Qt signals slots return value

Even though signals in Qt can indeed return values, this is rarely used, if ever. Namely because it doesn't make a lot of sense. What you probably want to do is not return but emit the image with a signal, this way you can connect it to a function that will receive the image and do something with it.

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 & Slots — Qt for Python An overview of Qt’s signals and slots inter-object communication mechanism. Signals and slots are used for communication between objects. The signals and slots mechanism is a central feature of Qt and probably the part that differs most from the features provided by other frameworks. c++ - How to send data through signal and slot? - Stack

QMetaObject Class | Qt Core 5.12.2

This method provides a way of connecting GObject signals to C++ slots, in a ... Unlike Qt, in GObject some signals are able to return values back to the sender. A Deeper Look at Signals and Slots Dec 19, 2005 ... implementation in Qt, which has used signals and slots since its initial ..... function can return values collected from multiple slots no return. [Quick PyQt5 : 1] Signal and Slot Example in PyQt5 – Manash's blog Sep 4, 2016 ... Signal-Slot is one of the fundamental topics of Qt one should have a firm ... Changing the position of the slider will change the value of the ...

There is nothing about passing return value from slot to signal - and it doesn't make sense (well, it may make sense in your sample, but what if I connect multiply slots to a single signal - what slot will return value, what if slots are executed asynchronously - should we wait for return value, etc.).

An overview of Qt’s signals and slots inter-object communication mechanism. Signals and slots are used for communication between objects. The signals and slots mechanism is a central feature of Qt and probably the part that differs most from the features provided by other frameworks. Signals & Slots | Qt 4.8 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. Qt: Return value of signal works, why is the official doc

I'm doing this by connecting up signals and slots for the methods. However now I need to Stack Overflow new. ... QT return value from a signal? ... And finally at one point in my application I want to query the SQLite db for some info and receive a return value: (still inside MainWindow)

Qt: Signals & Slots - PUC-Rio 2 Slots can be used for receiving signals, but they are also normal member functions. Just as an object does not know if anything receives its signals, a slot does not know if it has any signals connected to it. Qt in Education The Qt object model and the signal slot ...

Qt Signals - это синтаксический сахаризованный интерфейс для шаблона ... foreach slot in connectedSlotsForSignal(signal): value = invoke slot with ... call() { QString text; emit Get(&text); return text; } signals: void Get(QString *value); void ...

int value() const { return m_value; } public slotsОбратите внимание на то, что другие библиотеки, определяющие переменные с именем signals или slots, могут вызвать предупреждения и ошибки при компиляции с приложением, созданным на основе Qt. Signals and Slots Signals and slots are used for communication between objects. The signal/ slot mechanism is a central feature of Qt and probably the part that differs most from other toolkits. In GUI programming we often want a change in one widget to be notified to another widget. Qt - Сигналы и слоты — Кафедра ИУ5 МГТУ им.… Сигналы и слоты - это то, как в Qt взаимодействуют между собой объекты разных классов. Связь между объектами устанавливается следующим образом: у одного объекта должен быть сигнал, а у второго - слот.

Best Practices in Qt Quick/QML - Part III - SlideShare Jul 23, 2015 ... Qt Quick/QML brings designers and developers together to create and collaborate. ... Slots and Signals are the interface in QML • QML Items connect or bind to ... returns correct value • Could be called anytime • NOTIFY signal ... VTK: vtkEventQtSlotConnect Class Reference ... Class Reference. Manage connections between VTK events and Qt slots. ... Return 1 if this class is the same type of (or a subclass of) the named class. More. std.signals - D Programming Language