@Wieland Thanks. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. 0. Q_DECLARE_METATYPE ( blabla* ) Also qRegisterMetaType<T> () is only required for sending your object through queued signal/slot connections. See also state() and Creating Custom Qt Types. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. 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. 4] QString QWebSocket:: subprotocol const. 5 is compiled with GCC 4. In the header, after the class declaration, outside the namespace, I've included. void QLocalSocket:: abort ()The signal "orientationChanged" includes an enum of type "Orientation" to indicate if the card has been turned up or down. Is your Q_DECLARE_METATYPE in a header file or an implementation file? Incidentally, there is a mistake in TreeItem. Reply Quote. When the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. (Make sure 'QVector<int>' is. namespace CCS { Q_DECL_EXPORT Q_NAMESPACE. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. Re: Qt warning of type conversion already registered Originally. Research The QMetaType class manages named types in 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. See also state() and Creating Custom Qt Types. This replaces the now-deprecated Q_ENUMS and will automatically register the metatype. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. I explicitly don't want to update it on every change to one of the quantities, so they don't. However, when attempting to compile QCustomPlot in a project using "QT += 3dinput" in its . The QMetaType class manages named types in the meta-object system. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Do do you register the meta type with the call qRegisterMetaType("your custom meta type")? 1 Reply Last reply Reply Quote 0. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. Greetings. Basically, I created a library containing a type: struct MyCustomType {. QML Qvariant from custom class. Any class or struct that has a public default constructor, a public copy constructor, and a. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. Q_DECLARE_METATYPE(Pkg) and this does not give compile errors, but in my main. qRegisterMetaType () is called to register the TYPE and generate a TYPE ID. This is by design. int videoSourceMetaTypeId = qRegisterMetaType< VideoSource > ();Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. To start viewing messages, select the forum that you want to visit from the selection below. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. 4 which does not support all C++11 features. the type name must be specified without the class, as in. canConvert<x> (); } and. no I didn't, do I need to put in the file generated by repc or I can put it anywhere ? – Houss_gc. Use Q_DECLARE_METATYPE (std::string) in one of your headers. 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. The. But with the shared_ptr object, not a pointer to the shared pointer! You will have to register std::shared_ptr<yourclass> with the Qt meta object system before this can work, i. qRegisterMetaType vs. The third without Q_DECLARE_METATYPE. 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. See also state () and Creating Custom Qt Types . Read and abide by the Qt Code of Conduct. . Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. The file (called a "rep" file) uses a specific (text) syntax to describe the API. Also Q_DECLARE_METATYPE does not register a type, but declares it. Q_DECLARE_METATYPE. 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. no unexpected garbage. wysota. Declare new types with Q_DECLARE_METATYPE () to make them available to. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Sorted by: 2. What worries me is that. Q_DECLARE_METATYPE(MyClass*); That's how Qt handles it with QObject and QWidget. Sorted by: 3. When these files are processed by repc, repc generates both. Without this reference, it compiles just fine. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. To use the type T in queued signal and slot connections,. You may have to register before you can post: click the register link above to proceed. Qt Code: Switch view. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. Duplicate Question(s):Q_DECLARATIVE_METATYPE in and out; Using EventExport vs. 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. Connect and share knowledge within a single location that is structured and easy to search. There's also no need for that typedef, it only makes the code less readable. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. rep file extension, short for Replica. To start viewing messages, select the forum that you want to visit from the selection below. Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. To start viewing messages, select the forum that you want to visit from the selection below. I can access the property. the type name must be specified without the class, as in. To start viewing messages, select the forum that you want to visit from the selection below. // But the split allows to. Labels: meta system, Meta type, qt. +50. hpp which is included in Class1. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. 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. Q_DECLARE_METATYPE与qRegisterMetaType学习. Ah, sorry, I didn't noticed that part. The other overload around has almost the same form but for the. Similarly you can create a mutable view of type QAssociativeIterable on any container registered with Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE(). ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. I meet a qt metatype issue. 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. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. 23k 10 10 gold. Here’s the list of what changed: QVariant used to forward isNull () calls to its contained type – but only for a limited set of Qt’s own types. Q_DECLARE_METATYPE. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. Returns the metatype of the parameter at the given index. 5 is compiled with GCC 4. 