📘QT QML Concept 2023

QML is a declarative language for designing user interfaces. It uses an XML-like syntax to declare UI components.

• QML code has to be executed by a QML engine. The engine parses the QML, creates the UI objects, and executes the JS code.

• QML uses a hierarchical component system. UI components are declared as child components of parent components.

• Qt attached properties allow using C++ properties and methods in QML. They start with "Qt." prefix.

• QML uses JavaScript for logic. JS functions can be defined and called from QML.

• Properties in QML are used to set values for UI components. Properties can be bound to each other to realize two-way data binding.

• Signals in QML are used to notify about events. Signals can be connected to JS functions to react to events.

• Models in QML provide data to data-bound UI elements like ListViews and Combos. Models are defined in C++ and exposed to QML.

• For animation and transitions, QML uses the Qt Animation framework. You define animations and transitions between states in QML.

• QML UI components are defined in separate QML files. They can then be imported and used as custom components in other QML files.

• C++ classes can be exposed to QML using the Q_OBJECT and Q_INVOKABLE macros to make methods callable from QML.

Hope this high-level overview helps clarify some of the main concepts in Qt QML! Let me know if you have any other questions.