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 (). I explicitly don't want to update it on every change to one of the quantities, so they don't. Now, that Q_DECLARE_METATYPE enables the type for Qt template classes and QVariant. Q_DECLARE_METATYPE(MyStruct) Q_DECLARE_METATYPE(MyList) QDBusArgument &operator<<(QDBusArgument &, const MyStruct&);. @Daddedebad As @Bonnie says qRegisterMetaType. 0. See full list on doc. Note: This function is thread-safe. That class receives a list of variants (wrapping various data) and converts those variants into a binary stream using QDataStream >. So using qRegisterMetaType () you will just trade Q_ENUM () for Q_DECLARE_METATYPE (). It is meant to be put in a header where the given type is declared. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). So you can call it from your constructor. the type name must be specified without the class, as in. Use Q_DECLARE_METATYPE (std::string) in one of your headers. Q_DECLARE_METATYPE vs qRegisterMetaType for non global namespace classes. Obviously then you would not do registerComparator (). The other overload around has almost the same form but for the. It seems that for a metatype that is a QList<MyClass::MyEnum> I must. . Q_DECLARE_METATYPE, as pointed out by @SingerOfTheFall, would register template based type into QVariant (so it can be retrieved using qvariant_cast<T>()). Learn more about Teams Declaring a meta type. Then after some time, we can begin answering them. There's also no need for that typedef, it only makes the code less readable. e. Actually, they are declared, but in a private section with the macro Q_DISABLE_COPY(). Q_DECLARE_METATYPE (T) requires the type T to be default-constructable, copiable and destructable. That always worked in Qt4, but in Qt5 I get the following error: @error: specializing member ‘::qRegisterMetaType<Subclass>’ requires ‘template<>’ syntax@. } But you'll most likely need to abstract the Q_DECL_EXPORT part so it is a Q_DECL_IMPORT in right circumstances, as described in Creating Shared Libraries. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. But I really would like to know the correct way to solve this problem; one where it is not possible to modify. Improve this answer. Q_DECLARE_META_TYPE (Fruit) and qRegisterMetaType were redundant: #define PluginInterface_iid "pluginInterface" Q_DECLARE_INTERFACE (PluginInterface, PluginInterface_iid) //Actual plugin implementing PluginInterface class. You may have to register before you can post: click the register link above to proceed. ) summary refs log tree commit diff stats Foo and Foo* are different types and need to be registered separately. Actually, they are declared, but in a private section with the macro Q_DISABLE_COPY(). Using Q_ENUM () allows you to retrieve at run-time the name of an enum value: Q_GADGET makes a class member, staticMetaObject, available. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. Consider the specific case of qRegisterMetaType. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. How: I linked qRegisterMetaType. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. void QLocalSocket:: abort ()The signal "orientationChanged" includes an enum of type "Orientation" to indicate if the card has been turned up or down. 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(). To start viewing messages, select the forum that you want to visit from the selection below. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit. QML Qvariant from custom class. The class in Qt responsible for custom types is QMetaType. The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. Call qRegisterMetaType() to register the data type before you establish the connection. 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(). 3. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. So I am doing this: Qt Code: Switch view. Good workaround: you may register your type with Q_DECLARE_METATYPE ( IBase * ) macro and wrap your. multithreaded software and I am getting the warning says: (Make sure 'QVector<int>' is registered using qRegisterMetaType (). In the header, after the class declaration, outside the namespace, I've included. 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. 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(). I am also using some in queued signal and slot connections. 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. However, as you need the type to be. akshatrai91 7 Jan 2021, 06:21. Type is declared with Q_DECLARE_METATYPE and registered with qRegisterMetaType. If the pointer stored in the QVariant can be qobject_cast to T, then that result is returned. