What is QEvent?
Basic Qt Data Types
| Qt Type | QML Basic Type |
|---|---|
| bool | bool |
| unsigned int, int | int |
| double | double |
| float, qreal | real |
What is eventFilter in Qt?
Event Filters
The QObject::installEventFilter() function enables this by setting up an event filter, causing a nominated filter object to receive the events for a target object in its QObject::eventFilter() function.
What is event loop in Qt?
An event loop in a thread makes it possible for the thread to use certain non-GUI Qt classes that require the presence of an event loop (such as QTimer, QTcpSocket, and QProcess). It also makes it possible to connect signals from any threads to slots of a specific thread.
Is Qt multithreaded?
Qt offers many classes and functions for working with threads. Below are four different approaches that Qt programmers can use to implement multithreaded applications.
What is qRegisterMetaType in Qt?
Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered.
How many threads does Qt use?
Generally, Qt will never create threads to do things in the background, Except: The Network code, which can create a thread to do DNS lookups. The QThreadPool will create N + 1 threads when you initialise it (or use it for the first time), where N is the number of CPU cores.
What is thread in Qt?
A QThread object manages one thread of control within the program. QThreads begin executing in run(). By default, run() starts the event loop by calling exec() and runs a Qt event loop inside the thread. You can use worker objects by moving them to the thread using QObject::moveToThread().
What is QMetaObject?
The QMetaObject class contains meta-information about Qt objects. The Qt Meta-Object System in Qt is responsible for the signals and slots inter-object communication mechanism, runtime type information, and the Qt property system.
What is QMetaType?
The QMetaType class manages named types in the meta-object system.
Is Qt MultiThreaded?
How do you use Qt threads?
To use it, prepare a QObject subclass with all your desired functionality in it. Then create a new QThread instance, push the QObject onto it using moveToThread(QThread*) of the QObject instance and call start() on the QThread instance. That’s all.
What is Q_property in QML?
A property can be specified for any QObject-derived class using the Q_PROPERTY() macro. A property is a class data member with an associated read function and optional write function. All properties of a QObject-derived class are accessible from QML.
What is QVariant in Qt?
Because C++ forbids unions from including types that have non-default constructors or destructors, most interesting Qt classes cannot be used in unions. Without QVariant, this would be a problem for QObject::property() and for database work, etc. A QVariant object holds a single value of a single typeId() at a time.
What is QObject in QML?
objectName : string. This property holds the QObject::objectName for this specific object instance. This allows a C++ application to locate an item within a QML component using the QObject::findChild() method.