Hello, when I run rviz_sim. Data Type Conversion Between QML and C++. Note that, as far as the meta-type system is concerned, MyClass, MyClass *, QVector<MyClass>, shared_ptr<MyClass> and so on are all different types, and as such, each one may need its own registration. Note: This function is thread-safe. cpp is void test (const Person* p)) qrc:example. You get this because you are creating the QNetworkAccessmanager in the constructor of Citizen, which is being called in the "original" thread. This feature is commonly used by proxy connections for virtual connection settings. If you need a socket, you have two options: Instantiate QTcpSocket or QUdpSocket. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. (Make sure 'QVector<int>' is. Undeclared QMetaObject::SuperData. To enable creation of objects at run-time, call the qRegisterMetaType () template function to register it with the meta-object system. The members of the class contain calls to qRegisterMetaType We can also use Q_DECLARE_METATYPE to declare custom variables, and package custom. This enum was introduced or modified in Qt 5. 1,609 4 22 34. A more complex program sending QSharePointer objects using slots has a similar situation with GDB, that can be reproduced with the previous example. ) I read on some forum, that this may be caused by calling qt-functions from another Thread, and that using signals & slots instead of plain function calling may fix the issue, but i have tried signals aswell, and i. 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 Answer. You only. From Qt documentation: Ideally, this macro should be placed below the declaration of the class or struct. I intially installed a later version of Qt but then reverted back to Version 5. 1. 2D Graphics #. All. ) What I have done is, declare in the main the qRegisterMetatype but it still complaining. This also makes the type available for queued signal-slot communication as long as you call it before you make the first connection that uses the type. If a field is empty, keep it in the result. The following code allocates and destructs an instance of MyClass: Type names can be registered with QMetaType by using either qRegisterMetaType() or registerType(). 步骤： (以自定义MyDataType类型为例）. I read on documentation that Q_DECLARE_METATYPE makes available type to QVariant, for example (I got it from documentation): @ struct MyStruct { int i;. Detailed Description#. Hm. Detailed Description. The QML engine provides built-in support for a. newStatuses. bool QMetaProperty:: writeOnGadget ( void * gadget, const QVariant & value) const. std::shared_ptr does not let you assign a plain pointer to it directly. Defining QML Types from C++. a copy of a cv::Mat object will point to the same data as the copied from item). If it is a partial specialization it might be template<class X> instead. Did you try to use qRegisterMetaType function? The official manual says: The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. 0. What's more, I can run the demo of MoveIt Quickstart in RViz correctly:That's created by this macro. iii. Improve this answer. When you think about, there are quite convincing reasons to disallow it implicitly happening. qRegisterMetaType () is called to register the TYPE and generate a TYPE ID. The QAbstractSocket class provides the base functionality common to all socket types. It is part of QMetaType, which is not implemented by PySide. QtGui import * from PyQt5. ;. Note following line #include. h. The Qt doc on qRegisterMetaType explicitly says : T must be declared with Q_DECLARE_METATYPE (). I my real world application Context holds a large number of physical quantities (masses, forces, velocities,. QSignalSpy itself is a list of QVariant lists. e. The following code allocates and destructs an instance of MyClass: The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. 1,609 4 22 34. I'm using Qt 5. (Make sure 'MyStruct' is registered using qRegisterMetaType (). When data values are exchanged between QML and C++, they are converted by the QML engine to have the correct data types as appropriate for use in QML or C++. complains that the metatype isn't registered. FollowThis can be made to work but it turns out there's a bit of manual labour to be done. If I save it just at the beginning of. Teams. receiver. Only users with topic management privileges can see it. QtのAPIのドキュメントに、thread-safeと書いてない限りは、QMutex等を使って自分で排他をする必要がある。. Instead, the following lines have been added to the adding. Asking for help, clarification, or responding to other answers. Where are you getting this from? qRegisterMetaType is not a member function of QSettings or any other class. See QMetaType docs for more