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. " and: "Warning: This function is useful only for registering an alias (typedef) for every other use case Q_DECLARE_METATYPE and qMetaTypeId() should be used instead. Q_DECLARE_META_TYPE (Fruit) and qRegisterMetaType were redundant: #define PluginInterface_iid "pluginInterface" Q_DECLARE_INTERFACE (PluginInterface, PluginInterface_iid) //Actual plugin implementing PluginInterface class. complains that the metatype isn't registered. Read and abide by the Qt Code of Conduct. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. Call qRegisterMetaType() to register the data type before you establish the connection. 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. So I don't stream the pointer itself just copy the properties and set them to a new created pointer object. h. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. QVariant::fromValue () returns a QVariant. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. F. As the docs state: Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. You may have to register before you can post: click the register link above to proceed. To achieve this you need Q_DECLARE_METATYPE macro and qRegisterMetaType () function. Note: it's also safe to call qRegisterMetaType () multiple times. Mixing doesn't work but if you always use one or the other it works. Macros Detailed Description The QMetaType class manages named types in the meta-object system. Step 1 (mark for MOC), build some QObjects That pattern uses Q_PROPERTY and Q_OBJECT and the MoC tool. 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. ) summary refs log tree commit diff statsFoo and Foo* are different types and need to be registered separately. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Q_DECLARE_METATYPE only registers a type in meta type system. Connect and share knowledge within a single location that is structured and easy to search. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Using the qRegisterMetaType () function The Q_DECLARE_METATYPE () macro is the preferred way to declare a variable in Qt. (Make sure 'MyStruct' is registered using qRegisterMetaType (). Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. Re: How to use Q_DECLARE_METATYPE. The object it returns should also be a member of the factory class. So you can call it from your constructor. I have created an qt bugticket hoping the documentation will be extended. The issue here is that Q_OBJECT forbids the copy and assignment constructors. I'm trying to use custom classes in QAbstractListModel, and the Q_DECLARE_METATYPE doesn't work at all! To test where the problem is, I've simplified the code as the following: #include <QMetaType> #include <QVariant> #include <QDebug> typedef int x; Q_DECLARE_METATYPE (x) void main () { QVariant v; qDebug () << v. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). I need to call the Q_DECLARE_METATYPE() to pass the smart pointer. That's created by this macro. // copiable, C++98 brace-initializable, etc. qRegisterMetaType vs. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. If you have to use Q_DECLARE_METATYPE yourself, the id is not constexpr. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. The class is used to send arguments over D-Bus to remote applications and to receive them back. @kshegunov said: you're doing it wrong. QMetaType registerNormalizedTypedef normalizedTypeName, type: metaType ); return. 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. This function was introduced in Qt 5. You may have to register before you can post: click the register link above to proceed. 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. @kshegunov said in Undocumented automatic metatype registration in Qt6?: Your original code (in the top-mentioned topic) assumes std::unique_ptr is copyable, which it isn't, so it can not ever be a metatype. There's also no need for that typedef, it only makes the code less readable. Call qRegisterMetaType<std::string> (); in the initialization of your code. 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。. See also Thread Support in Qt, QObject::connect(), qRegisterMetaType(), and Q_DECLARE_METATYPE(). The reasoning is found in the. The problem of owner ship of the memory is avoided. Q_DECLARE_METATYPE. qRegisterMetaType() docs say: Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. You should use Q_DECLARE_METATYPE macro for this. 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(). } 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. akshatrai91 7 Jan 2021, 06:21. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. qRegisterMetaType vs. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. I placed Q_DECLARE_METATYPE (DataPoint) after the class definition. qRegisterMetaType vs. e. 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. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. 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. 9k 9 34 52. Using the macro directly turned out to be impossible. There's no such thing as a "const reference" because references are always const -- you can't reseat them. 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. Thus you need to use the runtime check QMetaType::type (). I have a few instances of QVector<MyClass> which I want them to be exposed to QScriptEngine. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Declare new types with Q_DECLARE_METATYPE () to make them available. Also, to use type T with the QObject::property () API, qRegisterMetaType () must be. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. 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. 2 Answers. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. Registers the type name . It associates a type name to a type so that it can be created and destructed dynamically at run-time. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. In that case, I think you need to register them. E. 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. qRegisterMetaType vs. 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. Now, that Q_DECLARE_METATYPE enables the type for Qt template classes and QVariant. My workround was to explicitly cast the enum values to int when passing them onto a function requiring a QVariant type, in my case when adding a QComboBox item, and then casting it back to my enum class type at value retrieval. The other overload around has almost the same form but for the fact that it. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. You could also Q_DECLARE_METATYPE to register your custom type and then use qMetaTypeId() to get the metaType id. 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. I my real world application Context holds a large number of physical quantities (masses, forces, velocities,. From the docs: int qRegisterMetaType ( const char * typeName ) Registers the type name typeName to the type T. 16. Q_DECLARE_METATYPE only registers a type in meta type system. Did you also check the Q_DECLARE_METATYPE macro ? You should declare and register the types properly, lying to qRegisterMetaType will get you in trouble in the long run. Share Improve this answer Follow answered Jul 23, 2014 at 15:37. 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。. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Q&A for work. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. [since 6. I think it would be great if we could run requests in a QThread, but right now it's not possible because the r. qRegisterMetaType vs. There's no need to call qRegisterMetaType that many times, once is enough. EDIT: When you convert your class to QVariant it uses a. First of all, you always need to declare your meta type: Q_DECLARE_METATYPE (foo::MyClass) It works at compile time, so there are no limitations on how you refer to your class. ) which are updated by simulation code. 1 Answer. There's no need to call qRegisterMetaType that many times, once is enough. I am also using some in queued signal and slot connections. The Custom Type and Queued Custom Type examples show how to implement a custom type with the features outlined in this document. In Qt, you can declare a variable in two ways: 1. It associates a type name to a type so that it can be created and destructed dynamically at run-time. [edit] forgot to mention that you also have to use a worker object. in your main function or in the constructor of AudioGuiApplication. Q_DECLARE_METATYPE. e. One of these plugins uses Q_DECLARE_METATYPE on some types that need to be stored in a QVariant. But I really would like to know the correct way to solve this problem; one where it is not possible to modify. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). 4 which does not support all C++11 features. 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. Than I did read this copy constructor of derived QT class and the answer by BЈовић. This is not the case, since the following succeeded: @QMetaType::type("MyClass"); // success@. Consider the specific case of qRegisterMetaType. The id is constexpr in the special case of Qt built-in types only. Additional types can be registered using qRegisterMetaType() or by calling registerType(). But there would be no trouble using the QMetaType class or using qRegisterMetaType before creating an instance of QCoreApplication or QApplication. without providing the Q_DECLARE_METATYPE macro in the class header, but one could provide a macro where registration is automatically performed (more or less along with meta type declaration). This results in access violations when Qt. 【2】使用方法（声明 和 注册自定义数据类型）. 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. Jun 13, 2021 at 19:37. type() typeName() PySide6. So, if you had a custom type FooType, you'd put the Q_DECLARE_METATYPE directly after the declaration, and in. Learn more about Teams I can't figure out a way to automatically declare a meta type, i. PySide6. . I read on documentation that Q_DECLARE_METATYPE makes available type to QVariant, for example (I got it from documentation): @ struct MyStruct { int i;. Read and abide by the Qt Code of Conduct. 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. This makes them suitable for use with both static properties declared using the Q_PROPERTY() macro in class definitions and dynamic properties created at run-time. By the way, Qt 4. Additionally Qt5 always refers to Q_DECLARE_METATYPE, saying that qRegisterMetaType is only when you want to. It must appear in a code block. S 1 Reply Last reply Reply Quote 0. To enable creation of objects at run-time, call the qRegisterMetaType() template function to register it with the meta-object system. Re: How to use Q_DECLARE_METATYPE. Qt is throwing an exception because it doesn't know how to store the shared_ptr onto a QDataStream. The default access for a class is private, so that Container* data();. If the pointer stored in the QVariant can be qobject_cast to T, then that result is returned. There's also no need for that typedef, it only makes the code less readable. Creating and Destroying Custom Objects 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 class. It is still giving the error"QObject::connect: Cannot queue arguments of type 'quint32&' (Make sure 'quint32&' is registered using. That always worked in Qt4, but in Qt5 I get the following error: @error: specializing member ‘::qRegisterMetaType<Subclass>’ requires ‘template<>’ syntax@. In the example's Message class, a static method is included to do this. Enumerations that are declared with Q_ENUM have their QMetaEnum registered in the enclosing QMetaObject. Read and abide by the Qt Code of Conduct. Sorted by: 5. As said in int qRegisterMetaType () documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. Now you have a valid QObject. 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. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. To start viewing messages, select the forum that you want to visit from the selection below. It associates a type name to a type so that it can be created and destructed dynamically at run-time. Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system. 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(). h in the translation unit where you have that line. To start viewing messages, select the forum that you want to visit from the selection below. I haven't used that module yet but one thing you should do is remove the string argument from your qRegisterMetaType calls. I am also using some in queued signal and slot connections. It manages an insane amount of static variables and sets a static global pointer of. 