Exposing Q_INVOKABLE in Q_GADGET to QML. You can rate examples to help us improve the quality of examples. QML中使用全局变量. I tried to create a simple Class in C++ containing a StringList and an index. I check the code status and emit a signal to a qml component to call a slot. . rootContext(). The views used to access data models are described in the Presenting Data with Views overview. view->rootContext ()->setContextProperty ("test", "some random text"); setProperty (name, val) works if object has the property name defined as Q_PROPERTY. These are the top rated real world C++ (Cpp) examples of QQuickWidget extracted from open source projects. ts t1_sp. setContextProperty("myModel", modelFromCpp) to pass a model from Cpp to QML and replace myModel with it. quit() } }The above examples use QQmlContext::setContextProperty() to set model values directly in QML components. QtCore import QUrl app = QApplication( []) view = QQuickView() url = QUrl("view. Relative paths will be resolved against QQmlEngine::baseUrl(),. Hi, I'm back with Qt after a long pause. setContextProperty provides our model to QML. quickWindow (); QVERIFY (window); QSignalSpy beforeRenderingSpy (window. Qt 5. All properties added explicitly by QQmlContext::setContextProperty() take precedence over the context object's properties. When user log in, the qml login form switch to qml index compon. jcdelve last edited by jcdelve . Reply Quote 0. 1 Answer. getGlobalConfig () print (GlobalConfig,. My goal is to do a simple login form, with api call. In your Qml: import QtQuick. to create the translation files. We'll end off with a simple benchmark showing the difference in startup times between. For example. You can rate examples to help us improve the quality of examples. It must be of type Track*. @PouryaTorabi said in QML multithread client with c++ integration:. This function was introduced in Qt 6. transPath ) ; engine . Here You need create this class object before use setContextProperty (). However, this means my C++ code has to deal with the UI code. All the properties of the context object are available by name in the context, as though they were all individually added through calls to QDeclarativeContext. Item { // This Item is to provide needed properties for functionality in the original app that was elided out in this example. Unlike QQuickView, QQmlApplicationEngine does not automatically create a root. You can rate examples to help us. You must pass a name under which the object will be accessible and the pointer to a QML object. Ensure that the URL provided is full and correct, in particular, use QUrl::fromLocalFile() when loading a file from the local filesystem. When you set it afterwards, this binding is reevaluated and that's why the list is eventually correctly displayed in your case. 0 to provide data to a ListModel in my QML dynamically from C++. The following example shows a Qt model being bound to a context and then accessed from a QML file. I have a page where I need to keep the top and the bottom margin. Hi all , i am using Q_Property and setContextProperty to capture changes in C++ class variable into Qml file. If the Python object is exposed to QML using setContextProperty, you can call any slot of the object explicitly from QML, as shown in qmltopy1. Q&A for work. 8, with QtQuick 1. Now you can use QQmlContext::setContextProperty to expose the the string list to QML : QQmlContext *context = engine. Qt Quick の翻訳の仕組み. 在笔者刚接触编程的时候老师就说过全局变量有害，就跟 goto 一样；但在实际工程中它其实很有用，使用得当的话反而能让整个软件. problem statement : i dont want to call "setContextProperty" for every object created. here is my code. qm files used by the application at runtime. 0のドキュメント にデータを提供する ListModel 私のQMLではC ++から動的に。Detailed Description. In Qml it uses with GridLayout and Repeater. One fix is to name the context property _text - then there's no problem. If you need more than one instance of your class, use qmlRegisterType<> and instantiate your objects in QML. I have another QObject which gets initialized in each QQuickWidget whoose signals I want to capture in the Qml as shown. Note: Since all expressions evaluated in QML are evaluated in a particular context, if the context is modified, all bindings in that context will be re-evaluated. For example:QList <MyObject *>でsetContextProperty（）を呼び出す - c ++、qml、qt5、qtquick2 私は自分のコードをで見つけた例に基づいています Qt Quick 2. DenisKormalev last edited by . Below is the minimal code for my approach. rootContext()); You are constructing a new context, which is not the same as the one your engine is running on. QString QQmlEngine:: offlineStorageDatabaseFilePath (const QString & databaseName) const. database) and I want to use these items in a QML GUI. I am creating a QML Application with a C++ backend. Source File: mpl_qtquick1. qml from a qresource you should not use QUrl::fromLocalFile () since the qresource is not a local file but virtual. 