information. SIGNAL(ueSignalTaskFinished(UePosCommProtocolArch::UeCommand&, // reference QByteArray&)), //dittoCustom types registered using qRegisterMetaType() that have operators for streaming to and from a QDataStream can be stored using QSettings. You have to register your custom type for queued signals because by registering it, Qt can make a copy of it in its event loop (which certainly uses QVariant) and pass it as argument later (when the original passed value is long since out. Sorted by: 5. Returns QPartialOrdering::Unordered if comparison is not supported or the values are unordered. rows += self. My computer was updated and I needed to reinstall all the above tools. You can connect a signal to a slot with connect (). 150%) wider. e. 10, enumerations are directly supported in QML. It also reflects the size of the paging file at that time. You can define one with the enum keyword. 这两个东西真难理清，不妨看看源码吧。. Problem: There is no update of the UI. The correct syntax is Q_DECLARE_METATYPE (std::string) without the ;. Call qRegisterMetaType () to make type available to non-template based functions, such as the queued signal and slot connections. 2 @Alfredocubitos would it be possible to share an example of the threaded websocket. qRegisterMetaType<QSqlDatabase>("QSqlDatabase"); Just changing the signal to this form: void dbConnected(QSqlDatabase *db); And, in the slot side I'll use something like this: void onDBConnected(QSqlDatabase * const db); I'm concerned with the usage of db (as in the beginning I've made the reference const), so I make it const here (in the slot. The operating system can enlarge the paging file up to the maximum size set by the administrator. Make a typedef for QSharedPointer<UserDataType>, and use both Q_DECLARE_METATYPE as well as qRegisterMetaType () to register it for use. #pragma once #include <QObject> class MyClass : public QObject { Q_OBJECT public: static void initQML (); MyClass (); MyClass (const MyClass &myClass. QMetaType:: 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(). registerType () determines which register is used for the operations. Follow. QWaitCondition allows a thread to tell other threads that some sort of condition has been met. Registration is not required for most operations; it’s only required for operations that attempt to resolve a type name in string form back to a QMetaType object or the type’s ID. As explained in this thread you can try using a typedef, including the QMetaType header and then using both Q_DECLARE_METATYPE macro and the qRegisterMetaType function (as implied by this thread on a similar issue). king_nak king_nak. ) This is hard to track, so I would. qRegisterMetaType<MyStruct>("MyStruct"); 若已经使用 Q_DECLARE_METATYPEQ 标记过该类型，可以使用其不带参数的版本： qRegisterMetaType<MyStruct>(); 同样的，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，如： qRegisterMetaType<NSP::MyStruct>("NSP::MyStruct"); Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. Solution 1: somewhere. Detailed Description. ) @. To do this you first subclass logging. @RIJIK "very unlikely" doesn't mean never ever. Unless the property is readonly, you can also set a binding on this property. Provide details and share your research! But avoid. iv. Specifically, the function have to be called before using the struct in a queued signal/slot connection or. An "ugly solution" would be to hack the fairly simple QSignalSpy code in order to handle the reference passed arguments. . If you need a socket, you have two options: Instantiate QTcpSocket or QUdpSocket. See also convert(). By convention, these files are given a . Detailed Description. e. 12. ) ^C[rviz-2] killing on exit [laserMapping-1] killing on exit Hello guys, i have the following message when i run the launch file. QNetworkAccessManager is used for all network access by QML. Returns true if the column is inserted; otherwise returns false. (Parent is QTcpSocket (0x24a6ce8), parent's thread is ServiceSlots. That always worked in Qt4, but in Qt5 I get the following error: @error: specializing member ‘::qRegisterMetaType<Subclass>’ requires ‘template<>’ syntax@. Please visit robotics. 31. 默认会发送给主线程即默认的连接Qt::AutoConnection ，如果是多线程的话就是Qt::QueuedConnection了，所以要明确指定。. main. Convert this variant to type QMetaType::UnknownType and free up any. 2 @Alfredocubitos would it be possible to share an example of the threaded websocket. A single QMetaObject instance is created for each QObject subclass that is used in an application, and this instance stores all the meta-information for the QObject subclass. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. . 