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. To register VideoMeta you need to call qRegisterMetaType<VideoMeta>(). When using signals and slots with multiple threads, see Signals and Slots Across Threads. ", which suggests it is only for classes and structs. qRegisterMetaType vs. The class is used to send arguments over D-Bus to remote applications and to receive them back. QObject::connect: Cannot queue arguments of type 'MyStruct'. Since Qt 5. The Rep lica C ompiler (repc) generates QObject header files based on an API definition file. 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. 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. You can also use QMetaEnum::fromType() to get the QMetaEnum. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. 1）引入头文件：#include<QMetaType>. Add qRegisterMetaType and qDBusRegisterMetaType calls to enable the framework to work with the custom type. 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:. 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. You pass around pointers instead. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. 9k 9 34 52. Your Matrix type is not copiable, thus you can't use Q_DECLARE_METATYPE on it. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. After googling this, I found this correspondence, which was only available through a third party archival site as google. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. In that case, I think you need to register them. There is no way to add support for more of these value types like std::string (*). struct Matrix { double data [4] [4]; }; Ideally you should be using eigen3. Well, I certainly overplayed this particular point, but the statement I believe is valid in principle. I'm confused by this error, as the documentation states (emphasis mine): Returns the meta type id of type T at compile time. Read and abide by the Qt Code of Conduct. Some structure need to be registered to be queued in asynchronous signals using qRegisterMetaType<T>(name), such as signal which passes QVector<int>. 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. 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. I have an application that requires use of both Qt 3D and the QCustomPlot library. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. 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. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. The class is used as a helper to marshall types in QVariant and in queued. Also, to use type T with the QObject::property () API, qRegisterMetaType () must be. There's no need to call qRegisterMetaType that many times, once is enough. You should use Q_DECLARE_METATYPE macro for this. Share Improve this answer Follow answered Jul 23, 2014 at 15:37. You may have to register before you can post: click the register link above to proceed. Q_DECLARE_METATYPE. Registered enumerations are automatically registered also to the Qt meta type system, making them known to QMetaType without the need to use. That. Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template. QList<AnotherObject*> has of course been registered with Q_DECLARE_METATYPE and 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. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE() and qRegisterMetaType(). h" class Context : public QObject { Q_OBJECT Q_PROPERTY (MyGadget* gadget READ gadget CONSTANT) public: explicit Context () : QObject {nullptr} { } MyGadget* gadget () { return &_gadget; } private. Qt. @Mark81 Actually you'll probably need only Q_DECLARE_METATYPE as this is done at compile time - exposing the type to the metatype system (I know it is an enum but it's needed for the QVariant and the like). Q_DECLARE_METATYPE ( blabla* ) Also qRegisterMetaType<T> () is only required for sending your object through queued signal/slot connections. [override virtual] bool QLocalSocket:: waitForBytesWritten (int msecs = 30000) Reimplements:. QMetaType. このケースでも、Q_DECLARE_METATYPE(QSharedPointer<MyObject>)の宣言と、qRegisterMetatype<QSharedPointer<MyObject>>()の呼び出しが必要になる。 上のサンプルでは、同じsignalに対して2回connectを実行している。 The correct syntax is Q_DECLARE_METATYPE (std::string) without the ;. The following should work: Note that you also have to call qRegisterMetaType<MyMpiMessage> (); before you use the function the first time. Normally, you would only register the pointer form if your class cannot be copied, as in the case of QObject and derivatives, but. I think you need to add an explicit export/import directive to the QT_NAMESPACE macro. 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. So using a QString as the type of a Q_PROPERTY only works because it has special built-in support in the QML engine. qRegisterMetaType vs. It associates a type name to a type so that it can be created and destructed dynamically at run-time. However Q_DECLARE_METATYPE () is a bit more complicated. 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. But this is all useless if you are not using templates. @Q_DECLARE_METATYPE (std::unique_ptr<Thing>);@. 1. From the docs: int qRegisterMetaType ( const char * typeName ) Registers the type name typeName to the type T. Original Question. pro file, several errors appear referencing the QMouseEvent and QWheelEvent classes. 