这一行代码定义了暴露给QML访问的接口，这里我们提供的对象是一个 QString，READ 接口是一个名为 data 的函数， WRITE 接口是一个名为 setData 的函数，NOTIFY 接口用于通知的绑定，只有设置了 NOTIFY 接口，QML 才能自动与 C++ 中的属性同步。. . So the more general question would be how do I properly make a C++ object visible in QML context. Due to the tight integration of the QML engine with the Qt meta-object system, any functionality that is appropriately exposed by a QObject -derived class or a Q_GADGET type is accessible from QML code. This is just like we always initialize class fields before usage. Even in the Qt official documentation on best practices, section Pushing References to QML, they use a setContextProperty. i. 1. Contexts form a hierarchy. 注意：所有使用 QQmlContext::setContextProperty() 显式添加的属性都将优先于上下文对象属性。 上下文层次结构. This enables C++ data and functions to be accessible directly from QML. close(); Qt. Python QQmlApplicationEngine. rootContext ()->setContextProperty(" someProperty ", QVariant()); Context properties always takes in a QVariant , which means that whenever you access the property it is re-evaluated because in between each access the property may be changed as setContextProperty() can be used at any moment in time. These are the top rated real world Python examples of PyQt5QtQml. 1. I have a QList<Country*> and I want to display it on my QML ListView. This tutorial provides a quick walk-through of a python application that loads, and interacts with a QML file. 0. QtQuick import QQuickView from PySide2. getStuff(stuffId) // Creating the new context, based on the global one QQmlContext *context = new QQmlContext(this->rootContext()); // Exposing the object I need to show. rootContext()->setContextProperty("funzioni", this);"? instead of "this". 多个上下文能够组成一个层次结构。这个层次结构的根是 QML 引擎的"根上下文"。I have this main. happens when you assign Track* to the stream property of PianoRoll. exec_() If you are already familiar. However, I have a situation where it would be useful to attach the Property after defining the class, and this isn't working as I would expect. qml")); view. Thus, context. rootContext extracted from open source projects. This is accomplished using the matplotlib rcParams system. I think there is a problem with CppClass declaration in your main. In fact, for debugging purposes, I have changed the. import QtQuick 2. Controls 2. [slot] void QQmlComponent:: loadUrl (const QUrl &url) Load the QQmlComponent from the provided url. setContextProperty() doesn't create the class instance inside the qml file. must support value change notifications and automatic binding updates. py file displays a Tab Widget. A python list will automatically be converted to a QStringList for qml. 对象实例的生命期需要我们自己管理，所以对象需要在堆上创建，否则离开了当前作用域就被析构了Detailed Description. Qtが一般に普及しない理由は、単に学習曲線が急だからです。歴史的に見ても、ソフトウェアエンジニアは忍耐力がないことで知られており、おそらくユーザーもそうであるため、プラットフォーム全体を学ぶために投資する時間はほとんどないのです。For Qt 6. I Instantiated two Objects of this Class and exposed them via "setContextProperty" This should be used in QML to initialize a ListView and to be in sync with it. To simplify binding and maintaining larger data sets, a. The type you put into Q_PROPERTY is the type visible to external users, and for. Q&A for work. cpp => CppClass cppClass; and your CppClass constructor is CppClass::CppClass (QObejct *parent); which means that you are missing the constructor parameter. Now i want to be able to view and edit this data from 2 seperate representations in QML, so that if the values in View1 are changed, the data itself (C++) is changed and the value displayed by View2 as well (because it gets notified when the C++ data changes). class ModelWrapper(QObject): def __init__(self): super(). Each QDeclarativeContext contains a set of properties, distinct from its QObject properties, that allow data to be explicitly bound to a context by name. I do know that accessing a. Application Delegate Set on the Root ContextIn our example, we do: # lupdate main. So for new code use qmlRegisterSingletonInstance () and avoid QQmlContext::setContextProperty (). 1 Answer Sorted by: 1 Your problem has 2 errors: You have to set the context property before loading the . Using the same syntax. I have an app with QMdiArea as the central widget and each QMdiSubWindow has a QQuickWidget which displays a qml item. Depending on what type of Camera is connected, the C++ backend exposes objects to QML using setContextProperty(). setCursor(Qt. If you. Changes to the property's values are detected through the property's notify signal. I also use image providers. 12, Linux + Windows. Window 2. qml since otherwise at the time of loading those objects will not be defined. 