2 Answers Sorted by: 3 You do not need to call qRegisterMetaType () to use a type with QVariant. layoutAboutToBeChanged. I'm not sure how to do this in python but probably you should add similar call with QTextCursor. I understand that it has to do with Qt library but in which cpp file i have to put the argument ? The argument is this right ? qRegisterMetaType<QVector<int> >. Oct 17, 2020 at 11:47. ) INFO:cfclient. hi, I always after application running, receive debug text of: QObject::connect: Cannot queue arguments of type 'MyStruct'. The Windows registry and INI files use case-insensitive keys, whereas the CFPreferences API on macOS and iOS uses case. e. The related type must provide a public default constructor, a public copy constructor and a public destructor to be eligible to be declared as a metatype. Nejat Nejat. . ;. A common way to register the type is in main or with a static function register. Note: If you want to use your custom metatypes also in queued slot connections or with QMetaMethod, you have to call qRegisterMetaType<QPushButton*>() Share. QtCore import QObject works. mycompany. Thanks a lot for that!. QObject::connect: Cannot queue arguments of type 'QModbusDevice::State' (Make sure 'QModbusDevice::State' is registered using qRegisterMetaType (). QMetaType Synopsis Functions def __eq__ (b). qRegisterMetaType<QVector<int> >("QVector<int>"); Once you make this call, you should be able to emit the QVector type over queued connections. 1 Reply Last reply 0. Currently, on Linux and Android it is used for specifying connection to a server listening to a socket bound to an abstract address. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. – thuga. This requires the exchanged data to be of a type that is recognizable by the engine. We have a couple projects that we developed using Visual Studios 2017, VisualGDB Vers 5. Any ideas? Nope, registering with qRegisterMetaType<std::vector<int>>() has same effect as not registering at all (using QVector<int> works without registration, but does not expose length, either). QObject::connect: Cannot queue arguments of type 'QVector<int>'. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. Got the following warnings when running latest code in "develop": QObject::connect: Cannot queue arguments of type 'QTextBlock' (Make sure 'QTextBlock' is registered using qRegisterMetaType(). Someone may be able to correct me here, but I don't think you should be needing to register the type int&. Any class or struct that has a public default constructor, a public copy constructor and a public destructor can be registered in QMetaType. childEvent (event) # Parameters:. 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. Share. It's a bit tricky thing. 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. QObject::connect: Cannot queue arguments of type 'ProcessHandle*const' (Make sure 'ProcessHandle*const' is registered using qRegisterMetaType(). (Make sure 'QVector<QVector<int> >' is registered using qRegisterMetaType (). A. ) What I have done is, declare in the main the qRegisterMetatype but it still complaining. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. ChildAdded and ChildRemoved events are sent to objects when children are added or removed. QAbstractSocket is the base class for QTcpSocket and QUdpSocket and contains all common functionality of these two classes. Be very careful as cv::Mat is not implicitly shared, it is just shared (i. (Make sure 'QVector' is registered using qRegisterMetaType(). QVariant’s operator== now uses QMetaType::equals for the comparison. ) 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. ) QObject: Cannot create children for a parent that is in a different thread. when i use real velodyne VLP16, i got some problem! when i use velodyne VLP16 package,"roslaunch velodyne_pointcloud VLP16_points. – Kamil Klimek. call qRegisterMetaType() to register the data type before you establish the connection. h. The file (called a "rep" file) uses a specific (text) syntax to describe the API. It provides functions for creating and manipulating selections, and selecting a range of items from a model. Data Type Conversion Between QML and C++. If I register QVector I can't dissconnect this signal and the signal is emited. Note that if you intend to use the type in queued. 我们知道类中的成员函数并不一定会被调用 (即，该宏并不确保类型被注册到MetaType)。. ) So it seems to be a multi-threading issue caused by this instruction connect (process,&QProcess::started, [this. h file. Reproducible Example Of The. As you have already found out, you must use Q_DECLARE_METATYPE to make the type known to Qt. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. To call qRegisterMetaType (), you still need to use Q_DECLARE_METATYPE (). Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. ) ^C[rviz-2] killing on exit [laserMapping-1] killing on exit Hello guys, i have the following message when i run the launch file. 8 data bits. The Qt doc on qRegisterMetaType explicitly says : T must be declared with Q_DECLARE_METATYPE (). ) But if I change the Q_DECLARE_METATYPE call to: namespace my_namespace { Q_DECLARE_METATYPE(BathyHint) } everything workes fine. From the docs: int qRegisterMetaType ( const char * typeName ) Registers the type name typeName to the type T. Even though qRegisterMetaType(). (Make sure 'QDomDocument' is registered using qRegisterMetaType(). e. Follow answered Sep 16, 2014 at 4:21. Here is the list of information kept for each type in the meta-type system: The Type Name as registered. It is. Usually, we call the macro right below the class/struct declaration in the header file. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. Improve this answer. Where: before using any of the above. This way your metatype will be registered once at startup, and the registration is close by the implementation and does not require to modify <code>main</code>. You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. 这里您需要在使用setContextProperty ()之前创建此类对象。. Qt Base (Core, Gui, Widgets, Network,. ) QObject: Cannot create children for a parent that is in a different thread. You need to create your own factory that will register functors that will call qRegisterMetaType in runtime. Toggle Light / Dark / Auto color theme. Following this logic, the following code may not work: connect (senderObject. QDBusArgument is the central class in the Qt D-Bus type system, providing functions to marshall and demarshall the primitive types. on top of main. ) The form here shows the exactly same problem but I can't use signal and slot as. MEMORYSTATUSEX reflects the state of memory at the time of the call. aa73c08. See QMetaType docs for more information. Q&A for work. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. In this case the slot is executed as a normal function call. ) So it seems to be a multi-threading issue caused by this instruction connect (process,&QProcess::started, [this. It is almost. ) which are updated by simulation code. It enables things such as QVariant wrapping of custom types, copy of queued connection arguments, and more. emit (foo_text) def settext ( self, text ): print (text) Im sure you guys get this alot but im trying to thread and im getting this error: (Parent is QTextDocument (0x1243bfd4290), parent's thread is QThread (0x12437dd1260), current thread is. QSharedPointer is a smart pointer class in the Qt library. 5 and Qt Version 5. Note that this only works for QObject subclasses which use the Q_OBJECT macro. I created a. Data Type Conversion Between QML and C++. Yet, the first line is invisible and this line becomes visible only if we click on it! Very weird! QObject::connect: Cannot queue arguments of type 'QTextCursor'. Problem using qRegisterMetaType. Any QQmlContext's created on this engine will be invalidated, but not destroyed (unless they are parented to the. This function was introduced in Qt 5. It seems that for a metatype that is a QList<MyClass::MyEnum> I must. I have a class that is a subclass of QObject that I would like to register as a meta-type. This line has disappeared in Qt 5. Hello, Can someone tell me about how to register a metatype in pyqt5. otherwise. show(); int functionIndex = win. Each emission of the signal will append one item to the list, containing the arguments of the signal. #define. qRegisterMetaType<foo::FooState>(); Question. Nejat Nejat. 步骤： (以自定义MyDataType类型为例）. Then, connect this signal to a slot that will do the actual update of the data. layoutChanged. self. Originally I was passing a pointer to a type to signals which worked, the slots obviously had to returned the same pointer, again this worked. setFontStretch(factor) Sets the stretch factor for the font to. This property holds the state (high or low) of the line signal DTR. setContextProperty qmlRegisterType qRegisterMetaType等区别. We strongly advise against using it in new code. Returns a list of child objects. If you need a socket, you have two options: Instantiate QTcpSocket or QUdpSocket. setContextProperty : Use setContextProperty, When you want to use a single global class to access to or from QML. Also I get warnings: QObject::connect: Cannot queue arguments of type 'QTextBlock' (Make sure 'QTextBlock' is registered using qRegisterMetaType (). 23. (Parent is QTcpSocket (0x24a6ce8), parent's thread is ServiceSlots (0xea66488), current thread is QThread (0x2418a78) See also qRegisterMetaType(). 