0. QMetaType::type () returns the same ID as qMetaTypeId (), but does a lookup at runtime based on the name of the type. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. qRegisterMetaType<FileNodePointer> ("FileNodePointer"); should be called once (in main, constructor etc. To start viewing messages, select the forum that you want to visit from the selection below. 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. このケースでも、Q_DECLARE_METATYPE(QSharedPointer<MyObject>)の宣言と、qRegisterMetatype<QSharedPointer<MyObject>>()の呼び出しが必要になる。 上のサンプルでは、同じsignalに対して2回connectを実行している。The same plugin may be loaded multiple times during the application's lifetime. Returns the used WebSocket protocol. 5 is compiled with GCC 4. ) is supported. I tested your code on Qt 5. The class in Qt responsible for custom types is QMetaType . Any class or struct that has a public default constructor, a public copy constructor, and a. So I am doing this: Qt Code: Switch view. QMetaType registerNormalizedTypedef normalizedTypeName, type: metaType ); return. I tried to write one, but I failed. 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. Situation. 2、在类型定义完成后，加入声明：Q_DECLARE_METATYPE (MyDataType); 3、在main ()函数中. It's a bit convoluted to follow, and definitely depends on which Qt modules have been included (the meta type system is designed to be expandable this way -- eg. +50. . Note: it's also safe to call qRegisterMetaType () multiple times. Also Q_DECLARE_METATYPE does not register a type, but declares it. All I want to do is be able to convert this to a byte array in order to send on a socket, and get the object back (deserialize) on the other end. Q_DECLARE_METATYPE (std::string) Quoting Qt Doc. After googling this, I found this correspondence, which was only available through a third party archival site as google. Qt Base (Core, Gui, Widgets, Network,. Even though we do not intend. qRegisterMetaType vs. What worries me is that. 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. 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. You may have to register before you can post: click the register link above to proceed. Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system. Although I'm. See the Custom Type Example for code that demonstrates this. For pointer types, it also requires that the pointed to type is fully defined. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. But I can't see a method to insert myClass into. Detailed Description. 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. Constantin. Please note that I do not use Q_DECLARE_METATYPE on purpose because I don't actually need its features (QVariant expansion) right now. It is only useful to the code that follows it, in the same file. In. Detailed Description. To start viewing messages, select the forum that you want to visit from the selection below. Yes, templated types can be used in Qt signal/slots. It seems that for a metatype that is a QList<MyClass::MyEnum> I must. You may have to register before you can post: click the register link above to proceed. cruz Hello, To be completely candid, I haven't used GDB remotely and I'm certainly not so intimate with it for the log to speak to me much. The QMetaType class manages named types in the meta-object system. Current the only supported type info is QML_HAS_ATTACHED_PROPERTIES. Detailed Description The QMetaType class manages named types in the meta-object system. However, I cannot figure out how to verify that the included parameter is FACE_UP or FACE_DOWN. 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. container. ) 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. 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. Call qRegisterMetaType() to register the data type before you establish the connection. Make a typedef for QSharedPointer<UserDataType>, and use both Q_DECLARE_METATYPE as well as qRegisterMetaType () to register it for use. qRegisterMetaType() docs say: Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. I've registered my class with: @Q_DECLARE_METATYPE(MyClass);@ and. (Make sure 'QVector<int>' is. 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. qRegisterMetaType is also called in the class constructor. The QMetaType class manages named types in the meta-object system. However, it does appear (at least to me) that you're trying to debug a release build of the application. You had to use QMetaType::registerComparators () and the other static register functions in QMetaType to actually make use of that functionality, though. It is a static method, it does not (cannot) change x2. 1. Any class or struct that has a public default constructor, a public copy constructor, and a. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). Avoid having to qRegisterMetaType (pointer. From the docs: int qRegisterMetaType ( const char * typeName ) Registers the type name typeName to the type T. What you made is a const pointer to a non-const T; but top-level consts in function signatures are not part of the function. 0. qRegisterMetaType vs. Declare new types with Q_DECLARE_METATYPE () to make them available to. ), or any other callable, cannot declare a type for use outside of the call site. 3 Answers Sorted by: 13 "qRegisterMetaType" is a function. Also, Q_DECLARE_METATYPE(MyNamespace::MyType) should be in the header declaring MyType so that you don't have to repeat it all over again and again. your custom type definition. 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. Research The QMetaType class manages named types in the meta-object system. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). 24th July 2010, 09:54 #6. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. QMetaType registerNormalizedTypedef normalizedTypeName, type: metaType ); return. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Q_OBJECT derived class, inheritance. Using Qt 3D with QCustomPlot. Connect and share knowledge within a single location that is structured and easy to search. // This primary template calls the -Implementation, like all other specialisations should. cpp. qRegisterMetaType<cv::Mat>(); Modified: qRegisterMetaType< Mat >("Mat");The code generated by repc creates a Q_GADGET class for each POD, with corresponding Q_PROPERTY members for each type defined for the POD. Re: How to use Q_DECLARE_METATYPE. Workaround: use a class. By the way, Qt 4. This function returns the Qt meta type id for the type (the same value that is returned from qRegisterMetaType()). The default access for a class is private, so that Container* data();. Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. Q_DECLARE_METATYPE (std::string) Quoting Qt Doc. This fixed the issue. This function was introduced in Qt 6. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. Last updated at 2016-07-08 Posted at 2015-11-16. @user6556709 I've added both of those, and it does compile now, but the string is just being default initialized to "" when I call value<T>() and there's a red line under Q_DECLARE_METATYPE that says no instance of overloaded function "qRegisterMetaType" matches the argument list, argument types are: (const char [12],. [since 6. E. 1 Answer. Also Q_DECLARE_METATYPE does not register a type, but declares it. and Q_DECLARE_METATYPE uses qRegisterMetaType() internally. qRegisterMetaType you'll need if creating objects by class name dynamically, and it seems for queued connections,. Enumerations that are declared with Q_ENUM have their QMetaEnum registered in the enclosing QMetaObject. I just found multiple examples showing the usage of Q_ENUM and Q_ENUMS and looking into the definition of Q_ENUM showed me that it includes Q_ENUMS and other definitions. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. 【2】使用方法（声明 和 注册自定义数据类型）. This article will. So in your case you need to declare. Then the TYPE ID is saved in local static vairable metatype_id. state() Creating Custom Qt Types. When these files are processed by repc, repc generates both. Quote: bool QVariant::operator==(const QVariant & v) const. Learn more about Teams I can't figure out a way to automatically declare a meta type, i. QList of Custom Objects. e. S 1 Reply Last reply Reply Quote 0. 4 and it seems to work. nyaruko. 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. We all have started by asking questions. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit initialization. Labels: meta system, Meta type, qt. 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 (). I thought there was a bug with QMetaType or Q_DECLARE_METATYPE. Q_DECLARE_METATYPE () doesn't actually register the type; you must still use qRegisterMetaType () for that, particularly if you intend to use the type in signal and slot connections. I have a problem with a class that exchanges data using TCP/IP socket. Q_DECLARE_METATYPE QMetaType::type. Specifically, the function have to be called before using the struct. The reasoning is found in the discussion on Identity vs Value on the Qt Object Model page. Similarly you can create a mutable view of type QAssociativeIterable on any container registered with Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE(). void QAbstractSocket:: abort ()2 Answers. Jun 13, 2021 at 19:37. Now you have a valid QObject. genC last edited by . Re: How to use Q_DECLARE_METATYPE. call qRegisterMetaType with the name specified, else reading properties. 11. This is by design. Make sure you call it from within a method. I want to use drag-and-drop to drag a QTreeWidgetItem that has std::shared_ptr user data. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. h. G. F. G. 