Returns the internal ID used by QMetaType. until today. nyaruko. 该类型必须有公有的 构造、析构、复制构造 函数. D-Bus offers an extensible type system, based on a few primitive types and associations of them. qt. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). There's no such thing as a "const reference" because references are always const -- you can't reseat them. qRegisterMetaType is also called in the class constructor. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Detailed Description. 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. Now, that Q_DECLARE_METATYPE enables the type for Qt template classes and QVariant. ompiler (repc) generates header files based on an API definition file. Q_DECLARE_METATYPE. h" class Context : public QObject { Q_OBJECT Q_PROPERTY (MyGadget* gadget READ gadget CONSTANT) public: explicit Context () : QObject {nullptr} { } MyGadget* gadget () { return &_gadget; } private. See also state() and Creating Custom Qt Types. You may have to register before you can post: click the register link above to proceed. Is your Q_DECLARE_METATYPE in a header file or an implementation file? Incidentally, there is a mistake in TreeItem. 1. 1）引入头文件：#include<QMetaType>. There is no contradiction, because you can't register QObject descendants with Q_DECLARE_METATYPE. 0. If I get AnotherQGadgetClass via getter and change it's properties, the setters are called and. 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 () <<. For this, a function call (evaluated during runtime) needs to be made, and qRegisterMetatype is the tool for this: qRegisterMetaType<Area>("Area");@julio. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. Workaround: use a class. 4] QString QWebSocket:: subprotocol const. 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. Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system. hpp which is included in Class1. {. In. I have an application that requires use of both Qt 3D and the QCustomPlot library. qRegisterMetaType usage. In the header, after the class declaration, outside the namespace, I've included. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. Q_DECLARE_METATYPE(MyClass*); That's how Qt handles it with QObject and QWidget. Read and abide by the Qt Code of Conduct. 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. Teams. ", which suggests it is only for classes and structs. Share. To make the type known to this class, we invoke the Q_DECLARE_METATYPE() macro on the class in the header file where it is defined: Q_DECLARE_METATYPE (Message). This is by design. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Then the TYPE ID is saved in local static vairable metatype_id. (Make sure 'MyStruct' is registered using qRegisterMetaType (). Declare new types with Q_DECLARE_METATYPE () to make them available to. Q_DECLARE_METATYPE(MyObject*) somewhere in your code. Quote: bool QVariant::operator==(const QVariant & v) const. ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. J. void QAbstractSocket:: abort ()2 Answers. I want to use drag-and-drop to drag a QTreeWidgetItem that has std::shared_ptr user data. Well, I certainly overplayed this particular point, but the statement I believe is valid in principle. Update. Firstly, you shouldn't need to use Q_DECLARE_METATYPE (or qRegisterMetaType) with the enum at all, this is handled by the moc. It is only useful to the code that follows it, in the same file. Re: Qt warning of type conversion already registered Originally. 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. There's no need to call qRegisterMetaType that many times, once is enough. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Registers the type name . It is a static method, it does not (cannot) change x2. ) QObject::connect: Cannot queue arguments of type 'QVector<int>'. Q_DECLARE_METATYPE. This object can then be passed from QML to C++ via. The reasoning is found in the. It must appear in a code block. You may have to register before you can post: click the register link above to proceed. Please note that I do not use Q_DECLARE_METATYPE on purpose because I don't actually need its features (QVariant expansion) right now. e. Note: This function is thread-safe. I store them in QVariant :. To start viewing messages, select the forum that you want to visit from the selection below. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. There is no way to add support for more of these value types like std::string (*). Qt Base (Core, Gui, Widgets, Network,. 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. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with 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. Returns the internal ID used by QMetaType. 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. You may have to register before you can post: click the register link above to proceed. So, whatever Q_DECLARE_METATYPE is doing cannot be done by writing a function call. The other overload around has almost the same form but for the. @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. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. 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. To enable creation of objects at run-time, call the qRegisterMetaType() template function to register it with the meta-object system. You should use qmlRegisterType function for that. See also state() and Creating Custom Qt Types. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. 1. To use the type T in queued signal and slot connections,. Because Foo is not derived from QObject and QVariant only supports polymorphism for QObject -derived types. