal and slot connections. Make your own typedef and do the Q_DECLARE_METATYPE and qRegisterMetatype. 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. e. Firstly, you shouldn't need to use Q_DECLARE_METATYPE (or qRegisterMetaType) with the enum at all, this is handled by the moc. 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. Well, I certainly overplayed this particular point, but the statement I believe is valid in principle. ompiler (repc) generates header files based on an API definition file. Now, that Q_DECLARE_METATYPE enables the type for Qt template classes and QVariant. As a result, if the library connects a D-Bus signal to a slot with a signature "void mySlot (MyType)", it is. Has anyone else encountered this?See also qRegisterMetaType(). Yes, templated types can be used in Qt signal/slots. So you can call it from your constructor. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. Avoid having to qRegisterMetaType (pointer. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. qRegisterMetaType<Subclass> ("Subclass") also doesn't work. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). (Make sure 'MyStruct' is registered using qRegisterMetaType (). Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. QLocalSocket. 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. To start viewing messages, select the forum that you want to visit from the selection below. I have created an qt bugticket hoping the documentation will be extended. // This primary template calls the -Implementation, like all other specialisations should. It associates a type name to a type so that it can be created and destructed dynamically at run-time. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. See also state() and Creating Custom Qt Types. The. Follow answered Jun 5, 2009 at 15:14. The "traditional" way of doing this is to convert each element to a QVariant, and pass collection as a QVariantList. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. For this, a function call (evaluated during runtime) needs to be made, and qRegisterMetatype is the tool for this: qRegisterMetaType<Area>("Area");@julio. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. Q_DECLARE_METATYPE(TYPEDEF) Q_DECLARE_METATYPE(TYPEDEF) mainwindow. 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. The code compiles and runs ok. g. To start viewing messages, select the forum that you want to visit from the selection below. qRegisterMetaType vs. Sorted by: 2. g. 6. Note that you are technically lying to the meta type system. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. You may have to register before you can post: click the register link above to proceed. Good workaround: you may register your type with Q_DECLARE_METATYPE ( IBase * ) macro and wrap your. This won't work because you can't use qMetaTypeId<> () before Q_DECLARE_METATYPE<>. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Qt Remote Objects Compiler. Declare new types with Q_DECLARE_METATYPE () to make them available. 4] QString QWebSocket:: subprotocol const. This replaces the now-deprecated Q_ENUMS and will automatically register the metatype. qRegisterMetaType 必须使用该函数的两种情况. : Q_DECLARE_METATYPE(MyClass*); That's how Qt handles it with QObject and QWidget. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. 1 Answer. Note: This function is thread-safe. ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. So using a QString as the type of a Q_PROPERTY only works because it has special built-in support in the QML engine. But I can't see a method to insert myClass into. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. queued connections. 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. Assuming base and derived are Q_GADGETs you want to get a static member. Q_DECLARE_METATYPE only registers a type in meta type system. Similarly you can create a mutable view of type QAssociativeIterable on any container registered with Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE(). Q_DECLARE_METATYPE(MyObject*) somewhere in your code. QList<T> isn't really a pre-defined variant type (except QList<QVariant>) so it technically resolves to a QMetaType::UserType. 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. The Q_DECLARE_METATYPE() macro also makes it possible for these values to be used as arguments to signals, but only in direct signal-slot connections. I tried with and without the qRegisterMetaType<Schedule::TimePairMap>(), with and without Q_DECLARE_METATYPE(Schedule::TimePairMap). QMetaType::type () is a bit slower, but compilation succeeds if a type is not registered. First of all you need to declare your custom object for Qt metatype system. h" class Context : public QObject { Q_OBJECT Q_PROPERTY (MyGadget* gadget READ gadget CONSTANT) public: explicit Context () : QObject {nullptr} { } MyGadget* gadget () { return &_gadget; } private. This function was introduced in Qt 6. The QMetaType class manages named types in the meta-object system. I only care about runtime instantiation. To make the custom type. qRegisterMetaType vs. As you already have a typedef for your type, you can simply use Q_DECLARE_METATYPE as in the following example: #include <QtCore> template <typename T> struct Proxy { T data; }; typedef Proxy<QImage> TrayType; Q_DECLARE_METATYPE (TrayType) class Donor : public. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. Also Q_DECLARE_METATYPE does not register a type, but declares it. Connect and share knowledge within a single location that is structured and easy to search. 2. So I tried declaring the following at end of my worker thread class Q_DECLARE_METATYPE(cv::Mat);. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. the type name must be specified without the class, as in. The reason to need this is usually that Q_PROPERTY is used with a metatype which is not built-in (types such as int and QString are built-in and don’t. If the type was not declared with Q_DECLARE_METATYPE (), compilation will fail. Because Foo is not derived from QObject and QVariant only supports polymorphism for QObject -derived types. 基本理解. See the Qt D-Bus Type System page for more information on the type system. Using the Q_DECLARE_METATYPE () macro 2. It looks like one can register a type more than once, specifying different typenames, i. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. 3. Using the qRegisterMetaType () function The Q_DECLARE_METATYPE () macro is the preferred way to declare a variable in Qt. Q_DECLARE_METATYPE accepts objects with public constructor, copy constructor and destructor. Email This BlogThis! Share to Twitter Share to Facebook Share to Pinterest. . Declare new types with Q_DECLARE_METATYPE () to make them available to. 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. Note that you are technically lying to the meta type system. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. I want to use my objects as QVariants and for queued connections. Q_DECLARE_METATYPE. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. G. QML Qvariant from custom class. . Qt is throwing an exception because it doesn't know how to store the shared_ptr onto a QDataStream. call qRegisterMetaType with the name specified, else reading properties. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. As G. type() typeName() PySide6. Here you can see that the macro expands to nothing. The Custom Type and Queued Custom Type examples show how to implement a custom type with the features outlined in this document. If the type was not declared with Q_DECLARE_METATYPE (), compilation will fail. There's also no need for that typedef, it only makes the code less readable. in your main function or in the constructor of AudioGuiApplication. In that case, I think you need to register them. 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. QLocalSocket::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. The. Any class or struct that has a public default constructor, a public copy. qRegisterMetaType vs. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. Share. the type name must be specified without the class, as in. Returns the internal ID used by QMetaType. Any class or struct that has a public default constructor, a public copy constructor, and a. 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. Sorted by: 1. The ones I am registering for are mostly structs for storing data and just a few simple classes. You may have to register before you can post: click the register link above to proceed. fromValue <QList<double> > ( x1); To copy to clipboard, switch view to plain text mode. The documenation of this macro gives. The following should work: Note that you also have to call qRegisterMetaType<MyMpiMessage> (); before you use the function the first time. ) 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. That's created by this macro. qRegisterMetaType you'll need if creating objects by class name dynamically, and it seems for queued connections,. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. 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. Call qRegisterMetaType() to register the data type before you establish the connection. If you need the functionality provided by Q_DECLARE_METATYPE, you will have to use it. You could also Q_DECLARE_METATYPE to register your custom type and then use qMetaTypeId() to get the metaType id. The Q_DECLARE_METATYPE () macro also makes it possible for these values to be used as arguments to signals, but only in direct signal-slot connections. In my module tests, I turn the card up and down, and can verify that the number of signals are increasing using QSignalSpy. First of all you need to declare your custom object for Qt metatype system. There's no compile time error, but when I run. 1 Answer. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. Call qRegisterMetaType () to make types available to non-template based functions, such as the queued signal and slot connections. To use the type T in queued signal and slot connections,. This also makes the type available for queued. 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. 1. 2 Answers. 1 Answer. Step 1 (mark for MOC), build some QObjects That pattern uses Q_PROPERTY and Q_OBJECT and the MoC tool. 12. Although I'm. h instead ofQVariant x2; x2. 0. Duplicate Question(s):Q_DECLARATIVE_METATYPE in and out; Using EventExport vs. Q_DECLARE_METATYPE(MyClass); qRegisterMetaType<MyClass>(); I can use the type in queued connection with signals like this one: void MySignal(MyType o); Now I also would like to use the type with signals like this: void MyVectorSignal(QVector<MyType> v);Qt 5. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. QList of Custom Objects. We all have started by asking questions. Now you have a valid QObject. Once they're known you can use them, but you can't create them on the QML side. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. 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. You can also use QMetaEnum::fromType() to get the QMetaEnum. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. This requires the exchanged data to be of a type that is recognizable by the engine. Does your code ever call qRegisterMetatype() or use Q_DECLARE_METATYPE()? 10th November 2014, 06:23 #3. If I get AnotherQGadgetClass via getter and change it's properties, the setters are called and. See also state() and Creating Custom Qt Types. I read on documentation that Q_DECLARE_METATYPE makes available type to QVariant, for example (I got it from documentation): @ struct MyStruct { int i;. 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. It associates a type name to a type so that it can be created and destructed dynamically at run-time. Any class or struct that has a public default constructor, a public copy. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. 1. D-Bus offers an extensible type system, based on a few primitive types and associations of them. The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. I pass the MyClass pointer to the streaming operator and only stream things like QString, QPointF, etc. Share Follow edited Apr 29, 2013 at 7:21 We will still need to register it with the meta-object system at run-time by calling the qRegisterMetaType () template function before we make any signal-slot connections that use this type. I have a few instances of QVector<MyClass> which I want them to be exposed to QScriptEngine. 