幸哉~ Qt是支持自定义信号，且自定义信号可以发送自定义数据类型的对象。. The ones I am registering for are mostly structs for storing data and just a few simple classes. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. 0. Specifically, the function have to be called before using the struct. 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. @Q_DECLARE_METATYPE (std::unique_ptr<Thing>);@. 1 Answer. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. However, as you need the type to be. 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. 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. Make your own typedef and do the Q_DECLARE_METATYPE and qRegisterMetatype. I guess it's the qRegisterMetaType () call itself that's missing. Assuming base and derived are Q_GADGETs you want to get a static member. You should use qmlRegisterType function for that. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit. 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. Note that you are technically lying to the meta type system. 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. You can use Q_DECLARE_METATYPE(Widget*) but it is not needed as of Qt. QtCore. See QMetaType docs for more information. In my module tests, I turn the card up and down, and can verify that the number of signals are increasing using QSignalSpy. cpp 中，用connect函数 将抛出此结构体的信号和接收此结构体的槽函数关联之前，要调用qRegisterMetaType. Q_OBJECT derived class, inheritance. Actually, they are declared, but in a private section with the macro Q_DISABLE_COPY(). I thought there was a bug with QMetaType or Q_DECLARE_METATYPE. 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:. Thus you need to use the runtime check QMetaType::type (). :) QApplication is the root QObject of the program and its full initialization is required before anything can practically be done with anything else. 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. 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 have registered an enumeration type "ClefType" within my header file - this enum is registered with the MetaObject system using the Q_DECLARE_METATYPE and Q_ENUMS macros. until today. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. Learn more about Teams Declaring a meta type. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. 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. 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. Has anyone else encountered this?See also qRegisterMetaType(). {. queued connections. 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. One way to work around this is for example having a helper class (singleton or context property) with. One of the overloads is a function template that can be used to create an alias for a type and the form is: qRegisterMetaType<Type> ("alias"); That is, it wants to know the type for which you are declaring something. Detailed Description. 2 Answers. I want to use my objects as QVariants and for queued connections. Current the only supported type info is QML_HAS_ATTACHED_PROPERTIES. Q_DECLARE_METATYPE, as pointed out by @SingerOfTheFall, would register template based type into QVariant (so it can be retrieved using qvariant_cast<T>()). It looks like one can register a type more than once, specifying different typenames, i. Detailed Description. Compares this QVariant with v and returns true if they are equal;. Tried proposed solution using QVariant::fromValue, but kept getting compiler errors of type: . See also state() and Creating Custom Qt Types. cpp. [virtual] QAbstractSocket:: ~QAbstractSocket Destroys the socket. Enumerations that are declared with Q_ENUM have their QMetaEnum registered in the enclosing QMetaObject. Q_DECLARE_METATYPE(TYPEDEF) Q_DECLARE_METATYPE(TYPEDEF) mainwindow. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. The Problem: I want to create an object instance at runtime using QMetaType by the type name. This may make certain type comparisons fail. I read on documentation that Q_DECLARE_METATYPE makes available type to QVariant, for example (I got it from documentation): @ struct MyStruct { int i;. However, I cannot figure out how to verify that the included parameter is FACE_UP or FACE_DOWN. This object can then be passed from QML to C++ via. 14 vs 5. Any class or struct that has a public default constructor, a public copy constructor, and a. 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. 8. Any class or struct that has a public default constructor, a public copy. // - in a header: // - define a specialization of this template calling an out-of. Situation. Even though we do not intend to use the type with QVariant in this example, it is good practice to also declare the new type with Q_DECLARE_METATYPE (). This macro is used to specialise the template class QMetaTypeId with typename TYPE, in which, a static member function qt_metatype_id () is defined. Because Foo is not derived from QObject and QVariant only supports polymorphism for QObject -derived types. It will return the same result if it was called before. As said in int qRegisterMetaType () documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. 4. So in your case you need to declare. I have declared all the types with Q_DECLARE_METATYPE, Q_OBJECT and the properties with Q_PROPERTY with the proper getters and setters. It associates a type name to a type so that it can be created and destructed dynamically at run-time. As a workaround, I'm using QVariantMap instead of std::map. Q_DECLARE_METATYPE与qRegisterMetaType学习. I only care about runtime instantiation. Q_DECLARE_METATYPE(Pkg) and this does not give compile errors, but in my main. You may have to register before you can post: click the register link above to proceed. That. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. There's also no need for that typedef, it only makes the code less readable. If I get AnotherQGadgetClass via getter and change it's properties, the setters are called and. QVariant v = QVariant::fromValue<cMyClass>(MyObject); However, as soon as I use Q_DECLARE_METATYPE, I get errors about using a deleted function.