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. qRegisterMetaType vs. Current the only supported type info is QML_HAS_ATTACHED_PROPERTIES. In fact, all Qt classes derived from QObject (direct or indirect) use this macro to declare their copy constructor and assignment operator to be private. It does not say anything about registering the type. Q&A for work. Q_DECLARE_METATYPE与qRegisterMetaType学习. I explicitly don't want to update it on every change to one of the quantities, so they don't. Detailed Description. Q_DECLARE_METATYPE(Pkg) and this does not give compile errors, but in my main. To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. 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. h in the translation unit where you have that line. Follow. However, as you need the type to be. Using the macro directly turned out to be impossible. 手册中告诉我们，执行这个的时候，模板参数T必须用 Q_DECLARE_METATYPE() 声明过 能猜到原因吗？注意看前面 Q_DECLARE_METATYPE() 代码， 对了。类中的成员函数qt_metatype_id中包含对qRegisterMetaType(typeName)的调用 这儿就是辗转调用了这个带参数. Good workaround: you may register your type with Q_DECLARE_METATYPE ( IBase * ) macro and wrap your variable. Q_DECLARE_METATYPE QMetaType::type. You can also use QMetaEnum::fromType() to get the QMetaEnum. The QML engine provides built-in support for a. . Qt is throwing an exception because it doesn't know how to store the shared_ptr onto a QDataStream. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. An alternative would be to wrap shared_ptr<int> in your own class and implement comparison the way you want. 1 Answer. E. before saveload operation would happen. 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. The class in Qt responsible for custom types is QMetaType. It was also no big issue to call qRegisterMetaType () automatically. Any class or struct that has a public default constructor, a public copy. The following should work: Note that you also have to call qRegisterMetaType<MyMpiMessage> (); before you use the function the first time. 1. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. 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 ;. 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. 9k 9 34 52. A. append (QVariant::fromValue (l)); } return list; } The metatype system declaration and registration you have. The logical equivalent of a const T &r (reference to const T) is a const T * const p (const pointer to const T). That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Note that you are technically lying to the meta type system. It's not enough to get reflection features out of a type this way (it does not create a QMetaObject), so for the thing to be useful at all you need at least Q_GADGET in both base and derived classes. Now you have a valid QObject. This is not the case, since the following succeeded: @QMetaType::type("MyClass"); // success@. Any class or struct that has a public default constructor, a public copy. Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. Any idea what I'm missing please? BTW, no problem at all using Schedule in QMetaProperty or QVariant. 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. Labels: meta system, Meta type, qt. SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. 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. ) is supported. 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. There's no need to call qRegisterMetaType that many times, once is enough. If you have to use Q_DECLARE_METATYPE yourself, the id is not constexpr. 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). To start viewing messages, select the forum that you want to visit from the selection below. 4. 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:. QtCore. It is still giving the error"QObject::connect: Cannot queue arguments of type 'quint32&' (Make sure 'quint32&' is registered using. 0. g. // copiable, C++98 brace-initializable, etc. To make the type known to this class, we invoke the Q_DECLARE_METATYPE() macro on the class in the header file where it is defined: Q_DECLARE_METATYPE (Message). 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. cpp. Greetings. Q_GADGET makes a class member, staticMetaObject, available. Learn more about Teams Declaring a meta type. Macros Detailed Description The QMetaType class manages named types in the meta-object system. Qt Base (Core, Gui, Widgets, Network,. Avoid having to qRegisterMetaType (pointer. Now I want to read this property with Qt's meta object system. Since Qt 5. x however, the code generated by moc will call qRegisterMetaType for you if moc can determine that the type may be registered as a. You'll need Q_DECLARE_METATYPE () if you want to store your type within a QVariant and you will additionally need qRegisterMetaType<> () if you want to dynamically create and destroy objects of that type at runtime, mostly for queued signal and slots connections or the QObject property system. Q_DECLARE_METATYPE (std::string) Quoting Qt Doc. QMetaType. I. There's no compile time error, but when I run. When using signals and slots with multiple threads, see Signals and Slots Across Threads. Q&A for work. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. 14 vs 5. 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 (). typedef QVector<QSharedPointer<Tester> > TestPointerVector;. ) summary refs log tree commit diff statsFoo and Foo* are different types and need to be registered separately. Enumerations that are declared with Q_ENUM have their QMetaEnum registered in the enclosing QMetaObject. Basically, I created a library containing a type: struct MyCustomType {. As you have already found out, you must use Q_DECLARE_METATYPE to make the type known to Qt. 