Can qt slot retourwaarde

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Qt was created with the idea of removing this boilerplate code and providing a nice and clean syntax, and the signal and slots mechanism is the answer. Signals and slots Instead of having observable objects and observers, and registering them, Qt provides two high level concepts: signals and slots .

In multithreaded applications, you can use QTimer in any thread that has an event loop. To start an event loop from a non-GUI thread, use QThread::exec(). Qt uses the timer's thread affinity to determine which thread will emit the timeout() signal. Qt was created with the idea of removing this boilerplate code and providing a nice and clean syntax, and the signal and slots mechanism is the answer. Signals and slots Instead of having observable objects and observers, and registering them, Qt provides two high level concepts: signals and slots . Qt comes with its own set of tools to ease cross-platform development, which can otherwise be cumbersome due to different set of development tools. Qt Creator is a cross-platform IDE for C++ and QML. Qt Designer's GUI layout/design functionality is integrated into the IDE, although Qt Designer can still be started as a standalone tool. Yet in the generated moc code I see that if a slot returns a value this value is used for something. Any idea what does it do? Here's an example of could you post a minimal example? I REALLY suspect the answer to your question will be "emit a signal". Reply Quote 0. Qt's signals and slots mechanism ensures that if you connect a signal to a slot, the slot will be Signals and slots can take any number of arguments of any type . Dec 20, 2009 With current speed, it really does not matter an additional function call for a button press. I searched the Qt sources and could not find a non-void

This allows us to provide an implementation of timerEvent() that we can use to update the widget. TetrixBoard Class Implementation. In the constructor, we customize the frame style of the widget, ensure that keyboard input will be received by the widget by using Qt::StrongFocus for the focus policy, and initialize the game state:

Qt Designer's Signals and Slots Editing Mode In Qt Designer 's signals and slots editing mode, you can connect objects in a form together using Qt's signals and slots mechanism. Both widgets and layouts can be connected via an intuitive connection interface, using the menu of compatible signals and slots provided by Qt Designer. Signals and slots are loosely coupled: A class which emits a signal neither knows nor cares which slots receive the signal. Qt's signals and slots mechanism ensures that if you connect a signal to a slot, the slot will be called with the signal's parameters at the right time. Signals and slots can take any number of arguments of any type.

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Looking through the Qt source it seems that when a slot is called from QMetaObject::invokeMethod the return type can be specified and the return value obtained. (Have a look at invokeMethod in the Qt help) I could not find many examples of this actually being used in the Qt source. One I found was. bool QAbstractItemDelegate::helpEvent

Qt's signals and slots mechanism ensures that if you connect a signal to a slot, the slot will be Signals and slots can take any number of arguments of any type .

Qt will indeed call directly the function pointer of the slot, and will not need moc introspection anymore. (It still needs it for the signal) (It still needs it for the signal) But what we can also do is connecting to any function or functor: Mar 07, 2020 · PySide (deprecated), PySide2 (Active) is basically the same as PyQt, but with a different license and developed by the QT company, to makes things even less clear it also goes by the name QT for

The connection mechanism uses a vector indexed by signals. But all the slots waste space in the vector and there are usually more slots than signals in an object. So from Qt 4.6, a new internal signal index which only includes the signal index is used. While developing with Qt, you only need to know about the absolute method index.

Jan 19, 2009 · It's mostly the same. The main difference is that QThreads are better integrated with Qt (asynchrnous signals/slots, event loop, etc.). Also, you can't use Qt from a Python thread (you can't for instance post event to the main thread through QApplication.postEvent): you need a QThread for that to work. A general rule of thumb might be to use