它的作用是将自定义的数据类型转换为Qt元对象系统中的类型，使得这些类型可以在不同线程之间进行信号槽的传递。. (Parent is QTcpSocket (0x24a6ce8), parent's thread is ServiceSlots. Using the macro directly turned out to be impossible. Registers the type name typeName for the type T. [override virtual noexcept] QQmlEngine:: ~QQmlEngine Destroys the QQmlEngine. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. ui). It associates a type name to a type so that it can be created and destructed dynamically at. #include <QObject> #include <QVariant> class Record : public QPair<qreal, qreal> {. Also, to use type T with the QObject::property () API,. I pass the MyClass pointer to the streaming operator and only stream things like QString, QPointF, etc. ) QObject::connect: Cannot queue arguments of. Readers will master both the C++ language and Qt libraries,. Instead, the enum should be registered as soon as the shared library is loaded. Type names can be registered with QMetaType by using either qRegisterMetaType () or registerType (). Call qRegisterMetaType<std::string> (); in the initialization of your code. Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. qRegisterMetaType you'll need if creating objects by class name dynamically, and it seems for queued connections, generally you won't. 如果要使用单个全局类来访问QML或从QML访问. button. Consider for example the following (hypothetical) code:The Listmodel should be modified by an AMQP-Eventqueue. That's created by this macro. 5. QAbstractSocket is the base class for QTcpSocket and QUdpSocket and contains all common functionality of these two classes. you don't call qRegisterMetaType multiple times, even with the same type and the same string. No, everything is in separated folders. {. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. As G. Even if it works now, it may fail with new Qt versions. QObject::connect: Cannot queue arguments of type 'SomeUserDefinedType' (Make sure 'SomeUserDefinedType' is registered using qRegisterMetaType(). launch" and then "roslaunch velo2cam_calibration laser_pattern. Detailed Description. There is a name index for fast lookup of the meta type id. These are the top rated real world C++ (Cpp) examples of qmlRegisterUncreatableMetaObject extracted. 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. Sets the factory to use for creating QNetworkAccessManager (s). @pyqtSlot, in turn, is a decorator which converts simple python method to Qt slot. Pyqt is nothing more than a "translation" from the Qt library (written in C++) to Python, and as this library functions within an object-oriented paradigm, Python code must also be written that way, with widgets represented. )@. I also have to implement for cv::Mat type data. To use the enum, you have to explicitly include the full. If _message is a string then the slot must have the argument: foo_text = "Foo" self. The SplitBehavior type is a typedef for QFlags <SplitBehaviorFlags>. Now it works fine when pressButtonInsert is triggered but returns this. . In the case of this enum, which essentially aliases the int type, it will simply mean that the. . 1 Answer. So if you put the register in constructor, you have to instance your class once and then make the connection. And this should be used for each exe/dll instance. Here how connect looks in main constructor: connect (w1, SIGNAL (sentInt (int)), this, SLOT (receiveInt (int))); Such simple app works, but if i change parameters from int to "signed long long" it will give message during runtime and signal won't be emitted: QObject::connect: Cannot queue arguments of type 'signed long long'. On this windows 7 machine, I have installed Python 3. 0. qmlRegisterUncreatableType# qmlRegisterUncreatableType (pytype: type, uri: str, versionMajor. If such a connection is made, and a signal triggered, the runtime warning will be shown: QObject::connect: Cannot queue arguments of type 'T' (Make sure 'T' is registered using qRegisterMetaType (). The point is, if we provided answer for any very unlikely situation, especially if caused by user mistake or file corruption we could know anything about, StackOverflow would become a galaxy of unnecessary questions (infinitely more than it is right now) with a billion of unlikely answers. I also have to implement for cv::Mat type data. If I register QVector I can't dissconnect this signal and the signal is emited. ) I register my class like this after it's declaration: Q_DECLARE_METATYPE(taservices::ProcessHandle*); I also added this static method which I call from constructor: QObject::connect: Cannot queue arguments of type 'QProcess::ProcessError' (Make sure 'QProcess::ProcessError' is registered using qRegisterMetaType(). . clicked. 