步骤： (以自定义MyDataType类型为例）. Qt is throwing an exception because it doesn't know how to store the shared_ptr onto a QDataStream. }; Q_DECLARE_METATYPE (MyCustomType); Then in my application, I have a signal "void sendMsg (MyCustomType)" and I qRegisterMetaType (). You can make them known ( Q_DECLARE_METATYPE ), however you can't register them as QML type. You may have to register before you can post: click the register link above to proceed. By the way, Qt 4. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). 0. This worked very well. e. Adding a Q_DECLARE_METATYPE () makes the type known to all template based functions, including QVariant. Our first stop for registrations always is the macro Q_DECLARE_METATYPE. If you need the functionality provided by Q_DECLARE_METATYPE, you will have to use it. Any class or struct that has a public default constructor, a public copy. 8. // - in a header: // - define a specialization of this template calling an out-of. 4 which does not support all C++11 features. 6. To start viewing messages, select the forum that you want to visit from the selection below. qRegisterMetaType vs. Using the macro directly turned out to be impossible. See also isRegistered () and Q_DECLARE_METATYPE (). Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. no unexpected garbage. I my real world application Context holds a large number of physical quantities (masses, forces, velocities,. You don't pass around copies of QObject derived types because it is not copyable. 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. 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. @kshegunov said: you're doing it wrong. 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. This function is useful to register typedefs so they can be used by QMetaProperty, or in QueuedConnections. And once all of them are updated I'd like the Context object to inform QML to update the view. QVariant’s operator== now uses QMetaType::equals for the comparison. To use the type T in queued signal and slot connections,. Read and abide by the Qt Code of Conduct. 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. QtCore. The logical equivalent of a const T &r (reference to const T) is a const T * const p (const pointer to const T). Sorted by: 3. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. Q_DECLARE_METATYPE accepts objects with public constructor, copy constructor and destructor. 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. So my first idea:. But because QUuid stores its content as a QByteArray which is already supported by QVariant, you. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. The file (called a "rep" file) uses a specific (text) syntax to describe the API. See QMetaType docs for more information. Returns the used WebSocket protocol. Franzk 26 May 2011, 06:59. –To copy to clipboard, switch view to plain text mode. 2 Answers. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Share. 4. Here you can see that the macro expands to nothing. Execute qRegisterMetaType<QItemSelection> (); before it is used as such, e. The. h) of the derived class. Returns the metatype of the parameter at the given index. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. A separate point for your own benefit. Returns true if convert can convert from fromType to toType. So, you don't want 'Widget' to be a metatype, you want 'Widget*' to be a metatype so that you can put a Widget* in a QVariant for example. 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. Using the qRegisterMetaType () function The Q_DECLARE_METATYPE () macro is the preferred way to declare a variable in Qt. It does not say anything about registering the type. I read a bit and it seems that Q_DECLARE_SMART_POINTER_METATYPE is supposed to allow this to work. . To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. The macro will register your variable with the Qt Meta-Object System, which will allow you to. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Re: Q_DECLARE_METATYPE problem. call qRegisterMetaType with the name specified, else reading properties. 0. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. This is not the case, since the following succeeded: @QMetaType::type("MyClass"); // success@. // - in a header: // - define a specialization of this template calling an out-of. Avoid having to qRegisterMetaType (pointer vs reference), concern about const. QVariantList MyClass::getFooCollection (void) const { QVariantList list; for (const auto& l: fooCollection_) { list. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. 如果要使自定义类型或其他非QMetaType内置类型在QVaiant中使用，必须使用该宏。. 1. Follow. See also. Q_DECLARE_METATYPE only registers a type in 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. 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. Your code should look like this: Q_ENUM (StateEnum) //note the missing 'S' here Q_PROPERTY (StateEnum state READ state NOTIFY stateChanged) Share. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. due to requirements at my job, I had to revert by build from Qt5.