13 import QtQuick. To assign function to button I use setContextProperty. cw = CurrentView() engine. Extending to stacked data models. Thank you @raven-worx for pointing me in. ts files and produce the . cw = CurrentView() engine. At run-time I want to change or replace the meshes and/or textures. These are the top rated real world Python examples of PyQt5QtQml. cpp. comThese are the top rated real world C++ (Cpp) examples of QQmlApplicationEngine::addImageProvider extracted from open source projects. This would allow the model classes to be created. It is possible to create a QtQuick view directly from C++ and to expose to QML C++ defined properties. I based my code on the examples found in the documentation of Qt Quick 2. setContextProperty in root context for this object: root->setContextProperty("somename", object) open QML item/dialog that uses this context property; delete object then item/dialog closes; I cannot find anything in the docs for setContextProperty that says this is okay or not okay. I had this code: testclass1. I. QML is a declarative language that lets you design UIs faster than a traditional language, such as C++. Method/Function: addImageProvider. XLANGs. Modified 2 years, 7 months ago. Ah well, after some pondering on the findings, I resorted to the following way: Always set context before loading QML, even if it's just a setContextProperty("juice", nullptr). Here You need create this class object. The context properties can be defined and updated by calling setContextProperty () . See also loadUrl(). setContextProperty accepts const* because it accepts a QVariant, which can be created with bool. These are the top rated real world C++ (Cpp) examples of QmlDocument::setContextProperty extracted from open source projects. It should already have had Q_OBJECT too since it is a QObject, in order to register it with the Qt MOC system. setModel(model) selectionModel = table. The following example shows a Qt model. The solution is to create a QObject and export it to QML using setContextProperty () so that it is accessible from all the QMLs that are loaded through the QQmlApplicationEngine. show (qsTr ("You've pressed a button!")); This works alright, but I'd like to know why some particular changes give me errors:Design Pattern: Singletons. qml->documentContext()->setContextProperty("_app", this); Therefore, to make sure that the app delegate is visible from all contexts, you will need to use the root document context instead of main. An alternative to this is to register the C++ model class as a QML type (either directly from a C++ entry-point, or within the initialization function of a QML C++ plugin, as shown below). However, if you really don't want to go to C++,. Here's a prototype of my code: MyClass. These are the top rated real world Python examples of PyQt5QtQml. Then the TreeView finally displays something: the first value (in the example "Cat") - which is logical because I have got only one row for now. Contacto: carlosduarte. 将C++实现的类在QML中调用的. This is just like we always initialize class fields before usage. The context properties are defined and updated by calling QQmlContext::setContextProperty (). QML provides several types of data models among the built-in set of QML elements. In my QTCreator for QML code auto-completion for integrated C++ methods doesn't work. cpp: #include <QQmlContext> bool isMacOS; #ifdef Q_OS_MACOS isMacOS =. You can try to expose your root context property "thing" before loading your main component. setContextProperty() requires the name of a class object. py. setContextProperty ("my_model", model) Make the model an attribute of the context:Then instantiate your class object and expose it in main. What you need to do is delaying the instantiation to some point at which B is complete. py. Thus. BackEnd { id: backend } and it is different from the one created in C++: BackEnd m_can; There are several possible solutions: 1. Connect and share knowledge within a single location that is structured and easy to search. This example uses the setContextProperty function to create a new context property called "myData" and bind it to a QString value "HelloWorld". 0. show() app. ui. 1 Answer. First, you define a class in Python, inheriting from QObject: 1 class Console(QtCore. 関数 setContextProperty() を使用すると、C++ の QObject を QML プロパティにバインドすることができます。 第一引数には QML プロパティ名を指定します。 C++ オブジェクトを QML プロパティにバインドしているだけです。I have a C++ plugin system, where a QQmlComponent is created and a qml file is loaded when the user requests a new plugin instance. RangerQT 5 Oct 2022, 21:26. I am working with PySide2 and QML. If doesn't work, you need an extra step, check Generic Highlighter in Edit Prefrences -> Text Editor and Download or Reload. You must establish the contexproperties before loading the . Thus this is the only way to go about it: Call doc:QSharedPointer :: data () to get a pointer to the referenced class; Make sure the QML engine doesn't assume ownership: doc:QDeclarativeEngine :: setObjectOwnership (P). engine. Hello, I do an HTTP request and get a response from it . Detailed Description. QQmlContext::setContextProperty seems to be one of these cases. In my benchmarks the qmlRegisterSingletonType one is faster than setContextProperty. Lets start off with the most popular example, almost every tutorial you find uses it. You can read in the Qt documentation about QQmlContext:. Learn more about the Microsoft. var