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. Read and abide by the Qt Code of Conduct. Thus you need to use the runtime check QMetaType::type (). . Q_DECLARE_METATYPE. Q_DECLARE_METATYPE. Note: it's also safe to call qRegisterMetaType () multiple times. Similarly you can create a mutable view of type QAssociativeIterable on any container registered with Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE(). There's also no need for that typedef, it only makes the code less readable. type() typeName() PySide6. cpp. QVariantList , QString (if the list contains exactly one item) Casting between primitive type (int, float, bool etc. You may have to register before you can post: click the register link above to proceed. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. genC last edited by . Data Type Conversion Between QML and C++. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE() and qRegisterMetaType(). Jul 9, 2017 at 21:51. qRegisterMetaType<signed long long>() - do nothing. I read a bit and it seems that Q_DECLARE_SMART_POINTER_METATYPE is supposed to allow this to work. 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. Has anyone else encountered this?See also qRegisterMetaType(). As a workaround, I'm using QVariantMap instead of std::map. However, it does appear (at least to me) that you're trying to debug a release build of the application. Q_DECLARE_METATYPE (T) requires the type T to be default-constructable, copiable and destructable. Declare new types with Q_DECLARE_METATYPE () to make them available. When I emit a signal, then I get next error to the output stream:. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. 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. qRegisterMetaType 必须使用该函数的两种情况. So I don't stream the pointer itself just copy the properties and set them to a new created pointer object. . the type name must be specified without the class, as in. Detailed Description. waitForConnected ([msecs=30000]) # Parameters: msecs – int. 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. rep file extension, short for Replica. Additionally Qt5 always refers to Q_DECLARE_METATYPE, saying that qRegisterMetaType is only when you want to. Last updated at 2016-07-08 Posted at 2015-11-16. 0 and have problems registering my own class as a QMetaType. It associates a type name to a type so that it can be created and destructed dynamically at run-time. So I played around, copied the original macro and adapted it a bit: @. It looks like one can register a type more than once, specifying different typenames, i. 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. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). 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(). It associates a type name to a type so that it can be created and destructed dynamically at run-time. e. 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. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. QMetaType::type () is a bit slower, but compilation succeeds if a type is not registered. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Also you may need to use qRegisterMetaType function. ", which suggests it is only for classes and structs. 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 the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. It associates a type name to a type so that it can be created and destructed dynamically at run-time. " 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. The "traditional" way of doing this is to convert each element to a QVariant, and pass collection as a QVariantList. on top of main. Q_DECLARE_METATYPE on the other hand is (as far as I know) preprocessor bound. 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. The Rep lica C ompiler (repc) generates QObject header files based on an API definition file. 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. Jun 13, 2021 at 19:37. As the docs state: Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. // But the split allows to. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. qRegisterMetaType () is called to register the TYPE and generate a TYPE ID. 7. If the type was not declared with Q_DECLARE_METATYPE (), compilation will fail. // This primary template calls the -Implementation, like all other specialisations should. When these files are processed by repc, repc generates both. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. call qRegisterMetaType with the name specified, else reading properties. @kshegunov said: you're doing it wrong. no unexpected garbage. How: I linked qRegisterMetaType. namespace CCS { Q_DECL_EXPORT Q_NAMESPACE. See also. and Q_DECLARE_METATYPE uses qRegisterMetaType() internally. Similarly you can create a mutable view of type QAssociativeIterable on any container registered with Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE(). 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. See also state(). 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. To enable creation of objects at run-time, call the qRegisterMetaType() template function to register it with the meta-object system. The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. (Make sure 'QVector<int>' is. QVariant’s operator== now uses QMetaType::equals for the comparison. I have declared all the types with Q_DECLARE_METATYPE, Q_OBJECT and the properties with Q_PROPERTY with the proper getters and setters. 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. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. Connect and share knowledge within a single location that is structured and easy to search. 