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. no unexpected garbage. But there would be no trouble using the QMetaType class or using qRegisterMetaType before creating an instance of QCoreApplication or QApplication. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Returns the metatype of the parameter at the given index. 2. The class in Qt responsible for custom types is QMetaType. // But the split allows to. qRegisterMetaType 必须使用该函数的两种情况. container. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. 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. Since Qt 5. 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. Improve this answer. 2. But because QUuid stores its content as a QByteArray which is already supported by QVariant, you. QVariantList , QString (if the list contains exactly one item) Casting between primitive type (int, float, bool etc. 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. This worked very well. 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 (std::string) Quoting Qt Doc. The application using it does this: typedef QMap<int, int> MyOtherType; Q_DECLARE_METATYPE (MyOtherType) qRegisterMetaType<MyOtherType> (); Now the D-Bus marshaller and demarshaller get registered with the wrong type id. That class receives a list of variants (wrapping various data) and converts those variants into a binary stream using QDataStream >. Step 1 (mark for MOC), build some QObjects That pattern uses Q_PROPERTY and Q_OBJECT and the MoC tool. The logical equivalent of a const T &r (reference to const T) is a const T * const p (const pointer to const T). QVariant’s operator== now uses QMetaType::equals for the comparison. Q_DECLARE_METATYPE与qRegisterMetaType学习. How: I linked qRegisterMetaType. 3 to Qt4. To register VideoMeta you need to call qRegisterMetaType<VideoMeta>(). The other overload around has almost the same form but for the fact that it. So, whatever Q_DECLARE_METATYPE is doing cannot be done by writing a function call. 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. qRegisterMetaType<FileNodePointer> ("FileNodePointer"); should be called once (in main, constructor etc. Workaround: use a class. To call qRegisterMetaType (), you still need to use Q_DECLARE_METATYPE (). Q&A for work. 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. I also don't want to use qRegisterMetaType, since it is run-time bound. Q_DECLARE_METATYPE QMetaType::type. Qt Base (Core, Gui, Widgets, Network,. Now I want to read this property with Qt's meta object system. That always worked in Qt4, but in Qt5 I get the following error: @error: specializing member ‘::qRegisterMetaType<Subclass>’ requires ‘template<>’ syntax@. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. Alt. Quote: bool QVariant::operator==(const QVariant & v) const. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). 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. I think you need to add an explicit export/import directive to the QT_NAMESPACE macro. 1 Answer. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. The docs only talk about class or struct with public default constructor, copy constructor and. There's no such thing as a "const reference" because references are always const -- you can't reseat them. 0. QVariant v = QVariant::fromValue<cMyClass>(MyObject); However, as soon as I use Q_DECLARE_METATYPE, I get errors about using a deleted function. 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. This function returns the Qt meta type id for the type (the same value that is returned from qRegisterMetaType()). 14 vs 5. Now you have a valid QObject. 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. 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。. Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template. Qt Base (Core, Gui, Widgets, Network,. typedef QVector<QSharedPointer<Tester> > TestPointerVector;. qRegisterMetaType is also called in the class constructor. I'd understood if i want to pass my custom type like struct or so, but it is essential type. When these files are processed by repc, repc generates both Source and Replica header files. The third without Q_DECLARE_METATYPE. QObject can't be copied and all its descendants can't be copied also. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. For those who follow. Any class or struct that has a public default constructor, a public copy. Franzk 26 May 2011, 06:59. See also. In some cases in Qt 4, it is also necessary to use the qRegisterMetaType method. Ah, sorry, I didn't noticed that part. Sorted by: 3. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. I guess it's the qRegisterMetaType () call itself that's missing. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. call qRegisterMetaType with the name specified, else reading properties. You had to use QMetaType::registerComparators () and the other static register functions in QMetaType to actually make use of that functionality, though. QMetaType Synopsis Functions def __eq__ (b). I am also using some in queued signal and slot connections. 11. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. canConvert<x> (); } and. enum Qt:: ContextMenuPolicyQObject has neither a copy constructor nor an assignment operator. [override virtual] bool QLocalSocket:: waitForBytesWritten (int msecs = 30000) Reimplements:. Learn more about Teams Declaring a meta type. A. @kshegunov said: you're doing it wrong. nyaruko. e. Here you can see that the macro expands to nothing. The QMetaType class manages named types in the meta-object system. . Enum has been moved from outside of the class to inside of it. h in the translation unit where you have that line. Yes I tried with qRegisterMetaType, it. The Q_DECLARE_METATYPE () macro also makes it possible for these values to be used as arguments to signals, but only in direct signal-slot connections. 5 is compiled with GCC 4. 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. genC last edited by . It was also no big issue to call qRegisterMetaType () automatically. 4] QString QWebSocket:: subprotocol const. I want to use drag-and-drop to drag a QTreeWidgetItem that has std::shared_ptr user data. Returns the used WebSocket protocol. qRegisterMetaType vs. It is still giving the error"QObject::connect: Cannot queue arguments of type 'quint32&' (Make sure 'quint32&' is registered using.