trans = new Trans ( ) ; trans . QQuickView view; view. class API : public QObject { Q_OBJECT Q_PROPERTY (User *user READ getUser WRITE setUser NOTIFY userChanged) public: Q_INVOKABLE inline User *getUser (). Alternatively, you can instantiate your own objects using QQmlComponent and place them in a manually setup QQuickWindow. But I don't want to have to remember this naming convention (both to remember to use it, and to remember what it. 2 Answers. QML expects that the QObjects registered through qmlRegisterType only have a constructor that receives a QObject as parent (qmlRegisterType does not build the object, only makes it available in QML): class Foo (QtCore. engine. The name can be provided via QMetaEnum and QVariant's toString (), neither of which are available in QML. QQmlApplicationEngine. Viewed 318 times 1 The main. Qt Code: Switch view. This approach is word-for-word out of Qt's documentation, and yet. You can rate examples to help us. Scene Graph Item Qt Quick 2 makes use of dedicated scene graph for its rendering. Using setContextProperty means you need to stick to a naming convention to avoid shadowing of the names. The above examples use QQmlContext::setContextProperty() to set model values directly in QML components. The use of positioner items to arrange items from a model is covered in Using. Using a scene graph for graphics rather than the traditional imperative painting systems (QPainter or similar), means the scene to be rendered can be retained between frames and the complete set of primitives to render is known before rendering starts. When using setContextProperty, the property is available to every component loaded by the QML engine. Here You need create this class object before use setContextProperty(). e. setContextProperty sets the object as value of a property in the very root node of your QML tree, so it basically looks like this: property var myContextProperty: MySetContextObject {} ApplicationWindow { Item { Button { }. One is to set the singleton instance as a context property with QQmlContext::setContextProperty () and the other one is to register a singleton type. Solution: The solution is to extend the scope of the object of the MyModel () class and for this there are several solutions: Pass a parent to MyModel: def boot_model (context): model = MyModel () model. setContextProperty("current_view", cw) It works like a charm, when I press Ctrl+W the model instantly switches. These files can now be opened in Linguist and translated there. This tutorial is also available for PySide2 , PySide6 and PyQt5. 8 to Qt 5. append ("From QML"); } Share. Upon execution of this code and after clicking, the application is crashing (see the comment in main. In my tcpHandler class I create an. ts files to read the . First create a new method on the MainWindow named add. 7. Some people set up CLion for Qt development. Core namespace. <property>. Let’s go on by creating a new C++ class. . In the meantime, if there is a Mac OS user who is on 5. Thanks. 1 Answer. QVariant::fromValue(m_core. Values must be simple constants; either strings (quoted and optionally within a call to QT_TR_NOOP), boolean values (true, false), numbers, or enumeration values (such as AlignText. argv) View = QQuickView () Context = View. The MainWindow class has a Mapwidget attribute. So calling setContextProperty before you call engine. Yes, all communication between C++ and QML is based on. loadFolder ( Config . My favorite explanation of the problem solved by the singleton design pattern: The application needs one, and only one, instance of an object. Also, I tried qmlRegysterType and I got "module is not installed" but I prefer to use this method with setContextProperty. I'm porting my software from Qt 4. QObject): 2 @QtCore. Can you try registering the objects using setContextProperty & check it works ? I tried again, the behaviour of the program is exactly the same. Contexts allow data to be exposed to the QML components instantiated by the QML engine. ( Warning: there will be memory leaks around class Window, but it should helpt to understand C++ and Qml binding) Here is your PropertyList. 就是说 类实列化一次，QML中可以直接使用这个类。. I thought that doing view->rootContext()->setContextProperty("counter", &c); would be enough but it seems that I'm missing something. I do an HTTP request and get a response from it . Now, I am editing the cells on the QML side and after I. Detailed Description. setParent (context) context. @fcarney said in setContextProperty not setting context properly: QQmlContext *context = new QQmlContext(engine. I've tried overriding the headerData function in QAbstractTableModel with my custom headers. Object::someFunction () is callable from QML as it uses Q_INVOKABLE. QAbstractItemModel をサブクラス化することで、モデルを定義することができる。