qobject

I have some data stored in instances of a C++ class (Data.cpp). 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). Here is what I got so far: Data.h class Data : public QObject { Q_OBJECT Q_PROPERTY(QString name READ name WRITE setName NOTIFY nameChanged) public: Data(std::string name); QString name(); void setName(const QString &n); signals: void nameChanged(); private: std::string

I am writing some Qt class which is derived from QObject , it looks like: class A : public QObject { Q_OBJECT public: A() : QObject() {} ..... } but in several places I saw, that the QObject derived classes all have a parent, like: class A : public QObject { Q_OBJECT public: A(QObject* parent = 0) : QObject(parent) {} ..... } So the question is: do I need a parent or not? What is the difference if I have one, if I have a default one (0) or I don't have at all? Kunal As such you don't need a parent. But setting parent has some advantage in terms of garbage collection. If you set a parent then

I have a custom class I created, say MyClass. Now how to add a reference to MyClass's reference as second parameter in the combo box below: this->ui->comboBox->addItem("item-1", ); Purpose is to when item changed even is fired, i want to get that specific class instance of MyClass and process accordingly. First you need to use Q_DECLARE_METATYPE(MyClass*) , so that the type can be used in QVariant . Then you can add the item like this: this->ui->comboBox->addItem("item-1", QVariant::fromValue(myClass)); And get it back: this->ui->combobox->itemData(x).value<MyClass*>(); Above answer syntax is

I have thought a lot and read lot of articles before asking this question here. None of the articles gave me a proper answer. http://mayaposch.wordpress.com/2011/11/01/how-to-really-truly-use-qthreads-the-full-explanation/ QThread* thread = new QThread; Worker* worker = new Worker(); worker->moveToThread(thread); connect(worker, SIGNAL(error(QString)), this, SLOT(errorString(QString))); connect(thread, SIGNAL(started()), worker, SLOT(process())); connect(worker, SIGNAL(finished()), thread, SLOT(quit())); connect(worker, SIGNAL(finished()), worker, SLOT(deleteLater())); connect(thread, SIGNAL

I subclassed QGraphicsScene and added method mouseMoveEvent to handle mouse move event. I created a ruler on top of GraphicsView and have the ruler tracking mouse movement. In the QGraphicsScene::mousemoveEvent I calls mouseMoveEvent of the ruler widget explcitely. The purpose is to have the ruler knows that the current mouse position. Now it seems that QGraphicsScene::mousemoveEvent is not called when I move the mouse. However, I can get it to work if I press the left mouse button and move it while holding the button. This is not what I'd like to see; I'd like this method is called whenever I