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 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. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. From the docs: int qRegisterMetaType ( const char * typeName ) Registers the type name typeName to the type T. 14. The issue here is that Q_OBJECT forbids the copy and assignment constructors. Any class or struct that has a public default constructor, a public copy constructor, and a. Also, to use type T with the QObject::property () API,. h instead ofQVariant x2; x2. Is your feature request related to a problem? No, it's an improvement Please describe. QVariant::fromValue () returns a QVariant. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. Assuming base and derived are Q_GADGETs you want to get a static member. void Message:: registerMetaType {qRegisterMetaType < Message >. Using Q_ENUM () allows you to retrieve at run-time. You can make them known ( Q_DECLARE_METATYPE ), however you can't register them as QML type. Now, in your registerTypes function, it should be registered like this: qRegisterMetaType<AccReal > ("data::AccReal"); In other words, the typeName string must match exactly the type of the signal argument as it is written there. qRegisterMetaType vs. So in your case you need to declare. Note: it's also safe to call qRegisterMetaType () multiple times. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. Share Improve this answer Follow answered Jul 23, 2014 at 15:37. It associates a type name to a type so that it can be created and destructed dynamically at run-time. By convention, these files are given a . That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. 4 which does not support all C++11 features. 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. This article will. hpp and qRegisterMetaType<quint32>("quint32"); in both the Constructors of Class1 and Class2. [override virtual] bool QLocalSocket:: waitForBytesWritten (int msecs = 30000) Reimplements:. Output:Additionally Q_DECLARE_METATYPE and qRegisterMetaType are not purposed to be used for QObject derived classes. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. qRegisterMetaType<FileNodePointer> ("FileNodePointer"); should be called once (in main, constructor etc. To call qRegisterMetaType (), you still need to use Q_DECLARE_METATYPE (). 1. Re: How to use Q_DECLARE_METATYPE. Call qRegisterMetaType () to make type available to non-template based functions. 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. int videoSourceMetaTypeId = qRegisterMetaType< VideoSource > ();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. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. Gerald Gerald. I haven't used that module yet but one thing you should do is remove the string argument from your qRegisterMetaType calls. QList<AnotherObject*> has of course been registered with Q_DECLARE_METATYPE and qRegisterMetaType(). The code compiles and runs ok. 2）添加声明：利用宏 Q_DECLARE_METATYPE. 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. 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. There's also no need for that typedef, it only makes the code less readable. I believe this is related to the fact that. Re: Qt warning of type conversion already registered Originally. Returns the used WebSocket protocol. 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. Duplicate Question(s):Q_DECLARATIVE_METATYPE in and out; Using EventExport vs. 2 Answers. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. This now makes it possible for Message values to be stored in QVariant objects and retrieved later. The Custom Type and Queued Custom Type examples show how to implement a custom type with the features outlined in this document. Since \c{MyStruct} is now known to QMetaType, it can be used in QVariant: Some types are registered automatically and do not need this macro: /*! This macro makes the container \a Container known to QMetaType as a sequential. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. Note that you are technically lying to the meta type system. 3 Answers Sorted by: 13 "qRegisterMetaType" is a function. template <typename T> struct QMetaTypeId<Container<T>>. 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. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. So I tried declaring the following at end of my worker thread class Q_DECLARE_METATYPE(cv::Mat);. 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。. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE() and qRegisterMetaType(). To start viewing messages, select the forum that you want to visit from the selection below. qRegisterMetaType vs. In my project, MyClass is a cache for multi-dimensional data "point", and it looks like: class MyClass { public: MyClass(); /* Some functions */ private: int m_index; double m_time; QList<int> *m_data; };Firstly, you shouldn't need to use Q_DECLARE_METATYPE (or qRegisterMetaType) with the enum at all, this is handled by the moc. void QAbstractSocket:: abort ()Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. Now you have a valid QObject. I have a problem with a class that exchanges data using TCP/IP socket. But this is all useless if you are not using templates. As a workaround, I'm using QVariantMap instead of std::map. 0. w/out GUI module you wouldn't have any of those types available). qRegisterMetaType() docs say: Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. Q_DECLARE_METATYPE (std::string) Quoting Qt Doc. 步骤： (以自定义MyDataType类型为例）. staticMetaObject is of type QMetaObject and provides access to the enums declared with Q_ENUMS. Also you may need to use qRegisterMetaType function.