これは、他のアプローチでは対応できない. I'm following the s. rootContext () function. Example #1. If you want to connect a signal then the syntax is on<signal> where. This is a convenience subclass of QQuickWindow which will automatically load and display a QML scene when given the URL of the main source file. The classes in the Qt Declarative module allow QML components to be loaded and manipulated from C++, and through Qt's meta-object system, QML and C++ objects can easily communicate through Qt signals and slots. following task: I have to create custom meshes and textures in C++ (the data come from a. XMessage. @kengineer said in C++ Enums in QML with setContextProperty: MyCustomQMLClass myclass; view. compatibility with Settings to make the value changes persist across application runs. Setting a context object is both faster and easier than manually adding and maintaining context. Next we'll make it possible to add items from within the application. The factory must be set before executing the engine. This step is necessary since the only other way of keeping the engine from assuming ownership would be to give the object a. any wy that i capture c++ object in qml. Signal from c++ to QML with setContextProperty. . setContextProperty 是将对象暴露给 QML，一般默认就是全局单例。 就维护性上来说，setContextProperty 应该要用 qmlRegisterSingletonType 来代替，但是不排除一个应用有多个 QmlEngine 实例，使用 qmlRegisterSingletonType 是引擎单例，（当然取决于你如何实现的）。这个要作区分。To copy to clipboard, switch view to plain text mode. QML can easily be extended with functionality defined in C++ code. Unlike QQuickView, QQmlApplicationEngine does not automatically create a root window. The context properties are defined and updated by calling QQmlContext::setContextProperty (). In the code below the C++ program creates a QtQuick view and exposes to QML the height and width of the view as properties. To call the QML classes in C++, you need to set the objectName property. 2 Qt Quick - How to use setContextProperties() 0 Unable to hold QQmlContext in std::shared_ptr. QQmlContext *context = new QQmlContext (engine. 2. m_context->setContextProperty("resultModel",QVariant::fromValue(m_resultList)); where resultModel is the name of my model in QML and m_resultList is where the results of the search are being stored, to display the list in the ListView. 1 Answer. Alternatively, I wonder if it's possible to expose a class through setContextProperty and have one of its class variables be a model and then change the value of the said class variable. If I do the same with a method of the other object, TypeError: Property 'savePreset' of. If you've got for example an model in QML named myModel you could use rootContext(). @dheerendra Right now, I'm just doing it in the init() method that I call in main. pressed signal at the end of the __init__ block. This is enough for our basic QML setup. The context properties are defined and updated by. This is our callback which will take care of adding the current text from the input as a new todo. Text { id: txt1; text: qsTr("Back"); } Qt Quick の組み込み機器での採用が増えるにつれ、「アプリケーショ. All properties added explicitly by QDeclarativeContext::setContextProperty() take precedence over the context object's properties. Hi and welcome to devnet, Did you check that l_pitsCQObjectBase is not null before setting it as context property ?. Export a Backend object through setContextProperty () The advantage over the other proposed solution is that now the backend object can be accessed from any QML like console. rootObjects extracted from open source projects. Nov 13, 2022 at 17:59. setContextProperty qmlRegisterType qRegisterMetaType等区别. Each QQmlContext contains a set of properties, distinct from its QObject properties, that allow data to be explicitly bound to a context by name. I did a clean rebuild of my entire project tree, which showed a number of syntax errors that were not identified before. main. setSource, otherwise at the moment the qml file is read the property ggg is indeed not defined. 5 ApplicationWindow {. auto myclass = new MyCustomQMLClass;seaborn. Also an instance of StringListManager should be set as the context data for your qml file: QQmlEngine engine; StringListManager manager; engine. The Context Hierarchy. This might be problematic with 3rd-party code or coworkers. T 1 Reply Last reply 14 Feb 2020, 05:39 1. lgeyer last edited by . So I've@dheerendra this is the declaration of the list: QList<DataSourceObject*> m_DataSourceList; And this the header of the DataSourceObject: #ifndef DATASOURCEOBJECT_H #define DATASOURCEOBJECT_H #include <QObject> class DataSourceObject : QObject { Q_OBJECT Q_PROPERTY(int id READ id WRITE setid. setContextProperty extracted from open source projects. setContextProperty: Use setContextProperty, When you want to use a single global class to access to or from QML. 2 and has SDK 10. Mar 26, 2018 at 7:33 "However using setProperty from C++ means, your C++ part needs a profound knowledge of your QML. C++ (Cpp) QmlDocument::setContextProperty - 30 examples found. QtCore import Property, QCoreApplication, QObject, Qt, QUrl, Signal from PySide6. Different types of cameras can connect to my C++ backend. set_context(context=None, font_scale=1, rc=None) #. model = TableModel(8, 4, app) table = QTableView(0) table. setSource(url) view. Learn more about TeamssetContextProperty 是 QQmlContext 类的成员，用于在qml上下文上设置name属性的值。