15. If I save the image to disk in the DB thread just after emitting the signal, it is good. tabs. There is no use case for implementing qRegisterMetaType, because PyObject. ). Any QQmlContext's created on this engine will be invalidated, but not destroyed (unless they are parented to the. Sep 21, 2015 at 14:17. class QtGuiApplication : public QWidget { Q_OBJECT public: explicit QtGuiApplication (QWidget *parent = 0. If it gets destroyed elsewhere (passing by ref doesn't bump the ref count), your callback/lambda may crash. You need to (or at least this is how it works for me) create a signal that will be emitted every iteration of the for loop in your thread. The following code allocates and destructs an instance of MyClass: 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. ) changing rowCount in the main thread or commenting out setRowCount call in change_row_count() makes those errors. Edit: from @altaf comments : To clarify, the root of the problem was cause by qRegisterMetaType<Data> ("Data"); in my main. QT 信号和槽传递自定义对象问题. Make sure 'QTextCursor' is registered using qRegisterMetaType(). Obviously then you would not do registerComparator (). The syntax gets especially interesting when specializing a template function of a. However, you should verify its validity after construction. It was also no big issue to call qRegisterMetaType () automatically. The same plugin may be loaded multiple times during the application's lifetime. (Make sure 'QTextBlock' is registered using qRegisterMetaType (). You have to register your custom type for queued signals because by registering it, Qt can make a copy of it in its event loop (which certainly uses QVariant) and pass it as argument later (when the original passed value is long since out of. Custom types registered using qRegisterMetaType() that have operators for streaming to and from a QDataStream can be stored using QSettings. The following code: self. I'll take your word on that, because on my rig fixing the return type of area() and providing the empty template parameter list for the specialization leaves only get() failing to compile, and as near as I can tell it may be because of the order this was pasted into the question. There are two versions of each of these: one that accepts the SIGNAL () / SLOT () syntax and one that accepts the (recommended) function pointers. Replacing it with "%matplotlib qt5" (or deleting it entirely) worked for me. Returns the access specification of this method (private, protected, or public). After about 20 seconds of running LOAM, the laserOdometry module crashes with [laserOdometry-2] process has died [pid 6983, exit code -11, cmd /home/ab. launch" i got. flush ( self) This function writes as much as possible from the internal write buffer to the socket, without blocking. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. If you want both, then register both. QPainter::begin: Paint device returned engine == 0, type: 3 QPainter::setFont: Painter not active QPainter::setPen: Painter not active [ INFO] [1432901455. 12. It just allows you to queue types that. qRegisterMetaType<QSqlDatabase>("QSqlDatabase"); Just changing the signal to this form: void dbConnected(QSqlDatabase *db); And, in the slot side I'll use something like this: void onDBConnected(QSqlDatabase * const db); I'm concerned with the usage of db (as in the beginning I've made the reference const), so I make it const here. The Qt GUI module contains classes for 2D graphics, imaging, fonts, and advanced typography. This function was introduced in Qt 5. Nov 30, 2012 at 8:31. This site will remain online in read-only mode during the transition and into the foreseeable future. Detailed Description. data = new double [channel_count]; std::copy (input_data, input_data+channel_count, data); in the dtor of this class the data ptr is deleted. There's no compile time error, but when I run. Usually, I do this type of updates using signals and slots, but the run function is not PyQt specific. – 2、注册方法：在当前类的顶部包含：#include <QMetaType>，构造函数中加入代码：qRegisterMetaType<MyClass>("Myclass")； 3、Myclass的引用类型需单独注册：qRegisterMetaType<MyClass>("Myclass&")； A. Since Qt 5. . ) It's a bit tricky thing. runBtn. It will return correct type value like 1230 for type in function SomethingElse of class C. d. You can use Qt's typedef for unsigned char: quint8 and you don't need to register it. When I want to run hector_geotiff to print map in a existed map , rosrun hector_geotiff geotiff_saver , Some thing happens. Normally it's done directly in the main () How: Just call qRegisterMetaType<QMap<QString,long long unsigned int> > (); It doesn't matter how you refer to MyClass in the template argument. This requires the exchanged data to be of a type that is recognizable by the engine. tab) self.