您可以在Qt文档中阅读关于 QQmlContext ： 每个QQmlContext都包含一组不同于其 QObject属性，允许将数据显式绑定到 按名称指定上下文。上下文属性由定义和更新 正在调用QQmlContext. However, the line I mentioned above breaks on trying to envoke setContextProperty(), with this error: member access into incomplete type 'QQmlContext'. 15. 5. QML files loaded after that point will see it. - for future seekers – Muhammad Khuzaima Umair. @MoaMoaK You could say this is a permanent bug by design in C++; it does implicit type conversion from any pointer (const or not) to bool. qmlRegisterType<Country> ("mytest. def main(): app = QGuiApplication(sys. This means custom C++ objects can also be injected using this. Add a comment | 3 Answers Sorted by: Reset to default 4 If someone else is looking for an answer, I made a small app that connects to a database of actors with with a subclass of QAbstractListModel and displays the. @PouryaTorabi said in QML multithread client with c++ integration:. Contexts form a hierarchy. The most powerful way to expose data to views is by creating a C++ model. QtWidgets import QApplication from PySide2. The QQmlContext class defines a. This is code from main. log (). TL; DR; No, it is not possible. `rootContext` is a property of this class used to access the root QML context of the application engine. Again, it can't be. QQmlApplicationEngine. h: class MyObject: public QObject { Q_OBJECT Q_PROPERTY (QString name READ name WRITE setName NOTIFY nameChanged) public: MyObject (QObject *parent=0); ~MyObject ();. rootcontext()->setcontextproperty("",w1) to send my class instantiation w1 to qml file, which satisfy my requirement. The context properties are defined and updated by calling setContextProperty () . It will ensure that your "thing" property will be available once the component instance is created and its bindings are evaluated for the first time. 一方、setContextPropertyはQQmlContextクラスのメンバで、qmlコンテキストのnameプロパティの値を設定するために使用されます。 QMLのQ_propertyとは何ですか? プロパティを公開する Q_PROPERTY()マクロを使用すると、QObject 派生クラスに対してプロパティを指定することが. rootContext - 19 examples found. 15, it might be worth testing root setContextProperty to see if it errors out for you, that way I could report a bug if it's a real problem. We should register the class by calling qmlRegisterType (): // Register C++ class as a QML module, 1 & 0 are the major and minor version of the QML module qmlRegisterType<QmlCppBridge> ("QmlCppBridge", 1, 0, "QmlCppBridge"); In QML, use following code to call it: import QmlCppBridge 1. ease of use / low verbosity. Is there a suggested or simple approach to the backend logic. When using setContextProperty, the property is available to every component loaded by the QML. The `QQmlApplicationEngine` class in the Qt framework is used to provide a QML-based user interface for C++ applications. The third stack trace shows the place. Then instantiate your class object and expose it in main. Worker* workerObj = new Worker(); engine->rootContext()->setContextProperty("qmlWorker", workerObj ); This will only work for Signal/Slot-Connection, aswell as Q_INVOKABLE. 全局变量，顾名思义就是在程序中到处都能使用的变量。. List of all members, including inherited members; Detailed Description. Below I gave a small example how i am using it. 1@hotmail. To update the model, just call engine. I've fully edit my question since I've made some progress, and the first one was unclear. It's not all but only important parts. So what would be the most efficient way to implement a set of global properties in QML, considering the following criteria: lookup performance. engine ()->rootContext ()->setContextProperty ("myQmlClassInstance", &myclass) you can use context as well. Child contexts inherit the context properties of their parents; if a child context sets a context. The following example shows a Qt model being bound to a context and then accessed from a QML file. Create applications with QtQuick. qml") view. doStuffFromQmlSlot (); Qt. 0 Rectangle { width: 360 height: 360 Text { text: qsTr ("Hello World") anchors. rootContext ()->setContextProperty ("manager", &manager); Now you can access the the functions of the manager class from QML side : onClicked: { manager. The context properties are defined and updated by calling. There are multiple ways to expose a C++ class to QML, each with their own benefits and quirks. Finally, when the application is finished, you need to run lrelease on the . QList<QObject*>. It works only in this case int qmlTypeId = qRegisterMetaType<namespace::MenuModel*> ("MenuModel*"); You return a pointer in the property, so Qt Meta Object system needs to know about it. If you dont use Q_PROPERTY, you can instance the worker itself in QML You can also make your worker-instance a context-property by. cpp I add the following lines with the intention to make the types known to QML/javascript.